Vitamin D — Health Professional Fact Sheet Disclaimer Introduction Vitamin D is a fat-soluble vitamin that is naturally present in very few foods, added to others, and available as a dietary supplement. It is also produced endogenously when ultraviolet rays from sunlight strike the skin and trigger vitamin D synthesis. Vitamin D obtained from sun exposure, food, and supplements is biologically inert and must undergo two hydroxylations in the body for activation. The first occurs in the liver and converts vitamin D to 25-hydroxyvitamin D [25(OH)D], also known as calcidiol. The second occurs primarily in the kidney and forms the physiologically active 1,25-dihydroxyvitamin D [1,25(OH)2D], also known as calcitriol [ 1 ]. Vitamin D promotes calcium absorption in the gut and maintains adequate serum calcium and phosphate concentrations to enable normal mineralization of bone and to prevent hypocalcemic tetany. It is also needed for bone growth and bone remodeling by osteoblasts and osteoclasts [ 1 , 2 ]. Without sufficient vitamin D, bones can become thin, brittle, or misshapen.

Vitamin D sufficiency prevents rickets in children and osteomalacia in adults [ 1 ]. Together with calcium, vitamin D also helps protect older adults from osteoporosis. Vitamin D has other roles in the body, including modulation of cell growth, neuromuscular and immune function, and reduction of inflammation [ 1 , 3 , 4 ]. Many genes encoding proteins that regulate cell proliferation, differentiation, and apoptosis are modulated in part by vitamin D [ 1 ]. Many cells have vitamin D receptors, and some convert 25(OH)D to 1,25(OH)2D. Serum concentration of 25(OH)D is the best indicator of vitamin D status. It reflects vitamin D produced cutaneously and that obtained from food and supplements [ 1 ] and has a fairly long circulating half-life of 15 days [ 5 ]. 25(OH)D functions as a biomarker of exposure, but it is not clear to what extent 25(OH)D levels also serve as a biomarker of effect (i.e., relating to health status or outcomes) [ 1 ].

Serum 25(OH)D levels do not indicate the amount of vitamin D stored in body tissues. In contrast to 25(OH)D, circulating 1,25(OH)2D is generally not a good indicator of vitamin D status because it has a short half-life of 15 hours and serum concentrations are closely regulated by parathyroid hormone, calcium, and phosphate [ 5 ]. Levels of 1,25(OH)2D do not typically decrease until vitamin D deficiency is severe [ 2 , 6 ]. There is considerable discussion of the serum concentrations of 25(OH)D associated with deficiency (e.g., rickets), adequacy for bone health, and optimal overall health, and cut points have not been developed by a scientific consensus process. Based on its review of data of vitamin D needs, a committee of the Institute of Medicine concluded that persons are at risk of vitamin D deficiency at serum 25(OH)D concentrations <30 nmol/L (<12 ng/mL). Some are potentially at risk for inadequacy at levels ranging from 30–50 nmol/L (12–20 ng/mL).

Practically all people are sufficient at levels ≥50 nmol/L (≥20 ng/mL); the committee stated that 50 nmol/L is the serum 25(OH)D level that covers the needs of 97.5% of the population. Serum concentrations >125 nmol/L (>50 ng/mL) are associated with potential adverse effects [ 1 ] (Table 1). Table 1: Serum 25-Hydroxyvitamin D [25(OH)D] Concentrations and Health* [ 1 ] nmol/L** Emerging evidence links potential adverse effects to such high levels, particularly >150 nmol/L (>60 ng/mL) * Serum concentrations of 25(OH)D are reported in both nanomoles per liter (nmol/L) and nanograms per milliliter (ng/mL). ** 1 nmol/L = 0.4 ng/mL An additional complication in assessing vitamin D status is in the actual measurement of serum 25(OH)D concentrations.

Considerable variability exists among the various assays available (the two most common methods being antibody based and liquid chromatography based) and among laboratories that conduct the analyses [ 1 , 7 , 8 ]. This means that compared with the actual concentration of 25(OH)D in a sample of blood serum, a falsely low or falsely high value may be obtained depending on the assay or laboratory used [ 9 ]. A standard reference material for 25(OH)D became available in July 2009 that permits standardization of values across laboratories and may improve method-related variability [ 1 , 10 ]. Reference Intakes Intake reference values for vitamin D and other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board (FNB) at the Institute of Medicine of The National Academies (formerly National Academy of Sciences) [ 1 ]. DRI is the general term for a set of reference values used to plan and assess nutrient intakes of healthy people. These values, which vary by age and gender, include: Recommended Dietary Allowance (RDA): average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy people.

Adequate Intake (AI): established when evidence is insufficient to develop an RDA and is set at a level assumed to ensure nutritional adequacy. Tolerable Upper Intake Level (UL): maximum daily intake unlikely to cause adverse health effects [ 1 ]. The FNB established an RDA for vitamin D representing a daily intake that is sufficient to maintain bone health and normal calcium metabolism in healthy people. RDAs for vitamin D are listed in both International Units (IUs) and micrograms (mcg); the biological activity of 40 IU is equal to 1 mcg (Table 2). Even though sunlight may be a major source of vitamin D for some, the vitamin D RDAs are set on the basis of minimal sun exposure [ 1 ]. Table 2: Recommended Dietary Allowances (RDAs) for Vitamin D [ 1 ] Age Sources of Vitamin D Food Very few foods in nature contain vitamin D. The flesh of fatty fish (such as salmon, tuna, and mackerel) and fish liver oils are among the best sources [ 1 , 11 ]. Small amounts of vitamin D are found in beef liver, cheese, and egg yolks.

Vitamin D in these foods is primarily in the form of vitamin D3 and its metabolite 25(OH)D3 [ 12 ]. Some mushrooms provide vitamin D2 in variable amounts [ 13 , 14 ]. Mushrooms with enhanced levels of vitamin D2 from being exposed to ultraviolet light under controlled conditions are also available. Fortified foods provide most of the vitamin D in the American diet [ 1 , 14 ]. For example, almost all of the U.S. milk supply is voluntarily fortified with 100 IU/cup [ 1 ]. (In Canada, milk is fortified by law with 35–40 IU/100 mL, as is margarine at ≥530 IU/100 g.) In the 1930s, a milk fortification program was implemented in the United States to combat rickets, then a major public health problem [ 1 ]. Other dairy products made from milk, such as cheese and ice cream, are generally not fortified. Ready-to-eat breakfast cereals often contain added vitamin D, as do some brands of orange juice, yogurt, margarine and other food products.

Both the United States and Canada mandate the fortification of infant formula with vitamin D: 40–100 IU/100 kcal in the United States and 40–80 IU/100 kcal in Canada [ 1 ]. Several food sources of vitamin D are listed in Table 3. Table 3: Selected Food Sources of Vitamin D [ 11 ] Food 2 * IUs = International Units. ** DV = Daily Value. DVs were developed by the U.S. Food and Drug Administration to help consumers compare the nutrient contents among products within the context of a total daily diet. The DV for vitamin D is currently set at 400 IU for adults and children age 4 and older. Food labels, however, are not required to list vitamin D content unless a food has been fortified with this nutrient. Foods providing 20% or more of the DV are considered to be high sources of a nutrient, but foods providing lower percentages of the DV also contribute to a healthful diet. The U.S.

Department of Agriculture's (USDA's) Nutrient Database Web site lists the nutrient content of many foods and provides a comprehensive list of foods containing vitamin D arranged by nutrient content and by food name . A growing number of foods are being analyzed for vitamin D content. Simpler and faster methods to measure vitamin D in foods are needed, as are food standard reference materials with certified values for vitamin D to ensure accurate measurements [ 15 ]. Animal-based foods can provide some vitamin D in the form of 25(OH)D, which appears to be approximately five times more potent than the parent vitamin in raising serum 25(OH)D concentrations [ 16 ]. One study finds that taking into account the serum 25(OH)D content of beef, pork, chicken, turkey, and eggs can increase the estimated levels of vitamin D in the food from two to 18 times, depending upon the food [ 16 ]. At the present time, the USDA’s Nutrient Database does not include 25(OH)D when reporting the vitamin D content of foods. Actual vitamin D intakes in the U.S. population may be underestimated for this reason.

Sun exposure Most people meet at least some of their vitamin D needs through exposure to sunlight [ 1 , 2 ]. Ultraviolet (UV) B radiation with a wavelength of 290–320 nanometers penetrates uncovered skin and converts cutaneous 7-dehydrocholesterol to previtamin D3, which in turn becomes vitamin D3 [ 1 ]. Season, time of day, length of day, cloud cover, smog, skin melanin content, and sunscreen are among the factors that affect UV radiation exposure and vitamin D synthesis [ 1 ]. Perhaps surprisingly, geographic latitude does not consistently predict average serum 25(OH)D levels in a population. Ample opportunities exist to form vitamin D (and store it in the liver and fat) from exposure to sunlight during the spring, summer, and fall months even in the far north latitudes [ 1 ]. Complete cloud cover reduces UV energy by 50%; shade (including that produced by severe pollution) reduces it by 60% [ 17 ]. UVB radiation does not penetrate glass, so exposure to sunshine indoors through a window does not produce vitamin D [ 18 ].

Sunscreens with a sun protection factor (SPF) of 8 or more appear to block vitamin D-producing UV rays, although in practice people generally do not apply sufficient amounts, cover all sun-exposed skin, or reapply sunscreen regularly [ 1 , 19 ]. Therefore, skin likely synthesizes some vitamin D even when it is protected by sunscreen as typically applied. The factors that affect UV radiation exposure and research to date on the amount of sun exposure needed to maintain adequate vitamin D levels make it difficult to provide general guidelines. It has been suggested by some vitamin D researchers, for example, that approximately 5–30 minutes of sun exposure between 10 AM and 3 PM at least twice a week to the face, arms, legs, or back without sunscreen usually lead to sufficient vitamin D synthesis and that the moderate use of commercial tanning beds that emit 2%–6% UVB radiation is also effective [ 6 , 20 ]. Individuals with limited sun exposure need to include good sources of vitamin D in their diet or take a supplement to achieve recommended levels of intake.

Despite the importance of the sun for vitamin D synthesis, it is prudent to limit exposure of skin to sunlight [ 19 ] and UV radiation from tanning beds [ 21 ]. UV radiation is a carcinogen responsible for most of the estimated 1.5 million skin cancers and the 8,000 deaths due to metastatic melanoma that occur annually in the United States [ 19 ]. Lifetime cumulative UV damage to skin is also largely responsible for some age-associated dryness and other cosmetic changes. The American Academy of Dermatology advises that photoprotective measures be taken, including the use of sunscreen, whenever one is exposed to the sun [ 22 ]. Assessment of vitamin D requirements cannot address the level of sun exposure because of these public health concerns about skin cancer, and there are no studies to determine whether UVB-induced synthesis of vitamin D can occur without increased risk of skin cancer [ 1 ]. Dietary supplements In supplements and fortified foods, vitamin D is available in two forms, D2 (ergocalciferol) and D3 (cholecalciferol) that differ chemically only in their side-chain structure.

Vitamin D2 is manufactured by the UV irradiation of ergosterol in yeast, and vitamin D3 is manufactured by the irradiation of 7-dehydrocholesterol from lanolin and the chemical conversion of cholesterol [ 6 ]. The two forms have traditionally been regarded as equivalent based on their ability to cure rickets and, indeed, most steps involved in the metabolism and actions of vitamin D2 and vitamin D3 are identical. Both forms (as well as vitamin D in foods and from cutaneous synthesis) effectively raise serum 25(OH)D levels [ 2 ]. Firm conclusions about any different effects of these two forms of vitamin D cannot be drawn. However, it appears that at nutritional doses vitamins D2 and D3 are equivalent, but at high doses vitamin D2 is less potent. The American Academy of Pediatrics (AAP) recommends that exclusively and partially breastfed infants receive supplements of 400 IU/day of vitamin D shortly after birth and continue to receive these supplements until they are weaned and consume ≥1,000 mL/day of vitamin D-fortified formula or whole milk [ 23 ].

Similarly, all non-breastfed infants ingesting <1,000 mL/day of vitamin D-fortified formula or milk should receive a vitamin D supplement of 400 IU/day [ 23 ]. AAP also recommends that older children and adolescents who do not obtain 400 IU/day through vitamin D-fortified milk and foods should take a 400 IU vitamin D supplement daily. However, this latter recommendation (issued November 2008) needs to be reevaluated in light of the Food and Nutrition Board's vitamin D RDA of 600 IU/day for children and adolescents (issued November 2010 and which previously was an AI of 200 IU/day). Vitamin D Intakes and Status The National Health and Nutrition Examination Survey (NHANES), 2005–2006, estimated vitamin D intakes from both food and dietary supplements [ 4 , 24 ]. Average intake levels for males from foods alone ranged from 204 to 288 IU/day depending on life stage group; for females the range was 144 to 276 IU/day.

When use of dietary supplements was considered, these mean values were substantially increased (37% of the U.S. population used a dietary supplement containing vitamin D.) The most marked increase was among older women. For women aged 51–70 years, mean intake of vitamin D from foods alone was 156 IU/day, but 404 IU/day with supplements. For women >70 years, the corresponding figures were 180 IU/day to 400 IU/day [ 1 ]. Comparing vitamin D intake estimates from foods and dietary supplements to serum 25(OH)D concentrations is problematic. One reason is that comparisons can only be made on group means rather than on data linked to individuals. Another is the fact that sun exposure affects vitamin D status; serum 25(OH)D levels are generally higher than would be predicted on the basis of vitamin D intakes alone [ 1 ]. The NHANES 2005–2006 survey found mean 25(OH)D levels exceeding 56 nmol/L (22.4 ng/mL) for all age-gender groups in the U.S. population.

(The highest mean was 71.4 nmol/L [28.6 ng/mL] for girls aged 1–3 years, and the lowest mean was 56.5 nmol/L [22.6 ng/mL] for women aged 71 and older. Generally, younger people had higher levels than older people, and males had slightly higher levels than females.) 25(OH)D levels of approximately 50 nmol/L (20 ng/mL) are consistent with an intake of vitamin D from foods and dietary supplements equivalent to the RDA [ 1 ]. Over the past 20 years, mean serum 25(OH)D concentrations in the United States have slightly declined among males but not females. This decline is likely due to simultaneous increases in body weight, reduced milk intake, and greater use of sun protection when outside [ 25 ]. Vitamin D Deficiency Nutrient deficiencies are usually the result of dietary inadequacy, impaired absorption and use, increased requirement, or increased excretion.

A vitamin D deficiency can occur when usual intake is lower than recommended levels over time, exposure to sunlight is limited, the kidneys cannot convert 25(OH)D to its active form, or absorption of vitamin D from the digestive tract is inadequate. Vitamin D-deficient diets are associated with milk allergy, lactose intolerance, ovo-vegetarianism, and veganism [ 1 ]. Rickets and osteomalacia are the classical vitamin D deficiency diseases. In children, vitamin D deficiency causes rickets, a disease characterized by a failure of bone tissue to properly mineralize, resulting in soft bones and skeletal deformities [ 17 ]. Rickets was first described in the mid-17th century by British researchers [ 17 , 26 ]. In the late 19th and early 20th centuries, German physicians noted that consuming 1–3 teaspoons/day of cod liver oil could reverse rickets [ 26 ]. The fortification of milk with vitamin D beginning in the 1930s has made rickets a rare disease in the United States, although it is still reported periodically, particularly among African American infants and children [ 3 , 17 , 22 ].

Prolonged exclusive breastfeeding without the AAP-recommended vitamin D supplementation is a significant cause of rickets, particularly in dark-skinned infants breastfed by mothers who are not vitamin D replete [ 27 ]. Additional causes of rickets include extensive use of sunscreens and placement of children in daycare programs, where they often have less outdoor activity and sun exposure [ 17 , 26 ]. Rickets is also more prevalent among immigrants from Asia, Africa, and the Middle East, possibly because of genetic differences in vitamin D metabolism and behavioral differences that lead to less sun exposure. In adults, vitamin D deficiency can lead to osteomalacia, resulting in weak bones [ 1 , 5 ]. Symptoms of bone pain and muscle weakness can indicate inadequate vitamin D levels, but such symptoms can be subtle and go undetected in the initial stages. Groups at Risk of Vitamin D Inadequacy Obtaining sufficient vitamin D from natural food sources alone is difficult. For many people, consuming vitamin D-fortified foods and, arguably, being exposed to some sunlight are essential for maintaining a healthy vitamin D status. In some groups, dietary supplements might be required to meet the daily need for vitamin D.

Breastfed infants Vitamin D requirements cannot ordinarily be met by human milk alone [ 1 , 28 ], which provides <25 IU/L to 78 IU/L [ 23 ]. (The vitamin D content of human milk is related to the mother's vitamin D status, so mothers who supplement with high doses of vitamin D may have correspondingly high levels of this nutrient in their milk [ 23 ].) A review of reports of nutritional rickets found that a majority of cases occurred among young, breastfed African Americans [ 29 ]. A survey of Canadian pediatricians found the incidence of rickets in their patients to be 2.9 per 100,000; almost all those with rickets had been breast fed [ 30 ]. While the sun is a potential source of vitamin D, the AAP advises keeping infants out of direct sunlight and having them wear protective clothing and sunscreen [ 31 ]. As noted earlier, the AAP recommends that exclusively and partially breastfed infants be supplemented with 400 IU of vitamin D per day [ 23 ], the RDA for this nutrient during infancy.

Older adults Older adults are at increased risk of developing vitamin D insufficiency in part because, as they age, skin cannot synthesize vitamin D as efficiently, they are likely to spend more time indoors, and they may have inadequate intakes of the vitamin [ 1 ]. As many as half of older adults in the United States with hip fractures could have serum 25(OH)D levels <30 nmol/L (<12 ng/mL) [ 2 ]. People with limited sun exposure Homebound individuals, women who wear long robes and head coverings for religious reasons, and people with occupations that limit sun exposure are unlikely to obtain adequate vitamin D from sunlight [ 32 , 33 ]. Because the extent and frequency of use of sunscreen are unknown, the significance of the role that sunscreen may play in reducing vitamin D synthesis is unclear [ 1 ]. Ingesting RDA levels of vitamin D from foods and/or supplements will provide these individuals with adequate amounts of this nutrient. People with dark skin Greater amounts of the pigment melanin in the epidermal layer result in darker skin and reduce the skin's ability to produce vitamin D from sunlight [ 1 ].

Various reports consistently show lower serum 25(OH)D levels in persons identified as black compared with those identified as white. It is not clear that lower levels of 25(OH)D for persons with dark skin have significant health consequences. Those of African American ancestry, for example, have reduced rates of fracture and osteoporosis compared with Caucasians (see section below on osteoporosis). Ingesting RDA levels of vitamin D from foods and/or supplements will provide these individuals with adequate amounts of this nutrient. People with inflammatory bowel disease and other conditions causing fat malabsorption Because vitamin D is a fat-soluble vitamin, its absorption depends on the gut's ability to absorb dietary fat. Individuals who have a reduced ability to absorb dietary fat might require vitamin D supplementation [ 34 ]. Fat malabsorption is associated with a variety of medical conditions, including some forms of liver disease, cystic fibrosis, celiac disease, and Crohn's disease, as well as ulcerative colitis when the terminal ileum is inflamed [ 1 , 3 , 34 ]. In addition, people with some of these conditions might have lower intakes of certain foods, such as dairy products fortified with vitamin D.

People who are obese or who have undergone gastric bypass surgery A body mass index ≥30 is associated with lower serum 25(OH)D levels compared with non-obese individuals; people who are obese may need larger than usual intakes of vitamin D to achieve 25(OH)D levels comparable to those of normal weight [ 1 ]. Obesity does not affect skin's capacity to synthesize vitamin D, but greater amounts of subcutaneous fat sequester more of the vitamin and alter its release into the circulation. Obese individuals who have undergone gastric bypass surgery may become vitamin D deficient over time without a sufficient intake of this nutrient from food or supplements, since part of the upper small intestine where vitamin D is absorbed is bypassed and vitamin D mobilized into the serum from fat stores may not compensate over time [ 35 , 36 ]. Vitamin D and Health Optimal serum concentrations of 25(OH)D for bone and general health have not been established; they are likely to vary at each stage of life, depending on the physiological measures selected [ 1 , 2 , 6 ].

Also, as stated earlier, while serum 25(OH)D functions as a biomarker of exposure to vitamin D (from sun, food, and dietary supplements), the extent to which such levels serve as a biomarker of effect (i.e., health outcomes) is not clearly established [ 1 ]. Furthermore, while serum 25(OH)D levels increase in response to increased vitamin D intake, the relationship is non-linear for reasons that are not entirely clear [ 1 ]. The increase varies, for example, by baseline serum levels and duration of supplementation. Increasing serum 25(OH)D to >50 nmol/L requires more vitamin D than increasing levels from a baseline <50 nmol/L. There is a steeper rise in serum 25(OH)D when the dose of vitamin D is <1,000 IU/day; a lower, more flattened response is seen at higher daily doses. When the dose is ≥1,000 IU/day, the rise in serum 25(OH)D is approximately 1 nmol/L for each 40 IU of intake.

In studies with a dose ≤600 IU/day, the rise is serum 25(OH)D was approximately 2.3 nmol/L for each 40 IU of vitamin D consumed [ 1 ]. In 2011, The Endocrine Society issued clinical practice guidelines for vitamin D, stating that the desirable serum concentration of 25(OH)D is >75 nmol/L (>30 ng/ml) to maximize the effect of this vitamin on calcium, bone, and muscle metabolism [ 37 ]. It also reported that to consistently raise serum levels of 25(OH)D above 75 nmol/L (30 ng/ml), at least 1,500-2,000 IU/day of supplemental vitamin D might be required in adults, and at least 1,000 IU/day in children and adolescents. However, the FNB committee that established DRIs for vitamin D extensively reviewed a long list of potential health relationships on which recommendations for vitamin D intake might be based [ 1 ].

These health relationships included resistance to chronic diseases (such as cancer and cardiovascular diseases), physiological parameters (such as immune response or levels of parathyroid hormone), and functional measures (such as skeletal health and physical performance and falls). With the exception of measures related to bone health, the health relationships examined were either not supported by adequate evidence to establish cause and effect, or the conflicting nature of the available evidence could not be used to link health benefits to particular levels of intake of vitamin D or serum measures of 25(OH)D with any level of confidence. This overall conclusion was confirmed by a more recent report on vitamin D and calcium from the Agency for Healthcare Research and Quality, which reviewed data from nearly 250 new studies published between 2009 and 2013 [ 38 ]. The report concluded that it is still not possible to specify a relationship between vitamin D and health outcomes other than bone health. Osteoporosis More than 40 million adults in the United States have or are at risk of developing osteoporosis, a disease characterized by low bone mass and structural deterioration of bone tissue that increases bone fragility and significantly increases the risk of bone fractures [ 39 ].

Osteoporosis is most often associated with inadequate calcium intakes, but insufficient vitamin D contributes to osteoporosis by reducing calcium absorption [ 40 ]. Although rickets and osteomalacia are extreme examples of the effects of vitamin D deficiency, osteoporosis is an example of a long-term effect of calcium and vitamin D insufficiency. Adequate storage levels of vitamin D maintain bone strength and might help prevent osteoporosis in older adults, non-ambulatory individuals who have difficulty exercising, postmenopausal women, and individuals on chronic steroid therapy [ 41 ]. Normal bone is constantly being remodeled. During menopause, the balance between these processes changes, resulting in more bone being resorbed than rebuilt. Hormone therapy with estrogen and progesterone might be able to delay the onset of osteoporosis. Several medical groups and professional societies support the use of HRT as an option for women who are at increased risk of osteoporosis or fractures [ 42 , 43 , 44 ]. Such women should discuss this matter with their health care providers. Most supplementation trials of the effects of vitamin D on bone health also include calcium, so it is difficult to isolate the effects of each nutrient.

Among postmenopausal women and older men, supplements of both vitamin D and calcium result in small increases in bone mineral density throughout the skeleton. They also help to reduce fractures in institutionalized older populations, although the benefit is inconsistent in community-dwelling individuals [ 1 , 2 , 45 ]. Vitamin D supplementation alone appears to have no effect on risk reduction for fractures nor does it appear to reduce falls among the elderly [ 1 , 2 , 45 ]; one widely-cited meta-analysis suggesting a protective benefit of supplemental vitamin D against falls [ 46 ] has been severely critiqued [ 1 ]. However, a large study of women aged ≥69 years followed for an average of 4.5 years found both lower (<50 nmol/L [<20 ng/mL]) and higher(≥75 nmol/L [≥30 ng/mL]) 25(OH)D levels at baseline to be associated with a greater risk of frailty [ 47 ]. Women should consult their healthcare providers about their needs for vitamin D (and calcium) as part of an overall plan to prevent or treat osteoporosis.

Cancer Laboratory and animal evidence as well as epidemiologic data suggest that vitamin D status could affect cancer risk. Strong biological and mechanistic bases indicate that vitamin D plays a role in the prevention of colon, prostate, and breast cancers. Emerging epidemiologic data suggest that vitamin D may have a protective effect against colon cancer, but the data are not as strong for a protective effect against prostate and breast cancer, and are variable for cancers at other sites [ 1 , 48 , 49 ]. Studies do not consistently show a protective or no effect, however. One study of Finnish smokers, for example, found that subjects in the highest quintile of baseline vitamin D status had a threefold higher risk of developing pancreatic cancer [ 50 ]. A recent review found an increased risk of pancreatic cancer associated with high levels of serum 25(OH)D (≥100 nmol/L or ≥40 ng/mL) [ 51 ]. Vitamin D emerged as a protective factor in a prospective, cross-sectional study of 3,121 adults aged ≥50 years (96% men) who underwent a colonoscopy. The study found that 10% had at least one advanced cancerous lesion.

Those with the highest vitamin D intakes (>645 IU/day) had a significantly lower risk of these lesions [ 52 ]. However, the Women's Health Initiative, in which 36,282 postmenopausal women of various races and ethnicities were randomly assigned to receive 400 IU vitamin D plus 1,000 mg calcium daily or a placebo, found no significant differences between the groups in the incidence of colorectal cancers over 7 years [ 53 ]. More recently, a clinical trial focused on bone health in 1,179 postmenopausal women residing in rural Nebraska found that subjects supplemented daily with calcium (1,400–1,500 mg) and vitamin D3 (1,100 IU) had a significantly lower incidence of cancer over 4 years compared with women taking a placebo [ 54 ]. The small number of cancers (50) precludes generalizing about a protective effect from either or both nutrients or for cancers at different sites.

This caution is supported by an analysis of 16,618 participants in NHANES III (1988–1994), in which total cancer mortality was found to be unrelated to baseline vitamin D status [ 55 ]. However, colorectal cancer mortality was inversely related to serum 25(OH)D concentrations. A large observational study with participants from 10 western European countries also found a strong inverse association between prediagnostic 25(OH)D concentrations and risk of colorectal cancer [ 56 ]. Further research is needed to determine whether vitamin D inadequacy in particular increases cancer risk, whether greater exposure to the nutrient is protective, and whether some individuals could be at increased risk of cancer because of vitamin D exposure [ 48 , 57 ]. Taken together, however, studies to date do not support a role for vitamin D, with or without calcium, in reducing the risk of cancer [ 1 ].

Other conditions A growing body of research suggests that vitamin D might play some role in the prevention and treatment of type 1 [ 58 ] and type 2 diabetes [ 59 ], hypertension [ 60 ], glucose intolerance [ 61 ], multiple sclerosis [ 62 ], and other medical conditions [ 63 , 64 ]. However, most evidence for these roles comes from in vitro, animal, and epidemiological studies, not the randomized clinical trials considered to be more definitive [ 1 ]. Until such trials are conducted, the implications of the available evidence for public health and patient care will be debated. One meta-analysis found use of vitamin D supplements to be associated with a statistically significant reduction in overall mortality from any cause [ 65 , 66 ], but a reanalysis of the data found no association [ 45 ]. A systematic review of these and other health outcomes related to vitamin D and calcium intakes, both alone and in combination, was published in August 2009 [ 45 ]. Health Risks from Excessive Vitamin D Vitamin D toxicity can cause non-specific symptoms such as anorexia, weight loss, polyuria, and heart arrhythmias.

More seriously, it can also raise blood levels of calcium which leads to vascular and tissue calcification, with subsequent damage to the heart, blood vessels, and kidneys [ 1 ]. The use of supplements of both calcium (1,000 mg/day) and vitamin D (400 IU) by postmenopausal women was associated with a 17% increase in the risk of kidney stones over 7 years in the Women's Health Initiative [ 67 ]. A serum 25(OH)D concentration consistently >500 nmol/L (>200 ng/mL) is considered to be potentially toxic [ 5 ]. Excessive sun exposure does not result in vitamin D toxicity because the sustained heat on the skin is thought to photodegrade previtamin D3 and vitamin D3 as it is formed [ 6 ]. In addition, thermal activation of previtamin D3 in the skin gives rise to various non-vitamin D forms that limit formation of vitamin D3 itself. Some vitamin D3 is also converted to nonactive forms [ 1 ]. Intakes of vitamin D from food that are high enough to cause toxicity are very unlikely. Toxicity is much more likely to occur from high intakes of dietary supplements containing vitamin D.

Long-term intakes above the UL increase the risk of adverse health effects [ 1 ] (Table 4). Most reports suggest a toxicity threshold for vitamin D of 10,000 to 40,000 IU/day and serum 25(OH)D levels of 500–600 nmol/L (200–240 ng/mL). While symptoms of toxicity are unlikely at daily intakes below 10,000 IU/day, the FNB pointed to emerging science from national survey data, observational studies, and clinical trials suggesting that even lower vitamin D intakes and serum 25(OH)D levels might have adverse health effects over time. The FNB concluded that serum 25(OH)D levels above approximately 125–150 nmol/L (50–60 ng/mL) should be avoided, as even lower serum levels (approximately 75–120 nmol/L or 30–48 ng/mL) are associated with increases in all-cause mortality, greater risk of cancer at some sites like the pancreas, greater risk of cardiovascular events, and more falls and fractures among the elderly.

The FNB committee cited research which found that vitamin D intakes of 5,000 IU/day achieved serum 25(OH)D concentrations between 100–150 nmol/L (40–60 ng/mL), but no greater. Applying an uncertainty factor of 20% to this intake value gave a UL of 4,000 IU which the FNB applied to children aged 9 and older, with corresponding lower amounts for younger children. Table 4: Tolerable Upper Intake Levels (ULs) for Vitamin D [ 1 ] Age (100 mcg) Interactions with Medications Vitamin D supplements have the potential to interact with several types of medications. A few examples are provided below. Individuals taking these medications on a regular basis should discuss vitamin D intakes with their healthcare providers. Steroids Corticosteroid medications such as prednisone, often prescribed to reduce inflammation, can reduce calcium absorption [ 68 , 69 , 70 ] and impair vitamin D metabolism. These effects can further contribute to the loss of bone and the development of osteoporosis associated with their long-term use [ 69 , 70 ].

Other medications Both the weight-loss drug orlistat (brand names Xenical® and alliTM) and the cholesterol-lowering drug cholestyramine (brand names Questran®, LoCholest®, and Prevalite®) can reduce the absorption of vitamin D and other fat-soluble vitamins [ 71 , 72 ]. Both phenobarbital and phenytoin (brand name Dilantin®), used to prevent and control epileptic seizures, increase the hepatic metabolism of vitamin D to inactive compounds and reduce calcium absorption [ 73 ]. Vitamin D and Healthful Diets The federal government's 2015-2020 Dietary Guidelines for Americans notes that "Nutritional needs should be met primarily from foods. ... Foods in nutrient-dense forms contain essential vitamins and minerals and also dietary fiber and other naturally occurring substances that may have positive health effects. In some cases, fortified foods and dietary supplements may be useful in providing one or more nutrients that otherwise may be consumed in less-than-recommended amounts." For more information about building a healthy diet, refer to the Dietary Guidelines for Americans and the U.S. Department of Agriculture's MyPlate .

The Dietary Guidelines for Americans describes a healthy eating pattern as one that: Includes a variety of vegetables, fruits, whole grains, fat-free or low-fat milk and milk products, and oils. Milk is fortified with vitamin D, as are many ready-to-eat cereals and some brands of yogurt and orange juice. Cheese naturally contains small amounts of vitamin D. Includes a variety of protein foods, including seafood, lean meats and poultry, eggs, legumes (beans and peas), nuts, seeds, and soy products. Fatty fish such as salmon, tuna, and mackerel are very good sources of vitamin D. Small amounts of vitamin D are also found in beef liver and egg yolks. Limits saturated and trans fats, added sugars, and sodium. Vitamin D is added to some margarines. Stays within your daily calorie needs. References Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: National Academy Press, 2010. Cranney C, Horsely T, O'Donnell S, Weiler H, Ooi D, Atkinson S, et al. Effectiveness and safety of vitamin D. Evidence Report/Technology Assessment No.

158 prepared by the University of Ottawa Evidence-based Practice Center under Contract No. 290-02.0021. AHRQ Publication No. 07-E013. Rockville, MD: Agency for Healthcare Research and Quality, 2007. [ PubMed abstract ] Holick MF. Vitamin D. In: Shils ME, Shike M, Ross AC, Caballero B, Cousins RJ, eds. Modern Nutrition in Health and Disease, 10th ed. Philadelphia: Lippincott Williams & Wilkins, 2006. Norman AW, Henry HH. Vitamin D. In: Bowman BA, Russell RM, eds. Present Knowledge in Nutrition, 9th ed. Washington DC: ILSI Press, 2006. Jones G. Pharmacokinetics of vitamin D toxicity. Am J Clin Nutr 2008;88:582S-6S. [ PubMed abstract ] Holick MF. Vitamin D deficiency. N Engl J Med 2007;357:266-81. [ PubMed abstract ] Carter GD.

25-hydroxyvitamin D assays: the quest for accuracy. Clin Chem 2009;55:1300-02. Hollis BW. Editorial: the determination of circulating 25-hydroxyvitamin D: no easy task. J. Clin Endocrinol Metab 2004;89:3149-3151. Binkley N, Krueger D, Cowgill CS, Plum L, Lake E, Hansen KE, et al. Assay variation confounds the diagnosis of hypovitaminosis D: a call for standardization. J Clin Endocrinol Metab 2004;89:3152-57.

[ PubMed abstract ] Vitamin D Sources - Foods High in Vitamin D - AlgaeCal Vitamin D Sources Food Sources of Vitamin D In the 1930s, a vitamin D deficiency disease called rickets was a major public health problem in the United States so a milk fortification program was implemented nearly eliminating this disorder.4,9 Currently, about 98% of the milk supply in the US is fortified with 400 International Units (IU) of vitamin D per quart. Although milk is fortified with vitamin D, dairy products made from milk, such as cheese and ice creams, are generally not fortified with vitamin D. There are only a few foods that are good sources of vitamin D,4 so vitamin D supplements are often recommended unless you are exposed to sunlight on your skin regularly. Suggested dietary sources of vitamin D are listed below. Table 1: Selected food sources of vitamin D10-12 Food 12 4 *DV = Daily Value. DVs are reference numbers developed by the Food and Drug Administration to help consumers determine if a food contains a lot or a little of a specific nutrient. The DV for vitamin D is 400 IU for adults.

Sun Exposure as a Vitamin D Source Exposing yourself to sunlight is the most important source of vitamin D because sunlight is far more likely to provide you with your vitamin D requirement than food is.13 UV rays from the sun trigger vitamin D production in your skin.13-14 Lights from your home are not strong enough to produce vitamin D. Season, geographic latitude, time of day, cloud cover, smog, and sunscreen affect UV ray exposure and vitamin D synthesis.14 For example, sunlight exposure from November through February in Boston is insufficient to produce significant vitamin D synthesis in the skin. Obviously any point of north of Boston is worse. Complete cloud cover halves the energy of UV rays, and shade reduces it by 60%. Industrial pollution also filters sun exposure and may contribute to the development of rickets if you have insufficient dietary intake of vitamin D.15 Sunscreens with a sun protection factor (SPF) of 8 or greater will block UV rays that produce vitamin D. An initial exposure to sunlight of 10 to15 minutes allows you adequate time for Vitamin D synthesis and should be followed by application of a sunscreen with an SPF of at least 15 to protect the skin.

Ten to fifteen minutes of sun exposure at least two times per week to the face, arms, hands, or back without sunscreen is usually sufficient to provide adequate vitamin D.14 If you have limited sun exposure it is very important that you include good sources of vitamin D in your diet or supplement with AlgaeCal® Plus. What is the Recommended Intake for Vitamin D? The RDA, developed by the Institute of Medicine of the National Academy of Sciences,4 recommends the average daily intake that is sufficient to meet the nutrient requirements of healthy individuals in each age and gender group. An Adequate Intake (AI) is set when there is insufficient scientific data available to establish a RDA. The Institute of Medicine determined there was insufficient scientific information to establish a RDA for vitamin D. Instead, the recommended intake is listed as an Adequate Intake (AI), which represents the daily vitamin D intake that should maintain bone health and normal calcium metabolism in healthy people.

Vitamin D AI for infants, children, and adults, are listed below in International Units.4 Daily Adequate Intake of Vitamin D Age 600 IU 600 IU According to the Institute of Medicine, food consumption data suggests intakes of vitamin D for both younger and older women are below current recommendations.4 The data suggests more than 50% of younger and older women are not consuming recommended amounts of vitamin D. Their data also shows African American women are particularly prone to consuming low amounts of vitamin D in their diet. What is the Best Form of Vitamin D Supplement? Houghton, in a 2006 article appearing in the American Journal of Clinical Nutrition18 points out that vitamin D2, the synthetic variety used for fortification of milk and foods, is inferior to the natural form, vitamin D3 for several reasons. He suggests D2 “should not be regarded as a nutrient suitable for supplementation or fortification.” Authors Goldberg, and Cantorna, show it is very important to take adequate calcium and magnesium along with vitamin D3 supplementation as the three balance each other. More Vitamin D May Be Better! Recent science is showing that levels above the Adequate Intake may provide better health.

For example, professor Robert Heaney has reported in April 2006 in the Journal of Nutrition his study showing an additional 2600 IU/day of oral vitamin D3 should be given to older women.15 Vieth reported in the American Journal of Clinical Nutrition a recommendation of 4000 IU per day for adults.16 He also showed that levels of 10,000 IU per day were normal from body exposure to the sun and the only published vitamin D toxicity was at levels exceeding 40,000 IU/day. The National Institutes of Health indicates Vitamin D may have benefit for some forms of Cancer, Osteoporosis, Alzheimers, Chron’s Disease and other maladies.17 It seems more studies are warranted on proper vitamin D levels. Given that vitamin D3 is safe at very high levels and may provide extraordinary benefits with no known risk, we recommend individuals get reasonable sun exposure, eat foods rich in vitamin D, and supplement with AlgaeCal Plus.

12 Ways to Get Your Daily Vitamin D - Health.com 12 Ways to Get Your Daily Vitamin D 12 Ways to Get Your Daily Vitamin D By Ella Quittner View all 1 of 14 Photo: Getty Images Getting more vitamin D Vitamin D is essential for bone health. Recent research suggests it may have other benefits, too, such as protecting against colds and fighting depression . The good news is that most people get enough vitamin D , according to the Institute of Medicine (IOM). However, if you don't spend enough time in the sun or if your body has trouble absorbing the vitamin, you may not get enough. Here are 12 ways to ensure adequate intake. View all 1 of 14 Photo: Getty Images Getting more vitamin D Vitamin D is essential for bone health. Recent research suggests it may have other benefits, too, such as protecting against colds and fighting depression . The good news is that most people get enough vitamin D , according to the Institute of Medicine (IOM). However, if you don't spend enough time in the sun or if your body has trouble absorbing the vitamin, you may not get enough. Here are 12 ways to ensure adequate intake.

View all 2 of 14 Photo: Corbis Sunlight Sunlight spurs the body to make vitamin D. But because of the skin-cancer risk, there isn't an official recommendation to catch some rays. However, a small amount of sun exposure without sunscreen can do the trick. "If you're going to get it from the sun, about 20 to 25 minutes of exposure is helpful," says Stephen Honig, MD, director of the Osteoporosis Center at the Hospital for Joint Diseases, in New York City. The sun is less likely to provide your daily needs at higher latitudes, in the winter, or if you're older or dark skinned (skin pigment blocks light and the process is less efficient with age). And FYI: Light through a window won't work. 2 of 14 View all 3 of 14 Photo: Corbis Fatty fish Fatty fish can be a good source of vitamin D. Common options include salmon, trout, mackerel, tuna, and eel.

A 3-ounce sockeye salmon fillet contains about 450 international units (IUs) of vitamin Da good portion of the 600 IUs that is the Institute of Medicine's recommended dietary allowance (800 IUs if you're over 70). And you get a bonusheart-healthy omega-3 fatty acids! 3 of 14 View all 4 of 14 Photo: Corbis Canned tuna fish Fresh fish aren't the only way to boost your vitamin D intake; you can get vitamin D from a can, too. Canned tuna fish and canned sardines both contain vitamin D, and are usually less expensive than fresh fish. Plus, a longer shelf life makes the canned products easy to stock up on and use at your leisure. Canned light tuna has the most vitamin Dabout 150 IUs per 4 ounceswhile canned albacore tuna has about 50 IUs per 4 ounces, and canned sardines have a little more than 40 IUs per two sardines.

4 of 14 View all 5 of 14 Photo: Corbis Certain mushrooms Just like humans, mushrooms have the capacity to produce vitamin D when exposed to ultraviolet light. Mushrooms, however, are usually grown in the dark and don't contain the vitamin. Specific brands, however, are grown in ultraviolet light to spur vitamin D production. Check to see if vitamin D–rich 'shrooms, like Dole's Portobello Mushrooms, are available at a store near you. They're perfect for vegetarians looking for plant-based foods that contain the vitamin. Dole's portobellos will give you 400 IUs of vitamin D per 3-ounce serving (about 1 cup of diced mushrooms). 5 of 14 View all 6 of 14 Photo: Getty Images Fortified milk Almost all types of cow's milk in the U.S. are fortified with vitamin D, but ice cream and cheese are not. In general, an 8-ounce glass of milk contains at least 100 IUs of vitamin D, and a 6-ounce serving of yogurt contains 80 IUs, but the amount can be higher (or lower) depending on how much is added.

Some soy and rice milks are fortified with about the same amount, but check the label since not all contain vitamin D. 6 of 14 View all 7 of 14 Photo: Getty Images Some types of orange juice Not a dairy fan? No problem. You can get vitamin D from fortified orange juice. One 8-ounce glass of fortified juice usually has around 100 IUs of vitamin D, but the amount varies from brand to brand. Not all brands are fortified, so check the label. Two fortified brands, Florida Natural Orange Juice and Minute Maid Kids+ Orange Juice, contain 100 IUs per 8-ounce serving. 7 of 14 View all 8 of 14 Photo: Corbis Supplements Vitamin D supplements can help you get your proper daily dose, and as Dr. Honig points out, you don't run into the issue of skin cancer as you might with UV rays. "And it's not like calcium," he says. "You don't have to split up your vitamin D dose; you can take it all at one time." Too much vitamin D can be toxic, however.

The IOM sets the upper limit at 4,000 IUs for people aged 9 and older. That includes all sourcesfood, sun, and supplements. Talk to your doctor before choosing a dosage. 8 of 14 View all 9 of 14 Photo: Getty Images Egg yolks Eggs are a convenient way to get vitamin D. They're popular in many breakfast, lunch, dinner, and dessert recipes. Since the vitamin D in an egg comes from its yolk, it's important to use the whole eggnot just the whites. One yolk will give you about 40 IUs, but don't try to get your daily vitamin D just from eggs. One egg contains about 200 milligrams of cholesterol, and the American Heart Association recommends consuming no more than 300 milligrams a day for heart health. 9 of 14 View all 10 of 14 Photo: Getty Images Fortified cereal If you're a vitamin D seeker looking for a crunch, look no further than fortified cereals. Choose a low-calorie fortified cereal like Multi Grain Cheerios to get part of your daily fill of vitamin D.

You can pair it with fortified milk and a glass of fortified OJ too. A 1-cup (29 gram) serving of Multi Grain Cheerios with one-half cup of fortified milk is 90 IUs; add in an 8-ounce glass of fortified orange juice, and your total is close to 200 IUs. 10 of 14 View all 11 of 14 Photo: Getty Images Beef liver Although it might not be the most appealing source, a 3.5-ounce serving of cooked beef liver contains about 50 IUs of vitamin Dand several other nutrients. You'll also be getting vitamin A, iron, and protein. However, beef liver is also high in cholesterol, so you might want to choose an oily fish instead. 11 of 14 View all 12 of 14 Photo: Getty Images Cod liver oil While its name might suggest a less-than-savory flavor, cod liver oil is often flavored with mint or citrus, or comes in capsule form. One tablespoon contains about 1,300 IUs of vitamin D, which is more than twice the recommended dietary allowance of 600 IUs per day.

That amount doesn't exceed the maximum upper-level intake of 4,000 IUs for people over 8 years old, but it exceeds the daily maximum for infants (1,000 IUs). 12 of 14 View all 13 of 14 Photo: NatureBright SunTouch Ultraviolet lamps and bulbs People at high risk of vitamin D deficiency may resort to UV-emitting lamps and bulbs. This includes people unable to absorb the vitamin (malabsorption) or those who can't get enough in winter months, says Michael F. Holick, MD, a professor of medicine, sociology, and biophysics at Boston University Medical Center. These are similar to tanning beds, but smaller. "The lamp is only about 24 inches by about 16 inches," says Dr. Holick. These lamps carry the same skin-cancer risks and need for protective eyewear, so they're best for those with a doctor's recommendation. 13 of 14 Sunshine Vitamin Sun exposure to the skin is the human race’s natural, intended, most effective and most neglected source of vitamin D.

Vitamin D sufficiency, along with diet and exercise, has emerged as one of the most important preventive factors in human health. Hundreds of studies now link vitamin D deficiency with significantly higher rates of many forms of cancer‚ as well as heart disease‚ osteoporosis‚ multiple sclerosis and many other conditions and diseases. Because sunshine is a free commodity with no publicist or lobbyist, the Sunshine Vitamin Alliance is established as a coalition of right-minded physicians, individuals and organizations who advocate natural vitamin D production through regular, non-burning sun exposure. Humans make 90 percent of our vitamin D naturally from sunlight exposure to our skin – specifically, from ultraviolet B exposure to the skin, which naturally initiates the conversion of cholesterol in the skin to vitamin D3. Few foods naturally contain or are fortified with supplemental vitamin D. For example, an 8-ounce glass of whole milk is fortified with 100 IU (international units) of vitamin D – just 10 percent of what the most conservative vitamin D researchers now say we need daily. In contrast, sun exposure to the skin makes thousands of units of vitamin D naturally in a relatively short period of time.

While vitamin D supplements are an alternative means of producing vitamin D when regular, non-burning sun exposure is not possible, oral supplementation of vitamin D is not nature’s intended means of producing this vitamin. While overexposure to sunlight carries risks, the cosmetic skin care industry has misled the public into believing that any UV exposure is harmful. No research has shown that regular, non-burning exposure to UV light poses a significant risk of skin damage. Humans spend less time in the sun today than at any point in human history – which is why more than 1 billion people worldwide are vitamin D deficient. Vitamin D Comes From the Sun Sunlight is the best and only natural source of vitamin D. Unlike dietary or supplementary vitamin D, when you get your ‘D’ from sunshine your body takes what it needs, and de-metabolizes any extra. That’s critical – as vitamin D experts and many health groups now advocate 1,000 to 2,000 IU of vitamin D daily – five to ten times the old recommendations. Because too much ‘D’ from dietary supplements may cause the body to over-process calcium, nobody really knows for sure how much supplementary vitamin D is safe.

On the other hand, sunlight-induced vitamin D doesn’t have that problem – it’s the way your body is intended to make it! Sunlight Exposure (full body exposure)* 3,000 – 20,000 IU Best Sources of Vitamin D in Foods - Vitamin D Foods 1 Of 12 The Benefits of Vitamin D, the Sunlight Nutrient Many people are worried about a vitamin D deficiency, which the Institute of Medicine says has been over-diagnosed in recent years. Unlike other nutrients, vitamin D isn't really a vitamin at all: It's a hormone, made by your body as you are exposed to sunlight, that plays an important role in maintaining bone strength. If you eat a varied diet and get some sun (about 20 minutes a day, unfiltered by sunscreen) then you are probably getting all the vitamin D you need. Even if you aren't getting enough from sunlight, you probably don't need a vitamin supplement, according to the Institute of Medicine. Try eating more of these vitamin D-rich foods instead.

Paul Burns / Getty Images 2 Of 12 Salmon Salmon has by far the most vitamin D of any food (and wild salmon has much more than farmed salmon, which is cheaper and easier to find). Half a fillet of sockeye salmon has more than 1,400 iu of Vitamin D — more than twice as much as most people need in a day. Anthony-Masterson / Getty images 3 Of 12 Tuna A serving of tuna has a healthy dose of vitamin D — more than one-third of a daily dose. Light tuna in oil has the most. (Light tuna in water has about one-fourth of a daily dose, while white tuna has about one-tenth. Light tuna also has less mercury than white tuna , making it a safer choice.) The other fish-in-a-can, sardines, also have a lot of vitamin D — about one-fourth of a daily dose (along with a healthy dose of calcium), and pickled herring have about one-sixth of a daily dose. Bill Boch / Getty Images 4 Of 12 Sole or Flounder Flatfish like sole and flounder have about one-fourth a day's worth of vitamin D.

(The other white fish, cod, has less than one-tenth.) Look for Pacific flounder, sole or cod at the fish market, because Atlantic stocks are depleted . Anna Yu / Getty Images 5 Of 12 Milk Fortified milk has about one-fifth a day's worth of vitamin D — and whole milk has more than skim. Buena Vista Images / Getty Images 6 Of 12 Cereal Like fortified milk, fortified cereal provides a more balanced meal than a vitamin D supplement. The amount of vitamin D in cereals varies widely by brand and type, though, so read the label carefully. Gabriela / Fotolia 7 Of 12 Pork Three little ounces of pork can provide as much as 88 iu of vitamin D — almost one-seventh of a daily dose. The most can be found in ribs (though you might end up adding too much fat in the pursuit of nutrients), and the amount of vitamin D in pork varies greatly by cut and preparation. You'll barely get any Vitamin D from a slice of ham. Ciaran Griffin / Getty Images 8 Of 12 Eggs Two large eggs have about one-tenth of a daily dose of vitamin D.

Eggs from truly free-range chickens, like those many people are raising in backyards these days, are often more delicious and nutritious than the factory farmed kind; unfortunately, the free-range label on eggs isn't a regulated term, so it could be meaningless. Pidjoe / Istock 9 Of 12 Mushrooms Mushrooms can have a significant amount of vitamin D, but the amount varies widely by type. Shiitake mushrooms (pictured) have 45 iu — about one-thirteenth of a daily recommended serving. White mushrooms, on the other hand, have just 5 iu. James Baigrie / Getty Images 10 Of 12 Beef Liver A 3-ounce portion of beef liver has more than 42 iu of Vitamin D — about one-fourteenth of a daily dose needed for someone who doesn't get much exposure to the sun. Beef is also one of the best sources of vitamin B-12 and organ meats are one of the top sources of iron. If you're heading to the store for meat, look for grassfed beef to take advantage of additional nutrition, and more sustainable farming practices.

Hendrik Holler / Getty Images Vitamins and minerals - Vitamin D - NHS Choices Vitamins and minerals - Vitamin D Share: Vitamin D helps to regulate the amount of calcium and phosphate in the body. These nutrients are needed to keep bones, teeth and muscles healthy. A lack of vitamin D can lead to bone deformities such as rickets in children, and bone pain and tenderness as a result of a condition called osteomalacia in adults. Good sources of vitamin D From about late March/April to the end of September, most of us should be able to get all the vitamin D we need from sunlight on our skin. The vitamin is made by our body under the skin in reaction to sunlight. If you are out in the sun, take care to cover up or protect your skin with sunscreen before you turn red or get burnt. Between October and early March we don't get any vitamin D from sunlight. Vitamin D is also found in a small number of foods. Good food sources are: oily fish – such as salmon, sardines, herring and mackerel red meat fortified foods such as most fat spreads and some breakfast cereals Another source of vitamin D is dietary supplements.

In the UK, cows' milk is generally not a good source of vitamin D because it isn't fortified, as it is in some other countries. How much vitamin D do I need? Babies from birth to one year need 8.5 to 10 micrograms (8.5-10mcg) of vitamin D a day. Children from the age of one year and adults need 10 micrograms (10mcg) of vitamin D a day. This includes pregnant and breastfeeding women and population groups at risk of vitamin D deficiency (those with minimal exposure to sunshine and those from minority ethnic groups with dark skin). From about late March/April to the end of September, most of us should be able to get all the vitamin D we need from sunlight on our skin. Should I take a vitamin D supplement? Advice for infants and young children The Department of Health recommends that: Breastfed babies from birth to one year of age should be given a daily supplement containing 8.5 to 10mcg of vitamin D, to make sure they get enough.

Babies fed infant formula should not be given a vitamin D supplement until they are receiving less than 500ml (about a pint) of infant formula a day, because infant formula is fortified with vitamin D Children aged 1 to 4 years old should be given a daily supplement containing 10mcg of vitamin D You can buy single vitamin D supplements or vitamin drops containing vitamin D (for use by under-fives) at most pharmacies and supermarkets. Women and children who qualify for the Healthy Start scheme can get free supplements containing the recommended amounts of vitamin D. See the Healthy Start website for more information on the scheme. Advice for adults and children over five years old Because vitamin D is found only in a small number of foods, it might be difficult to get enough from foods that naturally contain vitamin D and/or fortified foods alone. So everyone, including pregnant and breastfeeding women, should consider taking a daily supplement containing 10mcg of vitamin D. Between late March/April to the end of September, the majority of people aged five years and above will probably obtain sufficient vitamin D from sunlight when they are outdoors. So you might choose not to take a vitamin D supplement during these months.

However, some groups of people will not get enough vitamin D from sunlight because they have very little or no sunshine exposure. So the Department of Health recommends that people should take a daily supplement containing 10mcg of vitamin D throughout the year if they: are not often outdoors, such as those who are frail or housebound are in an institution such as a care home usually wear clothes that cover up most of their skin when outdoors People from minority ethnic groups with dark skin, such as those of African, African-Caribbean or South Asian origin, might not get enough vitamin D from sunlight – so they should consider taking a daily supplement containing 10mcg of vitamin D throughout the year. What happens if I take too much vitamin D? Taking too many vitamin D supplements over a long period of time can cause more calcium to be absorbed by the body than can be excreted. This leads to high levels of calcium in the blood (hypercalcaemia). Too much calcium in the blood can weaken the bones and damage the kidneys and the heart. If you choose to take vitamin D supplements, 10mcg a day will be enough for most people.

Do not take more than 100mcg of vitamin D a day, as it could be harmful. This applies to adults, including pregnant and breastfeeding women and the elderly, and children aged 11-17 years. Children aged 1-10 years should not have more than 50mcg a day. Infants under 12 months should not have more than 25mcg a day. Some people have medical conditions that mean they may not be able to safely take as much. If in doubt, you should consult your doctor. If your doctor has recommended you take a different amount of vitamin D, you should follow their advice. Your body doesn't make too much vitamin D from sun exposure, but always remember to cover up or protect your skin if you are out in the sun for long periods, to reduce the risk of skin damage and skin cancer. Page last reviewed: 18/02/2015 Vitamin Chart Vitamin Chart Quantity Vitamin A Vitamin A prevents eye problems, promotes a healthy immune system, is essential for the growth and development of cells, and keeps skin healthy.

Good sources of vitamin A are milk, eggs, liver, fortified cereals, darkly colored orange or green vegetables (such as carrots, sweet potatoes, pumpkin, and kale), and orange fruits such as cantaloupe, apricots, peaches, papayas, and mangos. Teen guys need 900 micrograms of vitamin A each day. Teen girls need 700 micrograms each day. It is possible to get too much vitamin A, so be careful with supplements. Don't take vitamin A supplements If you're taking isotretinoin (such as Accutane) for acne or other skin problems. Oral acne medicines are vitamin A supplements, and a continued excess of vitamin A can build up in the body, causing headaches, skin changes, or even liver damage. Vitamin C (also called ascorbic acid) Vitamin C is needed to form collagen, a tissue that helps to hold cells together. It's essential for healthy bones, teeth, gums, and blood vessels. It helps the body absorb iron, aids in wound healing, and contributes to brain function. You'll find high levels of vitamin C in citrus fruits, strawberries, kiwi, guava, peppers, tomatoes, broccoli, and spinach.

Teen guys need 75 mg (milligrams; 1 milligram equals 1,000 micrograms) and girls need 65 mg of vitamin C a day. Vitamin D Vitamin D strengthens bones because it helps the body absorb bone-building calcium. This vitamin is unique — your body manufactures it when you get sunlight on your skin! You can also get vitamin D from egg yolks, oily fish such as salmon, tuna, and sardines, and fortified foods like milk, soy milk, and orange juice. Teens need 15 micrograms (600 IU) of vitamin D from food or supplements every day. Ask your doctor if supplements are right for you. Vitamin E Vitamin E is an antioxidant and helps protect cells from damage. It is also important for the health of red blood cells. Vitamin E is found in many foods, such as vegetable oils, nuts, and green leafy vegetables. Avocados, wheat germ, and whole grains are also good sources. Teen guys and girls need 15 mg of vitamin E every day. Vitamin B12 Vitamin B12 helps to make red blood cells, and is important for nerve cell function.

Vitamin B12 is found naturally in fish, red meat, poultry, milk, cheese, and eggs. It's also added to some breakfast cereals. Teens should get 2.4 micrograms of vitamin B12 daily. Vitamin B6 Vitamin B6 is important for normal brain and nerve function. It also helps the body break down proteins and make red blood cells. A wide variety of foods contain vitamin B6, including potatoes, bananas, beans, seeds, nuts, red meat, poultry, fish, eggs, spinach, and fortified cereals. Teen guys need 1.3 mg of vitamin B6 daily and teen girls need 1.2 mg. Thiamin (also called vitamin B1) Thiamin helps the body convert carbohydrates into energy and is necessary for the heart, muscles, and nervous system to function properly. People get thiamin from many different foods, including fortified breads, cereals, and pasta; lean meats; dried beans, soy foods, and peas; and whole grains like wheat germ. Teen guys need 1.2 mg of thiamin each day; teen girls need 1 mg.

Niacin (also called vitamin B3) Niacin helps the body turn food into energy. It helps maintain healthy skin and is important for nerve function. You'll find niacin in red meat, poultry, fish, fortified hot and cold cereals, and peanuts. Teen guys need 16 mg of niacin daily. Teen girls need 14 mg a day. Riboflavin (also called vitamin B2) Riboflavin is essential for growth, turning carbohydrates into energy, and producing red blood cells. Some of the best sources of riboflavin are meat, eggs, legumes (like peas and lentils), nuts, dairy products, green leafy vegetables, broccoli, asparagus, and fortified cereals. Teen guys need 1.3 mg of riboflavin per day and teen girls need 1 mg. Folate (also known as vitamin B9, folic acid, or folacin) Folate helps the body make red blood cells. It is also needed to make DNA. Liver, dried beans and other legumes, green leafy vegetables, asparagus, and orange juice are good sources of this vitamin. So are fortified bread, rice, and cereals.

Teen girls and guys need 400 micrograms of folate daily. Vitamin D FAQ: Vitamin D Food Sources, Deficiency, Recommendations, and More Which foods contain vitamin D ? Surprisingly few foods contain vitamin D -- unless it's added to the food. That's because your body is built to get vitamin D through your skin (from sunlight) rather than through your mouth (by food). But once your body has enough, it doesn't matter whether you got it through your skin or through your stomach . There are three vitamin D super foods: Salmon (especially wild-caught) Mackerel (especially wild-caught; eat up to 12 ounces a week of a variety of fish and shellfish that are low in mercury) Mushrooms exposed to ultraviolet light to increase vitamin D Other food sources of vitamin D include: Cod liver oil (warning: cod liver oil is rich in vitamin A ; too much may be bad for you) Tuna canned in water Sardines canned in oil

Question: Milk and sunlight are good sources of which vitamin?
Answer: D