Overview of Vitamins - Nutritional Disorders - Merck Manuals Professional Edition Deficiency: Night blindness, perifollicular hyperkeratosis, xerophthalmia, keratomalacia, increased morbidity and mortality in young children Toxicity: Headache, peeling of skin, hepatosplenomegaly, bone thickening, intracranial hypertension, papilledema, hypercalcemia Vitamin B6 group (pyridoxine, pyridoxal, pyridoxamine) Organ meats (eg, liver), whole-grain cereals, fish, legumes Many aspects of nitrogen metabolism (eg, transaminations, porphyrin and heme synthesis, tryptophan conversion to niacin) Nucleic acid biosynthesis Fatty acid, lipid, and amino acid metabolism Deficiency: Seizures, anemia, neuropathies, seborrheic dermatitis Toxicity: Peripheral neuropathy Meats (especially beef, pork, and organ meats [eg, liver]), poultry, eggs, fortified cereals, milk and milk products, clams, oysters, mackerel, salmon Maturation of RBCs, neural function, DNA synthesis, myelin synthesis and repair Deficiency: Meg

aloblastic anemia, neurologic deficits (confusion, paresthesias, ataxia) Citrus fruits, tomatoes, potatoes, broccoli, strawberries, sweet peppers Collagen formation Bone and blood vessel health Carnitine, hormone, and amino acid formation Wound healing Vitamin D (cholecalciferol, ergocalciferol) Direct ultraviolet B irradiation of the skin (main source), fortified dairy products (main dietary source), fish liver oils, fatty fish, liver Calcium and phosphate absorption Mineralization and repair of bone Tubular reabsorption of calcium Insulin and thyroid function, improvement of immune function, reduced risk of autoimmune disease Deficiency: Rickets (sometimes with tetany), osteomalacia Toxicity: Hypercalcemia, anorexia, renal failure, metastatic calcifications Vitamin E group (alpha-tocopherol, other tocopherols) Vegetable oils, nuts Scavenger of free radicals in biologic membranes Deficiency: RBC hemolysis, neurologic deficits Toxicity: Tendency to bleed The Body - Vitamin Chart The Body Vitamin A (beta carotene) Helps to keep eyesight and promote the growth of healthy skin, hair, bones and teeth.

Helps in cell reproduction and aids to strengthen the immune and reproductive systems. The body uses beta-carotene and converts it to vitamin A. Night blindness, dry skin, poor bone and teeth growth and development. Soy milk (and other dairy products) carrots egg yolks Vitamin B1 (thiamine) Used by the body to help convert carbohydrates into energy. Helps to keep the normal function of the nervous system, muscles heart and digestion. Less concentration, loss of appetite. Weakness, exhaustion and fatigue. Lean Pork Whole-grain and fortified cereals Vitamin B2 (riboflavin) Important for growth in the body. Assists skin, nails and hair to grow. Helps to prevent sores and swelling of mouth and lips. Aids in reproduction and cell regeneration. Also aids in the releasing of energy from carbohydrates. Itching and irritation of lips, eyes, skin and mucous membranes. Eggs Vitamin B3 (niacin) Helps to release energy from carbohydrates.

Aids in the functioning of the digestive system, nerves and Depression, diarrhoea, dizziness, fatigue, halitosis, headaches, indigestion, insomnia, limb pains, loss of appetite, low blood sugar, muscular weakness, skin eruptions, and inflammation. Beef liver Lentils Vitamin B9 (Folate/Folic acid) Helps produce and maintain red blood cells and the nervous system. Essential for mental and emotional health as it helps to maintain normal brain functions. Anaemia and a reduction in growth rates. Other subtle symptoms may include digestive disorders such as diarrhoea, loss of appetite, and weight loss can occur, as can weakness, sore tongue, headaches, heart palpitations, irritability, forgetfulness, and behavioural disorders Dark green vegetables Vitamin B12 needed for nerve cells and red blood cells, and to make DNA Demyelination and irreversible nerve cell death. Symptoms include numbness or tingling of the extremities and an ataxic gait. dairy products clams Vitamin C (ascorbic acid) Important in the production of collagen in the body - helps the connective tissues and organs. Can act as an anti oxidant to help protect the body from free radical.

Scurvy (though rarely seen today) which causes bleeding and inflamed gums, loose teeth and poor wound healing. citrus fruits (oranges, grapefruits, lemons, limes) berries leafy green vegetables Vitamin D Helps to promote the absorption of calcium and phosphorus levels in the body. Helps to maintain and form strong and healthy bones. Rickets and osteomalacia. Rickets results in soft bones and skeletal deformities Liver Sunlight Vitamin E An antioxidant that protects your cells against the effects of free radicals, which are potentially damaging by-products of energy metabolism. Intestinal disorders - cystic fibrosis, pancreatitis, and cholestasis. Prevent the absorption of dietary fats and fat-soluble nutrients. Margarine Peanuts and peanut butter Vegetable oils Wheat germ Vitamin K Helps to control blood clotting in the body and is essential for synthesizing the liver protein that controls the clotting A shortage of this vitamin may result in nosebleeds, internal haemorrhaging. Broccoli Vitamin and Mineral TABLE Vitamin and Mineral Table What foods? How does it help? Vitamin/Mineral Vitamin A (Retinol or Beta-carotene) Liver, egg yolk, dairy products, margarine.

Beta carotene (pro-vitamin A) is found in dark green and deep yellow fruits and vegetables. 5,000 IUb Keeps eyes healthy; develops bones; protects linings of respiratory, digestive and urinary tracts; maintains healthy skin and hair. Beta carotene fights free radicals (chemicals that damage cells). Vitamin B1 (Thiamine) Whole grains, cereals and enriched grain products; also legumes (dried beans, peas, and nuts), organ meats, lean pork and eggs. 1.1 - 1.5 mg Promotes healthy functioning of the nerves, muscles and heart. Metabolizes carbohydrates. Vitamin B2 (Riboflavin) Organ meats, enriched breads and cereals, legumes, almonds, cheese and eggs; also meat, fish and dark green vegetables. 1.3 - 1.7 mg Metabolizes carbohydrates, fats and proteins, produces hormones; promotes eye and skin health. Vitamin B3 (Niacin) Meat, organ meats, whole grains and cereals, and legumes; also eggs, milk, green leafy vegetables and fish.

15 - 19 mg Metabolizes carbohydrates and fats; helps functioning of digestive system; maintains health skin. Vitamin B5 Organ meats, yeast, raw vegetables, eggs and dairy products. None; Produces hormones and maintains body's immune system. Vitamin B6 (Pyridoxine) Whole-grain products, poultry, fish, and nuts; also meat, most fruits and vegetables, eggs and dairy products 1.6 - 2 mg Metabolizes protein; helps produce hemoglobin; promotes functioning of digestive and nervous systems, and healthy skin. Vitamin B12 Primarily organ meats; also fish, lean meats, poultry, cheese, and eggs. 2 µg Builds genetic material of cells and produces blood cells. Vitamin C (Ascorbic Acid) Almost exclusively fruits and vegetables (especially citrus fruits, tomatoes, peppers, strawberries, and cantaloupe) although breast milk and organ meats contain small amounts. 100 - 200 mg An antioxidant, fights and resists infection; heals wounds; promotes growth and maintenance of bones, teeth, gums, ligaments and blood vessels. Vitamin D (Cholecalciferol) For most people, sun exposure is the primary source of vitamin D.

Food sources include Vitamin D-fortified milk, eggs, fish-liver oils and fatty fish such as herring, mackerel and salmon. 400 IU Builds strong bones and teeth and maintains the nervous system. Vitamin E vegetable oils, nuts, wheat germ and whole-wheat products, egg yolks and green leafy vegetables. Women 8 mg; Men 10 mg Protects the lungs, nervous system, skeletal muscle and the eye's retina from damage by free radicals; may reduce risk of heart disease by protecting against atherosclerosis. Vitamin H Oats, organ meats, yeast and eggs (cooked); also whole-wheat products, dairy products, fish and tomatoes. None; Metabolizes proteins and carbohydrates; breaks down fatty acids. Vitamin K Dark green leafy vegetables, eggs, cheese, pork and liver. 60 - 80 mg vegetables (especially dark-green ones), organ meats, whole-wheat products, legumes and mushrooms. 180 - 200 µg Synthesis of protein and genetic materials; may help prevent some cancers, heart disease and stroke; when taken during pregnancy, protects against some birth defects.

Calcium (Ca) Primarily in milk and dairy products; also dark-green vegetables, legumes, shellfish, fish with edible bones and tofu; also calcium-fortified orange juice. 800 - 1,200 mg Builds bones and teeth; promotes blood clotting, contraction of muscles and nerve impulses. Chromium (Cr) Whole wheat and other whole grains and molasses. None; 50 - 200 µg suggested An essential nutrient required for normal sugar and fat metabolism; may also help prevent high cholesterol and atherosclerosis. Copper (Cu) Organ meats, shellfish, whole-grain products, legumes and dried fruits. None; 2 - 3 mg suggested Builds bones, red blood cells and hemoglobin; metabolizes iron, maintains connective tissue and blood vessels; may play a role in cancer prevention. Fluoride (F) Seafood, tea, coffee and soybeans; sodium fluoride is often added to the water supply to prevent tooth decay. None Promotes bone and tooth formation; prevents tooth decay. Iodine (I2) Saltwater fish, shellfish, sea kelp and iodized salt.

150 µg Helps produce thyroid hormones; adequate iodine intake during pregnancy is crucial to normal fetal development. Iron (Fe) Iron is poorly absorbed from food. The richest sources are red meat and organ meats; other sources include whole-wheat products, shellfish, nuts and dried fruit. Many breads and cereals are enriched with iron. Vitamin C aids absorption of iron and is often added to iron supplements. Women 15 mg; Men 10 mg Helps produce hemoglobin and red blood cells; delivers oxygen to muscles and other body tissues; protects against effects of stress Magnesium (Mg) Legumes, whole-grain cereals, nuts and dark-green vegetables; also meat, seafood and dairy products. Women 280 mg; Men 350 mg Builds bones and teeth; involved in functioning of muscular and nervous systems and hear and circulatory system. Manganese (Mn) Tea, green vegetables, legumes, oats and rice. 2 - 5 mg Involved in reproductive processes, sex hormone formation; essential for normal brain function and bone development. Molybdenum (Mo) Dairy products, legumes, whole-grain cereals and organ meats.

75 - 250 mg Meat, fish, eggs, legumes and dairy products; also whole wheat, corn and rice. 1 gram Builds bones and teeth. Potassium (K) Potatoes, dried fruits, bananas, legumes, raw vegetables, avocados and mushrooms; also lean meat, milk and fish. None; Helps nerves and muscles function; regulates heart's rhythm; regulates bodily fluids. Selenium (Se) Whole-grain cereals, fish and shellfish, meat and dairy products. Women 55 µg; Men 70 µg An antioxidant, helps protect cells and tissues from damage by free radicals; may also protect against some cancers. Sodium (Na) Naturally in many foods and is added to many prepared foods. 2,400 mg Maintains body's fluid balance; important for nerve function and muscle contraction; controls heart's rhythm. Zinc (Zn) 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 — 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 ] Nutrition - Egg Nutrition » Eggs.ca Nutrition Facebook Twitter Pinterest Instagram Nutrition Eggs aren't just delicious. They're also extremely nutritious, an excellent source of protein and provide essential nutrients. Find out why you should include eggs as part of your diet and learn how to maintain a healthy lifestyle from our nutrition experts. Egg Nutrition Nutrition facts One large (53g) Grade A egg contains 6 g of protein and only 70 calories.

Canada’s Food Guide considers 2 eggs one serving from the Meat and Alternatives food group.

Nutritional Information per 53 g serving: Calories The vitamins and minerals of an egg and how they benefit you: NUTRIENT BENEFIT Iron Carries oxygen to the cells, helps prevent anemia – the iron in eggs is easily absorbed by the body Vitamin A Helps maintain healthy skin and eye tissue; assists in night vision Vitamin D Strengthens bones and teeth; may help protect against certain cancers and auto-immune diseases Vitamin E An antioxidant that plays a role in maintaining good health and preventing disease Vitamin B12 Helps protect against heart disease Folate Helps produce and maintain new cells; helps prevent a type of anemia, helps protect against serious birth defects if taken prior to pregnancy and during the first 3 months of pregnancy Protein Essential for building and repairing muscles, organs, skin, hair and other body tissues; needed to produce hormones, enzymes and antibodies; the protein in eggs is easily absorbed by the body Selenium Works with vitamin E to act as an antioxidant to help prevent the breakdown of body tissues Lutein and zeaxanthin Maintains good vision; may help reduce the risk of age-related eye diseases, such as cataracts and macular degeneration Choline Plays a strong role in brain development and function Protein With 6 grams of the highest

 quality protein and 14 key nutrients, eggs provide the energy needed to keep you going.

They are a natural choice for a healthy, active lifestyle. Eggs are one of the few foods considered to be a complete protein, because they contain all 9 essential amino acids. Amino acids are considered the "building blocks for the body" because they help form protein. In addition to giving you energy, your body uses the protein found in eggs to: build and repair body tissue and cells grow strong hair and nails build and maintain healthy muscles help fight infections help keep your body fluids in balance To maintain a healthy, balanced diet, Canada's Food Guide recommends eating 1 to 3 servings of meat and meat alternatives every day, depending on age and gender. This includes a variety of protein sources, such as meat, poultry, fish, beans and eggs. Omega-3 First let’s start by explaining what omega-3 fats are and why they’re good for you. Omega-3s are a type of polyunsaturated fat, or healthy fat, known to help protect your heart. They are essential for good health, but our bodies don’t naturally produce them, which is why we have to get them from foods such as salmon, certain types of oils and nuts, and omega-3 eggs.

Omega-3 Eggs We’ve all seen eggs labeled with omega-3 at grocery store and wondered how these differ from regular eggs. Omega-3 eggs are produced by feeding hens a diet containing flaxseed, a known source of omega-3. Flaxseed naturally contains alpha-linolenic acid (ALA), a plant-based type of omega-3 fatty acid. Cholesterol You Can Probably Eat More Eggs Than You Think! If you've been avoiding eggs because of concerns linking them to dietary cholesterol and coronary heart disease, it's time to reconsider. The latest research shows that healthy adults can enjoy an egg every day without increasing their risk of heart disease. According to the American Heart Association, lutein found in egg yolks also protects against the progress of early heart disease. For more information on the Canadian Egg Industry, visit: eggfarmers.ca . Your cholesterol, your health. aneggadayisok.ca All about Vitamins Vitamin A Vitamin A is necessary for normal eyesight, body tissues, growth and bone formation, and resistance to infection.

Sources: Liver, fish liver oils, eggs; Orange vegetables like carrots, sweet potatoes, pumpkin; Dark-green leafy vegetables, like spinach, kai lan, kangkong, di wang chai; Orange fruits like mango, cantaloupe, papaya, persimmon Tomatoes, green beans Signs of Deficiency: Poor night vision or night blindness, loss of appetite, increased susceptibility to infection, and changes in the skin and teeth. Vitamin B-1 Vitamin B-1 (thiamin) is vital for the normal functioning of all body cells, especially nerves. It also helps the body break down carbohydrates, protein, and fat for energy. Sources: Oysters, green peas, brewer's yeast, organ meats, lean cuts of pork, dried beans and peas, oranges, wheat germ, breads and cereals whole grain, peanuts and peanut butter. Signs of Deficiency: Fatigue, loss of appetite, weight loss, gastrointestinal upsets, nausea and weakness. Signs of a severe deficiency include mental confusion, muscular weakness, paralysis of the extremities, heart problems and loss of reflexes.

Vitamin B-2 Vitamin B-2 (Riboflavin) is necessary for the normal release of energy from carbohydrate, protein and fat in food. It's also important for normal growth and development, the production and regulation of certain hormones, and the formation of red blood cells. Sources: Dairy products, meat, poultry, fish, enriched and fortified grains, cereals and bakery products, and green vegetables such as broccoli, asparagus and spinach. Signs of Deficiency: Soreness of the mouth, lips and tongue, burning and itching of the eyes, loss of vision, sensitivity to light. As the deficiency progresses, the inside of the mouth, and the eyes and skin become inflamed, and depression and/or hysteria develop. Vitamin B-3 Vitamin B-3 (Niacin) is essential for the release of energy from carbohydrates. It aids in the breakdown of protein and fats, in the synthesis of fats and certain hormones, and in the formation of red blood cells. Sources: Meat, poultry, fish, enriched cereals and grains, and nuts. Although milk and eggs contain very little niacin, they provide tryptophan, which is converted into niacin by the body.

Signs of Deficiency: Weakness, loss of appetite, indigestion, skin inflammation, and lethargy. A severe deficiency results in the disease pellagra, which causes scaly skin, swollen tongue, tremors and damage to the central nervous system. Vitamin B-6 Vitamin B-6 (Pyridoxine) helps the body build and break down carbohydrates, fats, and proteins. It plays a key role in the processing of amino acids, the building blocks of protein, and the nutrient aids in the formation and maintenance of the nervous system. Sources: Chicken, fish, kidney, liver, pork, eggs, unmilled rice, soy beans, oats, whole-wheat products, peanuts and walnuts. Signs of Deficiency: Depression, vomiting, increased susceptibility to disease and infection, skin and nerve inflammation, anemia, nausea and lethargy. Vitamin B-12 Vitamin B-12 is necessary for normal processing of carbohydrate, protein and fat, for the normal production of certain amino acids and fats, and to maintain the nervous system. Sources: Meat, poultry, fish, milk, dairy products and eggs. Signs of Deficiency: Anemia and neurological problems.

Vitamin C Vitamin C is necessary for the formation of collagen, a protein that gives structure to bones, cartilage, muscles and blood vessels, and contributes to the proper maintenance of capillaries, bones and teeth. Vitamin C promotes the healing of wounds, bone fractures, bruises, hemorrhages and bleeding gums. Sources: Citrus fruits and juices like oranges, papaya, honeydew, guava, pomelo Broccoli, sweet peppers, tomatoes, cabbage, potatoes, snow peas, cauliflower Leafy greens such spinach, kai lan, chye sim, bok choy Signs of Deficiency: An increased tendency to get black-and-blue marks, bleeding gums, nose bleeds and wounds that heal slower than normal. Other signs include damage to blood vessels, swollen, tender joints and aching bones, general weakness, loss of appetite and dry, scaly skin. The disease known as scurvy results from a severe vitamin C deficiency. Scurvy is characterized by anemia, tooth loss and bleeding under the skin. Vitamin D Vitamin D is essential in the formation and maintenance of bones and teeth by regulating the absorption and use of calcium and phosphorus. It also aids in the maintenance of a healthy nerve and muscle system.

Sources: Sunlight, fortified milk and margarine, eggs and butter. Signs of Deficiency: A prolonged lack of this nutrient results in changes in the bones of children and adults. Vitamin E Vitamin E protects fats and vitamin A in the body from destruction by destructive oxygen fragments. As an antioxidant, Vitamin E stabilizes cell membranes and protects tissues that are found throughout the body. Sources: Vegetable oils such as soyabean oil, corn oil Signs of Deficiency: Anemia in infants and nerve damage in adults. Vitamin K The main function of Vitamin K is to regulate blood clotting. Sources: Sunlight, fortified milk and margarine, eggs and butter. Signs of Deficiency: Vitamin K deficiency is very rare. But certain conditions or medications that affect vitamin K absorption may lead to abnormal blood clotting. Biotin Biotin is used by the body to manufacture and break down fats, amino acids, and carbohydrates. Sources: Liver, egg yolk, soy flour, cereals and yeast.

Signs of Deficiency: Skin inflammation, depression, conjunctivitis, hair loss, elevated blood levels of cholesterol, anemia, loss of appetite, tingling and numbness in the hands and feet, nausea, lethargy, muscle pain, and enlargement of the liver. Choline Directly related to B complex vitamins, choline promotes metabolism, maintains the nervous system, protects the liver from excess fatty deposits, attributed to retaining long and short term memory as well as coordination, it also has the ability to dissolve fats. Choline is found in all living cells and can be manufactured in the body with the help of Vitamin B12, folate, and methionine. Sources: egg yolks, kidney, liver, whole grains, fish and legumes. Signs of Deficiency: Choline is widely distributed in foods and therefore there is little known about deficiencies. It can be toxic, however, in large amounts and symptoms include: headaches, digestive problems, anorexia, neck & shoulder tightness, sweating, increased fatty deposits in the liver and in the long term it can cause nerve and cardiovascular problems. Folate Folate (Folacin, Folic Acid) is essential for the normal growth and maintenance of all cells.

Its main function is to maintain the cells' genetic code. Sources: Folate is found in many foods, but as much as fifty percent of it is destroyed during cooking, food processing and storage. Especially rich sources include liver, yeast, leafy green vegetables and legumes. Signs of Deficiency: Anemia, poor growth, digestive disorders, malnutrition, diarrhea, loss of appetite, weakness, irritability, sore tongue, headaches, heart palpitations and behavioral disorders. Pantothenic Acid Pantothenic Acid is a B-complex vitamin required for the breakdown of fats, carbohydrates, and protein for energy. It also functions in the production of fats, cholesterol, bile, vitamin D, red blood cells, and some hormones and neurotransmitters. Sources: Pantothenic Acid is found in many foods, but it is most abundant in meat, poultry, fish, whole grain cereals and legumes. Signs of Deficiency: Fatigue, heart and digestive problems, respiratory infections, skin inflammation and lack of coordination may develop under severe conditions. Nutrition.com.sg copyright 2000-2014 ᬬ rights reserved Reproducing content on this site, in any form, is prohibited without written permission.

Question: What is the main vitamin found in fish liver oils, egg- yolks, etc.?
Answer: VITAMIN D