А вы не в курсе,что витамин Д НЕ накапливается? И причём тут рахит... Рахит у детей бывает. У взрослых бывают другие всякие бяки, типа рака, сердечно-сосудистых заболеваний, да и вообще элементарного гриппа...http://en.wikipedia.org/wiki/Vitamin_DVitamin D3 is made in the skin when 7-dehydrocholesterol reacts with UVB ultraviolet light at wavelengths between 270–300 nm, with peak synthesis occurring between 295-297 nm. These wavelengths are present in sunlight when the UV index is greater than 3. At this solar elevation, which occurs daily within the tropics, daily during the spring and summer seasons in temperate regions, and almost never within the arctic circles, adequate amounts of vitamin D3 can be made in the skin after only ten to fifteen minutes of sun exposure at least two times per week to the face, arms, hands, or back without sunscreen. However, season, geographic latitude, time of day, cloud cover, skin cover, skin color, smog, and sunscreen affect UV ray absorption and vitamin D synthesis. For example, sunlight exposure from November through February in Boston is insufficient to produce significant vitamin D synthesis in the skin. With longer exposure to UVB rays, an equilibrium is achieved in the skin, and excess vitamin D simply degrades as fast as it is generated.Deficiency of vitamin D can result from a number of factors: inadequate intake coupled with inadequate sunlight (UVB) exposure, disorders that limit its absorption from the gastrointestinal tract, conditions that impair conversion of vitamin D into active metabolites, such as liver or kidney disorders and body characteristics such as skin color and body fat. Rarely, deficiency can result from a number of hereditary disorders. Deficiency results in impaired bone mineralization, and leads to bone softening diseases including:Rickets, a childhood disease characterized by impeded growth, and deformity, of the long bones. Rickets was first described in the 17th century, by Daniel Whistler and Francis Glisson. The role of diet in the development of rickets was determined by Edward Mellanby between 1918–1920. By altering the diets of dogs raised in the absence of sunlight, he was able to establish unequivocally that rickets was linked with a deficiency of diet, and identified cod liver oil as an excellent anti-rachitic agent. In 1921 Elmer McCollum identified a substance found in certain fats that could prevent rickets. Prior to the fortification of milk products with vitamin D, rickets was a major public health problem. In the United States, the fortification of milk with 10 micrograms (400 IU) of vitamin D per quart in the 1930s led to a dramatic decline in the number of rickets cases.Osteomalacia, a bone-thinning disorder that occurs exclusively in adults and is characterized by proximal muscle weakness and bone fragility. The effects of osteomalacia are thought to contribute to chronic musculoskeletal pain. A number of reports thus indicate that vitamin D deficiency may be related to various types of pain, but of the five small double-blind randomized controlled trials, only one found a reduction in pain after supplementation, and there is no persuasive evidence of lower vitamin D status in chronic pain sufferers compared to controls.Osteoporosis, a condition characterized by reduced bone mineral density and increased bone fragility. Vitamin D malnutrition may also be linked to an increased susceptibility to several chronic diseases, such as high blood pressure, tuberculosis, cancer, periodontal disease, multiple sclerosis, chronic pain, seasonal affective disorder, peripheral artery disease, cognitive impairment which includes memory loss and foggy brain,[43] and several autoimmune diseases including type 1 diabetes (see role in immunomodulation). There is an association between low vitamin D levels and Parkinson's disease, but whether Parkinson's causes low vitamin D levels, or whether low vitamin D levels play a role in the pathogenesis of Parkinson's disease has not been established. A resurgence of interest in vitamin D deficiency has led to continued studies on the topic and a focus on educating the consumer on the prevalence and degree of deficiency among the general public.Exposure to sunlight for extended periods of time does not normally cause vitamin D toxicity. This is because within about 20 minutes of ultraiolet exposure in light skinned individuals (3–6 times longer for pigmented skin) the concentration of vitamin D precursors produced in the skin reach an equilibrium, and any further vitamin D that is produced is degraded.