^ Agarwal SC, Stout SD (June 28, 2011). Bone Loss and Osteoporosis: An Anthropological Perspective. Springer Science & Business Media. ISBN 978-1-4419-8891-1. Archived (PDF) from the original on January 29, 2006. The high 25(OH)D concentrations, and relatively high vitamin D requirements of apes and monkeys are understandable in light of their biology—their body surface area relative to mass is generally greater than for humans, and they are inveterate groomers, consuming by mouth the vitamin D generated from the oils secreted by skin into fur. Although much of the vitamin D produced within human skin is absorbed directly, birds and furbearing animals acquire most of their vitamin D orally, as they groom themselves (Bicknell and Prescott, 1946; Carpenter and Zhao, 1999). Vitamin D is generated from the oily secretions of skin into fur. The oral consumption of UV-exposed dermal excretion is the way many animals acquire the "nutrient," vitamin D. Although Fraser (1983) has argued that dermal absorption of vitamin D may be more natural, what we know from animals indicates that oral consumption is equally physiological. Since vitamin D can be extracted from UV-exposed human sweat and skin secretions (Bicknell and Prescott, 1946), it is also reasonable to think that early humans obtained some of their vitamin D by mouth as well, by licking the skin.
Creating an industry estimated to have a 2015 value of $37 billion, there are more than 50,000 dietary supplement products marketed just in the United States, where about 50% of the American adult population consumes dietary supplements. Multivitamins are the most commonly used product. For those who fail to consume a balanced diet, the United States National Institutes of Health states that certain supplements "may have value."
Pregnant women need extra vitamin A for fetal growth and tissue maintenance and for supporting their own metabolism . The World Health Organization estimates that 9.8 million pregnant women around the world have xerophthalmia as a result of vitamin A deficiency . Other effects of vitamin A deficiency in pregnant and lactating women include increased maternal and infant morbidity and mortality, increased anemia risk, and slower infant growth and development.
Torregrosa, J. V., Bover, J., Cannata, Andia J., Lorenzo, V., de Francisco, A. L., Martinez, I., Rodriguez, Portillo M., Arenas, L., Gonzalez, Parra E., Caravaca, F., Martin-Malo, A., Fernandez, Giraldez E., and Torres, A. Spanish Society of Nephrology recommendations for controlling mineral and bone disorder in chronic kidney disease patients (S.E.N.-M.B.D.). Nefrologia. 2011;31 Suppl 1:3-32. View abstract.
Vitamin A is available in multivitamins and as a stand-alone supplement, often in the form of retinyl acetate or retinyl palmitate . A portion of the vitamin A in some supplements is in the form of beta-carotene and the remainder is preformed vitamin A; others contain only preformed vitamin A or only beta-carotene. Supplement labels usually indicate the percentage of each form of the vitamin. The amounts of vitamin A in stand-alone supplements range widely . Multivitamin supplements typically contain 2,500–10,000 IU vitamin A, often in the form of both retinol and beta-carotene.
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 .
The Age-Related Eye Disease Study (AREDS), a large randomized clinical trial, found that participants at high risk of developing advanced AMD (i.e., those with intermediate AMD or those with advanced AMD in one eye) reduced their risk of developing advanced AMD by 25% by taking a daily supplement containing beta-carotene (15 mg), vitamin E (400 IU dl-alpha-tocopheryl acetate), vitamin C (500 mg), zinc (80 mg), and copper (2 mg) for 5 years compared to participants taking a placebo .
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 . 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 . At the present time, the USDA’s FoodData Central 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.
The European Union's (EU) Food Supplements Directive of 2002 requires that supplements be demonstrated to be safe, both in dosages and in purity. Only those supplements that have been proven to be safe may be sold in the EU without prescription. As a category of food, food supplements cannot be labeled with drug claims but can bear health claims and nutrition claims.
Mockenhaupt, F. P., Reither, K., Zanger, P., Roepcke, F., Danquah, I., Saad, E., Ziniel, P., Dzisi, S. Y., Frempong, M., Agana-Nsiire, P., Amoo-Sakyi, F., Otchwemah, R., Cramer, J. P., Anemana, S. D., Dietz, E., and Bienzle, U. Intermittent preventive treatment in infants as a means of malaria control: a randomized, double-blind, placebo-controlled trial in northern Ghana. Antimicrob.Agents Chemother. 2007;51(9):3273-3281. View abstract.
Bischoff-Ferrari, H. A., Dawson-Hughes, B., Platz, A., Orav, E. J., Stahelin, H. B., Willett, W. C., Can, U., Egli, A., Mueller, N. J., Looser, S., Bretscher, B., Minder, E., Vergopoulos, A., and Theiler, R. Effect of high-dosage cholecalciferol and extended physiotherapy on complications after hip fracture: a randomized controlled trial. Arch.Intern.Med. 5-10-2010;170(9):813-820. View abstract.
Heart failure. Some early research suggests that people with low vitamin D levels have an increased risk of developing heart failure compared to those with higher vitamin D levels. Some research shows that taking vitamin D supplements can help reduce the risk of developing heart failure in some women. Also, most research suggests that taking vitamin D supplements may decrease the risk of death in people with heart failure.
Niu, C., Yan, H., Yu, T., Sun, H. P., Liu, J. X., Li, X. S., Wu, W., Zhang, F. Q., Chen, Y., Zhou, L., Li, J. M., Zeng, X. Y., Yang, R. R., Yuan, M. M., Ren, M. Y., Gu, F. Y., Cao, Q., Gu, B. W., Su, X. Y., Chen, G. Q., Xiong, S. M., Zhang, T. D., Waxman, S., Wang, Z. Y., Chen, Z., Hu, J., Shen, Z. X., and Chen, S. J. Studies on treatment of acute promyelocytic leukemia with arsenic trioxide: remission induction, follow-up, and molecular monitoring in 11 newly diagnosed and 47 relapsed acute promyelocytic leukemia patients. Blood 11-15-1999;94(10):3315-3324. View abstract.
In the United States, it is against federal regulations for supplement manufacturers to claim that these products prevent or treat any disease. Companies are allowed to use what is referred to as "Structure/Function" wording if there is substantiation of scientific evidence for a supplement providing a potential health effect. An example would be "_____ helps maintain healthy joints", but the label must bear a disclaimer that the Food and Drug Administration (FDA) "has not evaluated the claim and that the dietary supplement product is not intended to "diagnose, treat, cure or prevent any disease," because only a drug can legally make such a claim. The FDA enforces these regulations, and also prohibits the sale of supplements and supplement ingredients that are dangerous, or supplements not made according to standardized good manufacturing practices (GMPs).
Deficiencies of vitamins are classified as either primary or secondary. A primary deficiency occurs when an organism does not get enough of the vitamin in its food. A secondary deficiency may be due to an underlying disorder that prevents or limits the absorption or use of the vitamin, due to a "lifestyle factor", such as smoking, excessive alcohol consumption, or the use of medications that interfere with the absorption or use of the vitamin. People who eat a varied diet are unlikely to develop a severe primary vitamin deficiency, but may be consuming less than the recommended amounts; a national food and supplement survey conducted in the US over 2003-2006 reported that over 90% of individuals who did not consume vitamin supplements were found to have inadequate levels of some of the essential vitamins, notably vitamins D and E.