It is estimated a billion people do not get enough vitamin D worldwide and that at least 70 percent of children and adults in the US are vitamin D deficient. The cause of deficiency is a combination of not enough sun exposure, and insufficient vitamin D from sunshine and in the diet. Recommendations to decrease sun exposure as well as the advent of the clothes dryer put an end to hanging the family laundry. Additionally television and video games have kept children playing indoors especially in the US.
Vitamin D plays many roles in human health. It is a fat-soluble vitamin that is found in very few foods. It is often added to fortify milk and cereal and is available as a dietary supplement. It is produced by the body when the skin is exposed to sunlight through a series of chemical reactions in the body. “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 needed for bone growth and bone health. “Without sufficient vitamin D, bones can become thin, brittle, or misshapen. Vitamin D sufficiency prevents rickets in children and osteomalacia in adults. (1) Calcium along with vitamin D helps protects aging adults from osteoporosis.
Vitamin D has numerous other roles in the body, “…including modulation of cell growth, neuromuscular and immune function, and reduction of inflammation (2, 3)
It plays a role in managing musculoskeletal pain from rheumatoid arthritis and other diseases. It is not uncommon for people with chronic pain to have a vitamin D deficiency.
You may not know that a vitamin D deficiency has an increased risk for cancer and autoimmune diseases, such as rheumatoid arthritis MS, and lupus. Studies suggest that “… efforts to improve vitamin D status, for example by vitamin D supplementation, could reduce cancer incidence and mortality at low cost, with few or no adverse effects.” (3). Another study reveals that the vitamin D levels in the body can predict weight loss success..(4)
Vitamin D plays a vital role in the absorption of calcium which can be a risk for people with RA. It protects against seasonal affective disorder which in susceptible people can bring on a seasonal form of depression
“Ellen M. Mowry, M.D., M.C.R., an assistant professor of neurology at John Hopkins University School of Medicine and the principle investigator of a multicenter clinical trial of vitamin D supplementation, has been conducting the research with regard to vitamin D and multiple sclerosis since she worked at the University of California in San Francisco. Her research finds that a strong correlation exists between vitamin D levels found in blood samples and the characteristic brain lesions of MS.” (5)
Dr. Mowry points out however that vitamin D is not the cure for MS. Vitamin D is a hormone and over the counter supplements most likely will not contain ingredients that can provide the same co-factors that are found in natural vitamin D sources.(5)
Requirements and Sources
Sources of vitamin D include fish, such as salmon, mackerel and tuna, egg yolks and mushrooms. (6) Just 15 minutes of sun exposure can provide 20,000 IU of Vitamin D without sunblock. It is not recommended that you expose unportected skin to the sun for long amounts of time due to the danger skin damage and risk of skin cancer.
How much vitamin D you need depends on how deficient you are. It is recommended that you supplement by adding 1-2,000 IU of vitamin D per day.
Malabsorption of vitamin D can be affected by some drugs such as Hydroxychloroquine (Plaquenil) and corticosteroids, which are prescribed for rheumatoid arthritis. A blood test called, 25-hydroxy vitamin D test can evaluate your vitamin D levels. (7) “Both the weight-loss drug orlistat (Xenical and Alli) and the cholesterol-lowering drug cholestyramine (Questran, LoCholest, and Prevalite) can reduce the absorption of vitamin D and other fat-soluble vitamins (8,9,10) Both phenobarbital and phenytoin (Dilantin), used to prevent and control epileptic seizures, increase the metabolism of vitamin D (which can) inactive compounds and reduce calcium absorption.” (11, 12)
Excessive sun exposure does not result in vitamin D toxicity and vitamin D from food is not likely to cause toxicity. Toxicity is more likely from high intakes of dietary supplements. Symptoms range from “…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. (12) “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.” (13)
- Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: National Academy Press, 2010.
- 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.
- The Role of Vitamin D in Cancer Prevention by Cedric F. Garland, DrPH, Frank C. Garland, PhD, Edward D. Gorham, PhD, MPH, Martin Lipkin, MD, Harold Newmark, ScD, Sharif B. Mohr, MPH, and Michael F. Holick, MD, PhD; Am J Public Health. 2006 February; 96(2): 252–261; January 18, 2005.
- Ellen M. Mowry, Emmanuelle Waubant, Charles E. McCulloch, Darin T. Okuda, Alan A. Evangelista, Robin R. Lincoln, Pierre-Antoine Gourraud, Don Brenneman, Mary C. Owen, Pamela Qualley, Monica Bucci, Stephen L. Hauser, Daniel Pelletier. Vitamin D status predicts new brain magnetic resonance imaging activity in multiple sclerosis. Annals of Neurology, 2012; 72 (2): 234
- Earthman CP, Beckman LM, Masodkar K, Sibley SD: The link between obesity and low circulating 25-hydroxyvitamin D concentrations: considerations and implications. International Journal of Obesity (London) 36(3): 387-396, 2012.
- Buckley LM, Leib ES, Cartularo KS, Vacek PM, Cooper SM. Calcium and vitamin D3 supplementation prevents bone loss in the spine secondary to low-dose corticosteroids in patients with rheumatoid arthritis. A randomized, double-blind, placebo-controlled trial. Ann Intern Med 1996;125:961-8.
- Lukert BP, Raisz LG. Glucocorticoid-induced osteoporosis: pathogenesis and management. Ann Intern Med 1990;112:352-64.
- de Sevaux RGL, Hoitsma AJ, Corstens FHM, Wetzels JFM. Treatment with vitamin D and calcium reduces bone loss after renal transplantation: a randomized study. J Am Soc Nephrol 2002;13:1608-14.
- McDuffie JR, Calis KA, Booth SL, Uwaifo GI, Yanovski JA. Effects of orlistat on fat-soluble vitamins in obese adolescents. Pharmacotherapy 2002;22:814-22.
- Compston JE, Horton LW. Oral 25-hydroxyvitamin D3 in treatment of osteomalacia associated with ileal resection and cholestyramine therapy. Gastroenterology 1978;74:900-2.
- Gough H, Goggin T, Bissessar A, Baker M, Crowley M, Callaghan N. A comparative study of the relative influence of different anticonvulsant drugs, UV exposure and diet on vitamin D and calcium metabolism in outpatients with epilepsy. Q J Med 1986;59:569-77.
- Jones G. Pharmacokinetics of vitamin D toxicity. Am J Clin Nutr 2008;88:582S-6S.
- Institute of Medicine Committee to Review Dietary Reference Intakes for Vitamin D and Calcium. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: National Academies Press; 2011.
- Otten JJ, Hellwig JP, Meyers LD. Vitamin D. In: Dietary Reference Intakes: The Essential Guide to Nutrient Requirements. Washington, DC: National Academies Press, 2006.