Vitamin D is fat soluble vitamin that functions as a pro-hormone that is involved in bone health, maintaining healthy calcium levels in the blood and bones, immune health, it enhances insulin secretion, and so much more.
A study published in the American Journal of Clinical Nutrition in 2014 found that middle-age men and women with higher blood levels of vitamin D lived longer than those with lower levels. The 13 year prospective study was performed in Britain and included 14,641 men and women aged 42– 82 years old. “This inverse association was consistent after adjustment for age, sex, month of blood draw, BMI, physical activity, smoking, alcohol intake, plasma vitamin C concentrations, occupational social class, education, diabetes history, history of cardiovascular disease, and history of cancer.”
Vitamin D is produced by the body when strong sunlight hits our skin. To make Vitamin D in our skin, the sunlight has to be the strong sun from high in the sky that is more common in near the equator and in the Northwest we get this for about 6 months per year. Why are so many people, even in studies in sunny locations near the equator such as in the Middle East, India, and Australia, still vitamin D deficient? I think it’s as simple as clothing, sunscreen, and roofs. Our modern human lifestyles do not include enough sun on our skin.
Optimal vitamin D levels have wide ranging benefits; reducing the risk of falls, decreasing cell proliferation (growth in number) of cancer cells, and improving seasonal related mood changes. If you feel sad or depressed this time of year when there’s less sunlight in Seattle (something we call seasonal affective disorder when it becomes bad enough that it’s a problem), then I recommend that you get your vitamin D levels checked by your doctor.
Cancer prevention and death rate: Low levels of vitamin D are associated with getting colon, breast, and prostate cancer in the first place, and with higher levels of death from these cancers once one has them.
How does it affect the immune system? One mechanism is that vitamin D increases the body’s production of cathelicidin, a potent antimicrobial (antibiotic) peptide that is capable of destroying tuberculosis.
Vitamin D is an inexpensive, small, easy to swallow supplement, that you don’t even have to take every day, there’s no good reason not to optimize your levels.
PMID: 17634462; Vitamin D deficiency. N Engl J Med. 2007 Jul 19;357(3):266-81.
PMID: 25332334; Serum 25-hydroxyvitamin D, mortality, and incident cardiovascular disease, respiratory disease, cancers, and fractures: a 13-y prospective population study. Am J Clin Nutr. 2014 Nov;100(5):1361-70. Available free online.
Gaby, Alan. Nutritional Medicine, Fritz Perlberg Publishing, NH, 2011.