Vitamin D

Vitamin D is a fat soluble vitamin and insufficiency affects almost 50% of the population worldwide. (Hollack)  This  occurs across all ethnicities and age groups and can mainly be attributed to lifestyle and environmental factors that reduce exposure to sunlight, which is required for ultraviolet-B (UVB)-induced vitamin D production in the skin. African American people absorb more UVB in the melanin of their skin than do white people and, therefore, require more sun exposure to produce the same amount of vitamin D. (Rostand)

Because vitamin D is fat soluble, that means it remains in fatty tissues and the liver.  Vitamin D should not be consumed in excess without medical supervision.  Toxic reactions can occur.  That’s why it’s important to check with a health care provider to determine if vitamin D deficiency is causing any health issue for you and whether or not a supplement is necessary.

Role of Vitamin D

Vitamin D influences the bones, intestines, immune and cardiovascular systems, pancreas, muscles, brain, and the control of cell cycles. Given that it is an important part in so many important systems and organs, it’s worth making sure that you are not experiencing any health related issues due to an insufficiency.  Based on where you live, and the time of year, you could be one of the 50% of the population experiencing problems.  There have been many demonstrated clinical benefits for consuming an adequate amount of vitamin D.  Evidence suggests that it can decrease risk of some cancers (Ahn), lower heart disease risk (Wang) and even help with a range of brain related issues including depression (Jorde) and cognitive conditions (Llewellyn).

Dietary Reference Intakes

So, how much vitamin D do you need for good health?  It depends on many things, including your medical history.  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) are meant to provide guidance and are largely based on age and gender. To find out what is recommended for you, visit their site.  Again, you should also be discussing this with your health care provider if you have any concerns.

Good Sources of Vitamin D

Getting exposure to sunlight (without burning your skin) is very important but can be challenging in the north at this time of year.   You can also get Vitamin D from your diet:

  • Salmon
  • Tuna
  • Sardines
  • Mackerel
  • Oysters
  • Cod Liver Oil
  • Egg Yolks
  • Fortified Milk
  • Fortified Orange Juice
  • Fortified Breakfast Cereals

Be sure to discuss any concerns you may be having with your healthcare provider. They may be addressed very easily through diet or lifestyle. In some cases, a prescribed supplement may be what you need.

References
Ahn J, Peters U, Albanes D, Purdue MP, Abnet CC, Chatterjee N, Horst RL, Hollis BW, Huang WY, Shikany JM, Hayes RB, Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial Project Team. J Natl Cancer Inst. 2008 Jun 4; 100(11):796-804.

Holick MF. Vitamin D deficiency. N Engl J Med. 2007;357:266–81.

Jorde R, Sneve M, Figenschau Y, Svartberg J, Waterloo K. Effects of vitamin D supplementation on symptoms of depression in overweight and obese subjects: randomized double blind trial.  J Intern Med. 2008 Dec; 264(6):599-609.

Llewellyn DJ, Lang IA, Langa KM, Muniz-Terrera G, Phillips CL, Cherubini A, Ferrucci L, Melzer D.  Arch Intern Med. 2010 Jul 12; 170(13):1135-41. Vitamin D and risk of cognitive decline in elderly persons.

Rostand SG. Ultraviolet light may contribute to geographic and racial blood pressure differences. Hypertension. 1997;30:150–6.

Wang TJ, Pencina MJ, Booth SL, Jacques PF, Ingelsson E, Lanier K, et al. Vitamin D deficiency and risk of cardiovascular disease. Circulation. 2008;117:503–11.

 

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