January's Health Genie: Vitamin D

Note:This article is not meant as a substitute for proper medical advice. Please consult with your medical practitioner before using any type of remedy, herbal or otherwise.

Dear Health Genie,

For the last several years, we have been hearing about the benefits of vitamin D. My husband and I are active, healthy and eat a varied diet, so we don’t take many supplements. Can you tell us a little bit about vitamin D and whether it might hold some benefits for us as we age? 

Thank you,
Dee Winter

Dear Dee,

Improved calcium absorption and bone maintenance are among the most widely accepted benefits of vitamin D. Vitamin D promotes calcium absorption in the gut and promotes maintenance of calcium concentrations in the blood. Vitamin D also influences activities of osteoblasts and osteoclasts, cells that build, break down and remodel bone.

There are even studies correlating vitamin D supplementation with fewer falls among seniors. The reasons are not well understood and correlation is not the same as cause, but this is an interesting finding for those preparing for graceful aging. One theory is that vitamin D supports retention of skeletal muscle and, therefore, aids in stability.  

Vitamin D becomes particularly pertinent to winter health when we consider recent research on the role that adequate vitamin D may have in supporting healthy respiratory immunity. Current research suggests that vitamin D promotes production of antimicrobial peptides as part of our innate immune system. Some sources state that flu sufferers with higher levels of vitamin D experience less inflammation and less severe symptoms.

Furthermore, vitamin D is being promoted as a winter mood support vitamin and some researchers have found a correlation between mood and vitamin D levels. The research is not as strong for this use, but with all the other benefits of vitamin D it is probably worthwhile to ensure you are getting an adequate supply.

You may hear statements about vitamin D being considered a hormone. This refers to the fact that it can be synthesized and is not always necessary in the diet. Also the structure is cholesterol-like, which is a trait of many of the major hormones. Most importantly vitamin D regulates functions in many parts of the body according to the concentration circulating in the blood. Most traditionally, vitamin D is considered a nutrient. It is supplied naturally by some foods and vitamin D deficiency can cause disease. As a nutrient, it is grouped with the fat soluble vitamins.

General nutrition references state that in humans about 90% of our active form of vitamin D is derived from synthesis in the skin. Here in Burlington, sunlight is too weak from late October to through early March for us to synthesize vitamin D. This is why in Northern latitudes we are particularly concerned with supplementing vitamin D.

The Recommended Daily Allowance values (RDAs) for vitamin D are as follows:

Based on our disadvantage at capturing D from the sun, Vermonters may want to aim higher with D supplementation in the winter.

Apart from wool oil, commercial sources for vitamin D found in supplements are synthetic, cod liver oil and oils from other fish, algae and lichen. Suggested dietary sources are salmon, herring, mackerel, tuna, sardines, liver, eggs, fortified dairy and fortified cereal. Dark leafy greens contain small amounts of vitamin D, but this source is considered negligible. Some mushrooms contain variable amounts of D₂ a precursor to D₃.  D₃ is considered by far the superior form to supplement because it is closer to the form our bodies are ready to use. Almost all vitamin D on the market now is D₃ with the exception of a few labeled vegan.

If you have more questions about the sources and choices available in vitamin D supplements, please ask the staff in City Market’s Wellness Department for assistance.

Sincerely,
The Health Genie

Sources Cited:

• Girgis, C.M., Clifton-Bligh RJ, Hamrick M.W., Holick, M.F., Gunton, J.E. 2012.  The roles of vitamin D in skeletal muscle: form, function, and metabolism. Endocrinology Review.   http://www.ncbi.nlm.nih.gov/pubmed/231696762012 Nov 20.  Accessed on 12/13/2012. 
• Ilkka Laaksi (2012). Vitamin D and respiratory infection in adults. Proceedings of the Nutrition Society, 71, pp 90-97. doi:10.1017/S0029665111003351.  http://journals.cambridge.org/abstract_S0029665111003351.  Accessed on 12/13/2012.
• Jun Iwamoto, Tsuyoshi Takeda, Hideo Matsumoto. 2012. Strategy for prevention of hip fractures in patients with Parkinson's disease. World Journal of Orthopedics.2012 Sep 18;3(9):137-41. doi: 10.5312/wjo.v3.i9.137. http://www.ncbi.nlm.nih.gov/pubmed/23173109.  Accessed on 12/13/2012.
• Waldron, N, Hill A.M., Barker, A.  2012.  Falls prevention in older adults – Assessment and management.  Australian Family Physician. 2012 Dec;41(12):930-5.
• http://www.ncbi.nlm.nih.gov/pubmed/23210114.  Accessed on 12/13/2012.
• Wilkins C.H., Sheline Y.I., Roe C.M., Birge S.J., Morris J.C..  Vitamin D deficienct is associated with low mood and worse cognitive performance in older adults.  American Journal of Geriatric Psychiatry.  2006 Dec;14(12):1032-40.  http://www.ncbi.nlm.nih.gov/pubmed/17138809.  Accessed on 12/13/2012.