This site uses cookies to store information on your computer. Learn more x


Providing perspectives on recent research into vitamins and nutritionals


Be Informed, Vitamin D Affects Health, especially D3

By Michael McBurney

Many of you will have heard low vitamin D levels are associated with an increased risk of Alzheimer’s disease.  The risk was 2.25 higher for individuals who were severely deficient (serum 25(OH)D3 < 25 nmol/L) and 1.5 times higher for deficient (≥25 to <50 nmol/L). To be clear, this is a correlative study describing a relationship.

In a new report, Ford conclude baseline vitamin D concentrations do not predict mortality in adults with impaired lung function. It is true; that was the finding. But it was in adults with average serum 25(OH)D3 concentrations of 70-75 nmol/L.  Once again, this study suggests that people interested in participating in research studies have better than average nutritional status. Ford reports on men and non-pregnant women who agreed to participate in pulmonary function test. Men and women with average serum 25(OH)D3 concentrations >70 nmol/L.

Realistically, most of us are likely to be one of the 42% of American adults with 25(OH)D3 concentrations <50 nmol/L. The prevalence of vitamin D deficiency goes up to 48% for persons 55-64y and over 80% for black adults. These prevalence numbers use a vitamin D cutoff of 50 nmol/L not 70-75 nmol/L concentrations.  Shinkov and colleagues report winter rates of vitamin D deficiency are highest among European males with lower education and smokers. Most importantly, the 95% confidence level  for the entire study population did not even encompass 50-55 nmol/L.  Basically, Ford reports on a very small subpopulation of individuals which has little relevance to the general population.

So what does one do to increase vitamin D status outside of spending time in the sun? Few foods outside of fatty fish are naturally rich in vitamin D. Without fortification, milk isn’t even a good source. Foods and supplements can contain vitamin D3 (cholecalciferol) or D2 (ergocalciferol). Vitamin D3 is more effective than D2 in maintaining optimal vitamin D concentrations.  Exposing edible mushrooms to ultraviolet B light increases vitamin D2 content but does not significantly change serum 25(OH)D2 or 25(OH)D3 concentrations. So mushrooms don’t seem to be the solution.

In summary, research findings in vitamin D-sufficient individuals have little relevance to most people. Most people should be using a vitamin D supplement, especially in winter months. When choosing foods or supplements to increase your vitamin D status, select products with vitamin D3 over D2.

Main Citations

Ford ES. Lung function, 25-hydroxyvitamin D concentrations and mortality in US adults. 2014 Eur J Clin Nutr doi: 10.1038/ejcn.2014.162

Mehrotra A, Calvo MS, Beelman RB, Levy E, Siuty J, Kalaras MD, Uribarri J. Bioavailability of vitamin D2 from enriched mushrooms in prediabetic adults: a randomized controlled trial. 2014 Eur J Clin Nutr doi: 10.1038/ejcn.2014.157

Other Citations

Littlejohns TJ, Henley WE, Lang IA, Annweiler C, Beauchet O, Chaves PHM, Fried L, Kestenbaum BR, Kuller LH, Langa KM, Lopez OL, Kos K, Soni M, Llewellyn DJ. Vitamin D and the risk of dementia and Alzheimer disease. 2014 Neurol doi: 10.1212/WNL.0000000000000755

Forrest KYZ, Stuhidreher WL. Prevalence and correlates of vitamin D deficiency in US adults. 2011 Nutr Res doi: 10.1016/j.nutres.2010.12.001

Sesso HD, Gaziano JM, VanDenburgh M, Hennekens CH, Glynn RJ, Buring JE. Comparison of baseline characteristics and mortality experience of participants and nonparticipants in a randomized clinical trial: the Physicians’ Health Study. 2002 Controlled Clin Trials doi: 10.1016/S0197-2456(02)00235-0

Shinkov A, Borissova A-M, Dakovska L, Vlahov J, Kassabova L, Svinarov D. Winter 25-hydroxyvitaminD levels in young urban adults are affected by smoking, body mass index and educational level. 2014 Eur J Clin Nutr doi: 10.1038/ejcn.2014.163