Be Informed, Vitamin D Affects Health, especially D3
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.
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
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