Re: Vitamin D and chronic disease prevention
We are amazed that editors of the BMJ are advising not to supplement vitamin D to those who are apparently deficient. They concluded this from the umbrella review of Theodoratou et al.: “To improve health and prevent chronic disease, we should stick to what is proven: encourage better lifestyles in general and target established risk factors in people at elevated risk.”. However, Theodoratou et al. used such stringent criteria for risk of bias, we believe that once these criteria are applied on research on ‘proven’ healthy lifestyle factors, also these relationships will be refuted. Publication bias exists over the entire scope of scientific data.
In fact, are we forgetting nothing can ever be definitely proven? Our scientific knowledge is based on many different lego-bricks, some large, and some small. None of the bricks cover the complete truth, but together they give us a glimpse of what the truth may be. All too often we scientists present our research findings as having proven the causal relationship between x and y. We should realize that every study is just a part of the lego-castle.
Why should we be afraid of (normal supplementation of) vitamin D? The editor’s suggestion of it being dangerous and leading to hypercalcemia by referring to a letter to the editor from the fifties and a paper on idiopathic hypercalcemia is curious. The toxicity of a two-year dose of vit D is minimal and daily supplementation with vitamin D doses of 10.000 iU per day[6,7] is proven to be safe. On the other hand, drinking a one week quantity of water within an hour is killing but no one talks about that!
It is unwise and potentially dangerous to refute the beneficial effects of vitamin D. Vitamin D supplementation has chased rickets out of the western world and every day new studies are published to confirm the detrimental effects of a severely deficient vitamin D status.[2,8] For instance, in the same issue of BMJ, Chowdhurry et al. showed that the population attributable risk for death due to vitamin D deficiency is about 13%. Compare this with about 20% for smoking, about 11% for physical inactivity, and about 9% for alcohol consumption and you have a glimpse of the importance of a sufficient vitamin D status compared to a healthy lifestyle. A sufficient vitamin D status is - as well as a healthy lifestyle - very important for good health.
Dr. Marieke Hoevenaar-Blom, epidemiologist
Dr. Jos Wielders, clinical chemist and
Dr. Paul Hogeman, pediatrician
1. Welsh P, Sattar N. Vitamin D and chronic disease prevention. BMJ. 2014 Apr 1;348:g2280. doi: 10.1136
2. Theodoratou E, Tzoulaki I, Zgaga L, Ioannidis JP. Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational studies and randomised trials. BMJ. 2014 Apr 1;348:g2035. doi: 10.1136/bmj.g2035.
3. Lightwood R. Hypercalcaemia in infants and vitamin D. BMJ 1956;2:149.
4. Schlingmann KP, Kaufmann M, Weber S, et al. Mutations in
CYP24A1 and idiopathic infantile hypercalcemia. N Engl J Med 2011;365:410-21
5. Cipriani C, Romagnoli E, Scillitani A, et al. Effect of a single oral dose of 600,000 IU of cholecalciferol on serum calciotropic hormones in young subjects with vitamin D deficiency: a prospective intervention study. J Clin Endocrinol Metab. 2010 Oct;95(10):4771-7. doi: 10.1210/jc.2010-0502. Epub 2010 Jul 21.
6. Hathcock JN1, Shao A, Vieth R, Heaney R. Risk assessment for vitamin D. Am J Clin Nutr. 2007 Jan;85(1):6-18.
7. European Food Safety Authority. Scientific opinion on the tolerable upper intake level of vitamin D. EFSA Journal 2012; 10(7): 2813-2858.
8. Chowdhury R, Kunutsor S, Vitezova A, et al. Vitamin D and risk of cause specific death: systematic review and meta-analysis of observational cohort and randomised intervention studies. BMJ. 2014 Apr 1;348:g1903. doi: 10.1136/bmj.g1903.
Competing interests: No competing interests