Don’t be Misled, Vitamin D is Safe and Required for Health
I wonder if the American Medical Association is pleased with Dr Agus’ insinuation that we shouldn’t trust our doctor. In the CBSNews this morning, he says, “If your doctor says you should be on vitamin D, I want you to say where is the data it will benefit me and challenge for that data.” It is an extreme position for one doctor to casually dismiss evidence that 9 out of 10 Americans are not getting enough vitamin D. When Agus tells Gayle King she is unlikely to have rickets, does he realize that 31% of African Americans are at risk of vitamin D deficiency? Vitamin D deficiency does indeed cause rickets.
What caused Dr Agus to rant about the dangers of vitamin D? Apparently, it was a JAMA report concluding vitamin D supplementation does not lower blood pressure (BP). This was not a safety study. It was a systematic review and meta-analysis of randomized controlled trials (RCTs). Beveridge and colleagues included RCTs which did not have BP change as a primary outcome and regardless of baseline vitamin D status. Fourteen studies used monthly or less frequent dosing of vitamin D. Although not highlighted in the abstract (or headlines), subgroup analysis showed a significant effect of vitamin D supplementation on diastolic BP in individuals with baseline 25(OH)D3 concentrations ≥ 20 ng/mL (50 nmol/L). Interesting that this finding is not mentioned in the abstract or the discussion given that Witham and colleagues previously reported a significant decrease in BP with vitamin D supplementation in individuals with low vitamin D status and elevated baseline BP.
What about the dangers emphasized by Dr Agus of vitamin D supplementation in older women with respect to fractures? Well, Beveridge and colleagues acknowledge “this is the first study to demonstrate increased risk”. They write, “Our study used the largest total annual dose of vitamin D (500,000 IU) reported in any randomized controlled trial, raising the possibility that adverse outcome is dose-related.”
Agus makes reference to the study of Sanders and colleagues which reported a 26% increased risk of fractures in elderly women given a single 500,000 IU dose of vitamin D. First, this is an extremely high dose which should only be used under medical supervision. Second, other studies using lower doses have found benefits. Trivedi and colleagues gave 4 monthly oral doses of 100,000 IU and reported a 22% reduction in risk of first fracture and 12% in mortality risk (vs placebo) in men and women. Larsen and colleagues reported a 16% reduction in fracture incidence rate in community-dwelling elderly people.
To be fair, not all vitamin D supplementation trials show significant reductions in fracture risk. Many trials also fail to assess vitamin D status (by measuring serum 25(OH)D3 concentrations). Like most nutrients, too little, and too much, are not healthy. Vitamin D is not a drug. Vitamin D is required to prevent rickets. Vitamin D is required for normal functioning of cells, including the kidneys which play a role in blood pressure. Is it important to maintain adequate vitamin D status? The answer is yes.
The Institute of Medicine recommends serum 25(OH)D3 concentrations ≥ 50 nmol/L. When the majority of Americans do not meet these standards, a single physician should not undermine the recommendations of the medical field. What is the benefit to public health for one medical doctor to publically challenge the vitamin D recommendations of many doctors?
If alive, Hippocrates would be shaking his head in dismay.
Beveridge LA, Struthers AD, Khan F, Jorde R, Scragg R, Macdonald HM, Alvarez JA, Boxer RS, Dalbeni A, Gepner AD, Isbel NM, Larsen T, Nagpal J, Petchey WG, Stricker H, Strobel F, Tangpricha V, Toxqui L, Vaquero P, Wamberg L, Zitterman A, Witham MD, for the D-PRESSURE Collaboration. Effect of vitamin D supplementation on blood pressure: A systematic review and meta-analysis incorporating individual patient data. 2015 JAMA Intern Med doi: 10.1001/jamainternmed.2015.0237
Sanders KM, Stuart AL, Williamson EJ, Simpson JA, Kotowicz MA, Young D, Nicholson GC. Annual high-dose oral vitamin d and falls and fractures in older women: A randomized controlled trial. 2010 JAMA doi: 10.1001/jama.2010.594
Witham MD, Nadir MA, Struthers AD. Effect of vitamin D on blood pressure: a systematic review and meta-analysis. 2009 J Hypertens doi: 10.1097/HJH.0b013e32832f075b
Trivedi D, Doll R, Khaw KT. Effect of four monthly oral vitamin D supplementation on fractures and mortality in men and women living in the community: randomized double blind controlled trial. 2003 BMJ doi: 10.1136/bmj.326.7387.469
Larsen ER, Mosekilde L, Foldspang A. Vitamin D and calcium supplementation prevents osteoporotic fractures in elderly community dwelling residents: A pragmatic population-based 2-year intervention study. 2003 JBMR doi: 10.1359/JBMR.0301240
Bischoff-Ferrari HA, Willett WC, Orav EJ, Lips P, Meunier PJ, Lyons RA, Flicker L, Wark J, Jackson RD, Cauley JA, Meyer HE, Pfeiffer M, Sanders KM, Stahlein HB, Theiler R, Dawson-Hughes B. A pooled analysis of vitamin D dose requirements for fracture prevention. 2012 NEJM doi: 10.1056/NEJM01109617