December 19th, 2011

More Uncertainty About Vitamin D Supplements

Although many experts believe that vitamin D deficiency may play a significant role in cardiovascular disease, there is little evidence to support the use of vitamin D supplements for the prevention of cardiovascular disease. In a narrative review published in Annals of Internal Medicine, Cora McGreevy and David Williams write that the few available studies have been inconclusive and difficult to interpret. More and bigger studies are needed to test the possible beneficial effects of vitamin D supplements, they write.

A second publication in Annals presents an updated meta-analysis of studies of vitamins D and calcium supplements for fracture and cancer protection. The results will inform forthcoming draft recommendations from the USPSTF. Analysis of data from 19 trials and 28 observational studies found that for fracture prevention vitamin D alone was not effective, but that the combination of vitamin D and calcium supplements was effective in older patients. The evidence for vitamin D in cancer prevention is inconclusive, write the authors. An additional area of concern is the proper dosing of vitamin D, since too much vitamin D may cause renal and urinary tract stones.

2 Responses to “More Uncertainty About Vitamin D Supplements”

  1. Jose Gros-Aymerich, MD says:

    The problem is known from a while, Calcium and Vit D supplements that are prescribed, mainly for women, to prevent osteopenia and osteoporosis, are blamed with the same increase in the incidence of kidney stones, but also with a worsened Cardio Vascular Disease profile. High Uric acid levels are also a risk factor for CV disease, but it’s not known if Uric Acid lowering drugs do improve the cardiovascular risk. Low levels of vitamin D are linked to a big span of diseases, and authors disagree in the desirable levels and the benefits of supplements. It seems most will accept that levels below 20 must receive therapy, that 20-30 and above are acceptable, and more than 50 may be the danger threshold. To obtain the required levels of Vit D, a minimum of 12 hours a week of sun exposure are needed, hard to meet for many in the current living frame, but low Vit D levels may be linked also to a reduction in QoL from several minor symptoms. In the elderly, annual high dose Vit D is detrimental, some point to weekly Vit D3 dosing as the sole useful approach. A generalized use of Vit D testing and correction may cause a big increase in healthcare costs, and as the subject is gaining popularity, more research on it to reach an evidence-based policy for the Vit D case is very appropiate.

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  2. The quality of current DATA on vitamin D would allow anyone to conclude whatever they chose to conclude. Most studies use doses inadequate to raise serum levels of Vitamin D. That said, many good retrospective analyses show significant benefit of vitamin D supplementation.

    It is not logical to make the association between higher levels of vitamin D and lower incidence of heart attacks, then devise a study which is too short in duration, uses inadequate doses of vitamin D and does not measure resultant levels and then concludes that the value is not there. D detractors however rely heavily on these non-science studies to support their points.

    Stay tuned and in 10 to 15 years, we will see the value of vitamin D supplementation,which I think will prove to be very positive. In the mean time, looking at the potential benefits with heart attacks and cancer and the minimal risk of kidney stones, and the trivial cost, I feel that vitamin D should be supplemented now; it is foolish to wait 15 years to begin.

    Competing interests pertaining specifically to this post, comment, or both: