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Vitamin Doubt: Evidence Still Murky on D's Benefits — Physician’s First Watch

Medical News |
April 2, 2014

Vitamin Doubt: Evidence Still Murky on D's Benefits

By Joe Elia

Two BMJ meta-analyses on vitamin D have found that evidence for benefit is narrow and that if there is a benefit, the form of supplementation has a bearing on its magnitude.

One, an "umbrella review" of meta-analyses and systematic reviews, found no "highly convincing" evidence linking circulating vitamin D levels with any of 137 outcomes, such as colorectal cancer or hypertension. It found a "probable" link for only three outcomes: birth weight, parathyroid hormone levels in dialysis patients, and dental caries in children.

The other meta-analysis found, in observational data, a salutary effect of increasing vitamin D levels on mortality. In randomized, controlled trials, the analysis found a significant mortality benefit from vitamin D3 supplements, but not from the D2 form.

Editorialists champion new trials focusing on risks as well as benefits of supplementation, and advise against measuring circulating vitamin D beyond bone-disease-related conditions.

Reader Comments (7)

Elizabeth Murray Physician, Oncology, Cape Town South Africa

I think its far more complex than mentioned here. Effect of MATERNAL Vit D on diseases in later life is not mentioned and may be the key. I screen my breast cancer patients and boost where indicated - some have levels below 10ng/ml + all need attention to bone health . Also very inexpensive to monitor and boost accordingly BUT I think we need to be very careful of mega doses if we do not monitor

shailesh shah Physician, Critical Care Medicine, india

it is over asked 4 test.clinicaly less relavent

Jared Ellis, MD Physician, Family Medicine/General Practice, University of Alabama Family Medicine Residency Program

I have often found in the AA population, esp in women, very low 25-OH vit D levels. New evidence suggests a different binding protein relationship, so lower is not as low, but often these patients have elevated CPK levels which correct with supplementation. Those with very low vitamin D levels often don't tolerate statins, which has biologic plausibility. Therefore, I have and likely will continue to check this in such patients before starting statins, and if CPK levels are up, I see that this is normalized before initiating statin therapy.

* * Physician, Family Medicine/General Practice, Community Physician

I would not be surprised if patients coming from the alcoholics anonymous community had low vitamin levels, as well as increased incidence of myositis. These people probably should receive screening.

Martin Rossman MD Physician, Preventive Medicine

Why is the mortality benefit being given short shrift here? Seems like the most important end point of all.

William DeMedio Physician, Family Medicine/General Practice, Community Physician

One of the biggest lies I was told in medical school was that we could decrease mortality. The fact is we can only delay the inevitable.

That said, a "salutary" effect on mortality is a very rare bird indeed. There are only a few medications we prescribe that have shown better than a weak "mortality benefit" .

Perhaps we should consider cutting back on measuring levels of vitamin D except where clinically necessary and instead emphasize the proper intake of vitamin D.

Aliceann Carlton, LCPC Other Healthcare Professional, Other, Eastern Montana Community mental Health Center

Meta analyses are better used to indicate possible research paths than as outcomes. Studies chasing down cause and effect for Vitamin D are specious. What's not included is the link to cytokine modulation, immune system responses to pandemic illnesses because there isn't a specific variant to measure. D3 in particular is remarkable in this capacity.

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