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Opinion Makers is a new MedPage Today video exclusive weekly series, presenting leaders from all areas of medicine offering their views on current topics in clinical care, research, and policy.
In this video, JoAnn Manson, MD, DrPH, at the Harvard T.H. Chan School of Public Health, discusses the state of vitamin D studies and how screening for vitamin D deficiency should be approached. Below is a transcript of her comments.
The questions of whether to screen for vitamin D deficiency or to recommend high-dose vitamin D supplementation for patients is one of the most vexing issues in clinical practice. And many clinicians are seeking guidance on these issues.
Vitamin D research is at a crossroads right now with many observational studies suggesting that low blood levels of vitamin D are associated with an increased risk of a number of chronic diseases including heart disease, cancer, and diabetes.
Yet the randomized clinical trials of high-dose vitamin D supplementation that have been done today have been generally disappointing, including a meta-analysis of trials looking at blood pressure, showing minimal to no blood pressure lowering and a recent randomized trail of high-dose vitamin D supplementation published in JAMA Internal Medicine that showed little to no benefit in terms of muscle strength, bone mineral density, and even the risk of falls.
The U.S. Preventive Services Task Force and the Institute of Medicine do not endorse universal screening for vitamin D deficiency and also recommend moderate intakes of vitamin D, 600 to 800 IU's a day consistent with the recommended dietary allowance.
However, it's important for clinicians to understand that these are public health recommendations and population guidelines for a generally healthy population. And by no means do these guidelines interfere with or preclude individualized decision-making or clinical discretion. And targeted screening for vitamin D deficiency or supplementation with higher amounts of vitamin D than the RDA are appropriate in many clinical scenarios including patients who have osteoporosis, osteomalacia, and other bone health problems, or those who have malabsorption syndromes or take medications that can interfere with vitamin D metabolism such as anticonvulsants or anti tuberculosis drugs. Patients who have minimal to any time outdoors with a number of vitamin D risk factors for vitamin D deficiency.
In a generally healthy population, however, for healthy patients, universal screening is not recommended. And also taking very high-dose supplementation is not recommended and would be advisable to avoid getting above 4,000 IU's a day under virtually any circumstances because 4,000 IU's a day has been set as the tolerable upper intake level for the population associated with adverse events. However, that may not apply to individual patients who have risk factors and have very high vitamin D requirements.
There's several large scale randomized clinical trials of vitamin D supplementation that are ongoing. And over the course of the next 2 to 3 years there should be conclusive findings from these randomized trials that will inform clinical decision-making about vitamin D supplementation. So stay tuned for the results of those trials. Thank you so much for your attention. This is Dr. JoAnn Manson.