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Vitamins + Supplements

Vitamin D: What’s the “Right” Level”

Many of my patients who come into the office for their physical exams ask to have their vitamin D levels checked. They may have a family member with osteoporosis, or perhaps they have had bone thinning themselves. Mostly, they want to know that they’re doing everything they can to keep their bones strong. Vitamin D is critical for healthy bones. But when we check that blood level, how to act on the result is the subject of great controversy in medical-research land.

Pinpointing a “healthy” vitamin D level is tricky

So, what is the current cutoff value at which people are considered “low,” and thus at risk for developing bone thinning and having fractures? (We are talking about the blood level of 25-hydroxy-vitamin D, which is usually measured in nanograms per milliliter.) Ah. This is where there is a lot of argument.

In 2010, the venerable Institute of Medicine (IOM) issued a report based on lengthy examination of data by a group of experts. To sum up, they estimated that a vitamin D level of 20 ng/mL or higher was adequate for good bone health, and subsequently a level below 20 was considered a vitamin D deficiency.

In my practice, and in most, it is not uncommon to see a vitamin D level less than 20. When that happens, we tell the patient that they are deficient and recommend fairly aggressive replenishment, as well as ongoing supplementation. The majority of folks have a level between 20 and 40, in my experience, and this is corroborated by the IOM’s findings in that 2010 report.

But in 2011, the respected Endocrine Society issued a report urging a much, much higher minimum blood level of vitamin D. The society’s clinical practice guideline was developed by experts in the field assigned to a Vitamin D Task Force, and they concluded: “Based on all the evidence, at a minimum, we recommend vitamin D levels of 30 ng/mL, and because of the vagaries of some of the assays, to guarantee sufficiency, we recommend between 40 and 60 ng/mL for both children and adults.”

But wait, there’s more…

The most recent opinion on the right target level of vitamin D is presented in an article titled “Vitamin D Deficiency: Is There Really a Pandemic?” published in the New England Journal of Medicine. In this piece, several of the leading epidemiologists and endocrinologists who were on the original IOM committee argue for a lowering of the currently accepted cutoff level of 20, stating that the level they estimated as acceptable was never intended to be used to define vitamin D deficiency. They feel that we are overscreening for vitamin D deficiency, and unnecessarily treating individuals who are perfectly fine.