Monday, February 19, 2018

Enthusiasm should not outweigh evidence on vitamin D

- Kenny Lin, MD, MPJH

In 2005, Dr. Mark Ebell authored an AFP editorial on the rise and fall of vitamin E, subtitled "lessons in patient-oriented evidence." Observational studies associated lower vitamin E levels with coronary artery disease, leading many physicians to recommend that patients take vitamin E supplements for cardiovascular protection. 19 randomized, controlled trials later, the verdict was in: vitamin E supplementation actually increased all-cause deaths. Dr. Ebell viewed the "vitamin E saga" as an instructive cautionary tale:

It is important to remember that biochemical theory does not equal clinical benefit. Improvements in disease-oriented outcomes, such as free-radical activity, are no substitute for patient-oriented outcomes, such as all-cause mortality. Sometimes our enthusiasm for unproven treatments may harm our patients.


Physicians and patients, it turns out, were already turning to testing and treatment with another vitamin that was a marker of chronic health conditions in observational studies: vitamin D. Between 2000 and 2010, the volume of serum 25-hydroxyvitamin D levels in Medicare patients increased 83-fold, and by 2014, 4 out of 10 adults 70 years or older reported taking a daily vitamin D supplement of at least 1,000 IU, and nearly 7 percent of adults over 60 were taking more than 4,000 IUs daily, a level that the National Academy of Medicine considers to be potentially toxic.

Unfortunately, the vitamin D saga has much in common with the vitamin E saga. According to a review article in the February 15th issue of AFP by Drs. Michael LeFevre and Nicholas LeFevre, vitamin D supplementation in community-dwelling adults has not demonstrated any benefits for ischemic heart disease, cerebrovascular disease, or cancer in clinical trials. The U.S. Preventive Services Task Force and the American Academy of Family Physicians concluded that there is inadequate evidence that supplements improve psychosocial or physical functioning in persons with lower vitamin D levels.

In an accompanying editorial, I argued that the harms of routine screening and supplementation with vitamin D outweigh the benefits, especially when the costs of testing (more than $300 million annually in Medicare alone) are considered:

It is time for clinicians and patients to curb our enthusiasm for vitamin D screening and supplementation. Strategies to decrease unnecessary testing could include distributing the patient handout on vitamin D tests created by Consumer Reports for the Choosing Wisely campaign and implementing clinical decision support for ordering laboratory tests. ... Family physicians should also counsel patients on the recommended dietary allowance for vitamin D (600 IU per day in adults 70 years and younger, and 800 IU per day in adults older than 70 years), and discourage most patients from using supplements, especially in dosages near or above the tolerable upper limit of 4,000 IU per day.

1 comment:

  1. It is already so late in the game on this--we are almost beyond the point where real science and bona fide data help. New patients look at me like I have 2 heads when I tell them to stop taking their Vitamin D supplement and/or I won't check their Vitamin D level. I am met with the "Everyone Knows" syndrome: They say, "Everyone knows that ." Their friend, "who is a nurse, you know..." told them. Their oncologist told them. Their cousin who is a cardiologist said last Christmas. Their neighbor who is a urologist told them last night at a party.

    Heck, I am still fighting the battle on antibiotics for viral infections.

    I still fight the good fight, but I swear my stance against Vitamin D hurts my all-important patient satisfaction scores, no matter how nicely I tell them.

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