Should doctors recommend vitamin supplements?

The vitamin supplement industry in the United States is booming. Consider that, currently, there are over 90,000 dietary supplement products on the market, and the industry is valued at roughly $30 billion.

According to the National Health and Nutrition Examination Survey (NHANES) from 2011-2012, a full 52% of Americans reported taking at least one supplement product in the last 30 days, and 10% reported using at least four per month. Of these, vitamins are some of the most popular, taken by 48% of adults in the United States; minerals are in the same category, taken by 39%. All of this is done in the hopes of maintaining health and preventing disease.

Numerous studies have tried, and are continuing to try, to pin down the science behind vitamin supplements. But, scientifically, the jury is still out, warned authors JoAnn E. Manson, MD, DrPH, Brigham and Women’s Hospital, Harvard Medical School, and Harvard T.H. Chan School of Public Health, Boston, MA, and Shari S. Bassuk, ScD, Brigham and Women’s Hospital, Harvard Medical School.

“Despite this enthusiasm, most randomized clinical trials of vitamin and mineral supplements have not demonstrated clear benefits for primary or secondary prevention of chronic diseases not related to nutritional deficiency. Indeed, some trials suggest that micronutrient supplementation in amounts that exceed the recommended dietary allowance (RDA)—eg, high doses of beta carotene, folic acid, vitamin E, or selenium—may have harmful effects, including increased mortality, cancer, and hemorrhagic stroke,” they wrote in their recent “Viewpoint” article in JAMA.

In a recent editorial in the Annals of Internal Medicine, authors led by Eliseo Guallar, MD, DrPH, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, took a stronger stance, concluding that clinicians should not advise patients to routinely take vitamin and mineral supplements.

They considered three studies published in that issue of Annals that focused on the role of vitamin and mineral supplements in disease prevention and progression to disease chronicity:

• In the first, Fortmann et al reviewed 3 multivitamin trials and 24 studies of single or paired vitamins. They found no clear evidence of daily supplementation benefit on all-cause mortality, cardiovascular disease, or cancer incidence or mortality.
• In the second study, Grodstein et al assessed the efficacy of daily multivitamins in preventing cognitive decline in men aged 65 years and older from the Physicians’ Health Study II. Despite 12 years of follow-up, they found no differences in overall cognitive performance or verbal memory between the multivitamin and placebo groups.
• Finally, in the third study, Lamas et al¹ found no significant differences between vitamins and placebo in the rate of recurrent cardiovascular events in 1,708 men and women with previous myocardial infarction enrolled in the Trial to Assess Chelation Therapy (TACT).

“The large body of accumulated evidence has important public health and clinical implications. Evidence is sufficient to advise against routine supplementation, and we should translate null and negative findings into action. The message is simple: Most supplements do not prevent chronic disease or death, their use is not justified, and they should be avoided. This message is especially true for the general population with no clear evidence of micronutrient deficiencies, who represent most supplement users in the United States and in other countries,” they concluded.

Doctor recommended

Clinicians, however, play a unique role with their patients in promoting the proper use of, and discouraging the improper use of, vitamin and mineral supplements.

Drs. Manson and Bassuk offered a few pointers.

“Importantly, clinicians should counsel their patients that such supplementation is not a substitute for a healthful and balanced diet and, in most cases, provides little if any benefit beyond that conferred by such a diet,” they added.

They also stressed that clinicians do the following with patients:

• Stress the advantages of getting vitamins and minerals from food rather than supplements to patients.
• Always ask patients about their use of micronutrient supplements when reviewing medications.
• Remember that the FDA does not review dietary supplements for safety and efficacy before they are marketed.

“Thus, clinicians may wish to favor prescription products, when available, or advise patients to consider selecting a supplement that has been certified by independent testers (ConsumerLab.com, US Pharmacopeia, NSF International, or UL) to contain the labeled dose(s) of the active ingredient(s) and not to contain microbes, heavy metals, or other toxins,” they concluded.

References

1. Lamas GA, Boineau R, Goertz C, et al., and the TACT (Trial to Assess Chelation Therapy) Investigators. Oral high-dose multivitamins and minerals after myocardial infarction. A randomized trial. Ann Intern Med. 2013;159(12):797-804.