NUTRITION
June 11, 2014

Do Supplements Work? It's Debatable

Several studies find nutritional supplements provide little or no benefit. But not everyone agrees.

It probably tells us something about the state of our national nutrition that the debate about the virtues of vitamin and mineral supplements shows no signs of going away. In fact, it's heating up. Some people believe that taking supplements will make them healthier; others see the idea of supplements as an excuse not to eat properly.

Vitamins and supplements are also big business. About 40 million Americans take multivitamin and mineral supplements, spending around $28 billion a year. Yet the industry is poorly regulated and there have been cases where supplements make claims for their products that are either unproven or false.

Three Studies Find Supplements Offer Little or No Benefit

When the prestigious Annals of Internal Medicine published three studies showing supplements offered little or no health benefit last December, people on both sides of the issue took notice.

About 40 million Americans take multivitamin and mineral supplements, spending around $28 billion a year.

One of the studies found there was no clear evidence of a beneficial effect of supplements on all-cause mortality, cardiovascular disease, or cancer. Another reported that use of a multivitamin supplement in elderly people who were well-nourished did not prevent cognitive decline. And a the third study indicated that multivitamins made no significant difference to the risk of recurrent heart problems.

The prevailing sentiment was captured in an editiorial entitled, “Enough Is Enough: Stop Wasting Money on Vitamin and Mineral Supplements.” As the authors put it, “Despite sobering evidence of no benefit or possible harm, use of multivitamin supplements increased among U.S. adults from 30% between 1988 to 1994 to 39% between 2003 to 2006, while overall use of dietary supplements increased from 42% to 53%.”

Apparently, however, enough was not enough.

Researchers from the Linus Pauling Institute at Oregon State University (OSU), the University of Pittsburgh, and individuals in the field wrote to the journal, taking issue with the findings and editorial. They questioned some of the results and cited research showing the benefits of taking vitamins and supplements.

On the other side, a team from the U.S. Department of Health and Human Services defended the findings and voiced concern that “…[c]laims made on dietary supplement labels may be misleading.”

The letters have just been published in this month’s issue of the journal.

The Rebuttal: Supplements Can't Hurt and May Help

No one disputes that eating right is the best way to give your body the essential nutrients it needs, but, as the authors of letters in support of supplement use point out, many Americans don’t eat right. They eat too many foods with empty calories, robbing themselves of nutrients.

Dietary supplements fill nutritional gaps, improve overall health and may help prevent chronic disease, these doctors and researchers believe. From this perspective, vitamins and supplements are not harmful and are well worth the pennies a day they cost.

Most people in the U.S. do not follow the Dietary Guidelines for Americans, and they do not meet the current recommendations for intake of vitamins and minerals.

For some, the gaps are huge and potentially bad for their health. Why not encourage people who still aren't eating the fruits and vegetables they should to at least take a pill to prevent deficiencies? The director of the Linus Pauling Institute at OSU, Balz Frei, and his colleagues point out in their letter that most people in the U.S. do not follow the Dietary Guidelines for Americans, and they do not meet the current recommendations for intake of vitamins and minerals.

For example, 93 percent of Americans are deficient in vitamins D and E; 61 percent receive insufficient magnesium; and 50 percent do not consume adequate vitamin A and calcium.

It’s naïve to ignore the fact that most people have micronutrient inadequacies, and wrong to condemn a daily supplement that could cover these nutritional gaps safely and at low cost.

Intakes of potassium and calcium are below the recommended amounts for most Americans. It’s possible that these percentages are even higher in populations that have an increased need for vitamins and minerals such as older adults, obese individuals, African Americans, and those with chronic illness or injury.

According to Frei, “It’s naïve to ignore the fact that most people have micronutrient inadequacies, and wrong to condemn a daily supplement that could cover these nutritional gaps safely and at low cost.” He believes there is strong evidence that vitamin/mineral supplements support normal body functioning, help improve health, and could lower the risk of chronic disease.

“It’s irresponsible to ignore decades of nutrition research and tell the people of the United States that they have no need for a supplement that could be so helpful, and costs as little as $1 a month.”

There's No Visible Effect If There's No Deficiency

The studies in last December's Annals also found that supplements cause harm. Those favoring the use of vitamin and other supplements say that finding — that taking vitamins A and E raises the risk of mortality — was based on extremely high doses, much larger than any level found in a multivitamin. A comprehensive meta-analysis has since refuted the case against vitamin E.

You won’t find much effect from a supplement if it isn’t needed.

The findings showing no benefit from supplements are likewise skewed, Frei and his colleagues say, because too much research was performed with groups — such as doctors and nurses — that are not necessarily representative of the general population. Studies done with populations who have poor diets or defined nutritional deficiencies would have shown supplements to be more effective, Frei maintains.

“There are many issues that have helped to mislead people when it comes to the study of micronutrients. For instance, most research is done without first checking to see if a person's level of a nutrient is inadequate, and you won’t find much effect from a supplement if it isn’t needed.”

Research continues to show the potential of vitamin and mineral supplements to help prevent or reduce the incidence of chronic disease. Those critical of the original studies and editorial point to research showing that supplements can reduce the incidence of cancer, slow brain shrinkage in those with Alzheimer’s disease, decrease the likelihood of cataracts, and prevent vision loss from age-related macular degeneration.

Finally, proponents of supplements say that nutritional deficiency diseases are extremely rare in the United States because of our vast food supply and the fact that so many of the foods we buy are fortified with vitamins and minerals. In contrast, many developing nations struggle with deficiencies of nutrients such as vitamin A, iron, zinc, and iodine. A blanket message that supplements don't help and may harm could do a disservice to people living in these areas.

In their response to those supporting the value of dietary supplements, the authors of the editorial that helped start the furor took issue with claims that that supplements prevent disease and echoed others' concerns about the lack of regulation of the industry by the FDA.

This is unlikely to be the end of the debate, but with any luck, it will stimulate more and better research on what vitamins and supplements can or can't do for us.

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