Skip to main content

Don't be fooled by dietary supplement claims

By David S. Seres
updated 3:30 PM EDT, Wed June 25, 2014
STORY HIGHLIGHTS
  • More than half of Americans are taking supplements, fueling a $30 billion industry
  • David Seres: But supplements are not the amazing panacea that we are led to believe
  • He says vitamin E and selenium supplements, for example, may not be safe for men
  • Seres: We need to reassess regulation of dietary supplements and educate the public

Editor's note: David S. Seres, MD, is director of medical nutrition and associate professor of medicine in the Institute of Human Nutrition at Columbia University Medical Center. He is a Public Voice Fellow with the Op-Ed Project. The opinions expressed in this commentary are solely those of the author.

(CNN) -- Recently, the Senate Subcommittee on Consumer Protection successfully ignited a public discussion about dietary supplements. It's about time. But this is only a first step, and of no substantive value without continued careful objective and scientific re-evaluation of how we view these products.

The $30 billion dietary supplements industry, one of the fastest growing industries in the world, has reason to celebrate. More than half of Americans are taking supplements.

This year marks the 20th anniversary of the passage of one of the most skillful pieces of legislation ever to undermine the health of Americans: The Dietary Supplement Health and Educational Act of 1994. The result was to remove from regulation by the Food and Drug Administration any substances labeled as a dietary supplement. The act was passed with strong bipartisan support. After all, shouldn't we make it easier for Americans to access good nutrition? If it is nutrition, isn't it good for you? And, if a nutrient is essential for an important body function, shouldn't more of it improve that body function?

David S. Seres
David S. Seres

But supplements are not quite the amazing panacea that we have been led to believe. Supplements, which include substances such as vitamins and herbs, but can also include hormones and other pharmacologically active ingredients, can impact the effect and safety of various medications and alter our body's physiologic functions.

For instance, severe bleeding has been reported as a result of supplements taken at recommended doses around the time of even minor surgery. This is of great concern given that a survey conducted by researchers at the University of Colorado found that 40% of patients undergoing surgery were taking herbal and vitamin supplements that block normal blood clotting and predispose them to excessive bleeding, and 17% were taking supplements that may prolong the effect of anesthesia.

Nutrients are chemicals, and almost all are known to have toxicity when taken in high doses. Look in any nutrition textbook and you will find lists of vitamin toxicities, some of which may even be fatal.

For example, overdose of vitamin A will cause brain swelling and liver failure. This is, fortunately, not common. But intake of vitamin A, only slightly higher than the recommended daily allowance, has been associated with thinning of bones and a higher risk for fractures.

Some supplements, like zinc, may cause harm even at low doses, since it can cause a significant decrease in the levels of copper, another essential mineral for the body.

Vitamin E and selenium supplements have both been proven, in a well-designed randomized trial with more than 35,000 men, to cause statistically significant increases in the incidence of aggressive prostate cancer. The National Cancer Institute felt the results were concerning enough to post them on their website, with a strongly worded warning that men should not take these, despite the claims of supplement proponents who vehemently deny the scientific data, based on outlandish theories. Nor do these proponents disclose conflicts of interest, which real scientists are ethically bound to reveal when they are in a position to make personal gains.

Despite the proven risks, the market is glutted with supplement companies and vitamin pushers who argue that supplements, from multivitamins to herbal cures for everything from the common cold to obesity, are natural and thus, safe. They fiercely advocate for keeping access to dietary supplements unfettered by government regulation, claiming that further regulation would unfairly deprive the public of access to these potentially beneficial substances. They cite theory and inappropriate data to support their claims and dismiss any evidence to the contrary.

Proper randomized studies, such as those performed to establish safety and efficacy of prescription medications, are needed to establish cause and effect of supplements. Such studies require large numbers of patients and are extremely costly. Without regulatory pressures, there is little motivation for industry to do the studies, even as supplements bring in large profits from sales to the American public.

The other option is observational or epidemiological research, which is easier and less expensive. But conclusions from these studies can only be used to note the coincidence of events, not cause and effect. Erroneous conclusions are often drawn (e.g., only overweight people are on diets, therefore being on diets causes obesity). And guesswork, which some supplement proponents use to deny the science, costs nothing.

Most people, scientists and nonscientists, are not aware of the weaknesses in the scientific data on supplements. Part of this misunderstanding is the fault of us nutrition experts, who want very much to provide something to slake the hunger of the public for advice on what to do to stay young, thin, fit and healthy, and are loathe to say "we don't know."

It is a hopeful sign that this issue has come to the attention of the Senate Subcommittee on Consumer Protection. But there is so much to be done.

Just because a product is brought to market and labeled as a dietary supplements, guarantees neither efficacy nor, more importantly, safety. On this anniversary of the Dietary Supplement Health and Education Act, with lawmakers now willing to challenge this powerful industry, it is time to reassess the regulation of dietary supplements, consider our priorities in how funding is granted for nutrition research, reeducate the community of nutrition experts as well as the public, and be honest about our inability to offer definitive, safe and effective nutritional recommendations.

Read CNNOpinion's new Flipboard magazine.

Follow us on Twitter @CNNOpinion.

Join us on Facebook.com/CNNOpinion.

ADVERTISEMENT
Part of complete coverage on
updated 8:21 AM EDT, Mon September 1, 2014
Carlos Moreno says atheists, a sizable fraction of Americans, deserve representation in Congress.
updated 12:25 PM EDT, Sun August 31, 2014
Julian Zelizer says Democrats and unions have a long history of mutual support that's on the decline. But in a time of income inequality they need each other more than ever
updated 12:23 AM EDT, Sun August 31, 2014
William McRaven
Peter Bergen says Admiral William McRaven leaves the military with a legacy of strategic thinking about special operations
updated 12:11 PM EDT, Fri August 29, 2014
Leon Aron says the U.S. and Europe can help get Russia out of Ukraine by helping Ukraine win its just war, sharing defense technologies and intelligence
updated 1:24 PM EDT, Fri August 29, 2014
Timothy Stanley the report on widespread child abuse in a British town reveals an institutional betrayal by police, social services and politicians. Negligent officials must face justice
updated 9:06 PM EDT, Fri August 29, 2014
Peter Bergen and David Sterman say a new video of an American suicide bomber shows how Turkey's militant networks are key to jihadists' movement into Syria and Iraq. Turkey must stem the flow
updated 11:54 AM EDT, Mon September 1, 2014
Whitney Barkley says many for-profit colleges deceive students, charge exorbitant tuitions and make false promises
updated 10:34 AM EDT, Fri August 29, 2014
Mark O'Mara says the time has come to decide whether we really want police empowered to shoot those they believe are 'fleeing felons'
updated 10:32 AM EDT, Thu August 28, 2014
Bill Frelick says a tool of rights workers is 'naming and shaming,' ensuring accountability for human rights crimes in conflicts. But what if wrongdoers know no shame?
updated 10:43 PM EDT, Thu August 28, 2014
Jay Parini says, no, a little girl shouldn't fire an Uzi, but none of should have easy access to guns: The Second Amendment was not written to give us such a 'right,' no matter what the NRA says
updated 1:22 PM EDT, Sat August 30, 2014
Terra Ziporyn Snider says many adolescents suffer chronic sleep deprivation, which can indeed lead to safety problems. Would starting school an hour later be so wrong?
updated 9:30 AM EDT, Fri August 29, 2014
Peggy Drexler says after all the celebrity divorces, it's tempting to ask the question. But there are still considerable benefits to getting hitched
updated 2:49 PM EDT, Fri August 29, 2014
The death of Douglas McAuthur McCain, the first American killed fighting for ISIS, highlights the pull of Syria's war for Western jihadists, writes Peter Bergen.
updated 6:42 PM EDT, Tue August 26, 2014
Former ambassador to Syria Robert Ford says the West should be helping moderates in the Syrian armed opposition end the al-Assad regime and form a government to focus on driving ISIS out
updated 9:21 AM EDT, Wed August 27, 2014
Ruben Navarrette says a great country does not deport thousands of vulnerable, unaccompanied minors who fled in fear for their lives
updated 9:19 AM EDT, Wed August 27, 2014
Robert McIntyre says Congress is the culprit for letting Burger King pay lower taxes after merging with Tim Hortons.
updated 7:35 PM EDT, Tue August 26, 2014
Wesley Clark says the U.S. can offer support to its Islamic friends in the region most threatened by ISIS, but it can't fight their war
updated 4:53 PM EDT, Tue August 26, 2014
America's painful struggle with racism has often brought great satisfaction to the country's rivals, critics, and foes. The killing of Michael Brown and its tumultuous aftermath has been a bonanza.
updated 3:19 PM EDT, Tue August 26, 2014
Rick Martin says the death of Robin Williams brought back memories of his own battle facing down depression as a young man
updated 11:58 AM EDT, Tue August 26, 2014
David Perry asks: What's the best way for police officers to handle people with psychiatric disabilities?
updated 3:50 PM EDT, Mon August 25, 2014
Julian Zelizer says it's not crazy to think Mitt Romney would be able to end up at the top of the GOP ticket in 2016
updated 4:52 PM EDT, Mon August 25, 2014
Roxanne Jones and her girlfriends would cheer from the sidelines for the boys playing Little League. But they really wanted to play. Now Mo'ne Davis shows the world that girls really can throw.
updated 5:04 PM EDT, Mon August 25, 2014
Kimberly Norwood is a black mom who lives in an affluent neighborhood not far from Ferguson, but she has the same fears for her children as people in that troubled town do
updated 5:45 PM EDT, Fri August 22, 2014
It apparently has worked for France, say Peter Bergen and Emily Schneider, but carries uncomfortable risks. When it comes to kidnappings, nations face grim options.
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT