Multivitamin researchers say “case is closed” after studies find no health benefits

Questions about the health benefits of vitamin supplements have been percolating in the medical establishment for decades — even as the multivitamin industry has grown to a multi-billion powerhouse. In December, the respected journal the Annals of Internal Medicine put its well-heeled foot down.

“We believe that the case is closed — supplementing the diet of well-nourished adults with (most) mineral or vitamin supplements has no clear benefit and might even be harmful,” the journal said in an editorial. “These vitamins should not be used for chronic disease prevention. Enough is enough.”

The strong message was based on a review of the findings from three studies that tracked multivitamins link to cancer protection, heart health, and brain and cognitive measures.

The first study, which was released online Nov. 12 in Annals, was a review of 24 studies and two trials on more than 350,000 individuals that looked at vitamin supplementation’s role in preventing chronic disease. The review was conducted to find evidence that can be used to update vitamin treatment guidelines from the US Preventive Services Task Force, a panel of medical experts who recommend the government on treatments.

That review found no evidence that vitamin and mineral supplementation would reduce heart disease in pill takers. Two of the trials found a small, “borderline-significant benefit” in cancer risk reduction, but only in men. 

Overall, the panel concluded there was no solid evidence for or against taking vitamins and minerals alone, or that a multivitamin to prevent heart disease or cancer. More strikingly, it found enough evidence to recommend against taking beta-carotene or vitamin E for preventing both diseases, finding they not only didn’t help but the former may raise risk for lung cancer for already at-risk individuals.

“In the absence of clear evidence about the impact of most vitamins and multivitamins on cardiovascular disease and cancer, health care professionals should counsel their patients to eat a healthy, well-balanced diet that is rich in nutrients,” the Task Force concluded.

The next study, published Dec 16 in Annals, looked at cognitive health and whether long-term use of multivitamins would have any effect. Researchers assigned almost 5,950 male doctors aged 65 and older to take either a daily multivitamin or placebo for 12 years in a randomized, placebo-controlled trial,

Based on the results of memory tests, the researchers found the multivitamin did nothing to slow cognitive decline among men 65 and older compared to placebo takers.

“These data do not provide support for use of multivitamin supplements in the prevention of cognitive decline,” wrote the authors, led by Dr Francine Grodstein, an epidemiologist who studies aging at Harvard School of Public Health in Boston.

It’s worth noting this study only looked at cognitive test results, not actual development of dementia.

The third study looked specifically at multivitamins and minerals role in preventing another heart attack, or myocardial infarction. They looked at more than 1,700 people who had a heart attack at least six weeks earlier, and randomized them to receive daily high-dose multivitamins and minerals or placebos for five years.

Having a heart attack raises risk for another attack, or cardiovascular event like stroke or premature death, so if multivitamins could reduce risk, they could be a boon to public health.

The researchers found no difference in rates of another heart attack, chest pain, the need for hospitalization, cardiac catheterisation, or rates of stroke and early death between vitamin-takers and placebo-takers. But, they said the conclusions should be taken with caution, because several participants stopped taking vitamins early.

The authors of the editorial say the evidence is clear about multivitamin supplements, except for vitamin D, which has been shown to be both effective and ineffective for preventing falls and fractures in elderly. More studies are needed specifically looking at vitamin D, according to the editorial’s authors.

“Sales of multivitamins and other supplements have not been affected by major studies with null results, and the US supplement industry continues to grow, reaching $28-billion in annual sales in 2010,” wrote the authors of the editorial summary, led by Dr Eliseo Guallar, a professor of epidemiology who specialises in heart disease prevention at Johns Hopkins Bloomberg School of Public Health in Baltimore.

In light of these developments, The Week magazine questions how the vitamin industry convinced Americans, and the world, that they need to bulk up on vitamin A, vitamin C, various forms of vitamin B, and other vitamins or multivitamin supplements?

“Vitamin manufacturers argue that a regular diet doesn’t contain enough vitamins, and that more is better,” and most people wrongly assume that “at the very least, excess vitamins can’t do any harm,” Paul Offit, an infectious disease specialist at Children’s Hospital of Philadelphia, said in The New York Times in June.

But much of the blame lies with a flawed genius, Linus Pauling, Offit says. Pauling, the father of molecular biology and near-discoverer of DNA, was “so spectacularly right that he won two Nobel prizes and so spectacularly wrong that he was arguably the world’s greatest quack,” Offit wrote in The Guardian.

Starting in 1966, Pauling started evangelising about the wonders of vitamin C, making outrageous claims about its salutary effects.

In 1970, Pauling published a bestseller, Vitamin C And The Common Cold, arguing that 3 000 mg of the vitamin each day would eradicate the cold. He went on to insist that a multitude of vitamins, including A, E, and beta-carotine could treat or cure a whole host of maladies, from cancer to AIDS. Study after study after study proved him wrong.

Pauling really believed his claims, but the vitamin industry had more cynical motives: Money, as Offit recounted in The New York Times. The Food and Drug Administration proposed regulating vitamin supplements containing more than 150 percent of the recommended daily allowance in December 1972, meaning “vitamin makers would now have to prove that these ‘megavitamins’ were safe before selling them,” Offit continues:

Not surprisingly, the vitamin industry saw this as a threat, and set out to destroy the bill. In the end, it did far more than that. Industry executives recruited William Proxmire, a Democratic senator from Wisconsin, to introduce a bill preventing the FDA from regulating megavitamins…. Proxmire’s bill passed by a vote of 81 to 10. In 1976, it became law. Decades later, Peter Barton Hutt, chief counsel to the FDA, wrote that “it was the most humiliating defeat” in the agency’s history. [New York Times]

So, thanks to Linus Pauling, money, and politics, Offit concludes, “consumers don’t know that taking megavitamins could increase their risk of cancer and heart disease and shorten their lives.”

But surely consumers play some role in the rise of the vitamin industrial complex. Research about the ineffectiveness of vitamins, or worse, has been around since the 1940s, after all. “People over time and particularly people in the United States have been led to believe that vitamin and mineral supplements will make them healthier, and they’re looking for a magic pill,” Dr Cynthia Mulrow, another of the Annals of Internal Medicine editorialists, tells Reuters.

And the “magic pill” habit may be hard to break, scathing editorial or no. For what it’s worth, here’s the pushback from the supplement trade group the Council for Responsible Nutrition:

The Annals of Internal Medicine editorial “demonstrates a close-minded, one-sided approach that attempts to dismiss even the proven benefits of vitamins and minerals,” says the group’s CEO, Steve Mister. “It’s a shame for consumers that the authors refuse to recognize the real-life need for vitamin and mineral supplementation, living in a fairy-tale world that makes the inaccurate assumption that we’re all eating healthy diets and getting everything we need from food alone.”

Sources: CBS News, LA Times, New York Times, Reuters, The Week