Vitamins Don't Have Much of a Scientific Basis
(Bloomberg View) -- Proponents of science-based medicine are fond of saying that there’s a name for alternative treatments that pass scientific tests: medicine. But what they don’t mention are those parts of long-established medicine that get demoted to “alternative” status — or should be.
For years, doctors pestered me — and apparently many other people — to take a daily multivitamin and a calcium supplement. There was nothing wrong with me; doctors said it was a kind of insurance. The calcium was to protect against fractures, and the multivitamin … well, the doctors were never too clear on that, but they were adamant.
And now, Kaiser Health News is reporting that most older Americans are “hooked” on vitamins. The story, which ran in the New York Times, detailed a litany of scientific studies showing vitamin supplements either failed to deliver benefits or caused harm. Experts quoted in the story presented all this as if consumers were buying into some egregious form of pseudoscientific quackery — as if this were never part of established medicine.
Paul Offit, a pediatrician at the Children’s Hospital of Philadelphia, included vitamins alongside homeopathy and “energy healing” in his book on quack medicine, “Do You Believe in Magic?”. He notes that indeed, the medical establishment did once assume everyone should take vitamins, and universally recommending them has been a hard habit for the doctors to break.
The benefit of supplemental vitamins for healthy people was, he said, based more on assumptions than data, as are many other common practices in medicine. And even as 21st-century medicine advances at lightning speed, with precision genetic testing, immunotherapy and robotic surgeries, it can slow to a crawl in discarding outdated practices. Doctors were slow to stop pushing low-fat diets, Offit said, and are still reluctant to acknowledge data pointing to the downsides of the standard mass screenings for prostate and breast cancers. The notion that people should take antibiotics long after they feel better was never based on testing, he said. That’s now being called into question.
Unlike many forms of alternative medicine, vitamins can have real benefits for some people. It was a giant leap for public health when scientists discovered that foods contained essential trace compounds — named vitamins in 1912. For the first time, doctors understood why people got sick from an unbalanced diet even if they consumed enough calories to keep from starving. There’s no doubt early sailors and explorers living on nothing but hardtack would have done much better with a few bottles of One-A-Day in the hold.
Now many foods are already fortified with vitamins, and it’s rare for people without unusual health conditions to have vitamin deficiencies, even if they eat a less-than-perfect diet. But somewhere around the 1980s, doctors became soured on food as a source of nutrition. We were told it was unsafe to eat fat of any kind, or anything with salt. We were supposed to avoid shrimp, shellfish, nuts, eggs and cheese. Vegetables were still on the list of acceptable foods, but they were pretty grim fare when cooked with no oil, butter or salt.
And then there was the demonization of calories, which are a measure of energy — of how much food is in food. While calorie counts can be useful in protecting us from massive portions of low-quality food, some experts have said the whole obsession with calorie counting is premised on the notion that food is bad. Vitamins, meanwhile, are for the most part calorie-free and fat-free, and doctors assumed they couldn’t be harmful.
Gradually, scientific studies started to show that food was not nearly as dangerous as thought, and that vitamin and mineral supplements could do harm. There was data showing that calcium supplements did not decrease the risk of fracture and might increase the risk of kidney stones. A large-population study found that less than 3 percent of subjects were deemed deficient in iron, but around 13 percent had levels that were dangerously high.
In other studies, vitamin A supplements increased the risk of death among lung cancer patients, and vitamin E increased deaths among people with prostate cancer. These were doses higher than what’s in multivitamins, but low enough that scientists assumed they were safe. Here’s one of the doctors quoted in the recent Kaiser Health News piece:
“Vitamins are not inert,” said Dr. Eric Klein, a prostate cancer expert at the Cleveland Clinic who led the vitamin E study. “They are biologically active agents. We have to think of them in the same way as drugs.”
Considering that larger doses of certain vitamins can cause harm, isn’t the safest course of action to eat some spinach and avoid the pills? Back in 2008, physician Harriet Hall posed the same question regarding her own use of vitamins in a post for the blog Science-Based Medicine. She wrote that she considered her past use of multivitamins “irrational,” and that she continues to take calcium and vitamin D to address a problem, but has dropped the daily multivitamins. She told me she still agrees with what she wrote back then:
There are two philosophies: to take everything that is suggested just in case, or to wait for scientific validation before taking anything. Based on long experience, I consider the latter course more reasonable. I can’t begin to tell you how many times I’ve heard strong recommendations for something that was later shown to be useless or harmful.
Perhaps the enthusiasm for vitamins was also a product of that techno-optimism that was such a part of 20th-century culture. We were in the space age, and soon food would be replaced with technologically superior substances. But food is back in vogue, and finally, doctors are recommending people get their vitamins by eating it. If doctors are now concerned that too many people are hooked on vitamin pills, they might want to admit they were wrong.
Faye Flam is a Bloomberg View columnist. She has written for the Economist, the New York Times, the Washington Post, Psychology Today, Science, New Scientist and other publications. She has a degree in geophysics from the California Institute of Technology, and has been a Knight-Wallace fellow at the University of Michigan.
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