From USA Today:
When she was a young physician, Martha Gulati noticed that many of her mentors were prescribing vitamin E and folic acid to patients. Preliminary studies in the early 1990s had linked both supplements to a lower risk of heart disease.
She urged her father to pop the pills as well: “Dad, you should be on these vitamins, because every cardiologist is taking them or putting their patients on (them),” recalled Gulati, now chief of cardiology for the University of Arizona College of Medicine-Phoenix.
But just a few years later, she found herself reversing course after rigorous clinical trials found neither vitamin E nor folic acid supplements did anything to protect the heart. Even worse, studies linked high-dose vitamin E to a higher risk of heart failure, prostate cancer and death from any cause.
“‘You might want to stop taking (these),’” Gulati told her father.
More than half of Americans take vitamin supplements, including 68% of those age 65 and older, according to a 2013 Gallup poll. Among older adults, 29% take four or more supplements of any kind, according to a Journal of Nutrition study published in 2017.
Often, preliminary studies fuel irrational exuberance about a promising dietary supplement, leading millions of people to buy into the trend. Many never stop. They continue even though more rigorous studies — which can take many years to complete — almost never find that vitamins prevent disease and in some cases cause harm.
“The enthusiasm does tend to outpace the evidence,” said JoAnn Manson, chief of preventive medicine at Boston’s Brigham and Women’s Hospital.
There’s no conclusive evidence that dietary supplements prevent chronic disease in the average American, Manson said. And while a handful of vitamin and mineral studies have had positive results, those findings haven’t been strong enough to recommend supplements to the general U.S. public, she said.
The National Institutes of Health has spent more than $2.4 billion since 1999 studying vitamins and minerals. Yet for “all the research we’ve done, we don’t have much to show for it,” said Barnett Kramer, director of cancer prevention at the National Cancer Institute. […]
A big part of the problem, Kramer said, could be that much nutrition research has been based on faulty assumptions, including the notion that people need more vitamins and minerals than a typical diet provides, that megadoses are always safe and that scientists can boil down the benefits of vegetables such as broccoli into a daily pill.
Vitamin-rich foods can cure diseases related to vitamin deficiency. Oranges and limes were shown to prevent scurvy in vitamin-deprived 18th-century sailors. And research long has shown populations that eat a lot of fruits and vegetables tend to be healthier than others.
But when researchers tried to deliver the key ingredients of a healthy diet in a capsule, Kramer said, those efforts nearly always failed.