Vitamins & Supplements Archive

Research we're watching

Taking supplements that contain high levels of biotin (vitamin B₇) can lead to falsely low results on a blood test used to detect heart attacks, according to an FDA warning issued late last year.

For adults, the recommended dietary allowance (RDA) for biotin is 0.03 milligrams (mg), which is easily obtained through a healthy, varied diet. Many multivitamins and prenatal vitamins contain far more biotin than the RDA. And some supplements — particularly those marketed to improve hair, nails, and skin — contain 20 mg, or nearly 650 times the RDA.

For these popular pills, the evidence has been mixed. Here's advice about getting the recommended amounts of both nutrients.

In the body, calcium and vitamin D work together to build and maintain healthy bones. Many adults (especially women) take these two nutrients in supplement form, hoping to stave off osteoporosis, the bone-weakening disease that leaves older people prone to fractures. But how do these supplements affect cardiovascular health?

The answer is a bit complicated. Here are the key points, with additional context and advice below:

In the journals

Research continues to explore the possible benefits of omega-3 fish oil supplements, especially for heart health, and a recent review of existing data suggests they may protect against heart attack and coronary artery disease.

Researchers from Harvard's T.H. Chan School of Public Health and Brigham and Women's Hospital examined 13 trials, involving almost 128,000 people, to look for any association between omega-3 supplements and the risk of heart attacks, strokes, coronary artery disease, and death from cardiovascular disease. Their results were published online Sept. 30, 2019, by the Journal of the American Heart Association.

Your money might be better spent on something else.

During the winter months, you've likely seen ads for products that claim to give your immune system a boost to help you ward off colds and the flu. But can something in a bottle, whether a vitamin formulation or probiotic, really rev up your immune system to help you stay healthy?

"Unfortunately, the reality is that those kinds of products aren't really offering you any benefit," says Michael Starnbach, a professor of microbiology at Harvard Medical School. "There's no evidence that they help in fighting disease."

Probiotics are being promoted as a way for women to improve vaginal health, but unlike with the gut and digestion, there is almost no evidence for any benefit.

Ask the doctor

Q. I've been taking vitamin D supplements for several years because my doctor said they might help me live longer. Am I wasting my money, or even causing myself harm?

A. You're right to be skeptical. Vitamin supplements of all types repeatedly have been tested for theoretical health benefits, and often the studies have shown none. There's no doubt that vitamin D supplements can help prevent or treat osteoporosis. Theoretically, they might reduce the risk of various diseases. What about the question you asked: whether vitamin D supplements help you live longer?

It's not clear that supplements are effective, but some evidence is encouraging.

Some people are wary of taking antidepressants to treat their mild or moderate depression. They may not want to deal with the hassle of prescriptions, the costs, the potential side effects (such as sexual dysfunction), or the worry that medication treatment could mean an endless commitment.

A study shows that, for many people, less is more when it comes to vitamin D.

There's no question that vitamin D can help build strong bones. But there may be a sweet spot when it comes to how much.

A study published in the Aug. 27 issue of JAMA found that, compared with people who took moderate amounts of vitamin D, adults who took large amounts daily not only didn't see additional gains in bone density, but in some cases ended up worse off.

Research we're watching

While eating more foods rich in omega-3 fatty acids may lower the risk of heart attack, that doesn't seem to reduce the risk of developing diabetes, according to a study published Aug. 24 in The BMJ. Prompted by past findings that this type of healthy fat might reduce diabetes risk and improve blood sugar (glucose) control, researchers decided to look further into the issue. They reviewed 83 randomized trials involving more than 120,000 people, both with and without diabetes. Each trial went on for six months or longer. These trials looked at whether increasing consumption of omega-3 fats (derived from fish or plants), omega-6 fats (such as those in soybean or corn oil), or total polyunsaturated fats could help lower blood glucose or reduce the risk of developing diabetes. They found that increasing the amount of omega-3, omega-6, or total polyunsaturated fats in the diet over an average study period of nearly three years didn't seem to have any effect on glucose metabolism or diabetes risk. It didn't matter whether the additional healthy fats came from supplements, enriched foods, or foods that were naturally rich in these fats.

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Research we're watching

Yet another study has found that most vitamin, mineral, and other nutritional supplements provide no protection against heart disease.

The new analysis, published July 8 in Annals of Internal Medicine, reviewed data from hundreds of clinical trials that pitted 16 different vitamins or other supplements against placebos. Most of them — including vitamin A, vitamin B₆, vitamin D, multivitamins, calcium, iron, and selenium — showed no association with a higher or lower risk of heart disease or death.