Vitamins & Supplements Archive

In the US, supplements are not tested in the way prescription medicines are, and their manufacturers can make claims about their abilities that may or may not be true. But there are some rules supplement makers must follow, and the FDA's plan to revamp its regulation of dietary supplements is a step toward improving consumer protection.

The answer to that question is becoming clearer, thanks to new research.

Some 10% of American adults regularly take an omega-3 supplement, despite uncertainty about whether these products truly live up to their health claims. But two new studies published in November 2018 shed some light on who might benefit from omega-3 supplements — and who probably won't.

VITAL

The first study was the Vitamin D and Omega-3 Trial (VITAL), a large multiyear study with 25,871 healthy adults with no history of cardiovascular (heart or blood vessel–related) disease and at "usual risk" for it. The group was racially diverse and chosen to be representative of the general population, says the study's lead author Dr. JoAnn E. Manson, professor of medicine and the Michael and Lee Bell Professor of Women's Health at Harvard Medical School.

In the journals

Vitamin D and omega-3 fatty acid supplements have had mixed results when it comes to preventing heart attacks, strokes, and cancer in people who have already developed these problems or are at high risk for them. Yet a new study published online Nov. 10, 2018, by The New England Journal of Medicine found they may actually prevent these conditions among people who have never had these problems before.

Researchers recruited almost 26,000 people, ages 50 and older, who had no history of heart disease or cancer. The participants were divided into four groups. People in one group were given daily doses of 2,000 international units of vitamin D (an amount found to be linked to lower disease risk in observational studies) and 1 gram of a drug called Lovaza, which contained 840 milligrams of omega-3s (two to four times the amount in two servings of fish per week). The second group took vitamin D and a placebo, the third group took the omega-3s and a placebo, and the final group took two placebos. After more than five years, the researchers found that those given omega-3s were 28% less likely to suffer a heart attack compared with those given a placebo. Those who ate fewer servings of fish (less than the average of 1.5 servings per week) appeared to have a greater benefit from the additional omega-3s while those with higher fish intake had minimal benefit.

Millions of Americans take some kind of supplement, but because supplements are not regulated like prescription drugs are, taking one is not always safe. Researchers have found many instances of hidden ingredients and inaccurate quantities listed on the label.

Ask the doctor

 Image: © Elena_Danileiko/Getty Images

Q. I'm taking fish oil supplements to keep me from getting heart disease, because my doctor said they may help, though it's controversial. I hear new studies come to different conclusions. What's the truth?

A. In these pages, the best we can promise you is a balanced assessment of sometimes different study results: the "truth" usually is elusive. Your question likely was prompted by two important new studies published in November 2018, and they do seem to point in different directions. I'll do my best to give you my current "bottom line" and resolve the confusion. I reserve the right to change my mind as new studies are reported.

 Image: © Hunterann/Thinkstock

Research we're watching

For years, many have speculated that taking vitamin D and omega-3 fatty acid supplements might help to prevent heart attacks, strokes, and certain cancers. But a study by Harvard researchers published online November 10, 2018, by The New England Journal of Medicine has found that the benefits may be more limited than originally hoped.

The results of the Vitamin D and Omega-3 Trial (VITAL), which enrolled more than 25,000 people and ran for more than five years, showed that while omega-3 supplements did appear to reduce the risk of heart attack, particularly among African Americans, they did not appear to be effective in preventing stroke or cancer. Vitamin D supplements also saw few benefits when it came to preventing heart attack, stroke, or cancer — but they were associated with a drop in cancer deaths in people who had taken the supplements for at least a year or two.

Some vitamins and minerals — including vitamins C and E and the minerals copper, zinc, and selenium — serve as antioxidants, in addition to other vital roles. 

"Antioxidant" is a general term for any compound that can counteract unstable molecules called free radicals that damage DNA, cell membranes, and other parts of cells. Because free radicals lack a full complement of electrons, they steal electrons from other molecules and damage those molecules in the process. Antioxidants neutralize free radicals by giving up some of their own electrons. In making this sacrifice, they act as a natural "off" switch for the free radicals. This helps break a chain reaction that can affect other molecules in the cell and other cells in the body. But it is important to recognize that the term "antioxidant" reflects a chemical property rather than a specific nutritional property. 

Despite widespread assertions in the popular and scientific press that many Americans have a vitamin D deficiency, the term "deficiency" isn't strictly accurate. The official definition of a vitamin deficiency means that specific health problems stem solely from the lack of (or inability to use) a specific nutrient. An actual vitamin D deficiency results in bone disease, such as rickets, which is rare in the United States. 

On the other hand, lower-than-optimal levels of specific vitamins, including vitamin D, may increase your risk of numerous health problems, even though they are not solely responsible for these problems. "Insufficiency" may be a better term for these lower levels than "vitamin D deficiency". 

Iron supplementation may be all it takes to reduce symptoms of restless legs syndrome. But many doctors don't know about it.

 Image: © AlexRaths/Getty Images

People with restless legs syndrome (RLS) experience an overwhelming need to move the legs, particularly at night or as they fall asleep. But a simple treatment that may help reduce RLS symptoms is often overlooked as a potential first line of defense.

"The concern is that people are being started on medications first when iron might be a valuable treatment. It's simple, with relatively few side effects," says Dr. John Winkelman, an RLS specialist at Harvard-affiliated Massachusetts General Hospital.