Vitamins & Supplements Archive

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.

News briefs

 Image: © emiliozv/Getty Images

Omega-3 fatty acid supplements may help ease anxiety symptoms in people diagnosed with a range of physical and mental health problems, according to a review published in the Sept. 14, 2018, JAMA Network Open. The report pooled findings from 19 different studies and included 1,200 people. Most of the studies compared omega-3 supplements to a placebo. Taken together, the studies included people with a range of health problems, including heart attacks, attention deficit disorder, substance abuse, depression, and Parkinson's disease, as well as some groups without any specific clinical diagnosis. Researchers found that people who took high doses of omega-3s (up to 2,000 mg a day) seemed to have the most reduction in anxiety symptoms. Omega-3 fatty acids, which are usually derived from fish oil, have a number of biological effects in the body. Brain membranes contain a high proportion of these fats, and human studies suggest that a lack of omega-3s in the brain may induce various behavioral and psychiatric disorders. For now, it's too soon to recommend high-dose omega-3 supplements for treating anxiety. Larger trials testing the supplements (both alone and combined with standard treatments) are needed, the study authors say.

Research we're watching

Do you know someone who is using a supplement for weight loss, muscle building, or sexual enhancement? You might want to recommend a dose of caution. An analysis published on October 12 by JAMA Network Open found that many of these supplements contain unapproved and potentially dangerous pharmaceutical ingredients. From 2007 to 2016, FDA reviewers detected contaminants in 776 dietary supplements, produced by 146 different companies. Contaminants included sildenafil, which is the generic form of the drug Viagra; sibutramine (Meridia), a weight-loss drug taken off the market in the United States in 2010; and anabolic steroids or steroid-like substances. And 20% of products contained more than one unapproved ingredient.

These supplements could prove harmful for those who take them because their ingredients may interact with other medications or cause problems for people with underlying health conditions.

Most lack evidence of any health benefit — and some contain stimulants that could affect your heart.

 Image: © PeopleImages/Getty Images

Of the nearly $37 billion Americans spend on dietary supplements each year, about two-thirds are for vitamins and minerals. The rest are pills, powders, and tinctures that contain various substances isolated from an array of sources — mainly plants but also animals and microorganisms.

Why are these products so popular? Some people believe that our food supply has been stripped of important nutrients, so they take supplements to replace what's "missing" (although many foods are already fortified to replace vitamins that are destroyed during processing). Others feel that Western medicine relies too heavily on pharmaceuticals and prefer to take natural substances instead. (However, a number of common drugs are derived from plants.)

Vitamins don't seem to reduce cardiovascular risks, according to a new report.

 Image: © Thunderstock/Getty Images

There may be reasons to take a multivitamin, but improving your cardiovascular health is not one of them, says a report in the July 10 issue of Circulation: Cardiovascular Quality and Outcomes. The authors found that for the average person, taking a multivitamin supplement didn't help prevent cardiovascular problems, such as heart attacks and strokes.

The findings were based on a review of general population studies conducted from 1970 to 2016, involving more than two million people. Researchers looked for associations between multivitamin supplementation and cardiovascular outcomes. But they weren't able to find any links.