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.
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.
Researchers tested, among other things, whether a moderate dosage (1 gram a day) of an omega-3 supplement could help prevent major cardiovascular events, compared with a placebo. Cardiovascular events included not only heart attacks, but stroke, and angioplasty procedures to clear blocked arteries.
"The findings are somewhat complex and nuanced. It's not a simple yes, or no, or one-size-fits-all answer. Some groups tended to benefit, while other groups didn't," says Dr. Manson.
Although a daily 1-gram omega-3 supplement did not significantly reduce major cardiovascular events over all, there was a 28% reduction in heart attacks and promising signals for other heart-related endpoints, she says. While the supplement didn't seem to protect most healthy people against future heart problems, certain groups did appear to benefit, particularly people who ate less than 1.5 servings of fish a week or didn't eat fish at all. "For these people, there was a significant 19% reduction in the primary endpoint of major cardiovascular events, with a 40% reduction in heart attacks," says Dr. Manson.
The supplements also appeared to benefit African American participants, who saw a 77% reduction in heart attack for those receiving the omega-3 supplement, compared with those taking the placebo, says Dr. Manson. It's unclear why this group benefited more, and additional studies are needed to confirm the finding.
The second study, called the Reduction of Cardiovascular Events with EPA–Intervention Trial (REDUCE-IT), included more than 8,000 middle-aged and older adults who had elevated triglyceride levels and who had already experienced a cardiovascular event or had other significant risk factors for one. It aimed to find out if a daily high-dose, 4-gram prescription omega-3 medication could protect participants against future cardiovascular events, compared with a placebo. This trial, led by Dr. Deepak Bhatt, a cardiologist and professor of medicine at Harvard Medical School, found a substantial 25% reduction in the risk of dying from heart disease or suffering a cardiovascular event among people who took the medication, compared with those who had the placebo.
High doses of omega-3 supplements, like the high-dose omega-3 product used in this trial, aren't appropriate for everyone because they pose risks, such as bleeding or an increase in a type of abnormal heart rhythm known as atrial fibrillation, says Dr. Manson. "However, while high doses are associated with some risk, overall benefits of the high-dose omega-3 product used in the trial appeared to outweigh the risks for people with high triglyceride levels and a history of, or at high risk of, cardiovascular disease," says Dr. Manson.
Choosing the right supplement
Looking for an over-the-counter omega-3 supplement? Here's what to look for:
If your triglyceride levels are abnormally high and you have an elevated risk for cardiovascular disease, talk to your doctor about whether a high-dose omega-3 prescription might be an option.
Putting the findings into practice
So, what do these findings mean for you?
People in good health. If you're healthy and at low or average risk for heart disease, chances are you don't need an omega-3 supplement, provided you eat fish often, says Dr. Manson. You should eat at least two servings a week of fatty fish, such as salmon, tuna, or herring. Aim for fish that are high in two different omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), each of which provides unique health benefits.
Getting your omega-3 fatty acids from food is always preferable to a supplement. Not only do you get the marine omega-3 fatty acids from the fish, but you also potentially replace less healthful foods in your diet, such as red meat, processed foods, or refined grains, says Dr. Manson. "It's a good lifestyle change to make and has been a recommendation for a while. Nothing in these studies supersedes the recommendation for moderate fish intake," she says.
Non–fish eaters and African Americans. However, if you can't eat fish or don't like fish, an omega-3 supplement is something to consider. (Algae-based supplements are an option if you are a vegetarian or allergic to fish.) African Americans might also consider a supplement because of the unique benefits revealed in this trial.
For these two groups, a daily 1-gram supplement could provide a good balance between safety and efficacy. "Talk to your health care provider about whether you're a candidate for a supplement," says Dr. Manson.
Already taking omega-3s? If you're already taking an over-the-counter omega-3 supplement, you don't necessarily need to stop taking it if you don't fall into one of the categories above, unless your doctor tells you to. But if you're not taking an omega-3 supplement, whether you should start really depends on your individual risk factors, says Dr. Manson.
Regardless of whether you opt for an omega-3 supplement, you should always strive to maintain a healthy diet and lifestyle. "No dietary supplement is a substitute. We already know that, and I think this is an important point to reinforce," says Dr. Manson. "Healthy lifestyle practices, including regular physical activity, healthy diet, and not smoking, will reduce heart disease risk by close to 80%, and that's really the main recommendation for heart health," she says.
Cardiovascular risk factors. If you have an elevated triglyceride level and a history of cardiovascular disease or have major risk factors for it, a high-dose omega-3 medication may be advisable. This is true even if you're already taking a statin medication. The omega-3 drug does not replace the statin.
Fast facts about the two trials
The Vitamin D and Omega-3 trial (VITAL)
This study was published online Nov. 10, 2018, by The New England Journal of Medicine.
Funding source: The U.S. National Institutes of Health.
Who: 25,871 healthy, racially diverse individuals, including 12,786 men ages 50 and older and 13,085 women ages 55 and older.
What: A daily 1-gram omega-3 prescription supplement that included a combination of two omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). A 1-gram dose was chosen because it is a moderate amount that is unlikely to produce side effects. A control group took a placebo.
The Reduction of Cardiovascular Events with EPA–Intervention Trial (REDUCE-IT)
This study was published online Nov. 10, 2018, by The New England Journal of Medicine.
Funding source: Amarin, Inc., the company that makes the prescription-strength medication used in the study.
Who: 8,179 middle-aged men and women who had high triglyceride levels and risk factors for heart disease or had already experienced a heart attack, stroke, or cardiovascular event. Risk factors included conditions such as high blood pressure and diabetes. Everyone in the trial was taking a statin to reduce high cholesterol.
What: A daily high-dose, 4-gram prescription omega-3 medication or a placebo. Unlike over-the-counter omega-3s, the medication included EPA only.
Key takeaways: This medication may help to protect high-risk individuals from cardiovascular events. Those taking it were 25% less likely to die from heart disease or to have a heart attack, stroke, or a type of chest pain called angina. They were also less likely to need a procedure to open a blocked heart artery. If you have a high triglyceride level and have had a heart attack or stroke or have risk factors for cardiovascular disease, you might benefit from taking the high-dose omega-3 product.
While these two studies revealed some new knowledge about the potential benefits of omega-3 supplements, more information will likely be available in the near future. VITAL also examined the effect of omega-3 supplementation on cognitive decline, diabetes, depression, and autoimmune disorders, among other conditions, and those results will be published within the next year, says Dr. Manson.
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