Omega-3 fatty acids in fish and dietary supplements are associated with lower odds of heart disease even in people already at elevated risk because of excessive levels of fats or bad cholesterol in their blood, a research review suggests.
The American Heart Association recommends eating at least two servings of fish a week and considering supplements of omega-3 fatty acids when that's not possible. Previous research has linked omega-3s to a lower risk of abnormal heartbeats, less fats in the blood, reduced risk of artery-clogging deposits known as plaque, and slightly lower blood pressure.
For the current study, researchers examined previously published research on two omega-3s: EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). They found that consumption of omega-3s in food or supplements was associated with a 16 percent lower risk of heart disease in people with high triglycerides, or fats, in the blood, and a 14 percent lower risk for patients with elevated low-density lipoprotein (LDL) cholesterol, the bad kind.
"The collective evidence from all studies supports a beneficial role of EPA and DHA on coronary heart disease, and stronger associations were observed among those who may benefit acutely from EPA and DHA, such as those with elevated triglyceride levels and those with elevated low-density lipoprotein cholesterol," said lead study author Dominik Alexander of EpidStat Institute, with offices in Seattle, Washington, and Ann Arbor, Michigan.
To examine the connection between omega-3s and heart disease, researchers analyzed data from 18 trials that randomly assigned about 93,000 people to get a certain amount of these nutrients.
Across these randomized trials, they found omega-3s associated with a 6 percent lower risk of heart disease, but this was too small to rule out the possibility it was due to chance.
The study also reviewed results from another 17 previously published trials that observed about 732,000 people over long periods of time while they followed their usual diets. Over all of these studies, omega-3s were tied to a statistically meaningful 18 percent reduction in the risk of heart disease.
The study was funded by the Global Organization for EPA and DHA Omega-3s (GOED), an advocacy group with manufacturers and sellers of omega-3 dietary supplements among its members. Several study authors have also served as consultants to manufacturers of omega-3 supplements.
Limitations of the study include the wide variation in study designs for the randomized trials, which included patients with a range of eating habits and heart disease risk factors and tested omega-3s over different time periods, the authors note in Mayo Clinic Proceedings.
Some studies in the current analysis also didn't track heart health or the amount of omega-3s in people's diets at the start, making it harder to determine how much these nutrients might directly influence heart disease risk over time, the authors also point out.
Even so, the results from an analysis of data on close to one million patients suggest many people may benefit from boosting the amount of omega-3s they get from eating fish or taking supplements, said Dr. Chip Lavie, of the Ochsner Clinical School-University of Queensland School of Medicine in Australia.
Very few people in the U.S. or other countries who follow a typical Western meat-and-potatoes diet eat enough fish, so they might need to take dietary supplements to achieve close to 1,000 milligrams a day of EPA and DHA, Lavie, senior author of an accompanying editorial, said by email.
"Omega-3 fats are very important for health and well being, especially for the heart," Dr. James O'Keefe, lead author of the editorial, said by email.
"Try to eat 2 or 3 servings of naturally oily fish like salmon, sardines, and trout each week," advised O'Keefe, director of preventive cardiology at the Mid America Heart Institute at Saint Luke's Hospital in Kansas City, Missouri. "If you can't or won't do this, consider taking a daily omega 3 supplement containing about 1,000 milligrams of EPA and DHA."