Omega-3 fatty acids, found in fish and in supplements, play an important role in reducing inflammation in the body, which can damage your arteries and boost your risk of strokes, heart attacks and heart disease. But some research suggests omega-3s may protect your heart by reducing triglycerides.
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All About Omega-3s
The National Center for Complementary and Integrative Health (NCCIH) defines omega-3 fatty acids as a type of fat that's found in your body and foods — primarily fish, but also in some plant foods such as flaxseeds, chia seeds and black walnuts. There are three types of healthy fatty acids of interest: eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), both found in fish and shellfish, and alpha-linolenic acid (ALA), found in plant oils.
Fish with dark flesh, such as herring, salmon, bluefish and mackerel, tend to have a higher total fat content than fish with lighter flesh, according to Seafood Health Facts. The darker the flesh, the more significant the amount of omega-3 fatty acids.
Studies have shown that consuming high amounts of omega-3 fatty acids in seafood may result in a lower risk for cardiovascular disease and stroke than for those who never or rarely eat seafood, according to NCCIH — although some claims are still up for debate.
Read more: 5 Omega-3-Packed Recipes That Aren't Fish
Triglycerides and Omega-3s in Food
When you have your cholesterol checked, your doctor will also measure your triglycerides. Both cholesterol and triglycerides are lipids that circulate in your blood, but they're not the same. Cholesterol is a waxy, fatty substance that's found in your body's cells, and triglycerides are excess calories, alcohol and sugar stored as fat, says the Mayo Clinic.
Having borderline high or high triglycerides — in the range of 150 to 199 milligrams per deciliter (mg/dl) or 200 to 499 mg/dl, respectively — means you're at greater risk for a stroke, heart attack or heart disease due to possible thickening (sometimes called hardening) of your arteries, known as arteriosclerosis, notes the Mayo Clinic.
To manage lowering your triglycerides, Seth S. Martin, MD, MHS, a cardiologist at Johns Hopkins Medicine in Baltimore, recommends exercise and other healthy lifestyle changes, such as including more fruit, vegetables, fiber and high-quality fish in your diet. The U.S. Dietary Guidelines for Americans, 2015-2020, recommends that adults eat at least 8 ounces a week of some type of fish or seafood, averaging 250 milligrams daily of EPA and DHA.
Fish Oil Supplements
But what about taking a fish oil supplement on a daily basis? Results of the 2019 Vitamin D and Omega-3 Trial – VITAL, the largest multiyear study on this topic, were not very favorable toward supplement use, reports the American College of Cardiology.
Overall, the study showed no reduced risk for heart disease death, stroke or cancer among healthy middle-aged men and women who were followed for five years after taking these supplements. Heart attacks, however, were reduced among people who took fish oil supplements, according to ACC, noting that further study is needed.
A more definitive link relates to triglycerides. NCCIH notes that omega-3s in high doses can reduce triglyceride levels, but also cautions that products available in prescription form are different from over-the-counter options.
According to Harvard Medical School, if you decide to take an over-the-counter fish oil supplement, a 1-gram daily dose should be sufficient, unless your doctor recommends you take a higher dosage. Make sure the supplement has a combination of EPA and DHA fatty acids — each provides different benefits to your health — and look for a quality supplement that has seals from U.S. Pharmacopeia, NSF International or ConsumerLab.com.
However, Dr. Martin says there's also the question of purity regarding over-the-counter fish oil. "It's been found that some of them have saturated fats, and one of the most important things that determine somebody's cholesterol level is the amount of saturated fat in their diet," he says. "So if there's saturated fat in the fish oil, it could have an impact of raising the cholesterol, not actually lowering it."
Dr. Martin recommends that if you've changed your diet and are taking omega-3s, have another lipid test in about three months to see if there are any changes.
- American College of Cardiology: “Vitamin D and Omega-3 Trial – VITAL”
- National Center for Complementary and Integrative Health: “Omega-3 Supplements: In Depth”
- Seafood Health Facts: “Omega-3 Content of Frequently Consumed Seafood Products”
- Seth S. Martin, MD, MHS, cardiologist, Johns Hopkins Medicine, Baltimore
- Dietary Guidelines for Americans, 2015-2020: “A Closer Look Inside Healthy Eating Patterns” (from the U.S. Department of Agriculture and the Department of Health and Human Services)
- Harvard Medical School: “Should You Be Taking an Omega-3 Supplement?”
- Mayo Clinic: “Triglycerides: Why Do They Matter?”
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