Fish OIl

What Fish Oil Does for Your Health

Found in fatty fish or supplements, fish oil can work wonders, from preventing inflammatory diseases to reducing the stroke risk in people with heart disease.

By Beth W. Orenstein

Medically reviewed by Lindsey Marcellin, MD, MPH

There’s a good reason why the American Heart Association recommends that most people eat fish — particularly fatty fish — at least twice a week for heart health. Fatty fish has high levels of omega-3 fatty acids, which are essential nutrients that the body can’t make on its own.

Research has shown that fish oil offers many health benefits, but the strongest evidence points to fish oil benefits for heart health. Fish oil has been shown to:

• Lower triglycerides — fats which are unhealthy in high levels (its role in high cholesterol, however, is unclear)
• Cut the number of strokes in people with heart disease
• Prevent heart disease
• Slow the build-up of atherosclerotic plaques, also called hardening of the arteries
• Slightly reduce blood pressure

More Fish Oil Benefits: Reducing Inflammation

Because most of the benefits of fish oil come from omega-3’s anti-inflammatory properties, says clinical nutritionist Stella Metsovas, BS, CN, of Laguna Beach, Ca., fish oil may play a role in treating and preventing inflammatory conditions such as rheumatoid arthritis, ulcerative colitis, and osteoporosis.

“Inflammatory conditions like rheumatoid arthritis and osteoporosis are especially fascinating to me because current [treatment] methods [for example, calcium supplementation] are not as promising as once expected,” Metsovas says.

More Fish Oil Benefits: What Else It May Do

While fish has long had a reputation as a brain food, recent studies have shown that fish oil may specifically help with:

• Depression
• Attention deficit disorder
• Infant eye-brain development
• Alzheimer’s disease
• Schizophrenia
• Bipolar disorder
• Other brain disorders

Some studies are investigating the role that fish oil may play in preventing weight loss caused by cancer drugs, reducing the growth of colon cancer cells, and lowering rejection rates for heart and kidney transplant patients. Still others are looking at fish oil to help with dry eyes, glaucoma, and age-related macular degeneration, which can cause blindness.

Fish Oil: Fish or Supplement?

Your body doesn’t make omega-3s. To get the amount you need, you have to eat foods that have omega-3s or take supplements. Besides fatty fish, omega-3s are found in some nut oils (English walnuts) and vegetable oils, such as canola, flaxseed and linseed, olive, and soybean. Fish oil has two essential fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), while vegetable and nut sources contain the fatty acid alpha-linolenic acid (ALA). Some studies suggest that the benefits of EPA and DHA are greater than those of ALA.

“Although I might get some flak from vegetarians and vegans, the best sources of omega-3s are animal-based,” Metsovas says. Food sources include omega-3 enriched egg yolks, fatty fish, krill oil, and grass-fed beef. She recommends 1 gram of fatty acids per day. A 3.5-ounce serving of fish has about that amount.

Like most nutritionists, Metsovas recommends eating fish rather than taking supplements. When that’s not possible, she says, look for high-quality fish oils that offer concentrated sources of omega-3s per capsule.

Check with your doctor before taking higher doses of fish oil — more than 3 grams a day. People on anti-clotting drugs should take extra care, as fish oil can cause excessive bleeding.

Fish Oil: Watch for the Mercury

A problem with eating fish is that it can contain high levels of mercury and other environmental contaminants such as polychlorinated biphenyls (PCBs). The solution may be to choose fish by its size.

Smaller fish, such as sardines, tend to accumulate fewer toxins because they are lower on the food chain. Avoid larger fish such as shark or swordfish because the bigger the fish, the more mercury it can have.

Also, shellfish, salmon, or catfish may be lower in mercury. If you’re thinking of eating fish from local lakes, rivers, or streams, first check if any advisories about mercury levels or contaminants have been issued.

You also need to be careful about false claims, Metsovas says, regarding the actual purity and freshness of fish oil supplements. Recent studies suggest that many fish oils are prone to oxidation within a few days of processing. She says you should purchase high-quality fish oil that has added antioxidants, such as vitamin E, or a mixture of different forms of vitamin E, called mixed tocopherols, to make the oil less prone to breaking down and becoming rancid. Metsovas also says there is no standard definition of pharmaceutical-grade fish oil. Many companies will assign grades to their product to generate higher retail pricing.

Studies show fish oil has many good benefits, including promoting heart health and preventing inflammatory diseases. So eat fish often, and when you can’t, take fish oil supplements.