Slideshow Pictures: Omega-3 Fatty Acids - Benefits of Fish Oil, Salmon, Walnuts, & More

Omega-3: The Good Fat

Doctors may tell you to cut the fat, but not all fats are unhealthy. Omega-3 fatty acids may have far-reaching health benefits. Studies suggest they help lower the risk of heart disease, the nation’s top killer. They may also protect against depression, dementia, cancer, and arthritis. Omega-3s are found in salmon, walnuts, spinach, and more – but the health benefits can differ greatly from one source to another.

The Omega-3 Alphabet

Omega-3 fatty acids come in more than one form. The types found in fish, called DHA and EPA, have been studied most extensively and appear to have the strongest health benefits. Another form known as ALA is found in vegetable oils, flaxseed, walnuts, and dark leafy vegetables such as spinach. The body converts a small amount of ALA into EPA and DHA. ALA may also have some health benefits of its own.

How Omega-3 Fights Disease

Omega-3 fatty acids help fight disease by reducing inflammation in the blood vessels, joints, and elsewhere in the body. At high doses they also lower the risk for an abnormal heart rhythm and reduce unhealthy fats in the bloodstream known as triglycerides. Finally, they can slow plaque build-up inside the blood vessels. Our bodies can’t make omega-3s, so we must get them from foods or supplements.

Omega-3 and Heart Disease

If you've had a heart attack, a prescription dose of omega-3s may help protect your heart. Some studies show fewer heart attacks and fewer heart disease deaths among survivors who boosted their levels of omega-3. The American Heart Association recommends 1 gram a day of EPA plus DHA for people with heart disease. Eating fish is best, but your doctor might recommend a fish oil capsule.

Omega-3 and Arrhythmias

Omega-3s seem to have a stabilizing effect on the heart. They can lower heart rate and reduce the risk of life-threatening arrhythmias or abnormal heart rhythms. Several common sources of omega-3s are shown here: fish, walnuts, broccoli, and edamame, green soy beans that are often steamed and served in the pod.

Omega-3 and Triglycerides

Omega-3s can lower your triglycerides, a blood fat that’s linked to heart disease. Talk with your doctor before taking omega-3 supplements, because some types can make your "bad" cholesterol worse. You can also bring down triglyceride levels with exercise, by drinking less alcohol, and cutting back on sweets and refined carbohydrates.

Omega-3 and High Blood Pressure

There’s strong evidence that omega-3s lower blood pressure. The effect is small, though. One dietary strategy is to replace red meat with fish during some meals. But it’s best to avoid salty fish, such as smoked salmon. If you have high blood pressure, limiting salt, regular exercise, and medications, as recommended by your doctor, can help.

Omega-3 and Stroke

The evidence is mixed on whether omega-3 supplements can help prevent strokes. It curbs plaque build-up inside blood vessels and has anti-clotting effects, so it may help prevent the type caused by clots or a blocked artery. At high doses, omega-3 supplements might raise the risk of the less common type of stroke that involves bleeding in the brain.

Omega-3 and Rheumatoid Arthritis

Studies suggest omega-3s can reduce symptoms such as joint pain and stiffness in people with rheumatoid arthritis. A diet high in omega-3s may also boost the effectiveness of anti-inflammatory drugs.

Omega-3 and Depression

Omega-3 fatty acids may help smooth out mood disorders and make antidepressants more effective. However, results of studies have been mixed so far. Countries with higher levels of omega-3 in the typical diet have lower levels of depression. Although more studies are needed, the evidence so far is promising.

Omega-3 and ADHD

Some studies suggest omega-3 supplements may ease the symptoms of attention deficit hyperactivity disorder (ADHD). We know omega-3 fatty acids are important in brain development and function. Although evidence isn't conclusive and a diet supplement can't offer a cure-all for ADHD, omega-3s may provide some added benefits to traditional treatment.

Omega-3 and Dementia

The jury is still out, but there's some evidence that omega-3s may protect against dementia and improve mental function. In one study, older people with a diet high in omega-3 fatty acids had a lower risk of developing Alzheimer's disease. More research is necessary to confirm the link.

Omega-3 and Cancer

Omega-3s may help reduce the risk of colon cancer, breast cancer, and advanced prostate cancer, but more research is needed. The American Cancer Society recommends a diet that includes fish, but the organization stops short of endorsing omega-3 supplements for cancer prevention.

Omega-3 and Children

Be wary of promises that omega-3s have "brain-boosting" powers for children. The Federal Trade Commission asked supplement companies to stop that claim unless they can prove it scientifically. The American Academy of Pediatrics does recommend that kids eat more fish, as long as it's not breaded and fried. Pediatricians also caution against types of fish that are high in mercury, such as shark, swordfish, king mackerel, and tilefish.

Omega-3: Catch of the Day

The best source of omega-3 fatty acids is fish, though some varieties deliver a higher dose than others. Top choices are salmon, mackerel, herring, lake trout, sardines, anchovies, and tuna. The American Heart Association recommends at least two servings a week of fish, which is 3.5 ounces of cooked fish or ¾ cup of flaked fish.

Omega-3 and Tuna

Tuna is an old-school staple in many people's pantries that can be a good source of omega-3. Albacore tuna (often labeled "white") has more omega-3 than canned light tuna, but it also has a higher concentration of mercury contamination. The amount of omega-3 in a fresh tuna steak varies, depending on the species.

Dangers of Contaminated Fish

For most people, mercury in fish is not a health concern. But the FDA has this advice for pregnant women, nursing mothers, and young children:

• Limit albacore tuna to 6 ounces/week.
• Limit fish lower in mercury to 12 ounces/week.
• Avoid shark, swordfish, king mackerel, tilefish.
• Remove skin and fat before cooking fish.

Omega-3 Supplements

If you don’t like fish, you can get omega-3 from supplements. One gram per day is recommended for people with heart disease, but ask your doctor before starting. High doses can interfere with some medicines or increase the risk of bleeding. You may notice a fishy taste and fish burps. Read the label to find the amounts of EPA, DHA, or ALA you want -- amounts can vary greatly.

Omega-3 for Vegetarians

If you don't eat fish or fish oil, you can get a dose of DHA from algae supplements. Algae that is commercially grown is generally considered safe, though blue-green algae in the wild can contain toxins. Vegetarians also can get the ALA version of omega-3 from foods such as canola oil, flaxseed, walnuts, broccoli, and spinach -- or products fortified with omega-3s.

Avoiding the Omega-3 Hype

Many food products now boast that they have added omega-3 to support various aspects of your health. But be aware that the amount of omega-3 they contain may be minimal. They may contain the ALA form of omega-3, which hasn't yet shown the same health benefits as EPA and DHA. For a measured dose of omega-3, taking fish oil supplements may be more reliable.

Omega 6: The Other Healthy Fat

There's another healthy fat known as omega-6. Research suggests it may protect against heart disease, especially when eaten in place of less healthy fats. The AHA recommends getting up to 10% of your total daily calories from omega-6 fats, which are found in vegetable oils and nuts. And now for some good news -- most Americans already get enough omega-6 in their diet, thanks to cooking oils and salad dressings.

More Reading on Diet and Nutrition

• Omega-3 Polyunsaturated Fatty Acids
• Triglycerides
• 25 Foods to Protect Your Cardiovascular System
• Brain Foods That Help You Concentrate
• 15 Tips for Avoiding Heart Disease
• Stress-Reducing Foods