While eating too much fatty food can elevate cholesterol and triglyceride levels, not all fats are unhealthy. Omega-3 fatty acids may have significant benefits in lowering the risk of heart disease, the nation's top killer. They may also protect against depression, dementia, cancer, and arthritis. Omega-3 fatty acids are found in higher amounts in salmon, walnuts, and spinach. Find out how omega-3s fight disease and which foods have them in the following slides.
There are many forms of omega-3 fatty acids. The types found in fish, called DHA and EPA, have been studied most extensively and appear to have the strongest health benefits. Another form of omega-3 fatty acid known as ALA is found in vegetable oils, flaxseed, walnuts, and dark leafy vegetables such as spinach.
It is thought that omega-3 fatty acids help fight disease by reducing inflammation in the blood vessels, joints, and elsewhere. High doses of omega-3 fatty acids also lower the risk for an abnormal heart rhythm and reduce unhealthy fats in the bloodstream known as triglycerides. Moreover, omega-3 fatty acids can slow plaque buildup inside the blood vessels. We must get omega-3 fatty acids from foods or supplements since our bodies cannot make them.
Prescription doses of omega-3s are used to protect the heart after a heart attack. Studies have shown fewer heart attacks and fewer heart disease deaths among survivors who boosted their levels of omega-3s. It may also protect cognitive abilities in people with heart disease. 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-3s seem to reduce the risk of abnormal heart rhythms (arrhythmias) that can be life-threatening. Common sources of omega-3s include fish, walnuts, broccoli, and green soybeans steamed and served in the pod (edamame).
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.
Talk with your doctor before taking omega-3 supplements.
Omega-3s can lower blood pressure, although the effect seems to be small. 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.
For high blood pressure your doctor may suggest regular exercise, medications, and limiting salt.
The evidence is mixed on whether omega-3 supplements can help prevent strokes. Nevertheless, omega-3 fatty acids have been shown to prevent plaque buildup inside blood vessels. Studies suggest that at high doses, omega-3 supplements might raise the risk of the less common type of stroke that involves bleeding in the brain.
Studies suggest omega-3s can improve joint symptoms such as pain and stiffness from rheumatoid arthritis. Additionally, a diet high in omega-3s may also boost the effectiveness of anti-inflammatory drugs.
Omega-3 fatty acids may help to calm mood disorders and improve the effectiveness of antidepressants. However, results of studies have been mixed so far. Countries with higher levels of omega-3s in the typical diet have lower levels of depression, although more studies are needed.
Studies suggest omega-3 supplements may improve the symptoms of ADHD (attention deficit hyperactivity disorder). However, the evidence is inconclusive; a dietary supplement can't offer a cure-all for ADHD. Nevertheless, omega-3s may provide some added benefits to traditional treatment. We do know omega-3 fatty acids are important in brain development and function.
There is preliminary evidence to suggest 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 association.
More research is needed to determine whether omega-3s could help reduce the risk of colon cancer, breast cancer, and advanced prostate cancer. The American Cancer Society recommends a diet that includes fish, but the organization does not endorse omega-3 supplements for cancer prevention.
Parents 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--if it isn't breaded and fried, that is. Pediatricians also caution against types of fish that are high in mercury, such as shark, swordfish, king mackerel, and tilefish.
The best source of omega-3 fatty acids is fish, though different fish have different levels. 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.
Tuna is a staple in many people's pantries and can be a good source of omega-3 fatty acids. Albacore tuna (often labeled "white") has more omega-3s than canned light tuna, but it also has a higher concentration of mercury. Different tuna species have different levels of omega-3 fatty acids.
For most people, mercury in fish is not a health concern. But it can be a concern during pregnancy and nursing, as well as in the growing child. 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.
If you don't care to eat fish, you can use omega-3 supplements. One gram per day is recommended for people with heart disease. Ask your doctor before starting, for high doses can interfere with some medicines or increase the risk of bleeding. Some people taking fish oil supplements notice a fishy taste and breath.
Read the label. The amounts of EPA, DHA, and ALA can vary greatly, and that makes the quality of supplements vary greatly as well. When you choose your supplements, keep in mind the international recommended guidelines: 650mg a day of a combined mixture of EPA and DHA.
If you don't eat fish or fish oil, you can get a dose of DHA from algae supplements. Algae that is commercially produced 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. Some foods are fortified with omega-3s.
It is now common for food products to boast that they have added omega-3s. But the amount of omega-3s they contain may be minimal, so check the label. They may contain the ALA form of omega-3s, which hasn't yet shown the same health benefits as EPA and DHA. For a regular dosing of omega-3s, taking fish oil supplements may be more reliable.
Another healthy fat is known as omega-6. Omega-6s may protect against heart disease, especially when eaten in place of less healthy fats. The American Heart Association recommends getting up to 10% of your total daily calories from omega-6 fats. Omega-6 fats are found in vegetable oils and nuts. Most Americans already get enough omega-6s in their diets, thanks to cooking oils and salad dressings.
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- NIH Office of Dietary Supplements: "Omega-3 Fatty Acids and Health"
- UpToDate: "Fish oil and marine omega-3 fatty acids"