The fish oil story keeps getting better.
British researchers last month reported that eating fish cut the risk of dementia among a group of elderly people living in France. Those who ate fish or seafood at least once a week significantly lowered their risk of being diagnosed with the memory disorder. The British study was one of a series of reports this year that have helped bolster the case for increasing our consumption of certain types of fish. Consider:
Researchers in Scotland and England reported that fish oil supplements helped alleviate depression in patients who had not responded well to prescription antidepressants.
A major Italian study published found that fish oil supplements reduced the chance that heart-attack survivors would suffer sudden death from a cardiac arrest.
Several infant formula companies have begun adding a particular type of fat found in fish to their products based on research that links the fat to enhanced brain development in children.
This research centers on the health benefits of fats found in the flesh of deep-sea fish such as cod, salmon, shrimp, tuna, mackerel and herring.
Unlike some of the other so-called good fats found in olive oil or avocados, these fish fats have anti-inflammatory and other properties that can potentially improve many aspects of our health.
Researchers say they are truly “heart healthy” because they fight inflammation, reduce irregular heart rhythms and help maintain flexibility in blood vessels that stiffen with age. In revised guidelines being released today, the American Heart Assn. recommends these fish fats to protect healthy people’s hearts.
Scientifically rigorous studies have shown these fats can slow the progression of heart disease and help prevent the buildup of artery-clogging plaque leading to a heart attack.
Fish oil fats also can lower levels of two blood fats associated with heart disease: triglycerides and the very low-density lipoproteins, called VLDL, a component of LDL or bad cholesterol.
They also thin the blood and make platelets less apt to clump, reducing the risk of strokes or tiny strokes that can create a type of dementia.
Yet, the magnitude of these effects isn’t strong enough to substitute fish eating or fish oil pills for proven anti-clotting therapies, such as aspirin and the prescription drug heparin, said Dr. Mary Hardy, head of integrative medicine at Cedars-Sinai Medical Center in Los Angeles. Fish and fish oil contain two Omega-3 fatty acids: docosahexaenoic acid, or DHA, and eicosapentaenoic acid, or EPA. They belong to the same family as the alpha-linolenic acid, or ALA -- found in flaxseed oil, canola oil, soybeans and walnuts -- which the liver converts into DHA and EPA.
However, if you follow the typical American diet, heavy in the Omega-6 fatty acids found in corn, safflower, sunflower and soybean oils, it’s harder for your liver to break down the ALA into the fats you can easily get by eating fish.
While scientists are encouraged by many of the fish oil studies, some doubt remains about how strong the link is between increased consumption of fish and some diseases.
For example, the British researchers studying fish consumption and dementia could not tell whether fish had direct effects on the brain. They know that fish oil can reduce inflammation and plaque in the arteries, both of which are known Alzheimer’s risks.
In the study, published in the British Medical Journal, the authors cautioned that fish eaters might have less dementia because they were better educated and took better care of themselves.
Although it’s likely that anti-inflammatory properties of fish oil could account for improvements in conditions such as arthritis, the results are more mixed for psoriasis, an inflammatory skin disorder. Scientists continue to study whether fish oil is beneficial for mental health conditions, including depression, schizo- phrenia and attention deficit hyperactivity disorder, and some lung conditions including cystic fibrosis.
Doctors and nutritionists recommend making fish a regular part of your diet by eating at least two 3- to 6-ounce servings of fish weekly. For a meaty fish, such as a salmon steak, the appropriate serving size is about the size of a deck of cards. For thinner fish, such as trout, the serving size is about the size of a checkbook, said Joan Carter, a registered dietitian at Baylor College of Medicine in Houston. However, because cold-water fish such as tuna often are contaminated with mercury and other toxins such as PCBs, pregnant or nursing women and young children are advised to limit their fish eating, and questions have begun being raised about risks to healthy people.
Simply heating up a package of frozen fish sticks or reaching for a jar of picked herring is not a good option. The partially hydrogenated fats often used in fried foods can boost your heart disease risk, and salty pickled fish boosts your intake of sodium.
Instead, stick to grilled, broiled, baked, sauteed or poached fish. And don’t rule out canned salmon, which is wild salmon that contains more Omega-3s than the farm-raised salmon often found in your supermarket.
Vegetarians and people who dislike fish can get Omega-3s from eggs laid by chickens fed Omega-3-rich diets, which boosts the amount of the fatty acids in their yolks. You can find these in the egg section of your supermarket; the labels specify they’ve been enriched with Omega-3s. However, a dozen can cost twice as much as conventional eggs.
The American Heart Assn. recommends that healthy people get an average of 650 milligrams of combined EPA and DHA each day from their diet; some experts recommend from 800 to 1,000 milligrams. With fish oil capsules containing 300 to 500 milligrams of the fatty acids combined, that translates into two to three capsules a day.
Although the heart association has not formally recommended fish oil supplements for healthy people, its revised guidelines suggest that those with high triglycerides or cardiovascular disease may need more than they can get through diet alone, so they should talk to their doctors about fish oil supplements.
But they should be cautious. Anyone taking blood thinners, such as Coumadin, should avoid fish oils because of bleeding risks. Diabetics should monitor sugar levels because fish oil might interfere with glucose levels.
By choosing fish rather than fish oil supplements, said Carter, you avoid some uncertainties, such as the content of certain products, which the U.S. government does not regulate for safety or effectiveness. Also, the quality of the supplements may vary. ConsumerLab.com, an independent product-testing firm, found that six of 20 fish oil products it sampled had levels of DHA ranging from 50% to 83% of the amount stated on the label; two of those six contained less than stated amounts of EPA. Also, some people who take fish capsules complain of a lingering fishy taste and indigestion, or diarrhea.