Is fish really a wonder food or can its healthful benefits come from a pill?
By Kevin Davis
Pity the health-conscious carnivore. In recent years, frequent beef consumption has been associated in some studies with an increased risk of heart disease, obesity and some cancers. Fowl has been implicated in well-publicized cases of Salmonella and other types of food poisoning.
Yet through it all, the reputation of fish as a delicious and nutritious food source has stayed swimmingly well. In fact, some might consider fish to be the real treasure from Davy Jones' locker - with numerous studies finding that eating fish can reduce the risk of heart disease and recommending it replace other animal food sources as part of a heart-smart eating plan.
But the reported health benefits don't end there: Other studies have suggested that the omega-3 fatty acids found in all fish - but in highest concentrations in salmon, mackerel and other cold-water varieties - may help relieve rheumatoid arthritis, lower blood pressure and even protect against some cancers. Just a few months ago, Australian researchers reported that eating fish can help you lose weight, and another 1999 study suggested that fish oil can be effective in treating depression.
Granted, fish is a great replacement for a diet rich in beef, pork and other higher-fat animal sources. Most types of fish are rich in protein, lower in saturated fat or cholesterol and are more likely to contain "heart-healthy" fats - including the much-ballyhooed omega-3 fatty acids, which are believed to hinder the formation of blood clots that can cause heart attacks and stroke and reduce triglyceride levels, another risk factor of coronary disease.
But the question remains: Is it the fish itself, or the omega-3 fatty acids - commonly known as "fish oil" and available in over-the-counter supplements available at supermarkets, pharmacies, health food stores and elsewhere where vitamins are sold? And exactly how much is needed to lower your disease risk?
For instance, a recent and well-publicized study of 11,000 heart attack survivors found that those who took a daily 1,000-milligram fish oil supplement each day - the amount found in a 3 1/3-ounce serving of broiled salmon - had approximately half the risk of dying of heart disease in the next three years compared with those who didn't consume the fish oil.
Still, experts are reluctant to recommend taking fish oil capsules instead of eating fish. "There may be another component of fish (other than omega-3 fatty acids) that is giving these benefits," says Martha Daviglus, M.D., assistant professor of preventive medicine at Northwestern University School of Medicine, who has studied the health properties of fish and omega-3 fatty acids. "No study has examined the long-term effects of fish oil capsules."
In her own study, Dr. Daviglus and colleagues found that men who ate about two 3-ounce servings of omega-3-rich fish per week had a lower risk of dying of a heart attack than men who did not eat fish. Her study, like most others, didn't compare the benefits of eating fish versus taking fish oil capsules.
"The evidence is inconsistent to some extent," says Alberto Ascherio, M.D., an associate professor of nutrition and epidemiology at Harvard University. "The bottom line is that there is fairly good evidence that a small amount of fish - one or two servings per week - is likely to lower the risk of fatal coronary heart disease. Whether or not consumption of larger amounts of fish or fish oil supplements will provide further benefits remains uncertain."
Omega-3 fatty acids, whatever their source, seem to offer benefits beyond reducing heart disease risk. Among some recent findings:
Weight loss. Australian researchers found in 1999 that eating tuna, salmon or other fish rich in omega-3 fatty acids once a day as part of a weight loss plan helped people lose weight.
Mental illness and depression. A study published in the May 1999 issue of Archives of General Psychiatry reported that patients with bipolar disorder - known also as manic-depression - who took fish oil capsules regularly displayed fewer symptoms compared with another group taking capsules with olive oil. Researchers believe the omega-3 fatty acids help stabilize mood and can inhibit certain brain signal activity in ways similar to drugs used to treat the disorder. Meanwhile, another study has linked major depression with lower intake of omega-3 fatty acids, which are thought to contain components crucial to communication among brain cells.
Crohn's disease. Several studies show that taking fish oil capsules appears to reduce symptoms and aid in the remission of this often painful inflammation of the bowel that can also cause diarrhea and weight loss. Fish oil appears to also prevent relapse of the disease.
Rheumatoid arthritis. In the past 10 years, several studies have suggested that fish oil - both supplements and in fish - can help reduce or control inflammation of the joints. Studies have suggested that omega-3 fatty acids have helped patients reduce their need for anti-inflammatory drugs.
Cancer. Several studies during the past five years have found that people who consume a lot of omega-3 fatty acids seem to have a decreased risk of some types of common cancers - notably breast, colon and possibly prostate. Research in this area is still relatively new, and clinical trials are necessary to determine whether there is a direct link or if other factors may be involved.
Blood pressure. A 1998 study showed that combining a daily meal that includes fish with a weight reduction plan lowered the blood pressure and heart rate for overweight people suffering from high blood pressure more than those who did not eat fish as part of the plan.
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