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Eating fish just occasionally can help ward off stroke
Women who eat seafood as seldom as once a month may cut their risk of the most common kind of stroke by more than 40 percent, a study by the Harvard School of Public Health has found. Many studies over the last two decades have found that eating fish reduces the risk of heart attack and strokes caused by clogged arteries. What is surprising about this study is that it shows how little fish — one to three meals a month of virtually any fish or shellfish, from salmon sushi to tuna on rye to broiled lobster to McDonald's Filet-O-Fish (SNaC Bytes editor note: this is not recommended) — appears to produce a substantial benefit.
"Previous studies found that you had to eat fish once or twice a week," said Dr. Ka He, the Harvard nutritionist who led the study, which was made public by the Journal of the American Medical Association. "And they found a linear association — the more fish you ate, the more benefit you got. But in our study, we found a threshold. Further fish did not provide further benefit."
A Harvard study of strokes among 80,000 female nurses who were followed for 14 years reported in the Journal of the American Medical Association in January that women who ate fish five or more times a week had a 52 percent lower risk of stroke than women who ate fish less than one a month. However, it found that the relative benefit dropped to only 22 percent for those who ate fish once a week and 7 percent for those who ate fish once a month.
Dr. He agreed that the protocols of the two studies were roughly the same and said he could not explain why his study had found a threshold level, while the other study found a progressive benefit. Dr. He's study also deepened a mystery that has flummoxed nutritionists: it was believed for years that fish wards off heart disease and stroke because it is rich in omega-3 polyunsaturated fatty acids, and sales of fish oil capsules soared on this assumption. But this study, like other recent ones, found no definitive connection: fish with larger amounts of omega-3 fatty acids did not confer larger protection against stroke.
"Everybody continues to bark up the wrong tree," said Dr. Martha L. Daviglus, a preventive-medicine specialist at Northwestern University Medical School in Chicago, who led a 1997 study of fish and stroke risk in 1,800 employees of a Chicago electric company. "Everyone wonders: it is some other component of fish, some combination, or what?"
Dr. Daviglus did agree with the general conclusion that Dr. He's study reached: something in fish is good for the arteries and everyone should eat at least some fish each month.
Although the study did not reach conclusions about species or cooking methods, both Dr. Daviglus and Dr. He were quick to say that they thought it would be medically irresponsible to suggest that anyone eat only deep-fat-fried fish, such as that found in fishsticks and fast-food restaurants. They would still get the benefits of the fish, Dr. He said, but the fried breading is full of salt and transfatty acids, which have been associated with heart disease.
Bottom line: According to the study authors: “Every study shows that fish eaters are a very different kind of people…they smoke less, they eat more food, they eat many more fruits and vegetables. Fish could just be a marker for how healthy you are."
Women who eat seafood as seldom as once a month may cut their risk of the most common kind of stroke by more than 40 percent, a study by the Harvard School of Public Health has found. Many studies over the last two decades have found that eating fish reduces the risk of heart attack and strokes caused by clogged arteries. What is surprising about this study is that it shows how little fish — one to three meals a month of virtually any fish or shellfish, from salmon sushi to tuna on rye to broiled lobster to McDonald's Filet-O-Fish (SNaC Bytes editor note: this is not recommended) — appears to produce a substantial benefit.
"Previous studies found that you had to eat fish once or twice a week," said Dr. Ka He, the Harvard nutritionist who led the study, which was made public by the Journal of the American Medical Association. "And they found a linear association — the more fish you ate, the more benefit you got. But in our study, we found a threshold. Further fish did not provide further benefit."
A Harvard study of strokes among 80,000 female nurses who were followed for 14 years reported in the Journal of the American Medical Association in January that women who ate fish five or more times a week had a 52 percent lower risk of stroke than women who ate fish less than one a month. However, it found that the relative benefit dropped to only 22 percent for those who ate fish once a week and 7 percent for those who ate fish once a month.
Dr. He agreed that the protocols of the two studies were roughly the same and said he could not explain why his study had found a threshold level, while the other study found a progressive benefit. Dr. He's study also deepened a mystery that has flummoxed nutritionists: it was believed for years that fish wards off heart disease and stroke because it is rich in omega-3 polyunsaturated fatty acids, and sales of fish oil capsules soared on this assumption. But this study, like other recent ones, found no definitive connection: fish with larger amounts of omega-3 fatty acids did not confer larger protection against stroke.
"Everybody continues to bark up the wrong tree," said Dr. Martha L. Daviglus, a preventive-medicine specialist at Northwestern University Medical School in Chicago, who led a 1997 study of fish and stroke risk in 1,800 employees of a Chicago electric company. "Everyone wonders: it is some other component of fish, some combination, or what?"
Dr. Daviglus did agree with the general conclusion that Dr. He's study reached: something in fish is good for the arteries and everyone should eat at least some fish each month.
Although the study did not reach conclusions about species or cooking methods, both Dr. Daviglus and Dr. He were quick to say that they thought it would be medically irresponsible to suggest that anyone eat only deep-fat-fried fish, such as that found in fishsticks and fast-food restaurants. They would still get the benefits of the fish, Dr. He said, but the fried breading is full of salt and transfatty acids, which have been associated with heart disease.
Bottom line: According to the study authors: “Every study shows that fish eaters are a very different kind of people…they smoke less, they eat more food, they eat many more fruits and vegetables. Fish could just be a marker for how healthy you are."
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