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Fish Protects Diabetic Women from Heart Disease

The more you eat, the greater the protection, a new study finds

MONDAY, March 31, 2003 (HealthDayNews) -- Among the many health problems linked to Type 2 diabetes is an increased risk of heart disease.

Now, a group of Harvard University researchers suggests that eating fish may help reduce that risk, particularly in women.

"It has been shown in the past that fish can protect the hearts of healthy women, but we now know it can also protect the hearts of women with diabetes without disrupting control of blood sugar. And that's an important piece of information that we did not previously have," says Dr. Frank B. Hu, lead author of a study in the April online edition of Circulation.

As encouraging as these results are, some experts aren't convinced the finding is entirely accurate.

According to New York University endocrinologist and diabetes expert Dr. Loren Wissner-Greene, there is still too much scientists don't know about the women in the study to draw such broad conclusions about the power of fish.

"This was not a randomized trial, plus, we don't know if the women who ate fish also took other steps to protect their heart health, such as exercising or eating lots of fruits and vegetables, all of which could make as much of a difference as eating fish," Wissner-Greene explains.

While Hu says it's possible other dietary and lifestyle factors may have influenced the study's outcome, he believes his findings are on solid ground.

"We adjusted our findings to take into consideration some other risk factors for heart disease, and we still believe eating fish can make a difference," says Hu, an associate professor of nutrition and epidemiology at the Harvard School of Public Health.

The new data was gleaned from the massive Harvard Nurses Health Study, which began in 1976 with a database of nearly 122,000 women. At the start of the study, the nurses completed a questionnaire detailing their medical history and lifestyle factors. Every two years, they completed follow-up questionnaires to update information on risk factors and health problems.

Hu's study was based on data from 5,103 of the nurses who reported being diagnosed with Type 2 diabetes between 1976 and 1994. Those with a history of heart disease, stroke or cancer that was reported before 1981 were excluded from the new analysis.

The remaining women were divided into five categories, based on fish consumption: Less than once a month; one to three times a month; once a week; two to four times weekly; and five or more times a week.

Between 1980 and 1996, 362 women in the fish study developed heart disease; 221 had non-fatal heart attacks and 141 died as a result of heart disease.

After analyzing all the data, Hu concluded that not only could regular fish consumption reduce the risk of heart disease in women with Type 2 diabetes, the more they ate, the greater the protection.

Hu reports that, compared to diabetic women who ate fish once a month or less, those who ate it one to three times a month had a 30 percent decrease in their risk of heart disease. When fish consumption increased to once a week, the risk dropped by 40 percent.

Somewhat surprisingly, when fish intake increased to two to four times weekly, the reduced risk of heart disease was 36 percent. Hu can't explain the discrepancy, but says he doesn't believe it is statistically significant.

Finally, the group eating five or more servings of fish a week experienced a whopping 64 percent decrease in their risk of heart disease.

In addition, none of the fish eaters experienced any significant loss of control over blood sugar levels, and they all experienced a lower death rate from cardiovascular disease.

Wissner-Greene says eating more fish probably can't hurt, but that women with Type 2 diabetes must also "continue to eat lots of fresh fruits and vegetables, both of which are also extremely important to heart health and blood sugar control."

More information

For more heart-healthy food recommendations, visit The American Heart Association. To find out if you are at risk for Type 2 diabetes, click here.

SOURCES: Frank B. Hu, M.D., associate professor, nutrition and epidemiology, Harvard School of Public Health, Boston; Loren Wissner-Greene, M.D., professor, medicine, New York University School of Medicine, New York City, and co-author of Living With Diabetes; April 2003 online edition, Circulation
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