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Researchers Explore How Fish May Decrease Risk of Cardiovascular Disease (dateline November 6, 2002)

Though experts have known for years that a diet rich in fish provides a host of health benefits, new research explores how fish may work to reduce heart disease risk. In a study of African tribes, researchers found that tribe members who consumed large amounts of fish tended to have lower levels of a so-called obesity hormone called leptin. Leptin has been associated with high rates of cardiovascular disease. Tribe members who did not consume much meat had higher leptin levels, even though many were the same weight, had similar alcohol intake, etc. The researchers believe the study provides important clues about how fish rich diet can protect the heart.

Leptin is a hormone produced in the body’s fat cells and is thought to play a key role in appetite. Leptin signals the brain when fat cells are full, and the brain in turn reduces the body’s appetite. Much is still unknown about how leptin functions in the body, though research has linked high levels of the leptin hormone to an elevated risk of cardiovascular disease.

To explore the link between leptin and diet, Paolo Pauletto MD of the University of Padova in Padova, Italy and colleagues studied fish consumption in tribal populations of Tanzania. Members of one tribe consumed an abundance of freshwater fish while members of another tribe consumed a primarily vegetarian diet. Aside from the amount of fish intake, characteristics of tribe members were very similar. Both tribes consumed approximately the same number of calories each day and had similar body mass indexes, suggesting that obesity would not play a factor in the study results.

Of the 279 tribe members who consumed fish, Dr. Pauletto and his colleagues found that the men had less than 25% of the amount of leptin in their blood compared to the male tribe members who did not eat fish. Similarly, female fish-eaters also had significantly lower levels of leptin in their blood compared to female vegetarians. The results were the same regardless of age, body mass index, body fat, alcohol consumption, or insulin levels.

Based on the findings, the researchers conclude that leptin levels have important implications for understanding the lower risk of heart disease in people who consume large amounts of fish. Further research is needed to determine whether the results would be similar in Western populations.

Statistics show that heart disease is the leading cause of death among both men and women in the United States and in Europe and is a serious health problem worldwide. Approximately 12.8 million Americans suffer from coronary artery disease and nearly 500,000 Americans die each year from resulting heart attacks. Over 12 million Americans have a history of heart attack, angina (severe chest pain) or both.

Lifestyle factors that may help reduce heart disease risk include:

  • Maintaining a diet low in saturated fat and cholesterol
  • Exercising regularly
  • Maintaining a healthy weight, and losing weight if overweight or obese
  • Not smoking
  • Minimizing stress

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