By Alan R. Gaby, MD

Healthnotes Newswire (May 11, 2006)—Good scientific evidence has shown that eating fish can help prevent heart disease—the leading cause of death in the United States. However, new research suggests that the way fish is prepared affects its benefit, and that eating broiled or baked fish can help keep the heart strong, while eating fried fish might make it less healthy.

Known steps for preventing heart disease include maintaining normal body weight, blood pressure, and cholesterol levels; exercising regularly; and eating a low-fat, low-sugar diet consisting mainly of whole foods. The omega-3 fatty acids in fish may also reduce the risk of heart disease in a number of different ways. Fish oil prevents blood platelets from clumping excessively, thins the blood, lowers triglyceride levels, and helps keep the heart rhythm regular.

However, fried fish may not provide the same benefits. “Fried fish meals are commonly breaded fish from fast food restaurants or the grocery frozen section, often lower in omega-3 fatty acids and prepared with partially hydrogenated oils (containing trans fats) or oils reused for multiple frying cycles,” said Dariush Mozaffarian, MD, one of the researchers that performed the new study. Eating trans fats has been linked to an increased heart disease risk, and high-temperature frying destroys some of the beneficial fatty acids and causes new and potentially harmful compounds to form.

The new study evaluated heart structure and function in 5,073 elderly people enrolled in the Cardiovascular Health Study. Eating more tuna or other broiled or baked fish was associated with changes that indicate a healthier heart: a lower heart rate, a greater amount of blood pumped per heart beat, and greater ease of blood flow after the blood left the heart (lower systemic vascular resistance).

In contrast, eating more fried fish was associated with changes that indicate cardiovascular disease, such as less blood pumped per beat, greater systemic vascular resistance, and abnormal motion of the left ventricle wall.

The study didn’t show whether the relationship between eating fish and heart health were due to the fish itself or to other lifestyle factors. While the results were corrected for age, cigarette smoking, body weight, exercise, and other known cardiovascular risk factors, it is possible that there was, as Dr. Mozaffarian described it, “residual confounding.” In other words, eating different types of fish may have been associated with other, unidentified characteristics that influenced a person’s risk of developing heart disease.

Nevertheless, the findings from this study support previous research showing that eating fish one to three times a week may help prevent heart disease, but that eating fried fish is not such a good idea.

(Am J Cardiol 2006;97:216–22)

An expert in nutritional therapies, Chief Medical Editor Alan R. Gaby, MD, is a former professor at Bastyr University of Natural Health Sciences, where he served as the Endowed Professor of Nutrition. He is past-president of the American Holistic Medical Association and gave expert testimony to the White House Commission on Complementary and Alternative Medicine on the cost-effectiveness of nutritional supplements. Dr. Gaby has conducted nutritional seminars for physicians and has collected over 30,000 scientific papers related to the field of nutritional and natural medicine. In addition to editing and contributing to The Natural Pharmacy (Three Rivers Press, 1999), and the A–Z Guide to Drug-Herb-Vitamin Interactions (Three Rivers Press, 1999), Dr. Gaby has authored Preventing and Reversing Osteoporosis (Prima Lifestyles, 1995) and B6: The Natural Healer (Keats, 1987) and coauthored The Patient's Book of Natural Healing (Prima, 1999).

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