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How Low Fat Diets Increase Heart Disease Risk
For at least the last thirty years, Americans have been encouraged to eat less fat to protect their hearts. Now it seems low fat diets may not be as healthy as diets that contain a moderate amount of fat. The type of fat you consume is more important than the total amount of fat you take in, according to four experts who presented their evidence at the American Dietetic Association’s Food & Nutrition Conference & Expo earlier this month.
Dr. Walter Willett, chair of the Harvard School of Public Health’s nutrition department, told attendees that the focus on fat in dietary guidelines has been a "massive distraction," and he would like to see total fat and percent calories from fat removed from the Nutrition Facts label on food packages to prevent people from focusing so much on fat. He explained, "Diets with lower percent calories from total fat do not reduce risk of heart disease, diabetes, cancer, or adiposity...If anything, the literature shows a slight advantage of the high fat diet."
The low fat advice can be harmful for some people because it has the effect of causing them to reduce their intake of good fats and increase their consumption of carbohydrates. Another presenter, Harvard’s Dr. Dariush Mozaffarian, an assistnt professor of medicine, agreed. He said that such a trade-off is harmful since the carbohydrates Americans typically eat — refined grains loaded with sugar — are worse for the heart than saturated fat.
"Overall dietary quality is very important for cardiovascular risk," said Dr. Mozaffarian. "Saturated fat may raise LDL cholesterol but increasing levels of all fats lowers triglycerides." Triglycerides, a type of fat (lipid) in your blood, increases your risk of heart disease. Lowering your triglyceride level is heart protective.
Dr. Alice Lichtenstein, director of the cardiovascular health laboratory at Tufts University, said that the low fat message is an oversimplification of the recommendations. She explained, "The emphasis should be on displacing saturated fat and trans fat with unsaturated fat because that is where the data is. [The recommendation to] displace saturated fat with polyunsaturated fat was simplified to ‘low fat’. Then ‘low fat’ became ‘low calorie’. The low fat message is still very pervasive, especially in the lay press." Her belief is that the focus on individual dietary components needs to stop because when the consumption of one goes down, the consumption of others goes up.
In agreement with the other speakers in the symposium, which was billed as "The Great Fat Debate: Is There Validity in the Age-Old Dietary Guidance?" was Dr. Lewis Kuller, distinguished professor of public health and professor of epidemiology at the University of Pittsburgh’s Graduate School of Public Health. Dr. Kuller said that the dietary recommendation to reduce saturated fat in the diet should not change since Americans tend to eat too much saturated fat and not enough unsaturated fat.
Finding and Avoiding Saturated Fats
The primary contributors of saturated fat in the diets of most people are fats from animal sources. Tropical oils such as coconut, palm kernel, and palm oil also contain saturated fat. Trans fats are found in oils that have been hydrogenated to make them more solid and are found in shortening, stick margarine, and many commercial baked goods, fried foods, fast foods, and processed snack foods. The intake of saturated and trans fat, the "bad" fats, is linked to a higher risk of cardiovascular disease
Unsaturated fats are either polyunsaturated or monounsaturated. Polyunsaturated fats are found in vegetable oils like corn, safflower, and soybean oils, as well as seeds, and nuts. Olives, avocados, nuts and oils such as olive, canola, peanut, and sesame contain monounsaturated fats. Unsaturated fats are good for the heart, providing a protective effect against heart disease; but excessive intake of even these good fats can drive up calorie intake and lead to obesity. Like so much in nutrition, a good diet is a modest balance of protein, saturated and unsaturated fats, and complex carbohydrates. Replacing a hamburger with a larger side of fries is not the way to go.
The American Dietetic Association’s Food & Nutrition Conference & Expo was held November 6-9, 2010 in Boston.
November 28, 2010
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