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Low Carb Diets & Heart Disease
Tuesday, July 31, 2007
Low carbohydrate diets have been popular in recent years. Many individuals have turned to such eating strategies in hopes of rapid weight loss. Low carbohydrate eating plans include those employed in the Atkins diet, the South Beach diet, and the Zone diet, among others. Carbohydrates are one of the three basic constituents of foods, along with proteins and fats. All three are macronutrients, providing energy. Because carbohydrate intake is reduced with these eating regimens, the relative intake of protein and fat is greater.
Many health professionals have voiced concerns that high fat intake associated with low carb diets may raise the risk for coronary heart disease. A recent study published in the New England Journal of Medicine provides reassuring results for women who engage in low carbohydrate eating. The researchers analyzed data of over 82,000 women from the Nurses’ Health Study. This ongoing study has been underway for more than 20 years. The investigators used data from questionnaires on the intake of over 100 foods. They divided research participants into groups based on carbohydrate, protein, and fat intake as a percentage of total calories. The researchers found that diets that contained a lower percentage of carbohydrates and a higher percentage of protein and fat were not associated with an elevated risk of coronary heart disease in women. In fact, women whose diets were highest in vegetable protein and fat were about 30% less likely to develop heart disease than those who ate the most carbohydrates.
The investigators did find a significant association between the risk for heart disease and a high glycemic index. The glycemic index is a measure of the effect of food on blood sugar. The higher the glycemic index, the greater the elevation of blood sugar from carbohydrate. Refined carbohydrates, such as white bread and white rice, have a high glycemic index. Some vegetables, such as potatoes, also have a glycemic index. Unprocessed grains, such as whole-wheat products, have a lower glycemic index. The results of this study indicated that there was a direct correlation between having a diet consistently high in its glycemic index and the risk for coronary heart disease. The correlation was much stronger than that between carbohydrate intake and the risk of coronary heart disease.
One reason why diets that replace carbohydrates with fat and proteins may not have demonstrated an elevated risk for heart disease is because they may have contained a lower amount of refined carbohydrates in the diet.
There are potential adverse effects from consistently eating a low carbohydrate high protein/high fat diet that should be kept in mind. High protein intake is associated with a greater degree of calcium loss in the urine. There is a greater risk for bone demineralization (osteoporosis) in those who have a diet of high protein/low carbohydrate foods. There is also a greater risk for kidney disease and kidney stones. Low carbohydrate diets often are low in fruits and vegetables. Fruits and vegetable contain many healthful substances, referred to as phytochemicals. Fruits and vegetables also contain vitamins and fiber. The phytochemicals in fruits and vegetables consist of a whole host of chemical compounds that can have beneficial effects in the body, including reduced risk of heart disease, positive effects on blood cholesterol, and lowered risk of some types of cancer. The USDA recommends that adults consume 5-9 servings of fruits and vegetables daily.For more information: