Fiber and Complex Carbohydrates. In all cases, complex carbohydrates found in whole grains and vegetables are preferred over those found in starch-heavy foods, such as pastas, white-flour products, and potatoes. Fiber is an important component of many complex carbohydrates. Fiber is almost always found only in plants, particularly vegetables, fruits, whole grains, nuts, and legumes (beans and peas). (One exception is chitosan, a dietary fiber made from shellfish skeletons.) Fiber cannot be digested but passes through the intestines, drawing water with it and is eliminated as part of feces content. The following are specific advantages from high-fiber diets (up to 55 grams a day):
- Insoluble fiber (found in wheat bran, whole grains, seeds, nuts, and fruit and vegetable peels) has been associated with weight loss. Studies also suggest that diets rich in fiber from whole grains reduce the risk for type 2 diabetes.
- Soluble fiber (found in dried beans, oat bran, barley, apples, citrus fruits, and potatoes) has important benefits for the heart, particularly for achieving healthy cholesterol levels and possibly benefiting blood pressure as well. Simply adding breakfast cereal to a diet appears to reduce cholesterol levels. People who increase their levels of soluble fiber should also increase water and fluid intake.
High-Protein, Low-Carb Diets
High-protein, low carbohydrate diets such as the Atkins and South Beach diets have been touted as effective ways to produce short-term weight loss. Because of their emphasis on fats and proteins, many experts are concerned about long-term health problems. A report in the March 2006 Lancet linked the Atkins diet to life-threatening complications that caused the death of one woman. The 40-year-old woman had a deadly build up of acids called ketones in her blood, a condition called ketoacidosis. Ketoacidosis can cause coma. Ketones are a known by-product of high protein, low carb diet. At low levels they can cause nausea, lightheadedness, and bad breath.
Long-term effects on health are still unknown in people who use these diets long term. For example, the Atkins diet restricts some vegetables and most fruits that are known to protect against serious diseases such as heart problems and cancer. The diet also may cause too much calcium to build up in the urine. This can increase the risk for kidney stones and osteoporosis. In any case, high-protein intake, particularly from meat, can be harmful in people with kidney problems. Individuals at risk for kidney stones or who have other kidney problems should not go on high-protein diets without consulting their physicians. Unfortunately, many people with diabetes are subject to kidney problems, which could negate any possible benefits for them. A high meat intake has also been associated with certain common cancers, notably prostate and colon cancers. A 2002 study suggested that such diets during pregnancy may increase the risk for high blood pressure in the offspring.
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