The American Heart Association does not recommend high-protein diets. High-protein diets, such as Atkins, Protein Power and Stillman diets, highly restrict essential nutrients your body needs by being focused on protein intake. High dietary protein has harmful effects on glucose metabolism by promoting insulin resistance. Insulin resistance impairs the body’s ability to respond and use the insulin it produces. This inability leads to blood glucose abnormalities.
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Insulin is a hormone that is responsible for lowering blood glucose. When glucose levels rise in the blood, insulin stimulates the uptake of the excess glucose by liver and muscle cells. The cells use the stored glucose as an energy supply. Dietary changes in the carbohydrate to protein ratio produce changes in glucose regulation, as shown by Donald K. Layman and colleagues published in “Human Nutrition and Metabolism” 2003. Therefore, high-protein diets influence insulin levels within the body.
Types of Dietary Proteins
Three types of dietary proteins exist in human diets--meat protein, dairy protein and vegetable protein. Not all types of proteins affect insulin in the same manner. Studies on increased dietary milk or increased dietary animal protein have shown increased incidence of insulin resistance in children. Other types of proteins, such as soy or lean fish, lower the insulin response. Improved cholesterol is an added benefit of lean fish protein. Variations in protein sources, rather than amounts of proteins, represents a safer dietary option.
The recommended daily allowance, or RDA, for protein in the United States is 0.8 g of protein per kilogram of body weight in adults. Is it recommended that children intake only 9 to 20 g per day, while adults need 34 to 46 g per day. Recommended RDA for pregnant and lactating women is increased to 71 g per day. According to body weight, children need more protein per kilogram because they are building new body tissues. A typical American diet provides more than the RDA.
High Protein and Diabetes
Diabetes occurs when too much glucose is present in the blood and not enough insulin is made to remove it or the body is unable to use the insulin that is made. Prolonged high-protein diets increase amino acids present in the blood, which affect glucose equilibrium. Long-term high-protein diets in healthy individuals induce high glucose-stimulated insulin secretion and unsuppressed glucose output by the liver. In diabetics, too much protein decreases insulin sensitivity and causes increased insulin produced by the liver as well. Both examples indicate problematic responses to high-protein diets.
Many high-protein diets include high amounts of saturated fats from animal protein. Such fats elevate low-density lipoprotein cholesterol, or LDL, which is the "bad" cholesterol. High LDL cholesterol levels are associated with increased risk of heart disease. Also, high dietary animal proteins cause increased urinary output, which removes essential minerals, such as calcium, from the body. The body loses an average of 1.75 mg of calcium for every 1 g of ingested animal protein, and calcium deposits retained in the kidneys produce painful kidney stones.