Diseases from High Protein Intake

Proteins are key players in almost every process in your body but, too much of a good thing can be bad. As obesity rates in the developed world reach new levels, many have turned to high-protein diets to lose weight. Athletes and bodybuilders also have high-protein diets as a way of meeting their performance and recovery needs. Excessive protein intake has been linked to many health issues, from dehydration, constipation and nutritional deficiencies to obesity, heart and kidney diseases, insulin resistance and diabetes, prostate cancer, decreased thyroid function, metabolic acidosis and reduced immune function.

High Cholesterol

One of the major faults with high-protein diets is that they encourage eating more meat, to the exclusion of other nutrients. Because of the saturated fat found in meat, you increase your risk of elevated blood cholesterol levels and potentially, heart disease. Most high protein diets also call for a reduction in the amount of carbohydrates you consume.  Too few carbohydrates, especially fibre, deprives you of a natural cholesterol-lowering nutrient.  If for no other reason, this is should convince you that excessively high consumption levels of protein is not good for your health.

Progression of Kidney Disease

High protein diets can over-burden your kidneys and cause a rapid decline in kidney function. High protein is associated with elevated uric acid levels, a waste product created as your body breaks down protein. High uric acid levels are often precursors to high blood pressure and chronic kidney disease. As part of the Nurses' Health Study, Harvard University researchers examined kidney health of 1,624 women over 11 years. In the March 18, 2003, "Annals of Internal Medicine," they reported that every 10 g increase in protein intake was strongly linked with an accelerated decline in kidney function --- but only in women who already had mild impairment. This would include women with diabetes.

Osteoporosis

A side effect of high-protein diets on the kidneys is that it leads to an increased loss of calcium through urine. Continuous loss of calcium due to a high protein diet can increase your risk of osteoporosis. This happens because the excess protein causes you to shed fluid. While excreting fluids, you also lose nutrients. The Feminist Women's Health Centre reported that for every extra 1 g of animal protein you eat, you can lose an average of 1.75 mg of calcium in urine. This passing of calcium through your kidneys can also cause kidney stones.

Cancer

High-protein diets do not cause cancer, but scientists have linked the two in several ways. According to research published in the December 2006 "American Journal of Clinical Nutrition," high-protein diets are related to higher amounts of a substance called insulin-like growth factor, or IGF-1. Examining three groups of people eating varying amounts of protein, researchers found that those who ate greater than the recommend 0.4 g of protein per pound of body weight had more of this substance, which is linked to premenopausal breast cancer, prostate cancer, certain types of colon cancer and a shorter lifespan. The American Cancer Society says protein consumption is so wrapped up with saturated fat and cholesterol that it's difficult to disentangle and say which increases your risk of cancer. The society says meat, especially beef, pork and lamb, have been associated with colon and prostate cancer. In addition to the fat, dangerous compounds are created when meat is cooked at high temperatures. Fats alone also have been associated with cancers of the colon, rectum, prostate and endometrium, or uterus.

How Much Is Too Much?

Because the body cannot store amino acids, regular intake of complete proteins is required to spare body protein breakdown.  Dietary proteins are of great importance, not only to supply the essential amino acids, but also to provide enough nitrogen for the body to synthesise the non-essential amino acids required for protein synthesis in the body.

Dietary Guidelines from around the world generally suggest consuming a wide array of lean meats, poultry, fish, eggs, tofu, nuts, seeds and legumes to gain protein each day.  The Recommended Dietary Intake (RDI) for protein in Australia for adults is 0.75 grams of protein per kilogram of body weight.  This calculates out as 45g/day for women weighing 60 kg and 54g/day for men weighing 72kg.  In pregnancy, an additional 6g/day is recommended and in lactation, an additional 16g/day.

The RDI for protein may be higher for athletes in training (1.2 – 1.7g per kilogram of body weight) however this remains controversial and some argue that dietary protein needs are not increased by exercise.  However, even the proposed increased RDI for athletes can be easily achieved by athletes with high energy needs who eat more food and therefore more protein.  The Certificate of Nutrition, Leanne Cooper 2013, pp 60.

Copyright © 2014 by Drew Dale

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