Protein supplements have become a popular means of attaining increased muscle mass by athletes and bodybuilders as skeletal muscle following exercise or heavy lifting. In theory, protein supplements supply amino acids and proteins required for the muscle to rebuild itself, possibly with additional mass. Sources of protein in supplements include whey, casein, soy and egg. In addition, protein products are available in many forms including powder, bars and drinks. Although commonly used, excess protein intake through the use of supplements can pose potential health risks.
Kidney Disease
The kidney is primarily responsible for the elimination of excess protein and byproducts of protein metabolism. Protein supplements place increased burden on the kidneys and prolonged exposure could potentially lead to development of kidney disease. In addition, there is evidence to suggest that increased protein intake increases the amounts of uric acid and calcium in the bloodstream. The accumulation of these substances can lead to the formation of painful kidney stones.
Insulin Resistance
Studies have shown that people with higher than average protein intake had less insulin sensitivity than those with normal protein intake. In Japan, a correlation was found between the increased incidence of insulin dependent diabetes mellitus and diets high in protein and fat. The process by which excess protein reduces insulin sensitivity is complex and not well understood.
Immune System
Research has shown that high protein intake was associated with lower glutamine levels in the bloodstream. Glutamine is believed to be an important source of fuel for rapidly dividing cells of the immune system and intestine. As a result, high protein intake may impair the body's ability to respond to infections.
Heavy Metal Exposure
An investigation published in July 2010 by "Consumer Reports," found that samples from 15 protein drinks contained heavy metal contaminants including arsenic, cadmium, lead and mercury. Heavy metals are known carcinogens that can cause cancer or other serious health conditions. Since protein supplements are not considered medication, they are not as heavily regulated by the Food and Drug Administration. There is the possibility that besides heavy metals, protein supplements may contain other harmful impurities.
Other Findings
Although not proven, excess protein intake may play a role in liver disease and bone loss. Protein supplementation should be avoided by pregnant or nursing mothers as insufficient data exists regarding the safety of use in these populations. In addition, the risk of heavy metal contaminants poses a danger to the fetus.
References
- "Dietary Protein Intake and Renal Function"; Nutrition & Metabolism. William F Martin, Lawrence E Armstrong and Nancy R Rodriguez; Sep. 2005
- "Metabolic Consequences of a High Dietary-Protein Intake in Adulthood: Assessment of the Available Evidence"; Journal of Nutrition; Cornelia C. Metges and Christian A. Barth; Apr. 2000
- Consumer Reports: Alert: Protein Drinks
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