A continuing controversy in sports nutrition is the long-term effects of a high-protein diet. That’s of special concern to bodybuilders and other strength athletes who follow such diets for prolonged periods. Some scientists have speculated that high protein consumption may eventually lead to such problems as kidney failure, high blood pressure and osteoporosis. Thus far, however, none of those hazards has been proven or become apparent.
At the Experimental Biology 2002 meeting, held in New Orleans on April 20’24, French food scientists presented a study that focused on the long-term effects of high protein intake in rats. The rats got either a 14 percent or a 50 percent milk protein diet and were allowed to eat as they pleased. The researchers took various measurements of body composition, calcium, blood glucose, insulin, leptin, cortisol, nitrogen balance and oxidative status over six months.
The rats on the 50-percent-protein diet had significantly decreased fat deposition, decreased fasting blood glucose and insulin levels and lowered leptin and cortisol levels. Those measurements all point to decreased fat synthesis in the body. In addition, the higher protein intake did not lead to any abnormalities in structure or function of the kidneys or liver, nor did it increase oxidative stress in the rats. What’s more, the calcium balance didn’t differ between the two groups of rats.