Why this piece?
We often hear people say too much protein is bad for you, particularly the kidneys.
Ok, so what is the the truth?
In a review of 41 studies examining the purported adverse affects of high protein diets in athletes, it was noted that protein intakes of 2.8g/kg did not impair kidney function in the short term (Manninen 2004).
In an even more comprehensive review of 111 studies, specifically looking at protein intake and kidney function, it was found that athletes who habitually consumed over 2.0g/kg of protein showed no impairments in renal function (Martin et al, 2005).
In direct studies on non-athlete populations, similar results were found. This implies that neither the physical activity of athletes nor a possible bias held by the review authors is skewing the data. One study showed that there were no detrimental effects on kidney, liver or bone health after one year of consuming protein intakes of 2.2g/kg of lean body mass (Li et al, 2010). Another study showed that a diet consisting of 25% protein with an additional 50g of supplemental protein daily, had no ill effects on health (it also happened to be the best for maintaining a healthy weight after dieting) (Claessens et al, 2009).
Cliff Notes?
High levels of protein in hundreds of studies, have been shown to be healthy and not pose risk to a healthy adult.
