Eating lots of protein is bad for our health? Myth or Scientific Truth

Photo by Anastase Maragos on Unsplash

“Eating lots of protein is bad for our health”, “A high protein diet destroyed my friend’s tendons” “Protein powders are bad for the kidneys”.

These are just some of the statements I heard from athletes, medical professionals and fitness enthusiasts over the past 15 years. But is there any evidence to support these claims?

Regular protein has been shown to maximise muscle protein synthesis. In 2013, Jose Areta demonstrated that 20g of whey protein consumed every 3 hours had a more beneficial impact on muscle protein synthesis than 10g taken every 1.5hours or 40 g every 6 h.

Timing and distribution of protein ingestion during prolonged recovery from resistance exercise…

However, there is a belief that excess intake of protein has negative consequences for health.

Brenner Hypothesis

In 1982, Brenner proposed that habitual consumption of excessive
dietary protein negatively impacted kidney function by a sustained increased in glomerular pressure and renal hyperfiltration. Furthermore, high protein diets can cause osteoporosis.

This dates back further than the 1980s. In 1923 Addis and Drury observed a relationship between dietary protein and rates of urea excretion (GFR) Glomerular filtration rate a test used to check how well the kidneys are working. Specifically, it estimates how much blood passes through the glomeruli each minute.

Then Van Slyke et al. (1934) demonstrated that renal blood flow was the basis for GFR mediated changes in clearance rates in response to increased protein intake.
The majority of scientific evidence cited by the authors was generated from animal models and patients with co-existing renal disease
Increasing dietary protein increases urine calcium excretion such that for each 50 g increment of protein consumed, and extra 60 mg of urinary calcium is excreted. It follows that the higher the protein intake, the more urine calcium is lost and the more negative calcium balance becomes. Since 99% of the body’s calcium is found in bone, one would hypothesize that high protein-induced hypercalciuria would result in high bone increased prevalence of osteopenia

However, more recent studies, examining healthy individuals on high protein diets (~2.51–3.32 g/kg/d) showed no link between high protein diets and renal function or osteoporosis. So there is no proof to restrict protein intake in otherwise healthy individuals.

Myth Busted — Eat your protein!

A High Protein Diet Has No Harmful Effects: A One-Year Crossover Study in Resistance-Trained Males