Are High Protein Diets Detrimental For Your Bones and Your Kidneys
There’s a belief that bodybuilders or athletes who consume large amounts of protein may have bones that may be damaged. We are going to look at both aspects of this hypothesis (damage to bones as well as damage to kidneys) and see if the hypothesis holds water.
We are going to look at the correlation between bone damage and protein first
Where did the belief come from?
This belief stemmed from a research paper published in the Journal of Biological Chemistry (Calcium Requirement of Maintenance in Man) that suggested that increasing protein in the diet led to increased calcium excretion in urine. In the 1970’s a group of metabolic balance studies found that even when dietary calcium intake was controlled for, protein intake was not affecting intestinal absorption of calcium. The conclusion then was since protein was not increasing calcium absorption and had a direct correlation with calcium excretion in the urine then the calcium had to be coming from somewhere. The most likely source of this would be our bones since our bones are rich in calcium.
This phenomenon came to be known as the Acid – ash Hypothesis. What this means is that the extra amino acids our bodies acquire from an increase in dietary protein lead to a state of acidosis (unusually large amount of acid within an environment) within our body. Now, human bodies are quite adaptive and that is generally how we get better once we are sick. In the case of acidosis, the body tries to counter these unusual levels of acidity by buffering it with the release of alkaline (this can be considered the chemical opposite of acid) stores in the bones. These alkaline stores are found within the calcium in our bodies and as such the hypothesis seemed to hold water.
Where did the hypothesis go wrong?
The major error could be found in the 1970’s papers in which they concluded that higher dietary protein was not affecting intestinal calcium absorption. A 2017 paper by the National Osteoporosis Foundation found results that pointed to the contrary. The study showed that when using dual – stable calcium isotopes (a different form of calcium), increased dietary protein was actually associated with a significant increase in intestinal calcium absorption. So much so that nearly the entire increase in urinary calcium excretion could be accounted for by the improved calcium absorption. The conclusion then was that, at least for the short term, there was no increase in skeletal catabolism (breakdown). This implied that increased protein intake lead to increased calcium absorption in the intestines which led to more calcium in the blood and finally more calcium in the urine. Thus, the acid ash hypothesis, at least based on protein, was pivoted on an erroneous finding.
The same 2017 paper notes that protein can make up to about 50% of bone volume as well as about 33% of bone mass. This implies that there’s no adverse effects of increased intake of protein. Furthermore, evidence actually showed a positive correlation between increased protein intake and bone mineral density.
We’ve disproved the myth regarding protein, but there’s still the myth regarding the impact of increased protein.
Where did it come from?
This belief stemmed from the idea that increasing dietary protein in patients with pre – existing kidney disease would contribute to further deterioration of kidney function. Although this idea is actually right it presents a bias. The assumption is that since something is bad for people who already have a certain disease then that particular thing must have some contribution to the cause of that disease. This is especially popular in diabetics; since diabetics need to monitor and regulate their sugar intake then the sugar must play a central causative role in the development of diabetes.
Where did the hypothesis go wrong?
A 2015 paper in the Journal of Applied Physiology, Nutrition and Metabolism (Protein requirements beyond the RDA: Implications for optimizing health) conducted a research on the correlation between protein consumption and renal failure. The paper concluded that the belief had no foundation. On the contrary, an increase in dietary protein in individuals with normal renal function actually led to an increase in glomerular filtration rate (a normal process of the kidney).
Furthermore, in 2007, the World Health Organisation released a research paper on the requirements of protein and amino acids in human nutrition. They found that there was no foundation in the belief that the decline in kidney function in aging healthy individuals can be attenuated by reducing the protein in one’s diet.
What this means especially for bodybuilders and athletes is that protein supplements can be safely used in their workout diet without too much worry about the effect of the supplements on their body. For those looking for a good place to start, try Gold Standard Whey: – the protein content will be quite useful in replacing protein within the body.
Read Also:
