Disease
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High-Protein Causes Kidney Damage
The research most are referring to was a Nurses’ Health Study that followed approximately 1600 female participants for 11 years, concluding that a high-protein diet causes kidney dysfunction. What the media failed to communicate was that the participants that experienced the damage had pre-existing kidney damage.
Congratulations Science! Those with bad kidneys can compromise the function of those kidneys by eating a high protein diet.
That ’s like saying someone with an injured shoulder can compromise shoulder function by lifting weights, or a guy with a broken foot can compromise his recovery by jumping up and down.
One of the kidneys main functions is to process the waste products from the food we eat. Eating a high protein diet can increase the filtration work from the kidneys (hyperfiltration), but this is:
“A perfectly normal adaptive mechanism well within the functional limits of a healthy kidney.”
In the Nurse’s Health Study, those with healthy kidneys did not experience disrupted functionality and many did not even enter a state of hyperfiltration. Furthermore, there’s significant evidence suggesting that an increase in protein consumption and a corresponding state of hyperfiltration produces a favorable adjustment from the kidneys. Over time there’s less protein found in the urine, which suggests greater protein absorption. Muscle maintenance and growth is dependent on protein synthesis, so this adaptation from hyperfiltration should be considered a benefit.
Other than the misleading conclusions drawn from the Nurse’s Study, all research on high protein diets and kidney damage have found no correlation in healthy subjects. Even when protein intake was as high as 2.8g per kg of bodyweight, the kidney remained unharmed. For the record, that’s 252g of protein per day for a 200lb man, or the equivalent of four 12oz steaks or eight chicken breasts. Clearly we should be ignoring the biased recommendations from uninformed organizations and start listening to conclusions from legitimate research:
"It is clear that protein restriction does not prevent decline in renal function with age, and, in fact, is the major cause of that decline. A better way to prevent the decline would be to increase protein i ntake. There is no reason to restrict protein intake in healthy individuals in order to protect the kidney.”
Even for those with renal (kidney) disease, t here is no benefit from lowering protein intake. Research recommends an intake of at least 1.4g/kg of bodyweight in these individuals to maintain proper nitrogen balance, which is the equivalent of 127g/day for a 200lb man. Sadly, most come nowhere close to that minimum threshold because they’re too busy filling up on high fiber whole grains. Realistically, high carbohydrate (high sugar) diets should be blamed for kidney issues, not a diet high in animal protein.
High Protein Does NOT = Bone Loss
The theory that eating a diet high in protein causes bone loss stems from results showing a considerable (60mg) excretion of calcium in urine for every 50g increase in protein intake. With the majority of calcium stored in bone, it would be easy for one to make this conclusion. However, this is not the case, and in fact the opposite is true.
Before I get into the research, lets stop and think about this for a second. Protein helps individuals gain and maintain muscle. Muscle surrounds bone, protecting it from damage and providing strength and stability to the musculoskeletal framework. Muscle loss (atrophy) from a lack of dietary protein is highly correlated with bone loss, and a lack of muscle strength with an increased risk of fracture (usually from falling). It’s hard to prevent a fall without the muscles to provide stability and hard to prevent a bone fracture without the protection that