Debunking Protein Myths

By Mike Sisco | Uncategorized

Finishing my workout, I said my daily “see ya later” to my gym rat cohorts.

Then while walking away, a caveman looking guy said to me, “ I heard a high protein diet can damage your kidneys.”

Nothing flips the anger switch quicker than an uneducated statement in the gym.

Instead of yelling at the guy or fighting him, I told him to read my next article. This is my next article.

We’ve probably all heard similar statements:

  • “High protein diets are unhealthy.”
  • “High protein diets can cause kidney damage .”
  • “They can cause liver damage.”
  • “High protein diets can contribute to heart disease.”
  • “High protein diets have been linked to osteoporosis .”

Scientific communities (doctors) blindly accept these claims as scripture and spread false dogma.

“High Protein Diets Can Damage The Kidneys”

Nitrogen is a byproduct of protein that you pee out. So it’s been theorized that eating more protein can cause additional stress to the kidneys because they have to process more nitrogen.

A lower protein diet is often prescribed to people with a high level of nitrogen in their pee. This theory is simply not backed by literature:

  • This study examined bodybuilders with protein intakes of 2.8g/kg vs. well trained athletes with moderate protein intakes . It revealed no significant difference in kidney function between the groups
  • This review of the scientific literature on protein intake and renal function concluded that “there is no reason to restrict protein in healthy individuals.”  Furthermore, the review concluded that not only does a low protein intake NOT prevent the decline in renal function with age, it may actually be the major cause of the decline!
  • The Johns Hopkins School of Medicine reviewed literature and determined “it is clear that protein restriction does not prevent the 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 intake.”

There is no need to restrict protein intake in healthy individuals to preserve renal function. Caveman at the gym, you just got roasted.

“High Protein Diet Contributes to Liver Disease”

There is NO EVIDENCE to support a high protein diet contributing to liver disease. In fact, the opposite might be true:

Research has spoken. A High protein diet DOESN’T damage the liver, and it’s been investigated as a TREATMENT!

“High Protein Diets Cause Bone Mineral Density Deficiencies”

Some suggest that a high protein diets can contribute to the onset of osteoperosis. This is assumed because high protein diets cause high levels of calcium excretion..  The early studies are flawed because many them were limited by a low number of study participants, study design errors, and the use of the wrong types of protein.

More recent and better designed studies have shown a high protein diet:

  • May actually increase bone mass {1, 2, 3, 4]
  • Schurch et al. reported that supplementation with 20 g protein/day for 6 months increased blood IGF-levels and reduced the rate of bone loss in the unfractured hip during the year after the fracture.
  • Low protein diets may have a detrimental effect on bone. Although calcium excretion is increased, calcium absorption in the intestines is increased.
  •  The author of the most cited paper favoring the earlier hypothesis that high-protein intake promotes osteoporosis no longer believes that protein is harmful to bone, but now actually believes the opposite to be true.

Even though increasing protein intake may increase calcium excretion, there isn’t any evidence this calcium comes from bone. This means overall calcium balance is either unaffected, or increased in a high protein diet.

“High Protein Diets Contribute To Heart Disease”

Scientific literature simply does not support high protein diets contributing to heart disease. In fact, literature argues for the opposition:

Protein and Blood Pressure

The AHA Nutrition Committee suggests that high-protein intake may increase blood pressure. However, there is no scientific evidence supporting this either. Notice a pattern:

  • A negative correlation has been shown between protein intake and systolic and diastolic blood pressures in several epidemiological surveys analyzed by Obarzanek et al.
    • In this study of 6,406 Japanese-American men, a negative relationship was observed between systolic and diastolic blood pressures and the amount protein consumed. Meaning as protein consumption went up, blood pressure went down.
    • In this investigation of 2,672 adults men and women, a negative relationship was found between systolic pressure and the amount of animal protein consumed.
    • Based on 11,342 adult men, investigators observed a negative relationship between systolic blood pressure and the amount of total protein consumed.
    • This study shows an inverse relationship between systolic and diastolic blood pressure when dietary carbohydrates are replaced with protein.
  • One study in human volunteers with a family history of hypertension has shown that a high-protein diet may counteract the adverse effects of excessive salt intake.

Protein’s Contribution To Diabetes and Weight Loss

A high protein diet may also be beneficial for combating obesity and diabetes:

  • Subjects lost more weight, higher percentage of weight loss was fat, and muscle mass was preserved better
  • Investigations have shown high protein diets to be more satiating. Meaning you can diet without feeling hungry all the time.
  • People who consume high protein diets tend to eat less calories, but burn more throughout the day.

It’s clear that a diet with a higher protein/carbohydrate ratio is superior in supporting better weight loss, muscle retention, glucose control, and satiety.

What are your thoughts on protein myths? Did I miss anything you’d like covered?