Can You Have Too Much Protein?

Science is very unsettled about this question. Nutrition experts claim there have been studies done with huge protein intakes such as 4.5g per kg of body mass without any negative side effects (a normal human is recommended to take somewhere between 0.8g and 2g per kg of body mass).

However, longevity experts disagree and are leaning towards the lower end of the spectrum. They say there are many short-term benefits of eating a lot of protein, but generally, unless you are an athlete or you are going through a bulking-up phase, the excess amount of protein can cause more damage than good if longevity is your goal. Let’s see why.

Byproducts that need expelling

Dietary protein also contains high amounts of non-essential amino acids (NEAAs). Consuming excess NEAAs puts a strain on the liver and kidneys, creating more harmful by-products like urea and ammonia.

Growth signalling

Constant high protein diets are quite counter-productive for longevity because amino acids activate mTOR (the growth mechanism) and switch off the sirtuins (the genes that take care of DNA repair). You don’t want excess amino acids to be floating around as they signal growth to cells, including the damaged ones that you don’t want.

Mammalian target of rapamycin (mTOR) and insulin-like growth factor-1 (IGF-1) are proteins that play critical roles in two major growth pathways in the human body. The intake of amino acids regulates these two pathways, which must remain in balance to facilitate muscle growth and repair. Overactivity of mTOR and IGF-1 has been associated with quicker aging and diseases such as cancer.

Low amino acid intake is a good time for cell recycling

The body has a wonderful mechanism in place. When the food intake is low and the amino acid levels drop, the process of apoptosis (killing off the damaged cells) and autophagy (the recycling and repair of the damaged cells) can happen.

These two processes are always happening in the body, but they are more pronounced after 18 hours or more without calorie intake and kick into high gear after 3 days of fasting. Read more about fasting here.

Exercise correctly redistributes growth mechanisms

Exercise helps bring IGF-1 into the brain and muscles. So, as opposed to having your IGF-1 floating around in your bloodstream, which then goes to other tissues, or stays around and is a growth signal for potentially damaged cells, you can actually get into places where you want it like your brain and your muscle.

Animal vs plant sources

For whatever reason, there is a constant battle between consuming plant-based versus animal proteins. Getting your protein from a plant-based source rather than meat will mean the amino acids that we desperately need for survival are not going to be so bioavailable, says Dr David Sinclair from Harvard Medical School. This means the body will have to work harder to extract them from plants, which is not necessarily a bad thing. It means the body burns more energy and activates many defence mechanisms as it does it.

He adds that there is a molecule in red meat called TMA that gets turned into a toxic molecule TMAO in the liver. In animal studies, when consuming excess animal protein, this molecule is shown to cause cardiovascular disease and cancer.

Conclusion

In a nutshell, consuming excessive amounts of protein promotes growth. That is great and we need periods of growth. But with the growth of good cells, the “bad” ones grow too and ageing is accelerated.

A good balance of anabolism (the synthesis of molecules) and catabolism (the breakdown of complex molecules) is required for a long and healthy life. None of the centenarians studied stuff their faces with an excess amount of protein on daily basis. Likewise, our distant hunting and gathering ancestors went through regular periods of high and low protein intake.

Both animal and plant-based sources of protein can be a part of a healthy balanced diet as long as the food is produced in a humane and sustainable way. This couldn’t be farther from the truth for all mass-produced foods. Always seek small-scale local producers whose main goal is to produce food in harmony with nature.