We Looked Into The Protein Debate. We Wish We Hadn’t.
August 12, 2014

steak debate

The world of nutritional science seems rife with contradictions and turnarounds: top minds in the field  disagree about nutritional guidelines and basic facts, like whether milk is healthful or harmful. So we shouldn’t be surprised to see a debate raging around the value of protein from meat.

The loudest voices in the protein argument belong to Loren Cordain, PhD, and T. Colin Campbell, PhD.  Cordain wrote The Paleo Diet, which claims that the anthropological record documents our ancestors eating copious amounts of meat. He’s convinced protein can prevent and reverse disease. Meanwhile, Colin Campbell’s book The China Study offers similarly compelling evidence that animal protein causes diseases like cancer and heart disease. He is now a vegan and advocates a plant-based diet for all.

In Favor of Animal Protein


Author of the Paleo Diet, this expert on exercise research advocates eating more protein from animal meat.

Author of the Paleo Diet, Dr. Loren Corain advocates eating more protein from animal meat.

In favor of more protein, Cordain says our bodies can absorb lots of protein. The current “very high protein” diet for the average male is 125 – 186 grams per day, and 89 – 133 for females, but the body’s physiological limit for protein (after which point it becomes toxic) is much higher, up to 187 – 270 g/day for males, 134 – 246 for females, or almost half one’s calories.

There’s evolutionary evidence that our ancestors ate lots of animal meat. Ancient stones and animal bones indicate that humans have hunted and eaten meat since the very origin of the genus Homo. Historically studied hunter-gathers got most of their energy from meat. The Ethnographic Atlas showed that most (73%) of the world’s hunters-gathers obtained >50% of their energy from hunted fish and animal foods.

Against Animal Protein

Dr. Colin Campbell is the author of the China Study and sees a strong link between animal protein and cancer, as well as other diseases.

Dr. Colin Campbell is the author of the China Study and sees a strong link between animal protein and cancer, as well as other diseases.

Arguing against excess protein, Colin Campbell says most people need less than 9% of their total calories to come from proteins. That’s 48g for a 132 lb woman and 56 g for at 154 lb man. People eating this little protein can do very well in terms of physical health and athletic ability.

Animal protein is linked to cancer.

There is a 80-90% correlation between animal protein intake and breast, prostate, colon, ovarian and kidney cancer. The countries that eat more animal protein have higher incidences of these cancers. When animal protein intake increases beyond 10%, say from 10% to 20% of calories consumed in a day, heart disease, diabetes, hypertension, osteoporosis, multiple sclerosis and kidney stones become far more common.

The China Study finds a strong correlation between meat consumption and certain cancers.

The China Study finds a strong correlation between meat consumption and certain cancers.

Meanwhile, some diseases are cured by reducing or removing animal proteins from the diet. Switching away from animal-protein-based food to whole-plant-protein based food has been shown repeatedly to control conditions like multiple sclerosis and heart disease. In some cases, cutting out protein shrinks cancer tumors.

At Power 20, we believe Dr. Campbell is right. Here’s why.

We’re better off when we lower our animal-protein consumption. It’s our (non-medical) view that both may be right, but Dr. Campbell’s low-protein approach is far better for modern society. Here’s why we side with low-protein, no animal-fats:

  • Today’s meat is mostly terrible. The meat is cooked at super high heats, the animals are themselves often unhealthy, much of the meat we eat is processed, and much of the meat people eat has lots of fat in it.
  • Today’s meat is environmentally unsustainable. We spend more energy feeding cows and pigs than we get from eating them. They take a tremendous amount of water and fuel to raise and distribute.
  • Today’s meat is raised in unethical environments. Most meat comes from Concentrated Animal Feeding Operations, or CAFOs. Their lives are painful and miserable.
  • The evidence linking animal proteins to disease is too strong. The strong evidence of the many diseases brought on by a slight increase in animal proteins should be enough to compel anyone to at lease consider cutting out all processed meat. And when you do eat meat, go for high-quality, organic, lean cuts.
  • Cordain falls into a common science trap. He follows a long line of nutrition experts who think eating a vitamin C supplement is the same as eating an orange. It’s reductionist thinking – the kind that leads him to first calculate the absolute maximum amount of protein one can eat before it turns toxic, and then prescribe that limit to people. This approach seems, to us, unreasonable.

Power 20 recommends a bit of both.

Cordain is right on one point: we should avoid sugary foods and drinks, including pasta and potato chips, since these simple carbohydrates lead to insulin resistance, which in turn leads to diabetes and obesity. And Campbell is right to recommend a plant-based diet. If we must eat meat,  we should have lean cuts from organic sources. But the planet, the animals, our wallets, our water systems, and our personal health will all improve if everyone adopts a plant-based diet and stops trying to bulk up on protein from animal meat.

Get these books to learn more about the debate.