Nutrition science is frustrating! A large part of this frustration is because:
- the experts come with bias
- the media pares down the argument into sound bites
Case in point, this Larry King Live debate between Paleo and Vegan in 2013: there’s a lot of what they believe, but little scientific justification for why or how they came to their conclusions. As someone trying to learn, who am I to believe?
That’s why I’m excited to share this academic debate between the two leading experts in the field: Loren Cordain and T. Colin Campbell. You can download it here: The Protein Debate with Loren Cordain and T. Colin Campbell [PDF Download]
I can’t say that it’s free from expert bias, but with that said, it’s refreshing to read something that goes deeper into the science. You can take a look and decide for yourself.
The paper is over 30 pages long, and a bit dense, so I decided I’d highlight the main talking points below. I also included the takeaways in my latest talk Food is Confusing. Enjoy!
PS. Thanks to John Durant for sharing this with me.
What Cordain and Campbell both agree on:
- Learning about nutrition is confusion. Being confused about nutrition is a real matter both inside and outside of the field.
- Cow’s milk (casein) and other milk products are bad for you 
What Cordain and Campbell disagree on:
1. The philosophy of nutrition:
- Cordain looks to evolution as a lens for understanding nutrition
- Campbell looks to nutrition science, and his 20 years of research on The China Study (epidemiological studies)
2. The recommended daily amount of protein
- Cordain believes a “high protein diet” of 20-40% protein should be the norm. He cites research showing that a lean animal protein diet reduces the risk of cardiovascular disease, hypertension, and obesity.
- Campbell recommends a diet of 10% protein from calories, “mostly all from whole food plants”. He cites research showing that a whole food plant based diet reduces risk of cancer, cardiovascular disease, obesity, and diabetes.
3. On using epidemiological studies to prove
- Cordain thinks they’re bullshit. See page  for more details.
- Campbell thinks that they are a valid method of doing science.
4. Loren Cordain disagrees with T. Colin Campbell’s because Campbell is generalizing his “10% protein conclusion”: Cordain writes, “The milk of protein (casein) when consumed at more than 10% of energy promotes liver cancer in rodents exposed to high concentrations of aflatoxin. However, this experiment can be generalized to other animal proteins, such as those founds in lean meats.” 
5. T. Colin Campbell disagree’s with Loren Cordain’s evolutionary philosophy on nutrition: Campbell writes, “Our dietary evolutionary history, while interesting, absolutely does not yield critical clues for optimal nutritional practices.” Campbell clarifies by adding, “Human evolution required that our ancestors make dietary choices that maximized gene proliferation. And that is absolutely the ONLY thing that such practices yielded.”
Notable Quotes From The Debate
It’s tricky to rely on food science because the information is always changing, updating, and being debated. Instead, we need a universal paradigm to guide us (such as like in the study of the universe we have the “Big Bang”, something that most all scientists can agree on). [4, Cordain]
The first vitamin was “discovered” in 1912 and the last vitamin (b12) was identified in 1948. [4, Cordain]
The study of human nutrition remains an immature science because it lacks a universally acknowledged unifying paradigm. [4, Cordain]
For instance, in cosmology (the study of the universe) the guiding paradigm is the “Big Bang” concept showing that the universe began with an enormous explosion and has been expanding ever since. [4, Cordain]
Since the evolutionary split between hominins and pongids (apes) approximately 7 million years ago, the available evidence shows that all species of hominins ate an omnivorous diet composed of minimally processed, wild-plant, and animal foods. [7, Cordain]
No single procedure alone can establish cause and effect, nor can any single study prove causality. Observational epidemiological studies can only show relationships among variables and are notorious for showing conflicting results. [9, Cordain]
The evolutionary evidence indicates that so called “high protein diets” (20%-30% of total energy) and “very high protein diets” (30% – 40% total energy) actually represent the norm which conditioned the present human genome over more than 2 million years of evolutionary experience. […] Hence the current U.S. consumption of protein (15% total energy) may not optimally promote health and well being. There is now a large body of experimental evidence increasingly demonstrating that a higher intake of lean animal protein reduces the risk for cardiovascular disease, hypertension, dyslipidemia, obesity, insulin resistance, and osteoporosis while not impairing kidney function. [12, Cordain]
Main point: I believe that total dietary protein should be 10% of calories, with virtually all of it being in the form of plant-based protein. [20, Campbell]
If we are to buy into Colin’s…10% of energy (argument), then the system that shaped our present genome necessarily had to be conditioned over eons by a low protein intake. [22, Cordain]
There is no credible fossil, archeological, anthropological, anatomical, ethnographic or biochemical evidence to show that members of our genus (Homo) routinely consumed low protein diets. [22, Cordain]
The problem with this oversimplification [regarding zero nitrogen intake as optimal, when our daily intake = outake, and that negative balance causes ill health and disease] provides no information about optimal protein requirements. [23, Cordain]
The only logical conclusion that can be reached from his series of experiments is that only the milk protein, casein, when consumed at more than 10% of energy, promotes liver cancer in rodents exposed to high concentrations of aflatoxin. His experiments cannot be generalized to other animal proteins, such as those found in lean meats. [23, Cordain]
Finally, if vegetarian diets are “as near to an ideal diet as one can get” why then do meta-analyses of all cause mortality (including cancers) in vegetarians show them to be no better off than the general public [24, Cordain]
My critique of Professor Loren Cordian’s proposition almost entirely depends on my philosophy of nutrition. It is clearly different from that of Cordain’s understanding of this discipline. He mocks the science of nutrition as if it has little or nothing to offer. [27, Campbell]
Cordain laments nutrition researches as not being schooled in evolutionary theory. I shall turn for advice to two professionals who were so trained. (Dr. Alan Goldhamer, and Dr. Doug Lisle). “There is an important misconception among those who attempt to use evolutionary theory to guide their thinking in questions about human nutrition: that the diet consumed in human evolutionary history is the diet that optimally serves human health. This is a serious error, and that makes major mistakes quiet possible, even likely.” [Campbell]