Nitrogen in Your Bones Reveals How Much Meat You Eat

March 06, 2022

Nitrogen in Your Bones Will Tell You How Much Meat You Have Eaten

What we call modern civilization is the historically recent phenomenon of the industrial revolution wealth imposed on agrarian populations that have moved into large cities. This has all happened in the last 150-200 years. Our grandparents, or at least their parents, were almost all farmers. If one asks, "What did they eat?", we have to dig back to those meals at Grandma's house and try to remember what her home-cooking was. And if we follow that trend further back, in just 5-7,000 years we find the time when we humans transitioned from being hunter-gatherers to farmers. What did they eat? What diet is the healthiest? What diet makes humans the healthiest?

What did the hunter-gatherers eat? We don't know. All we know is that when we measure their skeletons, they were taller than we are with larger brains, stronger bones, fewer infections, and no evidence of diabetes. Sounds healthier! Hmm, there are those who claim that moving from the healthy state of hunter-gathering to farming was the greatest catastrophe for humans other than the Pop Tart and the mullet haircut. That move, however, did provide for food security, cities, written language, pyramids, and iPads. 

There are populations on planet earth that we have studied in just the last 100 years who are still essentially, hunter-gatherers. They have been studied in detail and often show a markedly different diet than what we term healthy. For example, Weston Price in his travels around the world described the Northwest Pacific coast Indians who harvested the ooligan, or candlefish, which is a smelt family, very high-fat fish. They dried it and used it as a trade item. Blocks of the fish were found hundreds of miles inland. It was their dominant food. Stefansson and Jorgenson famously lived with the Innuit for 5 years and didn't touch one vegetable or fruit and came home healthy and vibrant. When they returned to report their findings in New York, no one believed them and were convinced they would have died of scurvy. To prove their research, they lived in Bellview Hospital for a year and were tested daily to prove they hadn't cheated. All they ate was meat and fish for one full year and came out just fine.

When I hear "just meat and fish," I think of a diet that is 100% protein. The human body can only absorb so much protein. About 40% of your diet is the max you can absorb. You do need protein and it is good for you, but you have to chop it up and get rid of the amino (nitrogen part of it) component before you get energy. That means you need to get the remainder from elsewhere: either carbs or from fat. FAT. That is what the Innuit and the NW Indians were after. In fact, Stefansson described the Innuit as slaughtering caribou and saving the meat for their dogs in the permafrost. They went after the organs and the fat. And a whale or a seal, how there was a bonus because all that blubber was delicious fat. They knew they shouldn't eat that much protein. This same pattern has been observed in every hunter-gatherer society ever studied. The Massai in Africa, the aborigines of Australia, the Hazda of Tanzania. They prefer animal calories if they can get them, and the best part is the fat.

Now, can we take that knowledge and ask the question, "How much meat did our ancient ancestors really eat?' Yes. We can answer that question.

Turns out Nitrogen, Carbon, Phosphorus, Oxygen all come with different isotopes that are absorbed by plants and animals at different rates. What you eat turns into who you are. Your diet becomes your bones. We can look at your bones and measure those isotopes with incredible detail. Normal nitrogen has a molecular weight of 14 daltons but N15 (one extra neutron in the nucleus) is also around in smaller amounts. It gets concentrated up the food chain by plants, and then animals. Top predators have the highest levels. Plant eaters have lower levels. Same with fish. The higher you are on the predator scale, the higher the N15 is in your bones. This becomes an accurate measure of the quantity of animal protein versus vegetable protein in your diet.

Guess what we find in the bones of Neandertals and pre-history humans. You got it. Very high levels of N-15. Neanderthal bones have higher N-15 than hyena or fox bones at the same sites. Early humans were apex predators. And they ate animals, first and foremost. Vegetable matter is what you eat when the hunt failed or for the few weeks a year when the mulberry tree is ripening (or whatever plant source was in your neighborhood).

Our fore-parents were not idyllic vegetable eaters. We left that table when our brains began to evolve and become larger. That was some 2-5 million years ago. All the other hominids have primarily vegetarian diets and have bodies accommodated to that. But humans have changed to be meat and fat eaters. We can't eat too much protein, so fat it is. The stomach pH of a chimpanzee is 4.0. Human stomachs have a pH of 2.0. That is 100 times more acidic. Very high acid is good for breaking down protein. Low acid is good for plants. Humans are designed to eat animal. As much as we can successfully hunt.

Isn't that interesting? Doesn't it change your perception of what a healthy diet might be? But we have been told to avoid "saturated animal fat like the plague". We believe it raises your cholesterol and causes heart disease. Is there nuance to that fat story? You bet. Big time. Next week.

www.What will Work for me? Well, hunting has changed. I only have to walk to the fridge to find cheese, milk, eggs, and with Uber Eats, all I have to do is pick up the phone and in 20 minutes, I can have a bucket of something meaty. What I am recognizing is that we most certainly need protein, but there is a limit to how much protein we should eat. But, fat, there is no limit. It isn't bad for us, if it is "natural fat". The problem comes with the loss of natural fat. That's next week.

References: Pro Natl Acad Sci, Carnivore Code, Weston Price,J of Nutrition, Annual Rev Nutrition, American Antiquity, PLOS 1

Pop Quiz

1. What isotope of nitrogen can we measure in bones that reflects the amount of animal protein in the diet of the bone-owner? Answer: N-15

2. What happens to the level of N-15 as one goes up the food chain to predators? Answer: The higher order predators have more N-15. Apex predators have the most. Imagine T. rex.

3. And what apex predator have studies proven to have been at the top? Answer: Humans. Even tigers and lions are lower N15 because they eat herbivores that have less.

4. What it is in animals we like the best? Answer: (Clue -what food element can chefs add to any meal to make it taste better). Butter or bacon. Fat.

5. Is there any harm to eating more fat? Answer: Next week. It's all about the fat. Saturated fat is not normal in any animal. Omega fats are healthy as they can be. Our modern meat has been turned against us. Next week.