I eat quite a bit of meat, most of which I try to get from good sources. I feel better, calmer and more energetic after eating steak than I do when eating grains and vegetables. There’s a fair amount of research into why well-sourced animal protein is healthy for you, from its beneficial fat profile to its necessary amino acids and hard-to-find nutrients like Vitamin B-12. Unlike cows which can build large muscles from eating plant matter, we don’t have four stomachs in which plant foods can ferment and generate the requisite bacteria for B-12 and essential amino acids.
But not every human is suited to the same diet. I was talking with my health-consultant friend, Caroline, the other day, and she described three genetic types, one that thrives mostly on meat, one that thrives mostly on plant foods and one (incidentally, my type) that thrives on a mix, what’s commonly known as a Mediterranean Diet. If you were to give mostly grains and vegetables to the carnivore type, he would be weak and sickly. But if you were to give a diet high in saturated animal fats to the one more suited to plant foods, he would suffer similarly.
One’s genetics apparently (at least according to her research) do matter when it comes to optimizing one’s diet. Moreover, it might not solely be genetics, but epigenetics, i.e., the genes that are expressed under particular environmental conditions. So it might be that people who thrive mostly on root vegetables and other plant foods have a gut biome that’s better able to turn those raw materials into the amino acids they require. That properly soaked grains, leafy grains and green bananas (prebiotics) over time feed the biome in such a way as to enable a healthy mostly vegetarian diet. Whereas someone like me, and especially a carnivore type, would currently lack the gut biome to extract the requisite nutrients from those foods.
Or, take for example, the problem of Vitamin C, which humans (unlike apes) cannot synthesize for themselves and must get from external sources, lest they come down with scurvy. In prior centuries, sailors on long cross-ocean voyages died of scurvy, and it’s why the English took to bringing supplies of limes on board and came to be called “Limeys”. But if we need Vitamin C to survive, how can we explain Eskimos, who live on a diet comprised mostly of fat from sources like whale blubber? Why are they not all dead from scurvy? Apparently they can make efficient use of small amounts of Vitamin C in animal fat. But if they could do that, why couldn’t the sailors? In part, it’s because Vitamin C competes with glucose (sugar) for bioavailability, and sailors (as well as modern humans) had much more glucose in their diets than eskimos. I would also imagine eskimos have a different gut biome, one that helps them get the most from their vitamin intake.
Even though it would be nice for me to believe I found the ideal diet (bone broth, liver, oysters, sardines, wild salmon, salads, limited grains and sugars), and feel good about my long-term prospects, I prefer the idea that humans are adaptable. That maybe if I were stuck in a place where root vegetables were the most reliable source of calories my gut biome would eventually adapt, and I’d be able to thrive once I made the conversion. That following strict rules and routines, i.e., x is good, y is bad, is not the secret to good health, any more than following strict behavioral rules is the secret to success or happiness.
We are not robots — the world is far too mysterious, too sublime for there to be one simplistic “correct” procedure to which everyone should adhere. It’s not only preferable but more plausible to me that a healthy diet, like everything else, is about adapting well to a changing environment, both internally (biome) and externally (activity level, air quality, closeness with nature.) In-sourcing your nutrient acquisition through epigenetic adaptation or outsourcing it to healthy animals*, it might turn out, are both viable choices for health, depending on your circumstances. I find this similar to the debate around medical treatments too — for some, outsourcing immune function, for example, might be more desirable than for others.
In the end, to eat well, perhaps it’s less important what you do, and more important what you do not do. Processed garbage with non-food ingredients like seed oils extracted at high heat and foods with high fructose corn syrup are bad for virtually everyone, as are drain cleaner and cyanide. It’s like giving someone life advice: Don’t become a drug addict or rapist is universally applicable. But if someone asks what kind of livelihood to pursue or what kind of person he should marry, it’s impossible to say with any specificity because it depends on the individual and his environment. There are many paths toward a fulfilling existence, such that specific affirmative advice for everyone is inapt. Eating well is similarly more about avoiding negatives, understanding and adapting to one’s environment. This might be annoying to read — everyone loves a good life hack, an easy rule to follow — but as with most lessons of value, you have to discover what works for yourself.