Lifespan: The Revolutionary Science of Why We Age—and Why We Don't Have To

by David A. Sinclair

There isn’t much debate on the downsides of consumption of animal protein. Study after study has demonstrated that heavily animal-based diets are associated with high cardiovascular mortality and cancer risk. Processed red meats are especially bad. Hot dogs, sausage, ham, and bacon might be gloriously delicious, but they’re ingloriously carcinogenic, according to hundreds of studies that have demonstrated a link between these foods and colorectal, pancreatic, and prostate cancer.20 Red meat also contains carnitine, which gut bacteria convert to trimethylamine N-oxide, or TMAO, a chemical that is suspected of causing heart disease. That doesn’t mean a little red meat will kill you—the diet of hunter-gatherers is a mix of plants packed with fiber and nutrients, mixed with some red meat and fish in moderation21—but if you’re interested in a long and healthy life, your diet probably needs to look a lot more like a rabbit’s lunch than a lion’s dinner. When we substitute animal protein with more plant protein, studies have shown, all-cause mortality falls significantly.22 From an energy perspective, the good news is that there isn’t a single amino acid that can’t be obtained by consuming plant-based protein sources. The bad news is that, unlike most meats, weight for weight, any given plant usually delivers limited amounts of amino acids. From a vitality perspective, though, that’s great news. Because a body that is in short supply of amino acids overall, or any single amino aci...