Don't we need meat to be healthy?

The objection

“Humans evolved eating meat, complete protein, iron, zinc, B12 in forms we use efficiently. Cutting out a whole food group is risky, and a diet that needs supplements can’t be the one we’re built for.”

The answer

Take the nutritional concern at full strength, because it’s the testable part. The largest body of dietitians in the world, the Academy of Nutrition and Dietetics, holds that appropriately planned vegetarian and vegan diets are healthful and nutritionally adequate for all stages of life, covering pregnancy, infancy, childhood and athletic performance, and may reduce the risk of heart disease, type 2 diabetes and several cancers [1]. This is the consensus of the relevant experts rather than a fringe claim. Every nutrient named is obtainable from plants and fortified foods.

The supplement point sounds decisive, but it folds quickly. B12 is made by bacteria, not animals. Meat contains it largely because farmed animals are themselves routinely supplemented, directly or via cobalt added to feed. When you eat meat for B12, you’re usually eating a supplement that has passed through an animal first. Taking it directly is simply a more efficient route to the same molecule.

Then there’s the side of the ledger the objection omits. The WHO’s cancer agency classifies processed meat as a Group 1 carcinogen, the same evidence category as tobacco smoke, with each 50g eaten daily associated with an 18% higher risk of colorectal cancer; red meat is classed as probably carcinogenic [2]. So this was never a contest between a safe food and a risky diet. A well-planned plant-based diet meets our needs, and on several measures the food being defended carries documented harms of its own.