Some animal foods actually lower disease risk
Some of these associations are real and worth conceding rather than arguing with. What they almost always compare against is red and processed meat rather than a well-planned plant diet, and where the protective component has been identified it is something obtainable without the animal. Across total cancer risk the pattern still favours plant-based eating.
The evidence is not all in one direction, and treating animal foods as a single harmful block ignores that. Fish consumption is associated with lower colorectal cancer risk in large European cohorts, and in one of them fish eaters came out lower than vegetarians, not just lower than meat eaters. Dairy is associated with lower colorectal cancer risk too, largely through calcium. A diet that removes the harmful animal foods and the protective ones together is not self-evidently an improvement.
The honest place to start is by granting the specific finding, because it is real. In the EPIC-Oxford cohort, fish eaters had the lowest colorectal cancer incidence of the diet groups studied, below meat eaters and below vegetarians. Colorectal cancer is the one major outcome where plant-based eaters have not consistently come out ahead, and pretending otherwise would be the kind of selective reading this argument is accusing us of. Dairy and calcium intake show a protective association for the same cancer, which major evidence reviews rate as reasonably strong.
With that said, three things decide how much it carries.
The comparison group is usually the point. Most findings that a particular animal food is protective compare people eating it with people eating a lot of red and processed meat, which the IARC classifies as carcinogenic to humans for this same cancer. Fish looking good against that is not the same as fish looking good against lentils. Where the protective agent has actually been identified rather than inferred, it tends to be long-chain omega-3, which algae supply directly, or calcium and vitamin D, which are in fortified plant milks, or simply the displacement of red meat from the plate.
The outcome chosen also matters. Across total cancer incidence, and across cardiovascular disease and type 2 diabetes, plant-based eaters do better in the same cohorts that produce the colorectal finding. Picking the single outcome where animal food looks protective and presenting it as the verdict is choosing the scoreboard after the game.
And then there is what it would establish if entirely granted. It would be a reason to eat some fish, or to take care over calcium. It would not be a reason to eat pigs or chickens or cows, and it leaves the question of whether any of that is necessary exactly where it was. An argument for pescatarianism is not an argument against veganism so much as an argument for a much smaller version of animal farming than the one being defended.
- Fish protects against bowel cancer
- Dairy lowers colorectal cancer risk
- Not all animal foods are harmful, some are protective
- The evidence on animal foods is not all one way
- Some animal products are shown to reduce cancer risk
Different wording, same argument. The response above answers all of them.
Presenting only the evidence that supports a conclusion while leaving out evidence that tells against it.
How it applies here: Selects the single outcome where an animal food looks protective and presents it as the verdict, while total cancer incidence and cardiovascular outcomes in the same cohorts point the other way.
Composition: assuming what is true of the parts must be true of the whole. Division: assuming what is true of the whole must be true of each part.
How it applies here: Takes a finding about one animal food and treats it as a defence of animal foods generally. At most it supports eating some fish, and says nothing about the farming of pigs, chickens or cattle.