The Vegan Debate
Beyond the well-known unhealthy compounds in animal products (saturated fat, heterocyclic amines / PAHs) vegans are not able to pinpoint precise compounds or empirically explain the purported ill effects of an omnivorous diet.
They may resort to ethical claims that taking an animal's life is a spiritual sin punishable by karma. Mysticism is delightful undertaking, but it is not accessible to science and often leads to occultism.
Today's eggs are not the same as our ancestors' eggs. A pasture-raised egg will have substantially more vitamin K, D, A, and magnesium than eggs from a factory-farmed hen fed a complicit diet of corn and soy, living its entire life in the confines of a small cage and extremely stressful conditions.
When you are eating industrial livestock in large amounts, you are not following proper life extensionist protocol. You are in a delinquent category. The research needs to longitudinally track the mortality of those who eat pasture-raised foods, cook at a lower temperature, exercise moderation, and follow similar healthy practices in the rest of their life will likely show no difference from vegans in terms of adverse health outcomes. By including some animal products and being selective about them, it is easier to reach daily requirements for vitamin B12, iron, and protein.
There are some plant compounds which may be harmful as well: oxalates, phytates, aflatoxin to name a few. The idea that plants are absolutely superior is wrong.
Where science is misleading, it is generally due to individual error and a misinterpretation of results rather than a fault with the process as a whole. We are continually progressing in ideas. Previous thinkers are not wrong, they are essential stepping stones. There are no sudden leaps in the evolution of thought; everything proceeds steadily, building upon what came before, like bricks gradually stacked upon a building's foundation. To think ourselves wiser than them is wrong; they did not have access to the same information as us. Not nearly.
Confounding Variable (Research Bias)
Vegans as a population typically exhibit higher rates of fitness (regular exercise), and lower rates of drug addiction and violence.
Because there is a strong relationship between self-neglect and shortened life expectancy, it is not clear to what extent these other variables (e.g. more regular exercise) may explain any enhanced longevity in the vegan population. To what extent can we disentangle these causes and delineate the dietary contributions from other extraneous variables?