I disagree that there is no room for animal proteins and fats in our diet. All studies have used commercial feedlot meat and dairy. We are built to eat animals but healthy ones. However, one or two servings of animal protein is plenty in a day. Eggs from pastured chickens living a real chicken life are like perfect food. The entire egg, eaten together.
But yes, our main calories should come from plants. Our bacteria biome is essential and we must feed those babies when we eat. They are as important as we are, cell wise, to our health. One easy way: bake a tray full of potatoes. Chop and pan cook them sliced to eat with your meals, or slice for potato salads. Cooked and cooled white potatoes (go for organic and eat the skin too) have a lot of resistant starch, which our best gut bugs thrive on.
2/3rds of cancers result from chance mutations. As we age our DNA replication fidelity begins to fail, as more errors occur, and when those errors occur in oncogenes and suppressor genes, cancer results. Everything wears out as we age, all of our senses, and yes, even the ability to preserve our genome. Good nutrition and exercise will slow it down, but the inevitable happens.
The one chemical threat that most people ignore is probably the most important and that is air pollution. Humans are vacuum pumps exposing their 2 cell thickness respiratory membrane to about 12 liters of ambient air per minute. If you live in an urban area, there is no escape to the constant bombardment with particulates and chemicals in the air.