You may wonder does this mean that someone should not eat any non-plant foods such as meat, eggs or dairy? No, I am not saying you must be a strict vegan.
I do eat some these non-plant foods occasionally myself. By occasionally I mean fish/shrimp maybe 6 times a year, dairy in the form of ice cream as a dessert 6 times a year and eggs maybe twice a year if I find myself at a restaurant for breakfast that doesn't have any better food options.
I do recommend that these non-plant foods be VERY limited in your diet, because these non-vegan foods offer no phytonutrients and are calorie dense foods.
Meat consumption has also been linked to higher levels of IGF-1 which has been linked to cancer. Also, most processed/cured meats are high in sodium which has been linked to high blood pressure. Meat consumption can also increase cholesterol production by the liver in certain individuals who are genetically prone.
What about protein?
I know many athletes worry about getting enough protein in their diet. Many think eating meat is the only or best way to get protein and over estimate the amount of protein they need.
I will promise you that a person can get adequate protein to meet their needs and even build muscle if that is their desire without eating tons of meat. And this can be achieved with a much overall healthier diet than one that includes high amounts of animal protein.