https://www.theguardian.com/science/2014/mar/04/animal-protein-diets-smoking-meat-eggs-dairy
"A diet rich in meat, eggs, milk and cheese could be as harmful to health as smoking, according to a controversial study into the impact of protein consumption on longevity.
High levels of dietary animal protein in people under 65 years of age was linked to a fourfold increase in their risk of death from cancer or diabetes, and almost double the risk of dying from any cause over an 18-year period, researchers found. However, nutrition experts have cautioned that it's too early to draw firm conclusions from the research.
The overall harmful effects seen in the study were almost completely wiped out when the protein came from plant sources, such as beans and legumes, though cancer risk was still three times as high in middle-aged people who ate a protein-rich diet, compared with those on a low-protein diet."
