Peak Moment 191: What we eat is destroying both our bodies and the planet, according to author Lierre Keith, a recovering twenty-year vegan. While she passionately opposes factory farming of animals, she maintains that humans require nutrient-dense animal foods for good health. A grain-based diet is the basis for degenerative diseases?we take for granted?(diabetes, cancer, heart disease) - diseases?of civilization. Annual grain production is destroying topsoil and creating deserts on a planetary scale.? Lierre urges the restoration of perennial polycultures for longterm sustainability.