Dr. Steven Gundry says humans weren't designed to eat grains, beans, or nightshades, as their defense chemicals damage gut lining. He advises avoiding lectin-rich foods like peanuts and potatoes, or else pressure cooking them to deactivate these plant toxins. Since we lack defenses against New World crop compounds, Dr. Gundry believes peeling peppers and tomatoes or eliminating them boosts health. Ultimately he aims to prevent disorders caused by our mismatch with modern diets.