Soybean Meal

Soybean meal is a protein-rich ingredient made from soybeans after the oil is removed. Its balance of amino acids is one of the better ones among plants. In one study in dogs, though, a diet based on soy flour was less digestible overall than diets based on animal by-products.

Soy contains some sugars that ferment in the gut and can cause gas. It was reported in about 6% of dogs with food reactions in one review.