Dark green leafy vegetables work well with most food combinations, Dr. Gioffre says. Salads typically combine very well with proteins or starches. “With that said, if I wanted to make my digestion as optimal as possible, the only food group I would want to eat the salad first is with heavy proteins like steaks.” Animal proteins tend to digest slowly in the stomach, and foods that are eaten afterwards that tend to digest more quickly (like high water content fruits and dark green leafy vegetables) will get backed up behind them and can ferment and literally rot while they wait, Dr. Gioffre adds. “Other than that, a big salad should ideally be combined with every meal.”