What foods are the best sources of protein?

The best source is probably spinach, which has 13 grams of protein in a 100-calorie serving. Firm tofu is a runner up, with 11.7 grams.

Soybeans have 9.6 grams of protein per 100 calories; lentils, 7.8 grams; romaine lettuce, 7.2 grams; broccoli and kale, 6.8 grams; black beans 6.7 grams; kidney beans and peas, 6.4 grams; black-eyed peas, 6.2 grams.

Cottage cheese has 11.3 grams of protein per 100 calories, but it also has 4.4 grams of fat, 17 mg of cholesterol, and 371 mg of sodium. Eggs have 8.8 grams of protein in along with 6.7 grams of fat and 260 mg of cholesterol. Cheddar cheese has 6.2 grams of protein, with 8.2 grams of fat and 26 mg of cholesterol.

Pinto beans and lima beans have 5.7 grams of protein per 100 calories, and peanut butter has 4.3 grams.

A 100-calorie serving of regular ground beef has 4.3 grams of protein, more than 9 grams of fat, and 24 milligrams of cholesterol.

All of the plant sources of protein have zero cholesterol and most are very low in fat.