Harvard School Of Public Health
The Protein Package
Animal protein and vegetable protein probably have the same effects on health. It's the protein package that's likely to make a difference.
What Is Protein?
Protein is found throughout the body—in muscle, bone, skin, hair, and virtually every other body part or tissue. It makes up the enzymes that power many chemical reactions and the hemoglobin that carries oxygen in your blood. At least 10,000 different proteins make you what you are and keep you that way.
Twenty or so basic building blocks, called amino acids, provide the raw material for all proteins. Following genetic instructions, the body strings together amino acids. Some genes call for short chains of amino acids, others are blueprints for long chains that fold, origami-like, into intricate, three-dimensional structures.
Because the body doesn't store amino acids, as it does fats or carbohydrates, it needs a daily supply of amino acids to make new protein.
A 6-ounce broiled porterhouse steak is a great source of complete protein—38 grams worth. But it also delivers 44 grams of fat, 16 of them saturated. (2) That's almost three-fourths of the recommended daily intake for saturated fat. The same amount of salmon gives you 34 grams of protein and 18 grams of fat, 4 of them saturated. (2) A cup of cooked lentils has 18 grams of protein, but under 1 gram of fat. (2)
The bottom line is that it's important to pay attention to what comes along with the protein in your food choices. Vegetable sources of protein, such as beans, nuts, and whole grains, are excellent choices, and they offer healthy fiber, vitamins, and minerals; nuts are also a great source of healthy fat. The best animal protein choices are fish and poultry. If you are partial to red meat, such as beef, pork, or lamb, stick with the leanest cuts, choose moderate portion sizes, and make it only an occasional part of your diet: A major report on cancer prevention recommends consuming less than 18 ounces a week of red meat and avoiding processed meats (such as hot dogs, bacon, or ham) to lower the risk of colon cancer.