Although soy and meat are both rich in dietary protein, they differ greatly in nutritional content. Both soy and meat proteins are high-quality, complete proteins because they contain all of the essential amino acids your body requires daily. However, soy offers nutrients meat lacks, and vice versa. The type of protein that’s right for you depends on your health risks and food preferences.
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Grams of Protein
Although they are both rich sources of dietary protein, meat contains more protein per ounce than soy. The U.S. Department of Agriculture National Nutrient Database for Standard Reference reports that 3 ounces of 95-percent lean ground beef provide 25 grams of dietary protein, while a 3-ounce portion, or 85 grams, of soy-based firm tofu contains about 13 grams of protein and one-half cup of soybeans provides about 16.5 grams of dietary protein.
Carbs and Fiber
While meat is carb- and fiber-free, most soy products contain carbohydrates, including dietary fiber. For example, 3 ounces of lean ground beef contain no carbs, while a 3-ounce portion of firm tofu provides 4 grams of total carbs -- including 2 grams of dietary fiber. Getting plenty of fiber in your diet aids in weight management and helps control blood cholesterol, according to a 2009 review published in “Nutrition Reviews.”
While the fat present in meat is mainly unhealthy saturated fat, which contributes to high blood cholesterol and heart disease when eaten in excess, the majority of dietary fat in soy is heart-healthy, unsaturated fat -- including essential omega-3 fatty acids. Replacing saturated fat with healthier mono- or polyunsaturated fat helps reduce your chronic disease risks. If you’re at risk for high blood cholesterol or heart disease, skip high-fat meats and choose very lean cuts of meat or soy protein.
Although meat and soy are both good sources of dietary iron, the iron in meat is a form of iron called heme iron, which is better absorbed by your body than the non-heme iron found in soy and other plant-based foods. Furthermore, some soy proteins can actually inhibit iron absorption, according to the Office of Dietary Supplements. Consuming protein found in meat, poultry and seafood or vitamin C with non-heme iron sources enhances non-heme iron absorption.
- U.S. Department of Agriculture National Nutrient Database for Standard Reference Release 26: Basic Report: 23560, Beef, Ground, 95% Lean Meat/ 5% fat, Crumbles, Cooked, Pan-Browned
- U.S. Department of Agriculture National Nutrient Database for Standard Reference Release 26: Basic Report: 16426, Tofu, Raw, Firm, Prepared with Calcium Sulfate
- U.S. Department of Agriculture National Nutrient Database for Standard Reference Release 26: Basic Report: 11450, Soybeans, Green, Raw
- Nutrition Reviews: Health Benefits of Dietary Fiber
- Office Dietary Supplements: Iron
- Nutrition in Clinical Practice: Nutrition Concerns and Health Effects of Vegetarian Diets