Soy foods, which are high in protein, have been touted as healthy and environmentally friendly alternatives to animal-based foods since the early 1990s. Soybeans are relatively easy and cheap to grow and have been used as a secondary source of protein in Asian countries for hundreds of years. However, popular soy foods in North American and European markets contain compounds that could be harmful to human health. Consequently, interest in high protein alternatives to soy foods is growing.
Issues with Modern Soy Foods
Although soy foods are eaten in Asian countries, traditionally, it has been more as a condiment than a primary source of protein or calories. Furthermore, most soy foods eaten in Asian countries are fermented, such as natto, miso and soy sauce, which make them more digestible and better assimilated, as cited in "Contemporary Nutrition." In contrast, many unfermented soy foods, such as tofu, soy milk and soy supplements, are made from soy protein isolate, a protein-rich waste product of soy oil manufacturing that creates problems within the body. For example, most soy foods are high in phytic acid, which blocks the absorption of essential minerals, especially zinc. According to "Biochemistry of Human Nutrition," other potentially harmful compounds in soy foods include trypsin inhibitors, which disrupt protein digestion; phytoestrogens, which mimic estrogen and suppress testosterone production; and toxins such as lysinoalanine and aluminum particles.
Flesh-Based Sources of Protein
The flesh from animals, poultry and fish are excellent sources of protein and usually are considered complete, which means they contain all the essential amino acids needed by the body. Ground beef is not only a great source of protein, at about 7 grams per ounce, but inexpensive and versatile. Chicken is an even better protein choice, at about 8 g per ounce. Turkey, especially when ground, is usually less expensive than chicken and contains slightly more protein per ounce. Fish is high in protein and rich in omega-3 fatty acids. Fresh fish, such as salmon and trout, are nutritious protein sources, but often expensive. Canned tuna, on the other hand, is affordable and a concentrated source of protein, with a 6 oz. can containing about 40 g.
Dairy Sources of Protein
Dairy products, usually from cows and goats, are considered high in protein and very affordable. A large egg, for example, contains about 6 g of protein, which is a very high protein-to-cost ratio. Other dairy products high in protein include yogurt, whey and cheeses, especially ricotta cheese and cottage cheese. Milk remains perhaps the best source of protein and the most convenient to consume, although lactose intolerance is a common concern. There are about 8 g of protein per cup of milk.
Vegetable Sources of Protein
Beans, legumes and nuts are all high in protein and excellent sources for vegetarians, although most would be considered incomplete sources. However, mixing and matching different varieties would provide all the essential amino acids the body requires. A 2 tbsp. serving of peanut butter contains about 8 g of protein. Vegetables that contain high amounts of plant protein and amino acids include spinach, kale, wheatgrass, wheat and potatoes.
References
- "Contemporary Nutrition"; Gordon Wardlaw; 2010
- "Biochemistry of Human Nutrition"; George Gropper; 2000
- "American Dietetic Association Complete Food and Nutrition Guide"; American Dietetic Association; 2006
- "Advanced Nutrition: Macronutrients, Micronutrients, and Metabolism"; Carolyn Berdanier; 2009
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