Proteins are macronutrients that people must consume in abundance to meet the body's need for tissue synthesis and repair. Protein makes up about 20 percent of the weight of the heart, skeletal muscles and liver, and 10 percent of brain tissue. The quality of protein you consume can significantly affect your health. With an increasing number of vegans and vegetarians, the quality of protein in vegetable versus animal sources is a prevalent topic.
Quality
Protein is composed of amino acids, which are needed to regulate a variety of bodily functions. Protein quality can be determined by its amino acid content and pattern, the National Strength and Conditioning Association says. Proteins that are derived from animal sources contain amino acids that are more similar in proportion to the body's needs. Plant protein sources are of lower biological value, and are often low in certain amino acids such as lysine and cysteine.
Protein Content
Many plant sources contain as much protein as meat, but still lack key amino acids.. A 3 oz. serving of beef contains between 20 and 25 g of protein, while a 3 oz. serving of salmon contains 16.9g. Of lower-quality plant sources, soy is the most biologically complete. Soy protein and beans have about 22g of protein per serving, while peanuts have about 40g.
Fat and Cholesterol
Protein from animal sources is often higher in fat and cholesterol than that derived from plant sources. A 3 oz. serving of beef contains up to 25 percent of the recommended daily value of fat, and up to 30 percent of cholesterol. Vegetable protein such as soy has no cholesterol and just 1 percent of the daily recommended value for fat. The strong link between a high-fat, high-cholesterol diet and heart disease gives vegetable protein a huge advantage in this respect.
Requirements
Healthy adults with moderate activity levels should consume about 10 percent to 15 percent of their total caloric intake from protein sources, according to the National Strength and Conditioning Association. You should consume about .8g of protein per kilogram of body weight to help promote tissue growth and repair. At least 65 percent of this protein should be from high-quality sources.
Considerations for Vegans
Because vegans obtain their protein strictly from plant sources, there is concern about the lack of essential amino acids in their diets. Therefore, vegans need to be vigilant about consuming a wide variety of complementary protein sources throughout the day. The combination of beans and legumes with grains can help achieve the appropriate amino acid ratio, the National Strength and Conditioning Association reports.
References
- "Essentials of Strength Training and Conditioning"; Thomas R. Baechle and Roger W. Earle (eds.); 2008
- "The Family Nutrition Book: Everything You Need to Know"; William Sears and Martha Sears; 1999
- "The Post-Workout Protein Puzzle: Which Protein Packs the Most Punch?"; G. Damon Wells; Journal of Strength and Conditioning Research; February 2009
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