The following statement is a common tidbit of knowledge: meat is high in protein. Everyone is well aware of the fact, and nearly as many are perplexed by the idea of a strict vegan diet. The question how can one obtain enough protein without any animal consumption? has haunted the dietary concept for years. Simple research into the vast, varied realm of nutrition, yields interested and perhaps even surprising results.
As stressed by the Vegetarian Resource Group and veganhealth.org, the issue is not simply in consuming protein, humans actually require the different amino acids found in protein. Nine essential amino acids, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, and histidine, are derived in adequate amounts through “complete proteins.” Unfortunately, the majority of non-animal-based food products are considered “incomplete proteins,” due to a less-than-adequate amount of at least one amino acid in most examples.
Savvyvegeterian.com delivers the stern, familiar warning; “Vegetarians and vegans need complete protein to get all the essential amino acids, so their bodies don’t fall into a negative protein balance, otherwise known as starvation.”
Prospective vegans should not be discouraged just yet. The Vegetarian Resource Group, and many others, confirm that soybeans, quinoa, and spinach stand as proud examples of complete proteins, and most deficiencies can easily be remedied through simple daily combinations & “complimentary” relationships. An example of such a relationship is the high-lysine/low-methionine composition of legumes and the inverse value of grains.
Which amino acid is among the greatest concern for the average vegan? Veganhealth.org claims that lysine is often the “limiting amino acid” of the vegan diet despite its prevalence in tofu, tempeh and soy meat analogues. The same website explains that one of the conflicting factors is related to caloric content in the generally recommended legume serving.
“Generally” is an important term; everyone is different and everyone faces different nutritional requirements based on age, weight, and physical activity level. The United States Department of Agriculture (USDA) and Recommended Dietary Allowance (RDA), suggests an intake of 0.8 grams of protein for every kilogram of body weight (g/kg) or the rough equivalent of 0.36 grams of protein per pound. The Vegetarian Resource Group considered the digestive differences between plant and animal protein consumption to update the suggestion to 1 g/kg (about 0.45 grams per pound) of body weight. The American Dietetic Association (ADA) recommends a slightly higher protein intake for vegetarian and vegan athletes (1.3 to 1.8 g/kg of protein a day) under the same justification. According to veganhealth.org, those over the age of 60 should consume between one and 1.3 g/kg of protein.
It has ultimately been determined that 10-12 percent of the standard daily vegan diet is based in protein, which is slightly less than the average non-vegan diet, but within a healthy range. Two noted studies have analyzed the nitrogen balance of a temporary vegan diet. A 1965 study determined that 0.75 g/kg of protein (with 0.25 g/kg of soy protein) is sufficient, and a 1967 study found nine out of 12 participants in protein balance after consuming 0.91g/kg of protein a day. Veganhealth.org also lists a cross-sectional study in which vegans were found to have a higher serum albumin level than non-vegetarians, which indirectly relates to protein intake.
Meat is irrefutably high in protein, as common wisdom dictates. One should also remember another common piece of wisdom; there can be too much of a good thing. The vegetarian resource group provides the following statement: “diets that are high in protein may increase the risk of osteoporosis and kidney disease.”
In the midst of dietary concern, vegans are not at a disadvantage. Through complimentary combinations, protein and all of its necessary amino acids, can easily be found after all.
For more information and tables illustrating ways to obtain sufficient protein, protein contents of selected vegan foods, and the amounts of food providing recommended amounts of amino acids: http://www.vrg.org/nutrition/protein.htm
For descriptions of specific amino acid functions and a table displaying complimentary vegetarian amino acid sources: http://www.savvyvegetarian.com/articles/get-enough-protein-veg-diet.php
For more information and tables displaying US RDA & Vegan Recommendations, Plant Protein Studies, and Protein & Amino Acid Content of Plant Food RDA based on ideal body weight (IBW):