DEAR DR. BLONZ: My wife and I really liked your recent column that answered a question on protein. We are vegetarians. You mentioned that vegetarians "can easily meet their daily protein requirements by combining different foods so that sufficient amounts of essential amino acids are consumed during the day." Our question is: What are those food combinations? Please help us with some examples of vegetarian foods that form a complete protein when eaten together. -- P.G., Freemont, Calif.
DEAR P.G.: From a vegetarian perspective, the concept of a protein requirement can be misleading. It's not the complete protein the body needs as much as the amino acids the proteins are made from. When we eat protein foods such as meat, poultry or fish, the human digestive process breaks down the "complete" protein to its individual amino acid parts. This is an essential prelude to absorption.
Once inside, the body can custom-make its own protein according to what is needed at the moment. Need more muscle? Time to make a few new red blood cells? Have to replace some organ tissue? Whatever is on the body's build/replace/repair menu, the on-site construction team goes to work by grabbing essential amino acids out of bodily fluids to assemble the desired protein substance. The message here is that we have to eat in a way that ensures our body has all the amino acids available. We are able to manufacture most amino acids from scratch, but the essential amino acids (EAAs) are those we have to get from the foods we eat.
Vegetarians can easily meet their daily protein requirement by combining different foods so that sufficient amounts of all the EAAs are present during the day. There are three basic types of vegetable protein: whole grains, such as rice, corn, oats and barley; legumes, such as beans and lentils; and nuts and seeds, such as almonds, sunflower seeds and sesame seeds. By combining foods from different groups, you end up supplying the EAAs the body requires, the same as if you had eaten a complete protein. For example, bean protein, from the legume group, has most of the EAAs, but comes up short with tryptophan and methionine. Nuts, grains and seeds are relatively short in lysine and isoleucine, but they have higher levels of the EAAs that legumes lack. By having foods from both groups during the day, you can satisfy your protein requirement.
Factors that often drive people towards vegetarianism include health, the environment, cost, religion and animal welfare. Health statistics for vegetarians include lower rates of heart disease, obesity, obesity-related diabetes, colon cancer, lung cancer, breast cancer, hypertension, osteoporosis, kidney stones, gallstones and diverticular disease. Though some of these gains can be attributed to a healthier lifestyle that's frequently adopted with new eating habits, the data are certainly impressive.
As regards cost, I recommend reading an article in the October 2009 issue of the Agricultural and Resource Economics Review (available online in pdf format here: tinyurl.com/cxfq6ms). Vegetarianism does not have to be thought of as an all-or-nothing proposition. Having one or more vegetarian days during the week can get you thinking more about what you eat and effectively expand the selection of healthful foods on your table.
Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to email@example.com. Due to the volume of mail, personal replies cannot be provided.