You cannot live on incomplete proteins alone. But well-informed vegetarians like our science teacher friend have learned how to use them to make complementary proteins. Complementary proteins all from plant sources are complete, and they can supply your protein needs quite adequately. If they couldn’t, many more of the world’s people would be deprived of their protein than already are. Grains alone supply almost 50 percent of humankind’s supply.
The West has discovered soybeans as animal feed and as food for humans in fairly recent times. In the Orient, people have known about soybeans for centuries, and have used them to supply protein at low cost in the absence of cheap meat. Like all legumes, soybeans have low levels of the essential amino acid tryptophan and certain others as well but are high in lysine. To enhance their biological value you can combine them with complementary proteins such as nuts, grains, and seeds, which are low in lysine and high in tryptophan. And in these countless complementary combinations, they make a variety of delicious dishes.
You have probably become familiar with two of the most common soybean products in Chinese foods: tofu (bean curd), to which the Chinese give the name “meat without bone,” and soybean sprouts. Tofu is made by a process similar to that used for making cheese, curdling the soybean milk, and packing the solids in layers of cloth. It has an NPU of 65, only slightly lower than animal flesh, and is well complemented by grains such as brown rice. Sprouted soybeans have large quantities of vitamins A, E, and B, and they combine well with any member of the grain family. If you cook Chinese food, stir-frying either bean curd or sprouts with soy sauce, ginger, and garlic and serving the dish with brown rice provides an excellent complete protein and a delicious meal.
Whole soybeans can also be eaten either on their own or in casseroles and soups. You can buy them already roasted in health food shops and some supermarkets, though steaming, boiling, or pressure cooking raw beans is better if you’re planning a meal around them. Soybeans cannot be eaten raw because of the trypsin inhibitor they contain that impedes protein digestion; this inhibitor is destroyed by heat.35′ 36 Legumes may contain toxic substances, but these, too, are destroyed by heating or sprouting. In any case, it’s far better to deal with these naturally occurring substances than with the man-made additives that adulterate so much of the meat we eat.
If you have stopped eating meat, but miss its texture, you will be glad to discover tempeh. Tempeh is a soybean cake containing anywhere from 14 to 48 percent protein. It is made by cooking the beans and adding a mold to ferment them. It contains vitamin B12 (rare outside the meat family) and can be cooked in a variety of delicious ways. Try sprinkling it with sesame seeds and soy sauce and broiling it, or sauteing it with chopped onions. Serve it with brown rice, green vegetables, and a brightly colored salad for a perfect dinner. You can also make your own tempeh with a starter kit from the U.S. Department of Agriculture.
Soy flour, which contains more protein than meat, can be used in baking. You can find recipes in whole grain cookbooks.
Soy concentrate is the residue created when soybeans are pressed to make soy oil. It contains about 50 percent protein. It is usually used as feed for animals. But with proper treatment for digestibility and flavor enhancement, it can be turned into a fibrous meat substitute of nearly limitless versatility.
Have you ever eaten a delicious “ vegetarian veal cutlet” or “ vegetarian drumstick” at a dairy restaurant? They probably contained textured soy protein. Institutions such as hospitals also buy soy concentrate in numerous “disguised” forms, including imitation meats and fish. The flavor is excellent and the texture hardly distinguishable from whatever “ original” is being imitated. Other protein-yielding nuts, seeds, and grains can be used in the same way.28 You can find some of these recipes in older vegetarian cookbooks.
In short, soybeans are one of the most versatile of all our protein sources. One can only hope that their vast potential for feeding mankind will be fully realized and that the wasteful raising of animals for meat will be realized.
Not all members of the legume family are as versatile as soybeans, but they are excellent protein sources nonetheless. And they are numerous: mung beans, chick-peas (garbanzos), black-eyed peas, navy beans, red beans, pink beans, black beans, lentils of all types, split peas, etc. Like soybeans, they tend to be low in certain amino acids (particularly tryptophan) but high in others (such as lysine and isoleucine). And they, too, can be combined with grains, nuts, and seeds to form complementary proteins of high nutritive value. Eaten by themselves, the legumes have an NPU ranging from about 31 (lentils) to 61 (soybeans).
There are countless examples of legume-grain-seed complementation from the cuisine of nations poorer than the United States. The Indians eat dhal, their deliciously fragrant lentil puree, with herbed, nutty pulao rice. Central American and Caribbean nations use beans and rice as staple food. Middle Eastern countries combine chick-peas with sesame (tahini) paste to make houmus bi tahini and falafel, while the Italians mix lentils, chick-peas, or haricot beans with pasta to make pasta e Fagioli and other heartwarming soups. In all these countries, meat is treated as a luxury, rather than a staple. When an Italian family begins its meal with pasta e Fagioli, the meat course is likely to provide only a couple of ounces per person. Legumes also provide dietary fiber, which may help you avoid gastrointestinal disorders ranging from constipation to colorectal cancer. The long cooking time of legumes, a disadvantage, can be reduced by using a pressure cooker. The smaller beans split peas, lentils, aduki, red, and mung beans cook faster than the larger ones. To minimize digestive distress from beans, make sure they are soaked overnight and thoroughly cooked.
GRAINS AND CEREALS
These make an ideal complement to legumes because they are generally high in tryptophan and low in isoleucine and lysine. Their NPU can range up to 70 (for rice), but is usually in the area of 50 to 60 (for whole wheat, etc.). Grains and cereals supply about half the protein for the earth’s people. They are also among the best sources of fiber.
The protein content of grains and cereals varies from about 8 percent for com to 25 percent for wheat germ. One hundred grams of spaghetti or macaroni will provide about 5 grams of protein. When selecting grains for their protein content, you should also pay attention to their other nutrients. Elat brown rice instead of white for its fiber and vitamin content, and add fiber-rich bran flakes (10 percent protein) to baked goods and casseroles.
Creating complementary protein dishes from grains, seeds, and legumes is easy: we’ve already mentioned several possibilities in the preceding pages. You can also complement grains and cereals with complete protein from eggs and dairy products, which will raise the NPU of the incomplete sources. Breakfast cereals with milk achieve this very nicely. Macaroni and cheese and Italian risotto (the latter served with generous helpings of Gruyere or Parmesan cheese) also feature the grain /dairy combination. Eggs served with whole grain bread make an excellent breakfast. With adequate protein supplied, you can count on bulky whole grains, rice, pasta, and bread to prevent overeating.
NUTS AND SEEDS
Nuts and seeds are similar in amino acid composition to grains and cereals. They can be used for cooking in many of the same ways. The residue leftover from making peanut, sunflower, and sesame oil is often converted to textured protein and treated in preparation for use as a meat substitute.38 And the most delicious nuts almonds, pistachios, walnuts, pine nuts, cashews have a high protein content. Peanut butter, made from fresh-ground peanuts (actually a legume, not a nut), becomes a complete protein when spread on whole-grain bread. Sesame seeds can be toasted, eaten raw, or ground up to make tahini. Slivered almonds make a crunchy and delicious addition to any stir-fried vegetable dish or casserole. Some nuts are very expensive, particularly cashews and pine nuts, and are not economically practical as a protein source; they also have a higher fat content than many people would like to include in their diets. Used in smaller quantities, however, they can play a functional part in many vegetarian menus. Nuts and seeds complement each other. To make a relatively inexpensive ambrosia snack great when you’re hiking or coping with stress combine 3/4 cup of peanuts with 1 cup of sunflower seeds (NPU 64 percent, according to Ewald) and add some raisins or other dried fruit.
Vegetables supply a number of useful nutrients vitamins, minerals, fiber but they are generally low in protein. Corn (a grain), potatoes, and mushrooms have higher NPU levels than most. Corn combines well with beans, as in Mexican dishes. Try cottage cheese or yogurt with your baked potato instead of sour cream. Other vegetables have a high moisture content (and thus low nutrient density) combined with protein as low as 2 percent or less. They should be valued for their other nutrients, but not, generally, for protein. Dried mushrooms have a much higher protein content than the fresh variety.
How to Become a Vegetarian (If You Want To)
From this list, it should be obvious that there are numerous excellent protein sources available to us other than meat. If you want to become a vegetarian, the classic cuisines of the world can provide you with inspiration.
do it in stages rather than all at once. Changing the basis of one’s diet is a major step. It requires an entirely new orientation toward food and nutrition. Buy a good vegetarian cookbook. (Diet for a Small Planet by Frances Moore Lappe was one of the first books to explain fully the principles of protein complementarity. Recipes for a Small Planet by Ellen Buchman Ewald applied these principles through protein-rich recipes.)numerous excellent protein sources available to us other than meat. If you want to become a vegetarian, the classic cuisines of the world can provide you with inspiration.
Try new food combinations as side dishes at first, rather than the main course. Eventually, you can let vegetarian dishes take care of all your nutritional needs. Indeed, essential vitamins and minerals can more easily be obtained from a vegetarian diet than from one based on meat. The only exception to this is vitamin B12. But tempeh, various sea vegetables, miso, and milk can supply all your needs for that vitamin.
Remember, variety is all-important. Mix legumes and grains, and seeds or nuts and legumes; drink milk and eat eggs in moderation; concentrate on unrefined carbohydrates (fruit, vegetables, whole-grain bread, and brown rice); eat your vegetables raw or very lightly cooked, with the exception of legumes, which should be well cooked.
There are now millions of American vegetarians like our young science teacher who have learned how to utilize grains, nuts, and other protein sources in a balanced, nutritionally unsurpassed diet. Their choice is not necessarily the only way to attain good health, but it sets a standard by which all diets can be measured. It is particularly valuable for those seeking an alternative to the American meat-centered diet.