The conventional diet guidelines suggest that humans should acquire a large amount of their protein quotas from meats and animal sources like chicken, eggs, etc... unlike a pure vegetarian diet which acquires its intake from plant protein sources.
Can the pure vegetarian (vegan) diet provide enough protein for sound human health?
The medical community agrees about the distinct health advantages of a pure vegetarian diet, but the protein question stays with us because animal products have been promoted by the industries that produce them, sell them, and want people to think of them as the best source of protein. This assumption is wrong and can be harmful, as a quick study of the facts about daily requirements of protein and nutrition shows.
The Importance of Protein
Protein is essential to human health. Our bodies—hair, muscles, fingernails, and so on—are made up mostly of protein. As suggested by the differences between our muscles and our fingernails, not all proteins are alike. This is because differing combinations of any number of 20 amino acids may constitute a protein. In much the same way that the 26 letters of our alphabet serve to form millions of different words, the 20 amino acids serve to form different proteins.
Amino acids are a fundamental part of our diet. While half of the 20 can be manufactured by the human body, the other 10 cannot. These "essential amino acids" can easily be provided by a balanced vegan diet.
While just about every whole food contains some protein, the soybean deserves special mention, for it contains all the essential amino acids and surpasses all other food plants in the amount of protein that it can deliver to the human system. In this regard, it is nearly equal to meat.
The many different and delicious soy products (such as tempeh, soy "hot dogs" and "burgers," Tofutti brand "ice cream," soy milk, and tofu) available in health and grocery stores suggest that the soybean, in its many forms, can accommodate a wide range of tastes.
Note: Some people are "soy intolerant" and would be better off with other sources (below) of protein. Be sure to check with your doctor about getting testing for soy allergies, especially if you don't feel good after eating soy products.
Other rich sources of non-animal protein include legumes, nuts, seeds, yeast, and freshwater algae. Although food yeasts ("nutritional yeast" and "brewer’s yeast") do not lend themselves to forming the center of one's diet, they are extremely nutritious additions to most menus (in soups, gravies, breads, casseroles, and dips). Most yeasts get about 50 percent of their calories from protein.
It's important to note that most nutritionists, dieticians, and official sources agree that we need only 2.5%-10% of our calories from protein ,,, and ALL vegetables offer us more than that.
Here are some examples of vegetarian foods with high sources of plant protein:
Protein in Legume: Garbanzo beans, kidney beans, lentils, lima beans, navy beans, soybeans, split peas
Protein in Grain: Barley, brown rice protein, buckwheat, millet, oatmeal, quinoa, rye, wheat germ, wheat, wild rice
Vegetable Protein: Artichokes, beets, broccoli, brussels sprouts, cabbage, cauliflower, cucumbers, eggplant, green peas, green pepper, kale, lettuce, mushroom, mustard green, onions, potatoes, spinach, tomatoes, turnip greens, watercress, yams, zucchini
Protein in Fruit: Apple, banana, cantaloupe, grape, grapefruit, honeydew melon, orange, papaya, peach, pear, pineapple, strawberry, tangerine, watermelon
Protein in Nuts and Seeds: Almonds, cashews, filberts, hemp seeds, peanuts, pumpkin seeds, sesame seeds, sunflower seeds, walnuts (black)
One excellent ingredient to look for is hemp seed protein. Hemp seed is an nutritious dietary source of easily digestible gluten-free protein. It provides a well-balanced array of all the amino acids, including 34.6 grams of protein for each 100 grams. The fatty acid profile of the hemp seed is extremely beneficial, containing omega-6 and omega-3 fatty acids in a virtually ideal ratio. Other beneficial aspects of hemp seed include a strongly favorable unsaturated-to-saturated fat ratio; a high content of antioxidants; and a wide variety of vitamins and minerals.
Additionally, super green foods provide an excellent source of protein (70% in some cases).
How Much Protein?
As babies, our mothers' milk provided the protein we needed to grow healthy and strong. Once we start eating solid foods, non-animal sources can easily provide us with all the protein we need. Only 10 percent of the total calories consumed by the average human being need be in the form of protein.
The Recommended Dietary Daily Allowance for both men and women is 0.8 grams of protein for every kilogram (2.2 pounds) of body weight.People with special needs (such as pregnant women) are advised to get a little more.
Vegans should not worry about getting enough protein; if you eat a reasonably varied diet and ingest sufficient calories, you will undoubtedly get enough protein. Protein deficiency, or "kwashiorkor," is very rare in the U.S. and is usually diagnosed in people living in countries suffering from famine.
By contrast, eating too much animal protein has been directly linked to the formation of kidney stones and has been associated with cancer of the colon and liver.,  By replacing animal protein with vegetable protein, you can improve your health while enjoying a wide variety of delicious foods.
1 University of Arizona, Department of Biochemistry and Molecular Biophysics, “Amino Acids Problem Set,” The Biology Project, 25 Aug. 2003.
2 Paula Kurtzweil, “‘Daily Values’ Encourage Healthy Diet,” U.S. Food and Drug Administration, 2003.
3 Food and Nutrition Board, “Dietary Reference Intakes for Energy, Carbohydrates, Fiber, Fat, Protein and Amino Acids (Macronutrients),” National Academy of Sciences (2002): 10-1.
4 U.S. National Library and the National Institutes of Health, “Kwashiorkor,” MEDLINEplus Medical Encyclopedia, 11 Jul. 2002.
5 Gary C. Curhan et al., “A Prospective Study of Dietary Calcium and Other Nutrients and the Risk of Symptomatic Kidney Stones,” The New England Journal of Medicine 328 (1993): 833-8.
6 Kathleen M. Stadler, “The Diet and Cancer Connection,” Virginia Tech, Nov. 1997.
7 Gertjan Schaafsma, “The Protein Digestiblity-Corrected Amino Acid Score,” Journal of Nutrition 130 (2000):1865S-1867S.
8 USDA National Nutrient Database for Standard Reference, “Leavening Agents, Yeast, Baker’s, Active Dry,” 16 Jul. 2003.
9 Diet for a New America, John Robbins, 1987, p. 172, citing the American Journal of Clinical Nutrition
10 Protein and Amino Acid Requirements in Human Nutrition (PDF), World Health Organization (2002), p. 126. Recommendations are an "average requirement" of 0.66 g of protein per kg of ideal body weight, and a "safe level" of 0.86 g/kg. Percentages of protein vs. total calories were calculated by applying these figures for Estimated Energy Requirements as per the Dietary Reference Intakes, for a 5'5" woman and a 5'11" man, each 30 years old and 24.99 BMI, at various activity levels.
11 Dietary Reference Intakes, Food and Drug Administration. (The recommendations for protein are 56g/day for adult males and 46 g/day for adult females. The suggested caloric intake is 2301-3720 for a 5'11" man and 1816-2807 for a 5'5" woman. At 4 calories of protein per gram, this works out to 8.0-12.3% protein for men and 6.6-10.1%)
12 USDA National Nutrient Database for Standard Reference (accessed August to December 2009)
FRUIT: Average of Apples, Pears, Grapes, Bananas, Plums, Oranges, Grapefruit, Watermelon, Strawberries, Peaches, Nectarines, Cantaloupe.
VEGETABLES: Average of Broccoli 27.2%, Carrots 8.7%, Celery 17.3%, Corn 13.4%, Cucumber 17.3%, Green Beans 21.6%, Lettuce iceberg 25.7%, Mushrooms white 31%, Onions 12.4%, Peas 28.8%, Potato 10.8%, Spinach 49.7%, Tomato 19.6% (accessed December 2009)
Partial information reprinted with permission from People for the Ethical Treatment of Animals.
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