Can the vegan diet provide adequate protein for sound human health? Absolutely. Unlike animal protein, plant-based protein sources contain healthy fiber and complex carbohydrates. Animal products are often high in artery-clogging cholesterol and saturated fat, and the consumption of animal protein has been linked to some types of cancer. There’s no need to eat animal products to maintain good health, as a quick study of the facts about plant protein and nutrition shows.
The Importance of Protein
Our bodies-our hair, muscles, fingernails, and so on-are made up mostly of different kinds of protein that consist of varying combinations of amino acids. In much the same way that the 26 letters of the English alphabet can form millions of different words, 20 amino acids serve to form different proteins.
Although half these amino acids can be manufactured by the human body, the other 10 cannot.(1) These “essential amino acids” are easily obtained by eating a balanced vegan diet.
How Much Protein?
As babies, our mothers’ milk provided the protein that we needed to grow healthy and strong. Cow’s milk has about three times the amount of protein found in human breast milk. Once babies start eating solid foods, plant sources can easily provide them with all the protein that they need. Only 10 percent of the total calories consumed by the average human being need to be in the form of protein.(2) The recommended dietary allowance for both men and women is 0.80 grams of protein for every kilogram (2.2 pounds) of body weight.(3) People with special needs, such as pregnant women, are advised to get a little more. If a vegan eats a reasonably varied diet and consumes a sufficient amount of calories, he or she will undoubtedly get enough protein.
By contrast, eating too much animal protein has been directly linked to the formation of kidney stones and has been associated with cancers of the colon and liver.(4,5) By replacing animal protein with plant protein, you can improve your health while enjoying a wide variety of delicious foods.
Protein Sources
While virtually all vegetarian foods contain some protein, soybeans deserve special mention. Soybeans contain all the essential amino acids and surpass all other plant foods in the amount of protein that they can deliver to humans. The human body is able to digest 92 percent of the protein found in meat and 91 percent of the protein found in soybeans.(6) The availability of many different and delicious soy products (e.g., tempeh, tofu, and soy-based varieties of hot dogs, burgers, and ice cream) in grocery and health-food stores suggests that the soybean, in its many forms, can accommodate a wide range of tastes.
Other rich sources of non-animal protein include legumes, nuts, seeds, food yeasts, and freshwater algae. Although food yeasts, such as nutritional yeast and brewer’s yeast, do not lend themselves to being the center of one’s diet, they are extremely nutritious additions to many types of dishes, including soups, gravies, breads, casseroles, and dips. Most yeasts are 50 percent protein.(7)
Percentage of Calories From Protein (Value per 100 Grams Edible Portion)
From the U.S. Department of Agriculture’s National Nutrient Database for Standard Reference, 2005(8)
Fruits
Apple 2%
Banana 5%
Cantaloupe 10%
Grapefruit 8%
Grapes 4%
Honeydew melon 6%
Orange 8%
Papaya 6%
Peach 9%
Pear 3%
Pineapple 4%
Strawberry 8%
Tangerine 6%
Tomato 19%
Watermelon 8%
Grains
Barley 14%
Brown rice 8%
Buckwheat 15%
Millet 12%
Oatmeal 17%
Rye 18%
Wheat germ 26%
Wheat (hard red) 15%
Wild rice 16%
Legumes, Raw
Garbanzo beans 21%
Kidney beans 58%
Lentils 34%
Lima beans 24%
Navy beans 37%
Soybeans 35%
Split peas 29%
Nuts and Seeds
Almonds 15%
Cashews 13%
Filberts 9%
Peanuts 18%
Pumpkin seeds 18%
Sesame seeds 12%
Sunflower seeds 16%
Walnuts (black) 15%
Vegetables, Raw
Artichokes 28%
Beets 15%
Broccoli 33%
Brussels sprouts 31%
Cabbage 24%
Cauliflower 32%
Cucumbers 17%
Eggplant 17%
Green peas 27%
Green pepper 17%
Kale 26%
Lettuce 36%
Mushrooms 56%
Mustard greens 41%
Onions 9%
Potatoes 18%
Spinach 50%
Turnip greens 20%
Watercress 84%
Yams 5%
Zucchini 30%
References
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) National Academy of Sciences, Food and Nutrition Board, “Dietary Reference Intakes for Energy, Carbohydrates, Fiber, Fat, Protein, and Amino Acids (Macronutrients),” 2005: 589.
4) Gary C. Curhan et al., “A Prospective Study of Dietary Calcium and Other Nutrients and the Risk of Symptomatic Kidney Stones,” New England Journal of Medicine 238 (1993): 833-8.
5) Kathleen M. Stadler, “The Diet and Cancer Connection ,” Virginia Tech, Nov. 1997.
6) Gertjan Schaafsma, “The Protein Digestibility-Corrected Amino Acid Score ,” Journal of Nutrition 130 (2000): 1865S-1867S.
7) U.S. Department of Agriculture, National Nutrient Database for Standard Reference, “Leavening Agents, Yeast, Baker’s, Active Dry,” Aug. 2005.
8) U.S. Department of Agriculture, Agricultural Research Service, “Nutrient Data Laboratory,” Aug. 2005.
Vegetables Deliver Protein with Micronutrients
From Dr. Fuhrman's book Disease Proof Your Child:
When you eat to maximize micronutrients, your body function will improve; chronic illnesses like high blood pressure, Type II diabetes, and high cholesterol will likely disappear; and your youthful vigor will last into old age. Heart disease and cancer, the major killers of modern societies, would fade away and be exceedingly rare occurrences if the population adopted a cancer-preventive diet style and lifestyle. And we would hardly ever see any overweight children.
Maintaining a population of normal-weight individuals can be efficiently accomplished only by eating more high-nutrient foods, foods with higher nutrient-per-calorie ratio. The foods with the most nutrients per calorie are vegetables and beans. Vegetables are also very rich in protein and calcium. Most vegetables have more protein per calorie than meat and more calcium per calorie than milk. Nobody can consume too little protein by eating less animal products and substituting vegetables, beans, nuts, and seeds.
The focus on the importance of protein in the diet is one of the major reasons we have been led down the wrong path to dietary suicide. We were taught to equate protein with good nutrition and have though animal products, not vegetables, whole grains, beans, nuts, and seeds, are our best source of protein. We bought a false bill of goods, and the dairy-and-meat-heavy diet brought fourth a heart attack and cancer epidemic.
If we hear something over and over since we were young children, we just accept it as true. For example, it is myth repeated over and over that plant proteins are "incomplete" and need to be "complemented" for adequate protein. In fact, all vegetables and grains contain all eight of the essential amino acids (as well as the 12 other nonessential ones).1 While some vegetables have higher or lower proportions of certain amino acids than others, when eaten in amounts to satisfy one's caloric needs, a sufficient amount of all essential amino acids are provided. Because digestive secretions and sloughed-off mucosal cells are constantly recycled and reabsorbed, the amino acid composition in the bloodstream after meals is remarkably complete in spite of short-term irregularities in their dietary supply.
It is interesting to note that peas, green vegetables, and beans have more protein per calorie than meat. But what is not generally considered is that foods that are rich in plant protein are generally the foods that are richest in nutrients and phytochemicals. By eating more of these high-nutrient, low calorie foods we get plenty of protein, and our bodies get flooded with protective micronutrients simultaneously. Animal protein does not contain antioxidants and phtyochemicals, plant protein does. Plus, animal protein is married to saturated fat, the most dangerous type of fat.
| Food | Grams of Protein |
|---|---|
| Almonds (3 oz) | 10 |
| Banana | 1.2 |
| Broccoli (2 cups) | 10 |
| Brown Rice (1 cup) | 5 |
| Chickpeas (1 cup) | 15 |
| Corn (1 cup) | 4.2 |
| Lentils (1 cup) | 18 |
| Peas--frozen (1 cup) | 9 |
| Spinach--frozen (1 cup) | 7 |
| Tofu (4 ounces) | 11 |
| Whole wheat bread (2 slices) | 5 |
Even a professional body builder who wants to build one-half pound of extra muscle per week only needs about an extra seven grams per day over a normal protein intake. No Complicated formulas or protein supplements are needed to get sufficient protein for growth, even in the serious athlete. Exercise increases hunger, and as the athlete consumes more calories to meet the demands of exercise, they will naturally get the extra protein they need. Many world-class athletes thrive at world-class competitions on vegetarian and vegan diets.
When you reduce or eliminate animal protein intake and increase vegetable protein intake, you lower cholesterol radically. Vegetables, beans, and nuts and seeds are all rich in protein, and they also have no saturated fat or cholesterol. But the clincher is that they are higher in nutrients than any other foods. We must structure our diets around the foods that supply the most micronutrients.
The cholesterol-lowering effects of vegetables and beans (high protein foods) are without question. When adult subjects are feed a vegetable-based diet, cholesterol levels drop radically, much more than with the most powerful cholesterol-lowering drugs.2 These foods also contain an assortment of heart disease-fighting nutrients independent of their ability to lower cholesterol, and they fight cancer, too.
1. Young VR, Pellett PL. Plant proteins in relation to human protein and amino acid nutrition. Am J Clin Nutr 1994;59 (suppl 5): 1203S-1212S.
2. Jenkins DJ, Kendall CW, Popovich, et al. Effects of a very-high-fiber vegetable fruit and nut diet on serum lipids and colonic function. Metabolism 2001:50(4);494-503.
