Protein in the Vegan Diet

by Reed Mangels, Ph.D., R.D.

Topics in this article:

• Summary
• Table 1: Sample Menus Showing How Easy It Is To Meet Protein Needs
• Table 2: Protein Content of Selected Vegan Foods
• Table 3: Amounts of Foods Providing Recommended
  Amounts of Essential Amino Acids
• References

Some Americans are obsessed with protein. Vegans are bombarded with questions about where they get their protein. Athletes used to eat thick steaks before competition because they thought it would improve their performance. Protein supplements are sold at health food stores. This concern about protein is misplaced. Although protein is certainly an essential nutrient which plays many key roles in the way our bodies function, we do not need huge quantities of it. In reality, we need small amounts of protein. Only one calorie out of every ten we take in needs to come from protein ¹. Athletes do not need much more protein than the general public ². Protein supplements are expensive, unnecessary, and even harmful for some people.

How much protein do we need? The RDA recommends that we take in 0.8 grams of protein for every kilogram that we weigh (or about 0.36 grams of protein per pound that we weigh) ¹. This recommendation includes a generous safety factor for most people. When we make a few adjustments to account for some plant proteins being digested somewhat differently from animal proteins and for the amino acid mix in some plant proteins, we arrive at a level of 1 gram of protein per kilogram body weight (0.45 grams of protein per pound that we weigh). Since vegans eat a variety of plant protein sources, somewhere between 0.8 and 1 gram of protein per kilogram would be a protein recommendation for vegans. If we do a few calculations we see that the protein recommendation for vegans amounts to close to 10% of calories coming from protein. [For example, a 79 kg vegan male aged 25 to 50 years could have an estimated calorie requirement of 2900 calories per day. His protein needs might be as high as 79 kg x 1 gram/kg = 79 grams of protein. 79 grams of protein x 4 calories/gram of protein = 316 calories from protein per day. 316 calories from protein divided by 2900 calories = 10.1% of calories from protein.] If we look at what vegans are eating, we find that between 10-12% of calories come from protein ³. This contrasts with the protein intake of non-vegetarians, which is close to 14-18% of calories.

So, in the United States it appears that vegan diets are commonly lower in protein than standard American diets. Remember, though, with protein, more (than the RDA) is not necessarily better. There do not appear to be health advantages to consuming a high protein diet. Diets that are high in protein may even increase the risk of osteoporosis ⁴ and kidney disease ⁵.

Table 1: Sample Menus Showing How Easy It Is To Meet Protein Needs
		Protein (grams)
Breakfast:	1 cup Oatmeal	6
	1 cup Soymilk	7
	1 Bagel	9
Lunch:	2 slices Whole Wheat Bread	5
	1 cup Vegetarian Baked Beans	12
Dinner:	5 oz firm Tofu	11
	1 cup cooked Broccoli	4
	1 cup cooked Brown Rice	5
	2 Tbsp Almonds	4
Snack:	2 Tbsp Peanut Butter	8
	6 Crackers	2
TOTAL		73 grams
Protein Recommendation for Male Vegan [based on 0.8-1 gram of protein per kilogram body weight for 70 kilogram (154 pound) male]		56-70 grams
Breakfast:	2 slices Whole Wheat Toast	5
	2 Tbsp Peanut Butter	8
Lunch:	6 oz. Soy Yogurt	6
	2 Tbsp Almonds	4
	1 Baked Potato	4
Dinner:	1 cup cooked Lentils	18
	1 cup cooked Bulgur	6
Snack:	1 cup Soymilk	7
TOTAL		58 grams
Protein Recommendation for Female Vegan [based on 0.8-1 gram of protein per kilogram body weight for 57.5 kilogram (126 pound) female]		46-58 grams
Additional food should be added to these menus to provide adequate calories and to meet requirements for nutrients besides protein.

Table 2 shows the amount of protein in various vegan foods and also the number of grams of protein per 100 calories. To meet protein recommendations, the typical adult male vegan needs only 2.5 to 2.9 grams of protein per 100 calories and the typical adult female vegan needs only 2.1 to 2.4 grams of protein per 100 calories. These recommendations can be easily met from vegan sources.

Table 2: Protein Content of Selected Vegan Foods
FOOD	AMOUNT	PROTEIN(gm)	PROTEIN(gm/100 cal)
Tempeh	1 cup	41	9.3
Seitan	3 ounces	31	22.1
Soybeans, cooked	1 cup	29	9.6
Lentils, cooked	1 cup	18	7.8
Black beans, cooked	1 cup	15	6.7
Kidney beans, cooked	1 cup	13	6.4
Veggie burger	1 patty	13	13.0
Chickpeas, cooked	1 cup	12	4.2
Veggie baked beans	1 cup	12	5.0
Pinto beans, cooked	1 cup	12	5.7
Black-eyed peas, cooked	1 cup	11	6.2
Tofu, firm	4 ounces	11	11.7
Lima beans, cooked	1 cup	10	5.7
Quinoa, cooked	1 cup	9	3.5
Tofu, regular	4 ounces	9	10.6
Bagel	1 med. (3 oz)	9	3.9
Peas, cooked	1 cup	9	6.4
Textured Vegetable Protein (TVP), cooked	1/2 cup	8	8.4
Peanut butter	2 Tbsp	8	4.3
Veggie dog	1 link	8	13.3
Spaghetti, cooked	1 cup	8	3.7
Almonds	1/4 cup	8	3.7
Soy milk, commercial, plain	1 cup	7	7.0
Soy yogurt, plain	6 ounces	6	4.0
Bulgur, cooked	1 cup	6	3.7
Sunflower seeds	1/4 cup	6	3.3
Whole wheat bread	2 slices	5	3.9
Cashews	1/4 cup	5	2.7
Almond butter	2 Tbsp	5	2.4
Brown rice, cooked	1 cup	5	2.1
Spinach, cooked	1 cup	5	13.0
Broccoli, cooked	1 cup	4	6.8
Potato	1 med. (6 oz)	4	2.7
Sources: USDA Nutrient Database for Standard Reference, Release 18, 2005 and manufacturers' information. The recommendation for protein for adult males vegans is around 56-70 grams per day; for adult female vegans it is around 46-58 grams per day (see text).

It is very easy for a vegan diet to meet the recommendations for protein. Nearly all vegetables, beans, grains, nuts, and seeds contain some, and often much, protein. Fruits, sugars, fats, and alcohol do not provide much protein, so a diet based only on these foods would have a good chance of being too low in protein. However, not many vegans we know live on only bananas, hard candy, margarine, and beer. Vegans eating varied diets containing vegetables, beans, grains, nuts, and seeds rarely have any difficulty getting enough protein as long as their diet contains enough energy (calories) to maintain weight. [See the sections on Pregnancy, Lactation, and Infants and Children (pages 176-197 in Simply Vegan, 4th edition) for details about protein needs during these special times.]

What about combining or complementing protein? Doesn't that make the protein issue much more complex? Let's look at a little background on the myth of complementing proteins. Protein is made up of amino acids, often described as its building blocks. We actually have a biological requirement for amino acids, not for protein. Humans cannot make nine of the twenty common amino acids, so these amino acids are considered to be essential. In other words, we must get these amino acids from our diets. We need all nine of these amino acids for our body to make protein.

Some people say that eggs, cow's milk, meat, and fish are high quality protein. This means that they have large amounts of all the essential amino acids. Soybeans, quinoa (a grain), and spinach also are considered high quality protein. Other protein sources of non-animal origin usually have all of the essential amino acids, but the amounts of one or two of these amino acids may be low. For example, grains are lower in lysine (an essential amino acid) and legumes are lower in methionine (another essential amino acid) than those protein sources designated as high quality protein.

Frances Moore Lappe, in her book Diet for a Small Planet ⁶ advocated the combining of a food low in one amino acid with another food containing large amounts of that amino acid. This got to be a very complicated process, with each meal having specific amounts of certain foods in order to be certain of getting a favorable amino acid mix. Many people got discouraged with the complexity of this approach. Actually, Lappe was being overly conservative to avoid criticism from the "Nutrition Establishment." She has since repudiated strict protein combining, saying, "In combating the myth that meat is the only way to get high quality protein, I reinforced another myth. I gave the impression that in order to get enough protein without meat, considerable care was needed in choosing foods. Actually it is much easier than I thought" ⁷.

Table 3: Amounts of Foods Providing Recommended Amounts of Essential Amino Acids
12-1/3 cups of cooked corn OR 6-1/2 large potatoes OR 2-1/2 cups of tofu OR 15-1/2 cups of cooked brown rice Any one of the above foods, eaten in the amount specified, would provide the recommended ammounts of all essential amino acids for an adult male. Women would need about 20% less of each food due to lower recommendations. This concept is illustrated below:
Food	Try	Thr	Iso	Leu	Lys	Met+Cys	Phe+Tyr	Val
Adult RDA,154 lb male 1	350	1400	1330	2940	2660	1330	2310	1680
12-1/3 cups corn	443	2521	2521	6777	2660	1820	5326	3616
6-1/2 large potatoes	760	1768	1963	2940	2951	1365	3946	2743
2-1/2 cups tofu	780	2045	2480	3808	3298	1333	4112	2530
15-1/2 cups cooked rice	899	2573	2960	5766	2666	2418	6231	4108
Source: USDA Nutrient Database for Standard Reference, Release 18, 2005. Notes: Amounts of amino acids are in milligrams. Try=tryptophan, Thr=threonine, Iso=isoleucine, Leu=leucine, Lys=lysine, Met+Cys=methionine+cysteine, Phe+Tyr=phenylalanine+tyrosine, Val=valine

We recommend eating a variety of unrefined grains, legumes, seeds, nuts, and vegetables throughout the day, so that if one food is low in a particular essential amino acid, another food will make up this deficit ^8,9.

Even if you ate only one food and not the variety of foods typical of a vegan diet, you would probably get enough protein and essential amino acids. Remember, almost all protein sources of non-animal origin contain all of the essential amino acids. You would have to eat a lot of the protein source (if there was only one source of protein in your diet) to meet essential amino acid needs. Table 3 shows the amounts of various foods an adult male would have to eat if he relied on a single food source for his protein needs. Females would need about 20% less of each food due to the lower protein recommendation for women.

References

1. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: National Academy Press, 2002.

2. Nutrition and athletic performance - Position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine. J Am Diet Assoc 2000;100:1543-56.

3. Messina V, Mangels R, Messina M. The Dietitian's Guide to Vegetarian Diets, 2nd ed. Sudbury, MA: Jones and Bartlett Publishers, 2004.

4. Sellmeyer DE, Stone KL, Sebastian A, et al. A high ratio of dietary animal to vegetable protein increases the rate of bone loss and the risk of fracture in postmenopausal women. Am J Clin Nutr 2001;73:118-22.

5. Knight EL, Stampfer MJ, Hankinson SE, et al. The impact of protein intake on renal function decline in women with normal renal function or mild insufficiency. Ann Intern Med 2003;138:460-7.

6. Lappe FM. Diet for a Small Planet. New York: Ballantine Books, 1971.

7. Lappe FM. Diet for a Small Planet, 10th anniversary edition. New York: Ballantine Books, 1982.

8. Young VR, Pellett PL. Plant proteins in relation to human protein and amino acid nutrition. Am J Clin Nutr 1994;59 (suppl):1203S-1212S.

9. Mangels AR, Messina V, Melina V. Position of The American Dietetic Association and Dietitians of Canada: Vegetarian diets. J Am Diet Assoc 2003;103:748-65

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This article originally appeared in the book Simply Vegan: Quick Vegetarian Meals by Debra Wasserman. Nutrition section by Reed Mangels Ph.D., R.D. (ISBN 0-931411-30-0)