(Where do you get your) Protein (?)
It was once believed that vegetarians (and vegans) needed to combine protein sources at each meal to get "complete protein." Now we know that protein combining at each meal is not necessary. In their Position Paper on Vegetarian Diets, The American Dietetic Association states:
- "Plant protein can meet requirements when a variety of plant
foods is consumed and energy needs are met. Research indicates that an assortment of plant
foods eaten over the course of a day can provide all essential amino acids and ensure adequate nitrogen
retention and use in healthy adults, thus complementary proteins do not need to be consumed at the same
meal."
When I became vegan in 1988, the most common question I got was, "Where do you get your protein?" It's now been about 20 years since protein in vegan diets was determined to be a non-issue by nutrition researchers. Yet today, one of the most common questions I get is, "Where do you get your protein?"
The more things change, the more they stay the same.
Experts recommend that adult vegans eat .4 g of protein per day for every pound of healthy body weight.1 Recommendations for younger vegans are:2
| Protein Recommendations for Young Vegans | ||
| Age (yrs) |
Females (grams/day) |
Males (grams/day) |
| 1 - 2 | 18-19 | 18-19 |
| 2 - 3 | 18-21 | 18-21 |
| 4 - 6 | 26-28 | 26-28 |
| 7 - 10 | 31-34 | 31-34 |
| 11 - 14 | 51-55 | 50-54 |
| 15 - 18 | 50-55 | 66-73 |
The plant foods highest in protein are legumes (beans, peanuts, soyfoods such as tofu) and nuts, but grains and vegetables also contribute significant amounts.
| Protein Content of Common Vegan Foods | ||
| Serving | Protein (g) | |
| Naturade soy protein powder | 1/3 Cup | 23 g |
| Naturade soy-free protein powder | 1/3 Cup | 22 g |
| Seitan | 3 oz | 22.5 |
| Tofu | 1/2 Cup | 10 - 20 |
| Veggie dog/burger | 1 | 6 - 18 |
| Tempeh* | 3 oz | 15.5 |
| Soybeans* | 1/2 Cup | 14.3 |
| Texturized soy protein | 1/2 Cup | 11 |
| Soymilk | 1 Cup | 5 - 10 |
| Lentils* | 1/2 Cup | 8.9 |
| Peanut butter | 2 Tablespoons | 8 |
| Chickpeas* | 1/2 Cup | 7.5 |
| Refried beans* | 1/2 Cup | 6.9 |
| Sunflower seeds | 1/4 Cup | 6.2 |
| Oatmeal* | 1 Cup, instant | 5.9 |
| Brown rice* | 1 Cup | 5 |
| Broccoli* | 1 Cup chopped | 4.6 |
| Potato, baked | 1 medium | 4.5 |
| Walnuts | 1/2 oz (7 halves) | 4.3 |
| White rice* | 1 Cup | 4.1 |
| Almonds | 1/2 oz (12 kernels) | 3 |
| Kale* | 1 Cup chopped | 2.5 |
| Taco shell | 1 medium | 1 |
| Carrot | 1 med | 0.6 |
| *Cooked | ||
Click here to check the USDA National Nutrient Database for the content of protein or other nutrients in foods.
Vegans Might not Meet Protein Needs If...
Vegans might not meet their protein needs, resulting in a loss of muscle mass and/or reduced immunity, if:
- Food intake does not meet energy needs such as in cases of anorexia nervosa, depression, poverty, lack of appetite due to illness,3 or dieting.
- Higher-protein plant foods are not included in sufficient amounts. This can happen when:
- Most foods eaten are low-protein, junk food such as French fries, potato chips, and soda.
- Protein is believed to be unimportant and/or higher protein foods are avoided (such as in some fruitarian or raw food diets).
- Legumes are avoided.3 (Other high-protein foods should be used.)
High Quality Protein
Proteins are made out of chains of amino acids. Some amino acids can be made by the body (generally from other amino acids), but some cannot. The ones that cannot are known as "essential" or "indispensable."
Twenty amino acids are used to build protein, but they are not the only amino acids. Carnitine and taurine are amino acids that our bodies make and use, but which are not building blocks of protien. The discussion below is limited to the amino acids needed to build proteins.
Because some amino acids are essential, the RDA for amino acids should be as important as the RDA for protein. But because the RDA for protein takes into account the RDA for amino acids, the RDA for amino acids is rarely mentioned. As it turns out, essential amino acids are found in fairly consistent amounts in various foods and, thus, the RDA for protein is calculated with typical diets in mind.
Proteins in the human body tend to have a consistent percentage of the essential amino acids. The percentages of essential amino acids in both animal products and soy products closely mimic those found in human proteins. Non-soy plant proteins have a lower percentage of at least one amino acid (in particular, beans are lower in methionine and grains are lower in lysine).
When Frances Moore Lappe wrote her book, Diet for a Small Planet, in the early 1970s, she popularized the idea of combining proteins at each meal. By mixing beans and grains, you can make sure that you are getting both methionine and lysine at each meal. We now know that the liver can store the various essential amino acids and so it's not critical to combine different protein sources at each meal.
Some people are under the impression that some plant proteins are devoid of at least one essential amino acid. The truth is that all plant proteins (that I have looked up) have some of every essential amino acid. (See the tables below.)
There have not been many studies measuring the protein or amino acid status of vegans. Because vegans tend to have good health and vegan diets normally meet the essential amino acid RDA, it is assumed that amino acid and protein intake is a non-issue for those on a typical vegan diet. But, since I often get questions about protein and amino acids, and so that vegans can be more knowledgeable about them, I have put together the tables below to show:
- The RDAs for protein and amino acids for a person whose ideal body weight is 140 lbs.
- How much protein and essential amino acids are in typical vegan foods.
- How much of those foods a 140 lbs person would need to consume to meet the RDA if they were relying only on that food.
Please Note: The RDA for protein is supposed to cover the needs of 97% of the population. Most people will not need to meet the RDA to meet their protein needs. Because the amino acids in plant foods are harder to extract (less digestible), vegans are generally assumed to need about 10% more protein than non-vegetarians. For that reason, I have inflated the amino acid RDA for vegans by 10%. Similarly, I have used .9 g/kg of body weight in calculating the vegan RDA for protein, rather than the usual .8 g/kg for non-vegans. Also note that the Food and Nutrition Board, who sets the RDAs, says, "In conclusion, available evidence does not support recommending a separate requirement for vegetarians who consume complementary mixtures of plant proteins[.]" However, because there is still a debate about this for vegans, I have inflated the numbers as described above just to be safe.
In the tables below, the essential amino acid methionine is paired with the non-essential cysteine. Similarly, the essential amino acid phenylalanine is paired with the non-essential tyrosine. That is because the RDA is calculated for these pairs of amino acids together, assuming there are similar ratios in different foods. In the plant foods I surveyed, there are about equal amounts of methionine and cysteine, and usually more phenylalanine than tyrosine. So, there is no reason to be concerned that plant foods are not providing a high ratio of methionine and phenylalanine.
In the downloadable Excel spreadsheet below, you can enter various body weights and it will calculate the RDAs for that body weight. You can then enter amounts of selected foods to see how many of any individual food or combination of foods you need to meet the RDA. (You will need to have Microsoft Excel installed on your computer to view this file; we hope eventually to have the spreadsheet on a web page so everyone can use it.)
Again, this is mainly just for people's knowledge. There is no reason to get worried if you find that your particular diet doesn't surpass the RDA.
Protein and Amino Acid RDA
| RDA | Approximate RDA for a 140 lb Person Adjusted for Vegan Diet | |
| mg/kg ideal body weight | mg | |
| protein (g) | 57.3 | |
| histidine (mg) | 14 | 980 |
| isoleucine (mg) | 19 | 1330 |
| leucine (mg) | 42 | 2940 |
| lysine (mg) | 38 | 2660 |
| methionine + cysteine (mg) | 19 | 1330 |
| phenylalanine + tyrosine (mg) | 33 | 2310 |
| threonine (mg) | 20 | 1400 |
| tryptophan (mg) | 5 | 350 |
| valine (mg) | 24 | 1680 |
Protein Powders / Soy Products
| Naturade (Soy) Veg Protein Booster | Naturade (Soy-Free) Veg Protein Booster | Tofu | Soy Milk | |||||
| Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | |||||
| 1/3 C 28 g | 1/3 Cups | 1/3 C 28 g | 1/3 Cups | 1/2 C 126 g | Cups | 1 Cup 245 g | Cups | |
| protein (g) | 24 | 2.4 | 22 | 2.6 | 20 | 1.4 | 9.2 | 6.2 |
| histidine (mg) | 618 | 1.6 | 533 | 1.8 | 578 | 0.8 | 174 | 5.6 |
| isoleucine (mg) | 1178 | 1.1 | 1182 | 1.1 | 985 | 0.7 | 353 | 3.8 |
| leucine (mg) | 1939 | 1.5 | 1785 | 1.6 | 1511 | 1.0 | 590 | 5.0 |
| lysine (mg) | 1552 | 1.7 | 1455 | 1.8 | 1309 | 1.0 | 439 | 6.1 |
| methionine + cysteine (mg) | 640 | 2.1 | 445 | 3.0 | 530 | 1.3 | 213 | 6.2 |
| phenylalanine + tyrosine (mg) | 2184 | 1.1 | 1957 | 1.2 | 1633 | 0.7 | 644 | 3.6 |
| threonine (mg) | 912 | 1.5 | 918 | 1.5 | 811 | 0.9 | 277 | 5.1 |
| tryptophan (mg) | 305 | 1.1 | 228 | 1.5 | 310 | 0.6 | 105 | 3.3 |
| valine (mg) | 1157 | 1.5 | 1115 | 1.5 | 1003 | 0.8 | 345 | 4.9 |
| *For a 140 lbs person. | ||||||||
Legumes
| Pinto Beans - refried | Garbanzo Beans (Chick Peas) | Lentils | Black Beans | Kidney Beans | ||||||
| Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | ||||||
| 1 C 252 g | Cups | 1 C 164 g | Cups | 1 C 198 g | Cups | 1 Cup 172 g | Cups | 1/2 C 89 g | Cups | |
| protein (g) | 13.8 | 4.2 | 14.5 | 3.9 | 17.9 | 3.2 | 15.2 | 3.8 | 7.7 | 3.7 |
| histidine (mg) | 386 | 2.5 | 400 | 2.5 | 503 | 1.9 | 425 | 2.3 | 214 | 2.3 |
| isoleucine (mg) | 610 | 2.2 | 623 | 2.1 | 772 | 1.7 | 673 | 2.0 | 339 | 2.0 |
| leucine (mg) | 1104 | 2.7 | 1035 | 2.8 | 1295 | 2.3 | 1218 | 2.4 | 614 | 2.4 |
| lysine (mg) | 950 | 2.8 | 973 | 2.7 | 1247 | 2.1 | 1046 | 2.5 | 527 | 2.5 |
| methionine + cysteine (mg) | 360 | 3.7 | 385 | 3.5 | 386 | 3.4 | 394 | 3.4 | 198 | 3.4 |
| phenylalanine + tyrosine (mg) | 1139 | 2.0 | 1140 | 2.0 | 1358 | 1.7 | 1254 | 1.8 | 631 | 1.8 |
| threonine (mg) | 582 | 2.4 | 540 | 2.6 | 640 | 2.2 | 642 | 2.2 | 323 | 2.2 |
| tryptophan (mg) | 164 | 2.1 | 139 | 2.5 | 160 | 2.2 | 181 | 1.9 | 91 | 1.9 |
| valine (mg) | 723 | 2.3 | 610 | 2.8 | 887 | 1.9 | 798 | 2.1 | 402 | 2.1 |
| *For a 140 lbs person. | ||||||||||
Nuts - Part 1
| Peanut Butter | Peanuts | Almonds | ||||||
| Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | ||||
| 2 T 32 g | tablespoons | 1 oz 28 kernals 28 g | oz | kernals | 1 oz 22 kernals 28 g | oz | kernals | |
| protein (g) | 8 | 14.3 | 6.7 | 8.5 | 239.3 | 6.2 | 9.2 | 136.4 |
| histidine (mg) | 204 | 9.6 | 170 | 5.8 | 161.4 | 174 | 5.6 | 3828.0 |
| isoleucine (mg) | 284 | 9.4 | 236 | 5.6 | 157.8 | 204 | 6.5 | 4488.0 |
| leucine (mg) | 523 | 11.2 | 435 | 6.8 | 189.2 | 433 | 6.8 | 9526.0 |
| lysine (mg) | 290 | 18.3 | 241 | 11.0 | 309.0 | 177 | 15.0 | 3894.0 |
| methionine + cysteine (mg) | 202 | 13.2 | 168 | 7.9 | 221.7 | 139 | 9.6 | 3058.0 |
| phenylalanine + tyrosine (mg) | 746 | 6.2 | 621 | 3.7 | 104.2 | 494 | 4.7 | 10868.0 |
| threonine (mg) | 276 | 10.1 | 230 | 6.1 | 170.4 | 200 | 7.0 | 4400.0 |
| tryptophan (mg) | 78 | 9.0 | 65 | 5.4 | 150.8 | 56 | 6.3 | 1232.0 |
| valine (mg) | 339 | 9.9 | 282 | 6.0 | 166.8 | 236 | 7.1 | 5192.0 |
| *For a 140 lbs person. | ||||||||
Nuts - Part 2
| Walnuts | Pistachios | Cashews | ||||||
| Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | ||||
| 1 oz 14 halves 28 g | oz | halves | 1 oz 49 kernals 28 g | oz | kernals | 1 oz 28 g | oz | |
| protein (g) | 4.3 | 13.3 | 186.5 | 6.1 | 9.4 | 460.1 | 4.3 | 13.3 |
| histidine (mg) | 111 | 8.8 | 123.6 | 149 | 6.6 | 322.3 | 113 | 8.7 |
| isoleucine (mg) | 177 | 7.5 | 105.2 | 265 | 5.0 | 245.9 | 207 | 6.4 |
| leucine (mg) | 332 | 8.9 | 124.0 | 458 | 6.4 | 314.5 | 364 | 8.1 |
| lysine (mg) | 120 | 22.2 | 310.3 | 339 | 7.8 | 384.5 | 232 | 11.5 |
| methionine + cysteine (mg) | 126 | 10.6 | 147.8 | 205 | 6.5 | 317.9 | 158 | 8.4 |
| phenylalanine + tyrosine (mg) | 317 | 7.3 | 102.0 | 435 | 5.3 | 260.2 | 363 | 6.4 |
| threonine (mg) | 169 | 8.3 | 116.0 | 198 | 7.1 | 346.5 | 168 | 8.3 |
| tryptophan (mg) | 48 | 7.3 | 102.1 | 81 | 4.3 | 211.7 | 67 | 5.2 |
| valine (mg) | 213 | 7.9 | 110.4 | 365 | 4.6 | 225.5 | 295 | 5.7 |
| *For a 140 lbs person. | ||||||||
Grains - Part 1
| Spaghetti - white | Spaghetti - whole wheat | Rice - brown, medium grain | Rice - white, medium grain | |||||
| Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | |||||
| 1 cup 140 g | Cups | 1 cup 140 g | Cups | 1 C 195 g | Cups | 1 C 186 g | Cups | |
| protein (g) | 6.7 | 8.5 | 7.5 | 7.6 | 4.5 | 12.7 | 4.4 | 13.0 |
| histidine (mg) | 136 | 7.2 | 175 | 5.6 | 115 | 8.5 | 104 | 9.4 |
| isoleucine (mg) | 258 | 5.2 | 290 | 4.6 | 191 | 7.0 | 192 | 6.9 |
| leucine (mg) | 456 | 6.4 | 510 | 5.8 | 372 | 7.9 | 366 | 8.0 |
| lysine (mg) | 127 | 20.9 | 165 | 16.1 | 172 | 15.5 | 160 | 16.6 |
| methionine + cysteine (mg) | 292 | 4.6 | 275 | 4.8 | 156 | 8.5 | 195 | 6.8 |
| phenylalanine + tyrosine (mg) | 498 | 4.6 | 566 | 4.1 | 402 | 5.7 | 385 | 6.0 |
| threonine (mg) | 176 | 8.0 | 200 | 7.0 | 166 | 8.4 | 158 | 8.9 |
| tryptophan (mg) | 85 | 4.1 | 97 | 3.6 | 58 | 6.0 | 52 | 6.7 |
| valine (mg) | 284 | 5.9 | 323 | 5.2 | 265 | 6.3 | 270 | 6.2 |
| *For a 140 lbs person. | ||||||||
Grains - Part 2
| Bread - whole wheat | Bread - white | Corn | Oatmeal - instant, dry | Flour Tortilla | ||||||
| Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | ||||||
| 1 slice 28 g | slices | 1 slice 25 g | slices | 1/2 C 82 g | Cups | 1 cup 81 g | Cups | 1 med 46 g | medium | |
| protein (g) | 2.7 | 21.2 | 2.1 | 27.3 | 2.7 | 10.6 | 13 | 4.4 | 4 | 14.3 |
| histidine (mg) | 63 | 15.6 | 45 | 21.8 | 75 | 6.5 | 310 | 3.2 | 90 | 10.9 |
| isoleucine (mg) | 105 | 12.7 | 81 | 16.4 | 109 | 6.1 | 532 | 2.5 | 141 | 9.4 |
| leucine (mg) | 188 | 15.6 | 145 | 20.3 | 294 | 5.0 | 985 | 3.0 | 276 | 10.7 |
| lysine (mg) | 85 | 31.3 | 56 | 47.5 | 116 | 11.5 | 538 | 4.9 | 98 | 27.1 |
| methionine + cysteine (mg) | 103 | 12.9 | 79 | 16.8 | 79 | 8.4 | 552 | 2.4 | 154 | 8.6 |
| phenylalanine + tyrosine (mg) | 211 | 10.9 | 160 | 14.4 | 230 | 5.0 | 1126 | 2.1 | 322 | 7.2 |
| threonine (mg) | 83 | 16.9 | 61 | 23.0 | 109 | 6.4 | 441 | 3.2 | 113 | 12.4 |
| tryptophan (mg) | 39 | 9.0 | 24 | 14.6 | 19 | 9.2 | 180 | 1.9 | 49 | 7.1 |
| valine (mg) | 124 | 13.5 | 90 | 18.7 | 157 | 5.4 | 719 | 2.3 | 164 | 10.2 |
| *For a 140 lbs person. | ||||||||||
Fruit
| Apple | Banana | Orange | Strawberries | |||||
| Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | |||||
| 1 med 138 g | medium | 1 med 118 g | medium | 1 med 131 g | medium | 1 C whole 144 g | Cups | |
| protein (g) | 0.36 | 159.1 | 1.3 | 44.1 | 1.2 | 47.7 | 0.97 | 59.0 |
| histidine (mg) | 7 | 140.0 | 91 | 10.8 | 24 | 40.8 | 17 | 57.6 |
| isoleucine (mg) | 8 | 166.3 | 33 | 40.3 | 33 | 40.3 | 23 | 57.8 |
| leucine (mg) | 18 | 163.3 | 80 | 36.8 | 30 | 98.0 | 49 | 60.0 |
| lysine (mg) | 17 | 156.5 | 59 | 45.1 | 62 | 42.9 | 37 | 71.9 |
| methionine + cysteine (mg) | 2 | 665.0 | 20 | 66.5 | 39 | 34.1 | 12 | 110.8 |
| phenylalanine + tyrosine (mg) | 9 | 256.7 | 69 | 33.5 | 62 | 37.3 | 59 | 39.2 |
| threonine (mg) | 8 | 175.0 | 33 | 42.4 | 20 | 70.0 | 29 | 48.3 |
| tryptophan (mg) | 1 | 350.0 | 11 | 31.8 | 12 | 29.2 | 12 | 29.2 |
| valine (mg) | 17 | 98.8 | 55 | 30.5 | 52 | 32.3 | 27 | 62.2 |
| *For a 140 lbs person. | ||||||||
Vegetables
| Broccoli - chopped | Romaine Lettuce - shredded | Baked Potato - w/skin | ||||
| Amount to meet RDA* | Amount to meet RDA* | Amount to meet RDA* | ||||
| 1/2 C 78 g | Cups | 1/2 C 28 g | Cups | 1 med 173 g | medium | |
| protein (g) | 1.8 | 15.9 | 0.34 | 84.2 | 4.3 | 13.3 |
| histidine (mg) | 41 | 12.0 | 8 | 61.3 | 93 | 10.5 |
| isoleucine (mg) | 90 | 7.4 | 29 | 22.9 | 175 | 7.6 |
| leucine (mg) | 108 | 13.6 | 27 | 54.4 | 260 | 11.3 |
| lysine (mg) | 117 | 11.4 | 29 | 45.9 | 263 | 10.1 |
| methionine + cysteine (mg) | 44 | 15.1 | 11 | 60.5 | 121 | 11.0 |
| phenylalanine + tyrosine (mg) | 122 | 9.5 | 30 | 38.5 | 351 | 6.6 |
| threonine (mg) | 76 | 9.2 | 21 | 33.3 | 157 | 8.9 |
| tryptophan (mg) | 24 | 7.3 | 3 | 58.3 | 67 | 5.2 |
| valine (mg) | 106 | 7.9 | 24 | 35.0 | 244 | 6.9 |
| *For a 140 lbs person. | ||||||
Sources:
- Amino acid RDAs were taken from Dietary Reference Intakes for Energy, Carbohydrate,
Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients)
(2002) by the Food and Nutrition Board (FNB) of the Institute of Medicine.
Link
- The protein and amino acid content of foods was taken from the
USDA and
Naturade protein powder labels.
Footnotes
1. Messina M, Messina V. The Dietitian's Guide to Vegetarian Diets. Gaithersburg, MD: Aspen Publishers, Inc., 1996.
2. Messina V, Mangels AR. Considerations in planning vegan diets: children. J Am Diet Assoc. 2001 Jun;101(6):661-9