Plant Sources of Protein Building Blocks (Amino Acids)

Protein is one of three macro-nutrients along with carbohydrate and fat. Proteins are biological molecules that consists of amino acids.

Proteins are required for the structure, function, and regulation of the body’s cells, tissues, and organs. Each protein has unique functions. Proteins are essential components of muscles, skin, bones and the body as a whole. Examples of proteins include whole classes of important molecules, among them enzymes, hormones, and antibodies.

Amino acids are the building blocks of polypeptides. Peptides link together to form proteins. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen, though other elements are found in the side-chains of certain amino acids. About 500 amino acids are known and can be classified in many ways.

Only about one calorie out of every 10 we take in needs to come from protein. Vegan athletes, especially in the early stages of training, may have higher protein needs than vegans who exercise moderately or who are not active. Protein supplements are not needed to achieve even the highest level of protein intake. 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. (source)

Of the 22 (some say 20) standard amino acids, 9 are called essential amino acids because the human body cannot synthesize them from other compounds at the level needed for normal growth, so they must be obtained from food.

Here are the nine essential amino acids and where you can safely & smartly obtain them from plant foods:

1. Histidine – required by infants and growing children; apples, pomogranates, alfalfa, beets, carrots, celery, cucumber, dandelion, endive, garlic, radish, spinach, turnip greens (source)

2. Isoleucine – responsible for muscle structure; soy protein, watercress, chard, spinach, sunflower seed flour, kidney beans, avocados, papayas, olives, coconut

3. Leucine – responsible for muscle structure; soy protein, watercress, raw alfalfa seeds, kidney beans, tofu, sesame flour, sunflower seed flour, avocados, papayas, olives, coconut

4. Lysine – plays an important role in absorbing and conserving calcium and in the formation of collagen; soy protein, watercress, tofu, apples, apricots, grapes, papayas, pears, alfalfa, beets, carrots, celery, cucumber, dandelion greens, parsley, spinach, turnip greens

The RDA for lysine is more important than for protein. If you meet lysine requirements on a vegan diet, you will most likely meet protein requirements. Per serving, legumes and seitan are the foods highest in the amino acid lysine. Tofu, tempeh, soy meats, lentils, and seitan are the highest, followed by other legume foods. Quinoa, amaranth, pistachios, and pumpkin seeds are also decent sources of lysine. (source)

5. Methionine (+ Cysteine) – spinach, potatoes, sesame flour, spirulina, soy protein, sesame seeds, Brazil nuts, cereal grains (whole grain corn, rice, wheat, barley, sorghum, millet, oats, rye, triticale, buckwheat, fonio, pseudo-cereal quinoa, teff, amaranth), apples, pineapples, filberts, Brussels sprouts, cabbage, cauliflower, chives, dock (sorrel), garlic, horseradish, kale, watercress

Methionine assists in breaking down fats and thus prevents build-up of fat in the arteries and liver. Since it is converted to cysteine, it also assists with the removal of heavy metals (including lead) from the body. It’s also a powerful antioxidant, removing free radicals produced in the natural metabolic processes of the body. (source)

6. Phenylalanine (+ Tyrosine) – necessary for the production of the neurotransmitters serotonin and melatonin; soy protein, cottonseed flour, sesame flour, kidney beans, spinach, apples, pineapples, beets, carrots, parsley, tomatoes, nutritional yeast

7. Threonine – watercress, soy protein, spinach, sesame seed flour, sunflower seed flour, kidney beans

8. Tryptophan – necessary for the production of the neurotransmitters serotonin and melatonin; soy protein, spinach, sesame flour, sunflower seed flour, watercress, trunip greens, broccoli rabe, asparagus, kidney beans, oat bran, alfalfa, Brussels sprouts, carrots, celery, chives, dandelion greens, endive, fennel, snap beans, nutritional yeast

9. Valine – responsible for muscle structure; soy protein, watercress, white mushrooms, sunflower seed flour, sesame seed flour, snow/snap peas, kidney beans, apples, almonds, pomegranates, beets, carrots, celery, dandelion greens, lettuce, okra, parsley, parsnips, squash, tomatoes, turnips, nutritional yeast

The truth is that all plant proteins have some of every essential amino acid. As a general rule, legumes are lower in the amino acid methionine while most other plants foods are lower in lysine. Legumes include soybeans (edamame) and their products (tempeh, tofu, soy milk, soy meats, etc.), beans (garbanzo, kidney, pinto, black, etc.) and their products (falafel, hummus, refried, etc.), peas (green, split, black-eyed, etc.), lentils, and peanuts. (source)

Champion Vegan Foods that Contain All Essential Amino Acids (source)

Pumpkin Seeds
Pistachios
Cashews
Hemp seeds
Blackeyed peas
Potatoes
Asparagus
Buckwheat
Soybeans/Edamame – tofu – soy milk (2-3 servings per day max)
Lentils
Pinto beans
Quinoa

It is impossible to design an amino acid–deficient diet based on the amounts of unprocessed starches and vegetables sufficient to meet the calorie needs of humans. Furthermore, mixing foods to make a complementary amino acid composition is unnecessary. (source)

In the chart above, the plant-based foods are made up of equal parts of tomatoes, spinach, lima beans, peas, and potatoes, and the animal-based foods are made up of equal parts of beef, pork, chicken, and whole milk. Plants have all of the nutrients found in animals, but packaged better…together with thousands of disease-fighting phytochemicals and fiber. Plants are also beneficial because of what they do NOT have in them, when compared to animals…components such as heme iron, IGF-1, Neu5Gc, saturated fat, dietary cholesterol, industrial pollutants, and carcinogens. (source)

Cows, pigs, chickens, sheep, and goats eat plant foods, hence why their bodies digest, manufacture, and store a total panel of amino acids so that complete proteins are available in their flesh & fluids. However, we don’t need to eat someone who ate a decent natural or formulated (livestock feed) diet in order to get our necessary nutrition. We can eat plants, as the animals did, and source our nutrition directly without taking the life of someone who wants to live. Plant foods are safer for your health, better for the environment, and undoubtedly kinder to the animals.

Additional Resources

• Free copy of The Protein Report

• Tofu or Not Tofu, That is the Debate

• Nutrition Only in Animal-Based Foods