Amino acids are the building blocks of protein and responsible for a variety of functions in the body. All protein-rich foods (including protein powders) contain various levels of a variety of amino acids necessary for health.

There are eight amino acids that are generally considered essential. This means that the body cannot synthesize them and therefore must get them from food.

Some amino acids are “conditionally essential” meaning that certain people may need to acquire them from their diet. For example, infants cannot synthesize the amino acids cysteine, tyrosine, histidine and arginine but as they get older, they are able to synthesize these essential nutrients. Some people with certain medical conditions may require an increased dietary intake of certain amino acids that are otherwise not essential to healthy individuals.

The 8 Essential Amino Acids

Phenylalanine – Necessary for a healthy nervous system. Helps fight depression and suppress appetite. Food sources include raw soybeans, cacao, peanut and almond butter, almonds, peanuts, Lima beans, mung beans, lentils, winged beans, spinach, parsley, tomatoes, apples, beets, pineapples, carrots and nutritional yeast.

Valine – Necessary for muscle development. Food sources include dandelion greens, parsley, lettuce, celery, almonds, peanuts, sesame seeds, lentils, apples, pomegranates, beets, carrots, okra, parsnips, squash, tomatoes, turnips and nutritional yeast.

Threonine – Helps stabilize blood sugar levels. Food sources include leafy greens, kale, collards, lettuce, celery, Lima beans, sesame seeds, alfalfa sprouts, carrots, papayas, Nori and lentils.

Tryptophan – Necessary for the synthesis of serotonin. May help relieve migraine and depression. Food sources include spinach, dandelion greens, alfalfa, cacao, spirulina, raw soy beans, snap peas, Brussel sprouts, sesame seeds, banana, durian, carrots, celery, chives, mangoes, turnips, dates, sunflower seeds, pumpkin seeds, peanuts, potatoes, rice, chick peas and nutritional yeast.

Isoleucine – Necessary for the synthesis of hemoglobin and a major constituent of red blood cells. Food sources include spirulina, sunflower seeds, avocado, tofu, papaya, sesame seeds, pumpkin seeds, winged beans, lentils, coconut, olives and cow peas.

Methionine – Helps break down fats. Aids in reducing muscle degeneration. Food sources include kale, cabbage, garlic, sesame seeds, Brazil nuts, filberts, cauliflower, Brussel sprouts, chives and watercress. Most fruits such as pineapples and apples as well as most vegetables contain small amounts of this amino acid.

Leucine – Supports healing of skin, bone and tissue wounds. Promotes growth hormone synthesis. Food sources include coconut, avocado, soybeans, peanuts, almonds, sesame seeds, flax seeds, sunflower seeds, walnuts, asparagus, olives, snap peas, chick peas, hummus, cow peas, lentils and papaya.

Lysine – Component of muscle protein. Necessary for the synthesis of enzymes and hormones. Required for healthy nervous system function. Food sources include spinach, dandelion greens, parsley, alfalfa, turnip greens, buffalo gourd, watercress, cucumber, celery, soybean, carob, locust bean, common bean, lentil, Goa beans, amaranth, quinoa, buckwheat, carrot, beets, grapes, apricots, apples and pear.

Conditionally Essential Amino Acids For Infants, Growing Children And Those With Medical Problems

Cysteine – Cysteine is typically synthesized in humans, but may need to be obtained through diet for infants, the elderly and those with certain metabolic disease or malabsorption syndromes. Food sources include red bell peppers, garlic, onions, broccoli, Brussels spouts, oats, granola and wheat germ.

Tyrosine – Usually synthesized from phenylalanine, this amino acid may be essential in the diet for infants and growing children. Food sources include soy, peanuts, avocados, bananas, Lima beans, pumpkin seeds and sesame seeds.

Histidine – Is synthesized in adult humans, but is considered an essential amino acid for infants and young children. After a few years of age, humans are able to synthesize this amino acid. Food sources include spinach, dandelion greens, turnip greens, celery, sesame seeds, tofu, sunflower seeds, alfalfa, apples, pomegranates, beets, carrots, radish and garlic.

Arginine – Is synthesized in humans but may have dietary requirements if an individual suffers from impaired small bowel or renal function. Food sources include leafy greens, celery, cucumber, lettuce, wheat germ, alfalfa, beets, granola, oatmeal, buckwheat, coconut, carrots, leeks, peanuts, pecans, cashews, walnuts, almonds, Brazil nuts, hazelnuts, pine nuts, sesame seeds, sunflower seeds, pumpkin seeds, radishes, parsnips chick peas, soybeans, potatoes and nutritional yeast.

Glutamine – Plays a major role in protein synthesis, cell energy and acid-base balance in the kidneys. Glutamine is taken as a supplement by bodybuilders and has been studied for it’s effects in speeding up recovery from surgery. Glutamine is synthesized by humans, but may become essential (required in the diet) during illness or injury. Food sources include cabbage, beets, beans, spinach, parsley and wheat.

Further Reading: Looking for a protein supplement? Find out what my protein powder recommendations are.

Also, is spinach really a good source of protein?


About Tracy
Tracy Russell is the creator of the Green Smoothie Health & Weight Loss Program and founder of Incredible Smoothies. She is passionate about helping people improve their health with green smoothies and a whole foods lifestyle.


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