Amino acids are essential to all living things, from microbes to humans.
All living bodies contain the same 20 types of amino acids.
Amino acids make up about 20% of our bodies or about 50% of our solid body mass; they are the next largest component in our bodies after water. The body of a person who weighing 50 kg has about 10 kg of amino acids in their body make up.
Amino Acids are the building blocks of proteins. There are 100,000 types of proteins that are made up of just 20 amino acids.
Twenty types of amino acids make up the proteins for the human body.
Of total 20 amino acids, 9 amino acids cannot be synthesized in our bodies and we need to take them in through our diets. These are called essential or indispensable amino acids.
Essential amino acids are: Histidine, Isoleucine, Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan and Valine.
The 11 remaining amino acids can be synthesized from other amino acids in the body and thus are called non-essential (or dispensable) amino acids.
Non-essential amino acids are: Alanine, Arginine, Asparagine, Aspartic acid, Cysteine, Glutamic acid, Glutamine, Glycine, Proline, Serine, and Tyrosine. However, both essential and non-essential amino acids play an important role to support our life.
Some non-essential amino acids (e.g. Arginine, Cysteine, and Tyrosine) are called semi-essential or conditionally essential amino acids because they tend to run low during infancy or in health conditions such as being sick, injured or after surgery.
Amino acids which link together to make up proteins not only make up our bodies but also regulate most of the essential functions of our bodies. Some common examples of proteins are collagen, keratin, hemoglobin etc.
Amino Acids also regulate and maintain our body by becoming enzymes or hormones. Some commonly known hormones are Thyroid, Insulin, Adrenalin etc.
One more important function of amino acids is to supply energy to the body. Typically, a healthy body on an average diet uses carbohydrates as a primary source of fuel but proteins and amino acids can be used as a last resort when the primary sources are depleted due to rigorous exercise.
Amino acids also play an important role in food taste. Proteins do not have much taste, but every amino acid has its own taste, and the combination of these is one of the important factors in defining food taste. The most well-known amino acid is glutamic acid which is responsible for the fifth taste Umami and is also a raw material for the umami seasoning AJI-NO-MOTO®.
Since our bodies cannot make all amino acids, we must consume some necessary amino acids through our diets from various foods. A balanced diet complete with necessary amino acids is very important for proper function of body.
Obtaining balanced nutrition is important for a healthy life. It is necessary to get 5 major nutrients (proteins, fats and carbohydrates, plus vitamins and minerals) in a balanced way. Required daily intake of these nutrients is established by the World Health Organization (WHO) and in many countries. If this balance is broken such as any single nutrient is taken in excessively, the risk for obesity and lifestyle-related diseases increases.
Similarly, the required amounts of 9 essential amino acids for our body are defined by the international organizations (FAO / WHO / UNU). These are called the amino acids scoring patterns. If an amino acid is less than the amino acids scoring pattern, it is called the limiting amino acid. The nutritional value of a protein can be improved by supplementing the limiting amino acid. Amino acid score is a numerical value showing how much the smallest limiting amino acid satisfies the scoring pattern. It can be said that a protein with an amino acid score close to 100 is good quality protein.
In general, animal proteins such as eggs are good quality proteins with high amino acids scores. On the other hand, the scores of vegetable proteins such as wheat and corn are known to be low.
For a healthy life, it is essential to eat a diet with a proper balance of good-quality proteins; namely, essential amino acids, which cannot be made by the body. If amino acids are ingested in a proper balance, the body can effectively use them, and less waste will be excreted. A required daily intake is proposed for each of nine essential amino acids.
Balance of essential amino acids in food is often illustrated as a wooden barrel that is used for filling water. Each board of the barrel represents each type of essential amino acid in food. A food with an ideal balance of amino acids, such as an egg, has a barrel with every board neatly forming a line at the same height. In case of wheat, however, the boards are different in height. If any one of the boards is shorter than the others, you can only fill the barrel as high as the lowest board and the water beyond that runs out of the barrel. Similarly, if even one essential amino acid is absent, the remaining amino acids cannot be used effectively.
So, what would happen if amino acids lysine which is insufficient is added externally in the barrel for wheat? It has been found that the board for lysine gets taller, making other types of amino acids to be utilized more effectively.
This theory has been put to use for nutritional improvement in many countries with poor diets, contributing to the solution of social problems. For example, many countries in Africa have been suffering from poor development of infants due to nutritional deficiencies and resulting in high fatality rates.
*Koko, a porridge made from fermented corn is a traditional complementary food in Ghana. However, the levels of protein (amino acids balance) in koko do not meet the WHO’s nutrient requirements and dietary recommendations.
To address this nutrient gap, the Ajinomoto Group, in collaboration with various partners, developed KOKO Plus, a supplement containing amino acids and soybean proteins, which when added to koko during cooking, provides enough nutrients such as balanced protein along with Calcium, Iron, Zinc, Iodine, Folic Acid, Vit A, B1, B2, B6, Niacin, K1, D3, B12 for children. The World Food Programme (WFP) verified the efficacy of KOKO Plus and registered it as a “Nutritious powder” in its food basket in February 2018.
*The Koko Plus project in Ghana has been transferred to Ajinomoto Foundation since 2017
In our daily diets, high-lysine foods include dairy products, eggs, meat, fish, and bean whereas, rice has insufficient lysine. Thus, it is ideal to combine bean products such as miso and tofu with rice to secure intake of all essential amino acids. Eating mindfully considering the correct balance of amino acids is very important to have a healthier life.
The Ajinomoto group supports the healthy lives of people all around the world by unlocking the power of amino acids. Read more about our approach to Nutrition here.
Medically reviewed by Natalie Olsen, R.D., L.D., ACSM EP-C — Written by Jennifer Berry on January 21, 2019
The body needs 20 different amino acids to maintain good health and normal functioning. People must obtain nine of these amino acids, called the essential amino acids, through food. Good dietary sources include meat, eggs, tofu, soy, buckwheat, quinoa, and dairy.
Amino acids are compounds that combine to make proteins. When a person eats a food that contains protein, their digestive system breaks the protein down into amino acids. The body then combines the amino acids in various ways to carry out bodily functions.
A healthy body can manufacture the other 11 amino acids, so these do not usually need to enter the body through the diet.
Amino acids build muscles, cause chemical reactions in the body, transport nutrients, prevent illness, and carry out other functions. Amino acid deficiency can result in decreased immunity, digestive problems, depression, fertility issues, lower mental alertness, slowed growth in children, and many other health issues.
Each of the essential amino acids plays a different role in the body, and the symptoms of deficiency vary accordingly.
There are many types of essential amino acids, including:
Lysine
Lysine plays a vital role in building muscle, maintaining bone strength, aiding recovery from injury or surgery, and regulating hormones, antibodies, and enzymes. It may also have antiviral effects.
There is not a lot of research available on lysine deficiency, but a study on rats indicates that lysine deficiency can lead to stress-induced anxiety.
Histidine
Histidine facilitates growth, the creation of blood cells, and tissue repair. It also helps maintain the special protective covering over nerve cells, which is called the myelin sheath.
The body metabolizes histidine into histamine, which is crucial for immunity, reproductive health, and digestion. The results of a study that recruited women with obesity and metabolic syndrome suggest that histidine supplements may lower BMI and insulin resistance.
Deficiency can cause anemia, and low blood levels appear to be more common among people with arthritis and kidney disease.
Threonine
Threonine is necessary for healthy skin and teeth, as it is a component in tooth enamel, collagen, and elastin. It helps aid fat metabolism and may be beneficial for people with indigestion, anxiety, and mild depression.
A 2018 study found that threonine deficiency in fish led to these animals having a lowered resistance to disease.
Methionine
Methionine and the nonessential amino acid cysteine play a role in the health and flexibility of skin and hair. Methionine also helps keep nails strong. It aids the proper absorption of selenium and zinc and the removal of heavy metals, such as lead and mercury.
Valine
Valine is essential for mental focus, muscle coordination, and emotional calm. People may use valine supplements for muscle growth, tissue repair, and energy.
Deficiency may cause insomnia and reduced mental function.
Isoleucine
Isoleucine helps with wound healing, immunity, blood sugar regulation, and hormone production. It is primarily present in muscle tissue and regulates energy levels.
Older adults may be more prone to isoleucine deficiency than younger people. This deficiency may cause muscle wasting and shaking.
Leucine
Leucine helps regulate blood sugar levels and aids the growth and repair of muscle and bone. It is also necessary for wound healing and the production of growth hormone.
Leucine deficiency can lead to skin rashes, hair loss, and fatigue.
Phenylalanine
Share on PinterestSome diet sodas contain sweeteners with phenylalanine.
Phenylalanine helps the body use other amino acids as well as proteins and enzymes. The body converts phenylalanine to tyrosine, which is necessary for specific brain functions.
Phenylalanine deficiency, though rare, can lead to poor weight gain in infants. It may also cause eczema, fatigue, and memory problems in adults.
Phenylalanine is often in the artificial sweetener aspartame, which manufacturers use to make diet sodas. Large doses of aspartame can increase the levels of phenylalanine in the brain and may cause anxiety and jitteriness and affect sleep.
People with a rare genetic disorder called phenylketonuria (PKU) are unable to metabolize phenylalanine. As a result, they should avoid consuming foods that contain high levels of this amino acid.
Tryptophan
Tryptophan is necessary for proper growth in infants and is a precursor of serotonin and melatonin. Serotonin is a neurotransmitter that regulates appetite, sleep, mood, and pain. Melatonin also regulates sleep.
Tryptophan is a sedative, and it is an ingredient in some sleep aids. One study indicates that tryptophan supplementation can improve mental energy and emotional processing in healthy women.
Tryptophan deficiency can cause a condition called pellagra, which can lead to dementia, skin rashes, and digestive issues.
Many studies show that low levels of protein and essential amino acids affect muscle strength and exercise performance.
According to a 2014 study, not getting enough essential amino acids may cause lower muscle mass in older adults.
An additional study shows that amino acid supplements can help athletes recover after exercise.
Doctors previously believed that people had to eat foods that provided all nine essential amino acids in one meal.
As a result, unless an individual was eating meat, eggs, dairy, tofu, or another food with all the essential amino acids, it was necessary to combine two or more plant foods containing all nine, such as rice and beans.
Today, however, that recommendation is different. People who eat vegetarian or vegan diets can get their essential amino acids from various plant foods throughout the day and do not necessarily have to eat them all together at one meal.
Share on PinterestA person should speak to their doctor before taking essential amino acid supplements.
Although 11 of the amino acids are nonessential, humans may require some of them if they are under stress or have an illness. During these times, the body may not be able to make enough of these amino acids to keep up with the increased demand. These amino acids are “conditional,” which means that a person may require them in certain situations.
People may sometimes wish to take essential amino acid supplements. It is best to seek advice from a doctor first regarding safety and dosage.
Although it is possible to be deficient in essential amino acids, most people can obtain enough of them by eating a diet that includes protein.
The foods in the following list are the most common sources of essential amino acids:
- Lysine is in meat, eggs, soy, black beans, quinoa, and pumpkin seeds.
- Meat, fish, poultry, nuts, seeds, and whole grains contain large amounts of histidine.
- Cottage cheese and wheat germ contain high quantities of threonine.
- Methionine is in eggs, grains, nuts, and seeds.
- Valine is in soy, cheese, peanuts, mushrooms, whole grains, and vegetables.
- Isoleucine is plentiful in meat, fish, poultry, eggs, cheese, lentils, nuts, and seeds.
- Dairy, soy, beans, and legumes are sources of leucine.
- Phenylalanine is in dairy, meat, poultry, soy, fish, beans, and nuts.
- Tryptophan is in most high-protein foods, including wheat germ, cottage cheese, chicken, and turkey.
These are just a few examples of foods that are rich in essential amino acids. All foods that contain protein, whether plant-based or animal-based, will contain at least some of the essential amino acids.
Consuming essential amino acids is crucial for good health.
Eating a variety of foods that contain protein each day is the best way for people to ensure that they are getting adequate amounts of essential amino acids. With today’s modern diet and access to a wide variety of foods, deficiency is rare for people who are generally in good health.
People should always talk to a doctor before using supplements.
Last medically reviewed on January 21, 2019
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- Compound summary for CID 6106: Leucine. (n.d.)
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