What Are Amino Acids?
Amino acids are the building blocks of protein. These molecules come together to form proteins. Your body uses them for many important functions, such as making hormones, building muscle, and repairing tissue.
Your body needs 20 amino acids to work properly and makes many of these amino acids on its own. But your body can’t make nine of them. You have to get these amino acids through certain foods or supplements. They’re called essential amino acids and include:
- Histidine
- Isoleucine
- Methionine
- Phenylalanine
- Threonine
- Tryptophan
- Valine
Your body makes the other 11 amino acids. These amino acids are called non-essential:
- Alanine
- Arginine
- Asparagine
- Aspartic acid
- Cysteine
- Glutamic acid
- Glutamine
- Glycine
- Proline
- Serine
- Tyrosine
But in times of illness, stress, or pregnancy, your body may not make enough of some of these amino acids. These are called conditional amino acids. During these periods, you’ll need to get them from food or supplements. These include:
- Arginine
- Cysteine
- Glutamine
- Glycine
- Proline
- Serine
- Tyrosine
Amino Acids vs. Protein
Protein is a body tissue made up of amino acids. When amino acids connect to make a chain, they form proteins. If you think of it as a necklace, amino acids are the beads, while proteins are the completed necklace.
Like the colors in a necklace pattern, amino acids line up in a certain order. These sequences form a specific protein. There are thousands of different proteins with different jobs, such as creating energy or building muscle.
Amino Acids Structure
Amino acid molecules are made of four main elements. You may remember them from science class: carbon, hydrogen, oxygen, and nitrogen.
These elements form the same amino acid structure. In the center is a carbon atom. It’s attached to a hydrogen atom, a basic amino group (a group of elements), a carboxylic acid group (another grouping of elements), and an R group.
The R group is what makes amino acids different. It’s also called a side chain. The R group gives each amino acid its unique properties. It’s what separates each of the 20 amino acids. When amino acids connect together, they fold together in 3D shapes. This creates a protein.
Why Are Amino Acids Important?
Your body uses amino acids to:
Build muscle. Muscles are made mainly from protein, which amino acids help build.
Grow and repair tissue. Many amino acids, such as leucine and methionine, are used to grow and repair tissues. They’re important for healing wounds and injuries.
Make hormones. Amino acids help make many hormones. For example, phenylalanine is needed to produce the hormones epinephrine and norepinephrine. Other amino acids play a role in making thyroid and growth hormones.
Boost the immune system. Amino acids are an important nutrient for immune cells. They’re needed for these cells to work properly.
Make brain chemicals. Certain amino acids, such as tryptophan and phenylalanine, are used to make important chemicals in the brain, called neurotransmitters. These include dopamine and serotonin, which can affect your mood, sleep, and appetite.
Provide energy. Although your body prefers to burn carbohydrates or fat for energy, it can use protein as needed. After breaking down protein, the amino acids supply energy.
Support the digestive system. Amino acids help keep your digestive system running. They fuel the membrane that lines the small intestine and help your gut make key proteins and chemicals.
Amino Acids and Weight Loss
Research suggests that amino acids may help with weight loss. That’s because the proteins they make can decrease hunger. Proteins help you stay fuller for longer than other nutrients, such as carbs or fat, so you eat less.
Amino acids also help you build and maintain muscles. Muscle tissue burns more calories than body fat, so you use more energy even when you’re at rest. This may lead to weight loss.
Although getting enough amino acids is important, it’s not clear if taking an amino acid supplement will result in weight loss. Studies done on amino acid supplements and weight loss have mixed results.
Foods With Amino Acids
Many foods are rich in amino acids, and it’s generally easy to get your daily requirements.
Foods from animal protein sources are considered "complete" proteins because they contain all the amino acids. Plant foods also contain protein, but most of them are "incomplete" proteins. This means they may be missing one or more of the essential amino acids. But you can still get all the amino acids you need by eating a variety of plant foods.
These foods are some of the best sources of amino acids:
Eggs. An excellent source of protein, eggs contain all of the essential amino acids. Studies suggest that the amino acids provided by eggs are better utilized by your body than other sources such as casein or soy.
Turkey. It has high amounts of tryptophan, an amino acid the body uses to make the B vitamin called niacin, which is necessary for digestion, healthy skin, and nerves. Tryptophan also helps produce serotonin, which affects your mood and can contribute to feelings of happiness and relaxation. Because they’re all high in protein, other meats are good sources of amino acids as well.
Cottage cheese. One 100-gram serving of cottage cheese provides about 25% of your daily requirements for protein and contains significant quantities of several amino acids, including threonine and tryptophan.
Mushrooms. Mushrooms contain a total of 17 amino acids, including all of the essential ones. One study showed that supplementing a cereal diet with mushroom would help overcome lysine deficiency.
Fish. Most types of fish contain essential amino acids and other important micronutrients. Salmon is high in amino acids and Omega 3s (important fatty acids that support heart and other health).
Legumes and Beans. Legumes are a great source of high-quality protein — 20%-45% of their protein is rich in the amino acid lysine. Peas and beans contain 17%-20% high-quality protein, while lupins and soybeans contain 38%-45%. Legumes and beans include:
- Peas
- Chickpeas
- Lentils
- Soybeans
- Peanuts
- Cooked kidney beans
- Black beans
- Garbanzo beans
- Edamame
Soybeans are one of the few plant foods that provide complete proteins containing all the amino acids.
Quinoa. It is a nutritious grain and is also a complete protein. In addition to being a good source of fiber, it contains all nine essential amino acids that your body needs from food. It also has a higher amount of lysine than wheat or rice, making it a better source of these amino acids than other grains.
Amino Acids Supplements
You usually get all of the essential amino acids you need from food. Some people take extra amino acids in supplements for health benefits. The FDA hasn’t approved amino acid supplements, so always talk to your health care provider before you take a new supplement. Research suggests that certain amino acid supplements may help:
Boost mood. Your body uses tryptophan, an essential amino acid, to make serotonin. Serotonin is a brain chemical that causes feelings of happiness. One review showed that taking 0.14 to 3 grams of tryptophan with food a day can improve mood, although scientists noted that more research is needed.
Improve sleep. The amino acid glycine acts as a neurotransmitter, or brain chemical. Studies done on rats suggest that glycine supplements may lower body temperature and increase serotonin, both of which improve sleep. Other research shows that tryptophan may help you fall asleep faster and sleep more soundly.
Improve exercise performance and recovery. Three amino acids called branched-chain amino acids (leucine, isoleucine, and valine) can reduce muscle damage and act as an energy source during exercise. This, in turn, may help exercise feel easier, increase endurance, and help you recover faster after a workout.
Speed wound healing. Two non-essential amino acids, arginine and glutamine, may help cells multiply and repair wounds. A study showed that taking arginine and glutamine supplements increased markers of wound healing.
Amino acid supplements' side effects
Taking an amino acid supplement can lead to side effects. It can depend on which amino acid you get too much of, but common side effects include:
- Nausea and vomiting
- Diarrhea
- Cramps
- Bloating
- Dehydration
In rare cases, too much of a supplement containing the branched-chain amino acids (BCAAs) valine, leucine, and isoleucine may cause more serious side effects, such as kidney problems or metabolic issues.
Takeaways
Amino acids are molecules that your body needs to make protein. They play a big part in many crucial functions, such as making hormones and building muscles. Your body makes some amino acids on its own, but you need to get nine essential amino acids from the foods you eat. A healthy diet full of different foods can supply all of the amino acids you need.
Amino Acids FAQs
How do amino acids benefit muscle growth?
Your body needs amino acids to make protein, the main component of muscle tissue.
Can a vegan diet provide enough amino acids?
You can get enough amino acids from a vegan diet. Some plant-based sources of protein, such as nuts and beans, don’t contain all 20 essential amino acids. But you can cover all of your bases by eating a variety of different foods. Research shows that vegans, on average, consume more than enough protein.
What are some vegetarian sources of amino acids?
Nuts, brown rice, beans, chia seeds, green peas, and oats are high in amino acids, but they don’t contain all nine essential amino acids (called incomplete proteins). Soy products (such as tofu and tempeh), quinoa, amaranth, hemp seeds, and seitan pack in all of the essential amino acids. They’re complete proteins.
