Amino Acids: Function, Recommended Intake, and More
Amino acids each function differently, depending on their structure. They form proteins by linking up and bonding together with peptide bonds between them.
Experts may refer to essential and nonessential amino acids.
Some nonessential amino acids are considered conditional.
You need to have all 20 amino acids to maintain your health. However, essential amino acids are not made naturally in the body, unlike nonessential. Therefore, you need to get these other amino acids elsewhere.
You need all 20 amino acids to keep your body functioning well.
Besides building protein, amino acids produce hormones and neurotransmitters, which help regulate mood, behavior, and sleep. Amino acids also help with:
- repairing tissue
- transporting nutrients
- building muscle
- strengthening the immune system
Your body can make nonessential amino acids, but it cannot make essential amino acids. Therefore, you need to get these from an outside source. Essential amino acids can come from the food in your diet or from supplements.
The nine essential amino acids are:
Nonessential amino acids and their roles in the body include:
|Nonessential amino acid||Role in the body|
|alanine||transferring ammonia to the liver and helping manage blood sugar|
|arginine||boosting nitrous oxide and helping remove ammonia in the body|
|asparagine||carrying ammonia for the body to release and keeping the nervous system functioning|
|aspartate||regulating hormones and producing neurotransmitters|
|cysteine||important for protein synthesis, detoxification, and diverse metabolic function|
|glutamate||helping detoxify the liver and aiding in the inflammatory response|
|glutamine||carrying nitrogen to tissues and regulating pH balance|
|glycine||acting as a neurotransmitter in the central nervous system and having many roles, such as antioxidant, anti-inflammatory, cryoprotective, and immunomodulatory in peripheral and nervous tissues|
|proline||aiding in wound healing and boosting the immune system|
|serine||making antibodies and helping form the myelin sheath that covers nerve fibers|
|tyrosine||produced from the essential amino acid phenylalanine, making several hormones including dopamine and thyroid hormone|
Conditional amino acids
Conditional amino acids are considered nonessential amino acids. While your body can make these under normal circumstances, there are certain periods where they are considered essential. An essential amino acid is one that your body cannot make in adequate amounts.
Infants, and those who are sick, pregnant, or had an injury to the body, might need to take supplements to ensure the right amount of amino acids.
Conditional amino acids include:
- Arginine: Doctors recommend this during pregnancy to accommodate a growing fetus.
- Glutamine: This may be necessary if you are critically ill.
- Tyrosine: Extra tyrosine may be necessary during periods of high stress.
- Glycine: This may be useful during pregnancy to accommodate a growing fetus.
- Serine: Extra serine can be necessary during pregnancy.
One good way to get enough essential amino acids is to eat animal proteins because the body can absorb them efficiently. Complete proteins are foods that contain all nine of the essential amino acids and include:
- dairy products
- pea protein
Some foods are incomplete proteins, meaning they do not contain all the essential amino acids. If you follow a vegetarian or vegan diet, work with a dietician to make sure you are combining incomplete proteins. This can help ensure that you get all nine amino acids. These foods include:
- certain grains
According to the World Health Organization (WHO), adults have a daily requirement of essential amino acids per 2.2 pounds (lb), or 1 kilogram of body weight, as follows:
- Histidine: 10 milligrams (mg)
- Isoleucine: 20 mg
- Leucine: 39 mg
- Lysine: 30 mg
- Methionine: 10.4 mg
- Phenylalanine: 25 mg
- Threonine: 15 mg
- Tryptophan: 4 mg
- Valine: 26 mg
As long as you eat a balanced diet, you should not need to track your amino acid intake.
There are several reasons why you may want to take amino acid supplements.
Branched-chain amino acids (BCAA) may be useful when you want to recover more quickly from working out. Isoleucine, leucine, and valine are BCAAs that many athletes take to help decrease fatigue and improve their performance.
Since many amino acids aid in neurotransmitter production that regulates mood, giving yourself a boost of amino acids may help regulate your moods.
Recovering from surgery
Ensuring you have adequate amounts of amino acids can help heal wounds. You may need a boost of certain amino acids after an injury or trauma to your body.
If you are not getting enough essential amino acids in your diet, consider talking with your healthcare professional about which supplement is best for you. Like many supplements, they are not approved by the Food and Drug Administration (FDA).
Amino acid supplements can come in powders, capsules, or liquids. If you take amino acids for exercise, you can take them before, during, or after working out to aid muscle recovery. Taking BCAA may work better if you take them after a workout.
Your dosage will depend on what amino acid supplement you are planning on taking and why you are taking it. For example, one 2021 study indicates that 0.14–3 grams of tryptophan per day could help improve mood. Taking 115.6 mg of BCAA per lb can help decrease muscle soreness if taken daily, according to another 2021 study.
Talk with your healthcare professional about your individual dosage when it comes to supplements. High levels of amino acids can be harmful to your body.
As with all medications and supplements, there can be side effects when taking amino acid supplements. Side effects will vary depending on the amino acid supplement you are taking. For example, taking BCAAs in high doses can increase your chance of high blood pressure, according to a 2019 study.
In general, the FDA considers amino acid supplements to be safe. However, these supplements may interact with your other medications. If you are pregnant or breastfeeding, it is important to talk with your healthcare professional if you want to start a new supplement.
There are 20 amino acids present in your body. They are responsible for making proteins and playing other important roles. Your body naturally produces 11 of these amino acids, but you need to get the other nine from outside sources.
It is not usually necessary to take amino acid supplements since most people can get their essential amino acids by eating protein.
Discuss with your healthcare professional or dietician if you are concerned you may not be getting enough amino acids from your diet.