Amino acids are the building blocks of protein; they're essential to many mechanisms of the body.
Amino acids are considered the building blocks of bones, tissues, joints, and skin. While they can be found in supplements and multivitamins, amino acids are readily available in many food sources.
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Amino acids are generally separated into three groups, per the U.S. National Library of Health. These are:
1. Essential Amino Acids
There are nine essential amino acids, which include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. These amino acids cannot be made by the body and must be sourced from food and supplements.
Foods that contain all nine essential amino acids are known as "complete proteins," per Piedmont Healthcare. These include:
- Dairy products
- Soy beans
- Blue-green algae
2. Nonessential Amino Acids
Our bodies can produce nonessential amino acids, and they can also be found in some foods. Nonessential amino acids include alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine and tyrosine.
3. Conditional Amino Acids
Our bodies don't necessarily need conditional amino acids, but may in times of illness and stress, per the U.S. National Library of Health. Conditional amino acids include arginine, cysteine, glutamine, tyrosine, glycine, ornithine, proline and serine.
The benefits of amino acids are, simply put, that they enable us to live and perform daily functions. Every individual amino acid plays a somewhat different role in our health, from supporting immune function to regulating appetite to stimulating muscle growth.
Amino Acid Supplements
All proteins are made up of amino acids, so it's possible and generally preferable to get them from whole food sources, such as lean poultry, lean red meats, dairy products, eggs, soy or other plant-based proteins.
Getting high-quality amino acids in your diet, through whole foods or supplements, helps you maintain lean muscle mass, build more muscle if you are active and keep all of your organs and tissues healthy and functional.
Amino acids do have health benefits, and taking certain concentrated supplements has been associated with specific health benefits.
Amino Acid Supplements vs. Whole Food Sources
In general, it's best to get your vitamins, minerals and nutrients through whole foods in a balanced diet, as they provide higher-quality nutrition than supplements, according the Harvard T.H. Chan School of Public Health.
If you are healthy and regularly eat foods from all major food groups, you likely don't need supplements.
Amino Acid Supplements for Growth
Several of the amino acids are important in proper height and weight growth; L-arginine, L-lysine and L-ornithine, in particular, have been associated with increasing growth in the body.
Some people claim that L-arginine can increase the height of children, but there is no evidence that this is true.
Our bodies usually make all the L-arginine they need, according to the Mayo Clinic. L-arginine is also present in protein-rich foods like fish, red meat, poultry, soy, whole grains, beans and dairy products.
Although certain amino acids stimulate human growth hormone, there is little evidence that they can stimulate increased height or larger muscles.
In supplement form, L-arginine can be taken orally or used topically. It can also be administered intravenously. L-arginine is sometimes administered to treat conditions like angina, high blood pressure, preeclampsia, erectile dysfunction and peripheral arterial disease (PAD), per the Mayo Clinic.
Before taking L-arginine, especially if you take blood pressure medication, it's important to speak with your health care provider, advises the Mayo Clinic.
Branched-Chain Amino Acid Benefits
Branched-chain amino acids (BCAAs) are the three of the essential amino acids with a branched-chain chemical structure. The three BCAAs are leucine, isoleucine and valine.
These amino acids can be found in dietary protein, such as meat or eggs, or they can be supplemented. BCAAs are most commonly used for their role in building muscle, improving exercise performance and decreasing post-exercise soreness and recovery time.
Some exercise-focused folks supplement with BCAAs because of their positive effects on muscle growth and recovery. Here are three separate findings that show the potential benefits of BCAA supplements.
1. May Increase Muscle Growth
In one June 2017 study in Frontiers in Physiology, people who consumed a drink with 5.6 grams of BCAAs after performing a resistance workout saw a 22 percent greater increase in muscle protein synthesis compared to those who consumed a placebo drink.
While this one study showed promise, other research, including one July 2017 study in Amino Acids that examined the effects of supplementing with leucine, found that while BCAAs can increase muscle protein synthesis, they can't do as effectively as they may when working alongside the other essential amino acids.
These findings support the school of thought that getting nutrients, including amino acids, from whole food sources may be more effective than supplementing with individual vitamins.
2. May Decrease Muscle Soreness Post-Workout
BCAAs may help muscles recover faster.
An early September 2000 study in the Journal of Sports Medicine and Physical Fitness found that BCAA supplementation can cut down on muscle damage related to endurance exercise.
A later September 2008 paper also in the Journal of Sports Medicine and Physical Fitness showed that BCAA supplementation could promote muscle recovery while helping regulate the immune system. This may be particularly helpful in avoiding illness, as immune function can be weakened after intense or prolonged exercise.
3. May Reduce Exercise Fatigue
Research shows that branched chain amino acids may help improve exercise performance by both increasing the resistance to fatigue as well as sparing muscle glycogen, or energy stored in muscles.
A March 2011 study in the Journal of Sports Medicine Physical Fitness found that the branched chain amino acid supplements provided superior resistance to fatigue when compared to a placebo, in addition to increased fat burning.
Proline and L-Proline Supplements
Proline, also known as l-proline, is a non-essential amino acid with functions responsible for tissue repair, collagen formation, arteriosclerosis prevention and blood pressure maintenance.
Proline's amino acid structure is unique, as it is the only amino acid where the side chain is connected to the protein backbone two times, which forms a five-membered nitrogen-containing ring, as explained in Bioinformatic for Geneticists.
The body uses proline to make collagen, which is why some cosmetic and beauty products feature it as an ingredient.
Proline has been used in formulas to act as a moisturizer, and it has also been used in hair care formulas as a conditioning agent, per Cosmetics Info.
There is not enough research on the efficacy of proline supplements to determine whether, as sometimes claimed, supplementing with the amino acid can benefit the appearance of the skin or hair.
A Final Word on Supplements
Not all supplements are created equally or provide the same nutrient quality.
Dietary supplements are not regulated by the USDA, so manufacturers are responsible for the quality standards of their own products.
In December 2013, a group of medical professionals published a research review in the Annals of Internal Medicine asserting that few, if any, vitamin and mineral supplements had reliable and proven benefits and that select supplements may even be harmful, including vitamin E, vitamin A and beta-carotene.
Before you begin taking any vitamin or supplement, talk to your doctor.
- Annals of Internal Medicine: Enough Is Enough - Stop Wasting Money on Vitamin and Mineral Supplements
- University of Maryland Medical Center: Vitamins
- Harvard School of Public Health: Vitamins
- MD Anderson Cancer Center: Whole Foods or Supplements?
- National Institute of General Medical Sciences: Proteins Are the Body's Worker Molecules
- Medicine and Science in Sports and Exercise: Effects of Amino Acids Supplement on Physiological Adaptations to Resistance Training
- Journal of the International Society of Sports Nutrition: Consuming a Supplement Containing Branched-Chain Amino Acids During a Resistance-Training Program Increases Lean Mass, Muscle Strength and Fat Loss
- Journal of Sports Medicine and Physical Fitness: Branched-Chain Amino Acids Supplementation Enhances Exercise Capacity and Lipid Oxidation During Endurance Exercise After Muscle Glycogen Depletion
- U.S. National Library of Health: "Amino acids"
- Piedmont Healthcare: "What is a complete protein?"
- Bioinformatics for Geneticists (Hierarchical Exotoxicology Mini Series)
- Cosmetics Info: Proline
- Frontiers in Physiology: "Branched-Chain Amino Acid Ingestion Stimulates Muscle Myofibrillar Protein Synthesis following Resistance Exercise in Humans"
- Amino Acids: "Free leucine supplementation during an 8-week resistance training program does not increase muscle mass and strength in untrained young adult subjects"
- Journal of Sports Medicine and Physical Fitness: "Effects of branched-chain amino acid supplementation on serum creatine kinase and lactate dehydrogenase after prolonged exercise"
- Journal of Sports Medicine and Physical Fitness: "Branched-chain amino acid supplementation does not enhance athletic performance but affects muscle recovery and the immune system"
- Journal of Sports Medicine Physical Fitness: "Branched-chain amino acids supplementation enhances exercise capacity and lipid oxidation during endurance exercise after muscle glycogen depletion"
- Mayo Clinic: "L-arginine"