Amino acid supplementation: a topic many have opinions on, though, unfortunately, few of those opinions are substantiated by facts. Much of the coverage of amino acid supplements focuses on their ability to stimulate muscle growth, prevent muscle damage, and facilitate muscle recovery.
There's no question that amino acid supplementation proffers tantalizing—and very real—rewards for those pursuing athletic goals or seeking to change their body composition (either via increased muscle mass, weight loss, or a combination of both). However, amino acid supplements can also help you optimize physical well-being as you age, maintain a more balanced mood, avoid mental fatigue, and more.
While the impact of amino acids on the development and maintenance of muscle tissue can certainly benefit active individuals who want to maximize physical performance and gain strength, the benefits of amino acid supplementation extend to any individual looking to enhance wellness and safeguard against potential health issues now and in the future.
To give a taste of the scope of applications for the use of amino acid supplements, here are nine benefits validated by high-quality research:
- Enhanced muscle growth
- Higher levels of happiness
- Increased physical energy
- Improved athletic performance
- Preservation of skeletal muscle
- Facilitation of healthy weight loss
- Greater blood flow to muscles
- Faster muscle recovery
- Decreased mental fatigue
What Are Amino Acids?
Before exploring the nuances of how amino acid supplements support your overall health and well-being, let's review the basics of what amino acids are.
The essential scientific definition of amino acids is as follows: simple organic compounds that contain a carboxyl (-COOH) and an amino (-NH2) group. These compounds then join together to form proteins. Because of their foundational role in the makeup of protein molecules, amino acids have been bestowed with the venerable moniker “the building blocks of life.”
When we ingest dietary proteins, the body breaks them down into their constituent amino acids. To carry out its normal operations, the body must have a steady supply of 20 amino acids. Nine of those, known as the essential amino acids, must come from the food you eat. The remaining 11 are considered nonessential amino acids because the body can generate them without any specific dietary inputs.
One of the primary reasons to take amino acid supplements is the influence they have on muscle protein synthesis, or the building of new muscle protein. The nine essential amino acids are the key to stimulating muscle protein synthesis. In fact, essential amino acids are the only dietary macronutrients required for survival.
Understanding Muscle Protein Synthesis
Protein metabolism, which refers to all the biochemical processes responsible for muscle creation as well as muscle breakdown, is a constant, ongoing process.
Muscle protein is in a ceaseless state of turnover, meaning protein is being broken down and built back up continuously. When the balance between muscle protein synthesis and muscle breakdown tips in favor of breakdown, you begin to lose muscle mass. When muscle protein synthesis is stimulated to a greater degree than breakdown, you gain muscle mass.
9 Proven Benefits of Amino Acid Supplements
Amino acids link together in unique arrangements to form specific proteins that serve different functions in the body. We need amino acids not only to build and repair muscles and tissues, but also to make the chemicals our brains and other vital organs need to function.
1. Enhanced Muscle Growth
It just so happens that when you exercise, you increase the rate of muscle protein breakdown. Some of the amino acids released in the process of protein breakdown are oxidized to produce the energy needed for your muscles to contract. Amino acids that are oxidized are not available to help build new muscle protein.
The oxidation of amino acids is particularly problematic for the essential amino acids because they cannot be produced in the body. This is where amino acid supplements formulated with the appropriate blend of essential amino acids can become vital.
When you take amino acid supplements before, during, and after exercise, you minimize the accelerated protein breakdown that would otherwise occur while you work out. Amino acid supplements help support a positive balance between muscle protein synthesis and breakdown during exercise so that you can gain and maintain more muscle than you lose.
2. Higher Levels of Happiness
Your brain uses an amino acid called tryptophan as a precursor for the production of serotonin, a neurotransmitter known colloquially as the happiness hormone.
While that's a somewhat simplistic summary of serotonin's function, this neurotransmitter does help regulate mood as well as sleep and behaviors.
Research has established a clear link between low serotonin levels and depression, and it appears that supplementing with tryptophan can help to reduce symptoms of depression and increase feelings of happiness.
According to one study published in the British Journal of Nutrition, taking a gram of tryptophan daily can result in increased energy and more happiness. The randomized, placebo-controlled, parallel trial showed that tryptophan supplementation significantly changed the way participants processed emotions. Participants who took the placebo did not experience the same changes.
3. Increased Physical Energy
Mitochondria are the “power plants” of muscle. Most of the energy we need to perform a workout is in the form of ATP, which is mostly produced in muscle mitochondria. The more mitochondria per unit of muscle volume, the greater the capacity to produce ATP.
Essential amino acids, especially leucine, stimulate the production of new mitochondria, including the production of enzymatic proteins inside the mitochondria that process glucose and fatty acids for energy. A proportionately blended amino acid supplement will help increase the number of mitochondria in muscle, thereby augmenting the potential of muscle to generate ATP during exercise.
A small amount of energy is stored in muscle as creatine phosphate. Creatine is an amino acid that is produced by the liver, kidneys, and pancreas. Creatine enables the muscle to store more energy as creatine-phosphate. Creatine phosphate is a phosphorylated creatine molecule that is a ready-to-go source of energy—no time required for its production! As a result, creatine is an ideal component of amino acid supplements for providing energy for workouts that involve sudden bursts of energy, such as lifting weights or doing sprints.
4. Improved Athletic Performance
The synthesis of new muscle proteins replaces those damaged or metabolically degraded. Stimulating muscle protein synthesis not only helps you recover more quickly from workouts (more on this later) but also forms the metabolic basis both for improvements in muscle mass as well as functional capacity.
Amino acid supplements improve the functional capacity of muscle by increasing muscle strength and mass and bettering muscle’s ability to metabolize glucose and fatty acids for energy in mitochondria.
Studies have shown that branched-chain amino acid supplementation can be especially beneficial for exercise performance. Leucine, in particular, shows great promise as a safe and effective performance booster, both for high-intensity strength training as well as endurance exercise.
5. Preservation of Skeletal Muscle
As we grow older, we become ever more prone to skeletal muscle loss. Because of the essential contributions amino acids make to the muscle metabolism process, they can help to prevent the loss of lean body mass.
A randomized, double-blind, placebo-controlled study published in the Journal of Clinical Endocrinology & Metabolism found that essential amino acid supplementation helped to preserve as well as increase lean body mass for elderly female participants.
The results of a separate study found that essential amino acid supplementation can produce comparable benefits for athletes adhering to calorie-restricted diets. Participants who took amino acid supplements maintained lean mass and preserved skeletal muscle performance while simultaneously losing fat mass.
6. Facilitation of Healthy Weight Loss
In addition to its ability to change body composition by encouraging muscle growth, amino acid supplementation can also help support healthy weight loss by stimulating decreases to fat mass.
Findings published in the Journal of the International Society of Sports Nutrition indicate that supplementing with a dose of 14 grams of amino acids daily led to significant decreases in overall body fat percentage in comparison to the use of either whey protein powder or a sports drink.
7. Greater Blood Flow to Muscles
Exercise requires increased delivery of oxygen and energy substrates to active muscles. To meet these needs, the heart pumps more blood per minute (increased cardiac output).
Blood vessels in muscles dilate so that most of the increased blood pumped by the heart is routed to the muscle. Nitric oxide is the molecule responsible for the dilation of blood vessels.
The amino acid citrulline is the most effective way to increase the rate of nitric oxide production, thereby boosting blood flow to the muscle. Individuals who plan to take amino acid supplements specifically for this benefit should be sure to choose a formulation that includes citrulline as a component.
8. Faster Muscle Recovery
Yet another way amino acid supplements can help with exercise performance is by stimulating faster muscle recovery.
A meta-analysis of randomized clinical trials showed that amino acids, most notably BCAAs, have positive effects on moderate, exercise-induced muscle damage. Pooled data from the analyzed studies showed significant reduction to creatine kinase levels both before and after the 24-hour mark. Effects were less consistent, however, for perceived muscle soreness.
Nevertheless, the researchers concluded that using post-workout amino acid supplements is a superior option for the facilitation of muscle repair than either passive recovery or rest based on the ability to decrease the biological mechanisms responsible for muscle soreness and to ameliorate muscle function.
9. Decreased Mental Fatigue
During a long workout the balance of blood concentrations of amino acid precursors of neurotransmitter synthesis can become altered, favoring increased serotonin production in the brain. Serotonin is an inhibitory neurotransmitter best known for causing a feeling of sleepiness and fatigue—definitely not what you want during a workout!
For this reason, you’ll want to supplement with an amino acid formula with a balance of essential amino acids that counters the normal increase in the precursor of serotonin (tryptophan). The ideal amino acid formula will inhibit the brain’s uptake of the amino acid tryptophan, and subsequently reduce serotonin levels.
Check the formulation carefully, however, because many amino acid supplements target serotonin but don’t also increase the amino acid precursor of dopamine, the major excitatory brain neurotransmitter. In order to boost mental energy so you can sustain focus during a workout, an amino acid supplement must decrease the ratio of serotonin to dopamine in the brain. It should be formulated to increase the brain’s uptake of the amino acid tyrosine, which then causes dopamine levels to also increase.
This is one reason why although it may seem like taking BCAA supplements would provide a wealth of benefits related to physical performance, the evidence does not bear that out. Researchers have found that amino acid supplements formulated with only branched-chain amino acids do not work as effectively as balanced essential amino acid supplements.
As regards the benefit currently under discussion, choosing a composition that relies entirely on BCAAs will modulate serotonin (but not dopamine) production in the brain, yielding a less favorable effect on mental fatigue.
How to Choose the Best Amino Acid Supplement
When it comes to choosing the best amino acid supplement, the science overwhelmingly supports the use of a well-balanced blend of essential amino acids. From there, the specifics will depend on the results you hope to achieve.
The ideal amino acid composition for a supplement to support muscle growth, for example, will maintain an optimal balance of essential amino acids in the blood to stimulate muscle protein synthesis and reduce muscle protein breakdown.
Meanwhile, those looking for supplements designed to maximize exercise performance will see the most impressive changes from amino acid supplements that contain citrulline for boosting nitric oxide production and blood flow, and creatine to help maintain the energy stores of creatine-phosphate in the muscle so that your next workout can be completed effectively and you can recover from intense workouts quicker.
An amino acid supplement, especially for athletes, should also take electrolyte balance into account. Sweat contains electrolytes (sodium and potassium)—so named due to their ability to conduct the electrical signals that enable muscle to contract. Loss of electrolytes can lead to muscle cramps and eventually limit your ability to continue exercising.
For this reason, athletes will want to take an amino acid supplement that contains both sodium and potassium. The absorption of electrolytes will be enhanced because the active uptake of amino acids from the intestine is coupled with sodium transport. Therefore, the combination of essential amino acids plus electrolytes results in greater absorption than electrolytes alone.
When evaluating dietary supplements such as amino acids, remember to always do your research. An individual amino acid may be linked to impressive benefits, but those benefits can only be obtained when your body has an optimal and balanced supply of all the essential amino acids. The manufacturers of the best amino acid supplements will know this and formulate their products accordingly.