Enter a supplement store and you might be bombarded with rows and rows of fancy boxes of products claiming to make you stronger, get you leaner or improve your overall performance. Among these, you may have noticed essential amino acid (EAA) or branched chain amino acid (BCAA) supplements and wondered if they might work for you.
What Are Essential Amino Acids (EAAs)?
Amino acids are the building blocks of proteins. When you eat protein, whether it be a piece of meat or a whey shake, your body breaks it down into individual amino acids, which are essentially stockpiled. When your body needs a specific type of protein — say, to rebuild muscle after a tough workout, or to help your nails grow — it's able to build the nutrient from that amino reserve.
Proteins are a major component of all cells in the body, but most amino acid supplements focus on the impact of protein on muscle growth and repair.
There are 20 amino acids in total, nine of which are termed "essential." Our bodies can't make these EAAs, so it's essential that we seek them out in our diets. The nine EAAs include: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine.
Where Are EAAs Found?
EAAs are in all animal and plant proteins, but in varying amounts. The amount of EAAs in a food will determine its protein quality.
Proteins are often separated into two categories: complete and incomplete proteins. Complete proteins are those that contain all nine EAAs. Animal proteins are always complete proteins and include foods such as beef, fish, poultry, eggs and dairy. There are also some plant-based foods that are complete proteins, such as quinoa, soy and buckwheat.
Incomplete proteins indicate that a food is missing one or more EAA. For example, beans are missing the nutrient methionine, which can be found in grains such as rice. It was once thought that incomplete proteins needed to be paired with the missing EAA at the same meal, but this is no longer considered to be true. Eating a wide variety of plant-based protein throughout the day can complete your protein profile.
What's the Difference Between EAAs and BCAAs?
Of the nine EAAs, leucine, isoleucine and valine are considered to be branched chain amino acids (BCAAs), which refers to their unique chemical structures.
BCAAs are often marketed for their effects on muscle protein synthesis, or building muscle. And indeed, research published in May 2018 in Nutrition and Metabolism indicates that BCAAs are more likely to go to skeletal muscle than other areas of the body. Leucine, in particular, has been shown to stimulate muscle protein synthesis.
With the hype surrounding BCAAs, though, it's important to remember that all EAAs are needed to contribute to the rebuilding of proteins in the body. To specifically build muscle, both BCAAs and EAAs will be effective.
Here's where the science really counts. Research published in June 2017 in Frontiers in Physiology indicated BCAA supplements stimulated muscle protein synthesis by 22 percent. However, that was less than previous research that used similar amounts of BCAAs in conjunction with whey protein. Bottom line: Eating something with all EAAs, such as whey, is more effective in building muscle after exercise than BCAAs alone.
When Is the Best Time to Take EAAs and BCAAs?
Depending on why you are interested in EAAs, your timing of intake will differ. For those who are active and interested mainly in muscle growth, the International Society of Sports Nutrition (ISSN) recommends that you space your dietary protein intake evenly throughout the day, consuming 20 to 40 grams every three to four hours, with 10 grams coming from EAAs.
However, research shows that EAAs are especially important after a workout. Consuming high-quality protein that includes EAAs within two hours after a workout has been shown to support increases in strength and improvements in body composition.
Keep in mind, though, that amino acids are found naturally in many foods, so you don't necessarily need to take a supplement to receive these nutrients. In the sixth edition of the book Sports Nutrition, the authors conclude that taking isolated supplements is not necessary, and athletes would be better off consuming foods that contain all EAAs and are high in leucine. Examples of foods high in leucine include turkey, beef, fish, soybeans, eggs, white beans and kidney beans.
Who Benefits From EAA Supplementation?
EAA supplements have been studied for their benefits to older adults. A March 2018 review article published in the British Journal of Nutrition found that EAAs showed small beneficial effects for those older adults with loss of lean body mass, muscle strength and physical function. In fact, nutrition experts indicate that older adults should have a higher protein requirement than younger, non-exercising adults of up to 2 grams per kilogram of body weight.
Although BCAA supplements are popular in the active community, there is still no conclusive evidence as to effectiveness of BCAA supplementation overall. Research published in October 2017 in Genes and Nutrition indicates a wider-reaching benefit to EAAs, including better immune function as well as a role in body weight regulation and prevention of oxidative damage. Much of this research relied on animal studies, though, so more human studies are necessary to confirm the results.
How to Get EAAs and BCAAs From Your Diet
If you are eating a healthy diet with a wide variety of foods, including different sources of protein, you most likely do not need to take an individual supplement. When you eat a complete protein or pair your proteins to make a complementary protein, you are getting all of the EAAs you need, and by default, you are also getting BCAAs.
Here are two key things to keep in mind to make sure you're receiving enough amino acids each day:
- Get enough protein. The recommended dietary allowance (RDA) for protein is 0.8 grams per kilogram of body weight. So, a 150-pound individual would need to consume 55 grams of protein in a day. Athletes and older adults may need more protein and should speak with a health care professional to determine their individual needs.
- Eat high-quality protein foods. Complete proteins include all animal proteins, plus plant proteins such as quinoa and soy. Pair incomplete proteins such as rice and beans or peanut butter and whole wheat bread.
What Are the Potential Side Effects of EAA Supplementation?
Those with the rare genetic disorder phenylketonuria (PKU) should not take essential amino acid supplements. People with PKU are not able to break down the amino acid phenylalanine, and it can build up in the body causing neurological problems, rashes and delayed development.
In addition, people with diabetes, kidney disease or who are prone to kidney stones should use any type of protein supplement with caution.
Protein or amino acids should never be consumed in excess. The body does not have an unlimited need for extra amino acids. The excess amino acids will most likely either be excreted via the liver and kidneys, used for energy and/or stored as fat.
Research from May 2018 in the Journal of Diabetes indicates that those who develop type 2 diabetes and heart disease have higher levels of BCAAs. Studies such as this emphasize the need to speak with your primary health care team before taking EAA or BCAA supplements.
Children and adolescents can get all of their EAAs from dietary sources. Pregnant women should always speak with their doctor before starting any dietary supplement, as there is no recommendation on the safety of EAA supplementation.
- FDA.gov: "Protein"
- Nutrition and Metabolism: "Branched-chain amino acids in health and disease: metabolism, alterations in blood plasma, and as supplements"
- Academy of Nutrition and Dietetics: "Protein and the Athlete"
- Karpinski C, Rosenbloom, C. Sports Nutrition, 6th ed. Academy of Nutrition and Dietetics.
- Journal of the Society of Sports Nutrition: "Dietary Supplements and Sports Performance: Amino Acids"
- British Journal of Nutrition: "Systematic review and meta-analysis of the effect of protein and amino acid supplements in older adults with acute or chronic conditions."
- USDA Nutrient Database: "Leucine foods"
- Journal of Diabetes: "Diabetes and branched-chain amino acids: What is the link?"
- Frontiers in Physiology: "Branched-Chain Amino Acid Ingestion Stimulates Muscle Myofibrillar Protein Synthesis following Resistance Exercise in Humans"
- Genes and Nutrition: "Amino acid supplements and metabolic health: a potential interplay between intestinal microbiota and systems control"
- International Society for Sports Nutrition: "International society of sports nutrition position stand: nutrient timing."
- Nutrients: "Protein Consumption and the Elderly: What Is the Optimal Level of Intake?"
- Mayo Clinic: "Phenylketonuria"