Health Benefits of BCAA
Medically reviewed by Suzanne Fisher, RD
Amino acids are the building blocks of protein. There are 20 types of amino acids, nine of which are essential amino acids. Our bodies can’t make essential amino acids on their own, so we have to get them through food or supplements.
Three of these essential amino acids—leucine, isoleucine, and valine—are called branched-chain amino acids (BCAAs). BCAA supplements are popular with athletes and people who exercise often because they play a special role in muscle growth and development. Learn about the research-backed benefits of BCAAs, along with how much to take, safety considerations, and potential side effects.
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Benefits of Branched-Chain Amino Acids (BCAAs)
BCAAs are best known for their role in protein metabolism (how the body creates and breaks down protein for use). Unlike other amino acids, the liver can’t break them down.
Many people take BCAAs for muscle health and performance. BCAAs may also prevent muscle fatigue during exercise and reduce complications of liver disease.
1. Promote Muscle Growth
To gain muscle, your body needs to build protein faster than it breaks it down. That’s why protein powders are so popular with weightlifters. BCAAs are thought to play a special role in muscle growth. Leucine in particular is known to promote muscle growth.
One small study found that all essential amino acids are key for activating mTORC1—a group of proteins that controls protein synthesis (how cells make proteins). However, BCAAs might be mainly responsible for protein synthesis.
You need to consume all types of essential amino acids for muscle growth to occur. This is why consuming enough protein overall is more beneficial for muscle growth than supplementing with BCAAs alone. The International Society of Sports Nutrition (ISSN) recommends focusing on your overall intake of essential amino acids.
Older adults are the exception because they often struggle to consume enough protein, specifically the amino acid leucine. One study found that pairing BCAAs with vitamin D may help increase muscle strength in older adults who don't consume enough calories or who have sarcopenia. Sarcopenia is a continual loss of muscle mass and strength. It usually develops due to the natural aging process.
2. Prevent Muscle Breakdown
Muscle breakdown is common in older adults. It's sometimes diagnosed as sarcopenia, which is linked with health outcomes like:
Falls and fractures
Complications after surgery
Metabolic disorders (conditions, like diabetes, that disrupt metabolism, or how your body produces energy from the food you eat)
Consuming enough essential amino acids and doing resistance exercises can help prevent and treat muscle breakdown in older adults. Resistance exercises focus on increasing strength and endurance using resistance like weights or bands.
BCAA breakdown is a common feature of conditions that lead to muscle atrophy (loss). Supplementing with BCAAs, particularly leucine, may help prevent muscle breakdown in people with conditions like cancer or cirrhosis (a condition that causes extreme scarring and damage to the liver).
3. Prevent Fatigue During Exercise
BCAAs compete with other amino acids for transport to the brain, including tryptophan. Tryptophan is an amino acid that gets converted to the hormone serotonin. Serotonin is linked with fatigue. Consuming BCAAs right before or during exercise may lead to reduced fatigue during exercise since it limits how much tryptophan makes it to your brain and gets converted to serotonin.
4. Prevent Muscle Soreness
Numerous research reviews have found that oral (by mouth) supplementation of BCAAs leads to reduced muscle soreness, particularly in resistance athletes like weightlifters. Signs of muscle damage and reports of muscle soreness up to 48 hours after exercise were lower in participants who took BCAA supplements compared to those who didn't.
The studies in these reviews had many variations in terms of supplement timing and dosage. Some supplements also contained other amino acids or carbohydrates, so it's unclear whether the benefits were solely due to BCAAs. Researchers also wonder if leucine is more responsible for these muscular benefits than all three BCAAs combined.
5. May Reduce Complications of Liver Disease
People with cirrhosis typically have more BCAAs than aromatic amino acids (AAAs) in their blood. AAAs are essential amino acids that include tryptophan, phenylalanine, and tyrosine. A higher level of BCAAs increases the risk of muscle wasting and hepatic encephalopathy—a dangerous buildup of toxins in the brain due to improper blood filtering by the liver.
Supplementing with BCAAs can help reduce cachexia, a condition that causes muscles to waste away. It also normalizes the ratio of BCAAs to AAAs. This may help prevent hepatic encephalopathy. It may also improve immune function and glucose (sugar) metabolism as well as reduce fatigue in people who have cirrhosis.
Researchers need to continue evaluating the potential risks of BCAA supplementation in people with cirrhosis before it becomes a more routine recommendation.
Related: The Best Foods You Can Eat For A Healthy Liver
How To Take BCAA
BCAAs supplements are often found in powdered form, similar to other protein powders. You simply mix them with your favorite water or other beverage according to the manufacturer's instructions. You can also find BCAAs in capsule form, which are typically best taken with a meal.
Most people take BCAAs before or after a workout, or before bed. You may see improvements in muscle soreness in the day or two following your workout.
You can also find BCAAs in protein-rich foods like chicken, beef, fish, eggs, and dairy products. If you're already consuming adequate BCAAs from food, you may not see a big difference from BCAA supplementation.
Dosage
The recommended dietary allowances (RDAs) for BCAAs vary based on your age and whether you’re pregnant or lactating. It’s also important to note that these RDAs are for your overall intake of these amino acids, not specifically from supplementation.
The RDAs are in the form of milligrams per kilogram of body weight per day (mg/kg/day), so the number of recommended grams depends on your weight. One pound (lb) equals 2.2 kilograms.
Here are the RDAs for adults aged 19 and older:
Leucine: 42 mg/kg
Isoleucine: 19 mg/kg
Valine: 24 mg/kg
Here are the RDAs if you’re pregnant or lactating
Leucine: 56 mg/kg if pregnant, 62 mg/kg if lactating
Isoleucine: 25 mg/kg, 30 mg/kg if lactating
Valine: 31 mg/kg, 35 mg/kg if lactating
A common dose of BCAA supplements is 5–20 grams (g) per day, although some studies have used far higher doses.
Are BCAAs Safe?
Consuming moderate amounts of BCAAs from protein-rich foods or supplements is generally safe for most people. However, people with diabetes or preexisting mental health conditions may need to be careful about taking BCAA supplements.
People with diabetes tend to have higher blood levels of BCAAs. Researchers believe BCAAs may increase insulin resistance (when your body can't produce insulin and use sugar for energy). Therefore, people with diabetes should generally not take BCAA supplements, as they may worsen blood sugar control.
Excess BCAAs may also increase symptoms of mental health conditions. BCAAs compete with other amino acids that help produce important neurotransmitters. Neurotransmitters are molecules that communicate messages to the brain. They help control psychological functions like learning, behavior, and emotions.
People who have maple syrup urine disease (MSUD) should also avoid BCAAs. Maple syrup urine disease is a rare condition in which your body can't break down certain amino acids.
Pregnant or breastfeeding individuals should generally avoid BCAA supplements because their safety in these populations has not been evaluated.
Potential Drug Interactions
Certain drugs may interact with BCAA supplements, including:
Antidiabetic drugs: BCAA supplements may alter insulin resistance, which might interact with diabetes medications that work to improve insulin resistance.
Steroids: Steroids can also alter insulin resistance, so pairing them with BCAAs may cause further blood sugar changes.
Levodopa (L-dopa): This drug is used to increase dopamine levels in people with Parkinson's disease. Parkinson's disease is a progressive neurological disorder that affects motor function due to decreased levels of dopamine. Excess BCAAs might also alter dopamine levels, so there may be harmful interactions.
This list may not be exhaustive since there isn't much research on BCAA drug interactions. Always talk to your healthcare provider before trying any new dietary supplements. They will advise you on the safest supplement and dosage for your situation.
What To Look For
Supplements are not inspected by the FDA, so look for brands that submit their products for third-party testing. This can help ensure product quality and potency (strength), especially because untested BCAA supplements may be contaminated with anabolic steroids. Reputable third-party testers include the U.S. Pharmacopeia (USP) and the National Sanitation Foundation (NSF).
When in doubt, choose reputable brands and always speak with a healthcare provider before starting a new supplement—especially if you have a medical condition, are pregnant or breastfeeding, or take prescription medications.
Can You Take Too Much BCAA?
Taking too much of a BCAA supplement might lead to unpleasant side effects. More serious possible side effects include dangerous blood levels of a waste product called ammonia or even neurological issues.
The proposed tolerable upper intake level (UL) for leucine is 500 mg/kg per day. There are no tolerable upper intake levels for isoleucine or valine.
Side Effects of BCAA
The most common side effects of BCAA supplements are nausea, stomach discomfort, and decreased appetite. Some researchers also believe that they increase insulin resistance.
Consuming excess BCAAs may cause or increase neurological and psychiatric symptoms. BCAAs compete with other amino acids for transport to the brain. This limits the ability of those amino acids to produce dopamine, norepinephrine, histamine, and serotonin. These neurotransmitters play important roles in mental functioning and mood.
A Quick Review
BCAAs are popular for muscle growth, but they may be more effective at preventing muscle breakdown, soreness, and fatigue. If muscle growth is your goal, eating enough essential amino acids through your diet and doing resistance training will likely be more effective than supplementing with BCAAs.
BCAAs can affect insulin resistance and certain neurotransmitters that play key roles in brain functioning. Always talk to your healthcare provider before trying a BCAA supplement, especially if you're pregnant or on diabetes medication, or if you have a mental health condition.
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