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BCAA Benefits: A Review of Branched-Chain Amino Acids

Branched-chain amino acids (BCAAs) are a group of three
essential amino acids: leucine, isoleucine and valine.

BCAA supplements are commonly taken in order to boost musle
growth and enhance exercise performance. They may also help
with weight loss and reduce fatigue after exercise.

This article contains all the most important information about
branched-chain amino acids and their benefits.

What Are BCAAs?

BCAAs consist of three essential amino acids:

  • Leucine
  • Isoleucine
  • Valine

These amino acids are grouped together because they are the
only three amino acid to have a chain that branches off to one
side.

Their molecular structure looks like this:

Branched Chain Chemical Structure

Image Source: Bodybuilding.com

Like all amino acids, BCAAs are building blocks your body uses
to make proteins.

BCAAs are considered essential because, unlike non-essential
amino acids, your body cannot make them. Therefore, it is
essential to get them from your diet.

Bottom Line: The three BCAAs are leucine,
isoleucine and valine. All have a branched molecular
structure and are considered essential to the human body.

How Do Branched-Chain Amino Acids Work?

BCAAs make up a large chunk of the body’s total amino acid
pool.

Together, they represent around 35–40% of all essential amino
acids present in your body and 14–18% of those found in your
muscles (1).

Contrary to most other amino acids, BCAAs are mostly broken
down in the muscle, rather than in the liver. Because of this,
they are thought to play a role in energy production during
exercise (2).

BCAAs play several other roles in your body too.

First, your body can use them as building blocks for protein
and muscle (3, 4, 5).

They may also be involved in regulating your blood
sugar levels
by preserving liver and muscle sugar stores
and stimulating your cells to take in sugar from your
bloodstream (6, 7, 8, 9).

What’s more, BCAAs may help reduce the fatigue you feel during
exercise by reducing the production of serotonin in your brain
(10).

Out of the three, leucine is thought have the biggest impact on
your body’s capacity to build muscle proteins (3).

Meanwhile, isoleucine and valine seem more effective at
producing energy and regulating your blood sugar levels
(6, 11).

Bottom Line: Your body can use BCAAs to
build muscle protein and produce energy. They may also have
an effect on your brain that reduces fatigue.

BCAAs May Reduce Fatigue During Exercise

Consuming BCAAs may help reduce physical and mental fatigue.

Studies in human participants report up to 15% less fatigue in
those given BCAAs during exercise, compared to those who were
given a placebo (12, 13).

In one study, this increased resistance to fatigue helped the
BCAA group exercise for 17% longer before reaching exhaustion,
compared to the placebo group (11).

In another study, participants were put under heat stress
during a cycling test. They were asked to ingest either a drink
containing BCAAs or a placebo. Those who drank the BCAA drink
cycled for 12% longer than the placebo group (14).

However, not all studies found that decreased fatigue caused
improvements in physical performance (12, 13, 15, 16, 17).

In addition, BCAAs may be more effective at reducing exercise
fatigue in untrained compared to trained individuals (18).

Bottom Line: In some people, BCAAs may help
reduce exercise fatigue. Whether this improves exercise
performance is still up for debate.

BCAA Supplements Reduce Muscle Soreness

BCAAs may also help your muscles feel less sore after exercise.

One way they may do so is by lowering blood levels of the
enzymes creatine kinase and lactate dehydrogenase, which are involved in
muscle damage. This may improve recovery and provide some
protection against muscle damage (19).

Various studies asked participants to rate their muscle
soreness levels after performing certain strength-training
exercises.

Participants who were given BCAA supplements rated their muscle
soreness levels as much as 33% lower than those given a placebo
(20, 21, 22).

In some cases, those given BCAAs also performed up to 20%
better when they repeated the same strength-training tests
24–48 hours later (21, 23).

However, effects may vary based on your gender or the total
protein content of your diet (20, 24).

Bottom Line: BCAAs taken before or after
strength training may reduce muscle soreness following your
workout. However, the effects may vary from one person to
another.

BCAAs May Increase Muscle Mass

Muscular Man in Tank Top With Shake

Many people who purchase BCAA supplements do so to increase
their muscle mass.

After all, research shows that BCAAs do activate enzymes
responsible for building muscle (5).

Some studies also show that BCAA supplements may be effective
at increasing muscle mass, especially if they contain a higher
proportion of leucine than isoleucine and valine (25, 26).

However, there’s currently no evidence that getting your BCAAs
from a supplement is any more beneficial than getting them from
your diet or from a less-expensive
whey
or soy protein supplement.

In fact, studies show that taking supplements with whole
protein may, at least in some cases, be better for muscle
growth than taking supplements with individual amino acids
(27).

Bottom Line: Getting enough BCAAs is likely
to boost muscle growth. You can get them from high-protein
foods in your diet or through supplements.

BCAAs May Lower Blood Sugar Levels

BCAAs may also help maintain normal blood sugar levels.

Leucine and isoleucine are thought to increase insulin
secretion and cause your muscles to take in more sugar from
your blood, thereby decreasing your blood sugar levels
(6, 28, 29).

However, in practice, not all studies back up these effects
(30, 31, 32).

In fact, some even report potential rises in blood sugar
levels, depending on the type of diet participants followed.
For instance, when BCAAs are combined with a high-fat diet,
consuming them in supplement form may lead to insulin
resistance (33, 34).

That said, many of these studies were done on animals or cells,
which means that their results may not be totally applicable to
humans.

In humans, effects also seem to vary between participants.

For example, one recent study gave participants with liver
disease 12.5 grams of BCAAs three times per day. In 10
participants, blood sugar levels were reduced, while 17
participants experienced no effects (35).

Therefore, more studies are needed before strong conclusions
can be drawn.

Bottom Line: BCAAs may help promote blood
sugar control, at least in some cases. However, more studies
are needed to confirm their effects.

BCAAs May Enhance Weight Loss

Branched-chain amino acids may help prevent weight gain and
enhance fat loss.

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In fact, observational studies report that those consuming an
average of 15 grams of BCAAs from their diet each day may have
up to 30% lower risk of becoming overweight or obese than those
consuming an average of 12 grams per day (36, 37).

However, it’s worth noting that those consuming fewer BCAAs
also consumed around 20 fewer grams of total protein per day,
which may have influenced results.

If you’re attempting to lose weight, BCAAs may help your body
get rid of unwanted fat more effectively.

Competitive wrestlers consuming a high-protein,
calorie-restricted diet supplemented with BCAAs lost 3.5 more
pounds (1.6 kg) than those given a soy protein supplement over
the 19-day study period (38).

The BCAA group also lost 0.6% more body fat than the soy
protein group, despite consuming equivalent calories and
slightly less total protein each day (38).

In another study, weightlifters given 14 grams of BCAAs per day
lost 1% more body fat over the eight-week study period than
those given 28 grams of whey protein per day. The BCAA group
also gained 4.4 lbs (2 kg) more muscle (39).

That said, these two studies have some flaws. For instance,
they provide little information about the composition of the
supplement and of the diet followed, which could have
influenced the outcomes.

What’s more, studies examining the effects of BCAAs on weight
loss show inconsistent results (40).

Bottom Line: BCAAs may help prevent weight
gain and enhance weight loss. However, more research is
needed to determine whether supplements provide any added
benefits over a high-protein diet.

BCAAs May Reduce Complications in Liver Disease

BCAAs may help reduce complications linked to liver failure.

One possible complication is hepatic encephalopathy (HE), which can lead to
confusion, loss of consciousness and coma.

A recent review suggests that in patients with liver disease,
BCAA supplements may be more beneficial than other supplements
at reducing the severity of HE (41).

However, BCAAs did not improve overall survival rate, nor did
they lower the risk of other complications, such infections and
gastric bleeding (41).

Another recent review of studies in patients undergoing liver
surgery reported that BCAA-enriched solutions may help improve
liver function, reduce the risk of complications and decrease
the duration of hospital stay (42).

BCAA supplements may also be effective at reducing fatigue and
improving weakness, sleep
quality
and muscle cramps in individuals with liver disease
(43).

In cases of liver cancer, taking BCAA supplements may help
reduce water retention and decrease the risk of premature death
by up to 7% (44).

Bottom Line: BCAA supplements may be
effective at improving liver function and decreasing the risk
of complications in individuals who have liver disease.

Dosage Instructions

If you’d like to start supplementing with branched-chain amino
acids, how much you should take will depend on your individual
needs and goals.

A World Health Organization report from 1985 states that the
average adult should consume a minimum of 15 mg of BCAAs per
pound (34 mg/kg) of body weight each day (45).

However, according to more recent research, the daily
requirements may actually be as high as 65 mg/lb (144 mg/kg) of
body weight per day (1, 46).

Based on these newer studies, healthy adults should aim to
consume:

  • Women: A minimum of 9 grams of BCAAs per
    day.
  • Men: A minimum of 12 grams of BCAAs per day.

People who include sufficient
protein-rich foods
in their diets most likely do not need
to take supplements.

However, daily requirements may be slightly higher for athletes
and people doing heavy resistance training. In these cases,
supplements may be beneficial.

Most of the studies observing the benefits in trained
individuals used supplement doses ranging from 10–20 grams of
BCAAs per day.

The best time to take BCAA supplements is before and/or after
your workout. Many people who are trying to gain muscle also
take them in the morning and before bed.

However, whether the exact timing makes a big difference for
this has not been studied properly.

Bottom Line: Average daily intakes of 5–12
grams of BCAAs are probably sufficient for most people, and
can be easily met through diet alone. Athletes may benefit
from supplements with 10–20 grams of BCAAs per day.

Top Food Sources

Luckily, there’s a large variety of foods that contain BCAAs.
Those with the highest amounts include (47):

  • Meat, poultry and fish: 3–4.5 grams per 3 oz
    (84 grams).
  • Beans and lentils: 2.5–3 grams per cup.
  • Milk: 2 grams per cup (237 ml).
  • Tofu and tempeh: 0.9 to 2.3 grams per 3 oz
    (84 grams).
  • Cheese: 1.4 grams per 1 oz (28 grams).
  • Eggs: 1.3 grams per large egg.
  • Pumpkin seeds: About 1 gram per 1 oz (28
    grams).
  • Quinoa: 1 gram per cup.
  • Nuts: 0.7–1 gram per 1 oz (28 grams),
    depending on the variety.

Bottom Line: Adding foods from the list
above to your diet will help you increase the amount of BCAAs
you get each day.

Safety and Side Effects

Taking BCAA supplements is generally safe and without side
effects for most people.

Studies on the safe upper intake levels of BCAAs are rare, but
studies report that total BCAA intakes between 15–35 grams per
day seem generally safe (1, 48).

However, BCAA supplements are not recommended for those
suffering from ALS, also known as Lou Gehrig’s disease
(49).

In addition, individuals with a rare congenital disorder called
maple syrup urine disease should limit
their intake of BCAAs because their bodies cannot break them
down properly (50).

Bottom Line: BCAA intakes of 15–35 grams per
day are considered safe for most people. However, those with
ALS or maple syrup urine disease should limit their intakes.

Take Home Message

Branched-chain amino acid supplements may provide impressive
benefits in certain circumstances, especially when it comes to
muscle growth and physical performance.

However, BCAAs can also be found in whole protein supplements
as well as in a large variety of protein-rich foods.

Therefore, taking BCAA supplements may not be necessary,
especially if you get sufficient amounts through your diet or a
protein supplement.

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