BCAA's: What you need to know!
The inside scoop on BCAA'sby John Gunstream, MSc.Branched chain amino acids (BCAAs) may improve athletic
performance, increase anabolic hormone levels and slow the breakdown
of protein. Therefore, BCAAs may be one of the most beneficial
supplements (actually food) a bodybuilder or athlete can take. The
BCAAs are three amino acids (AAs) named leucine, isoleucine and valine
commonly found in proteins. They are referred to as BCAAs because the
carbon atoms in these three AAs are not arranged in a straight line,
instead they branch out. All three of these AAs are essential for
human health meaning that the human body can't make these AAs so they
must be consumed in the diet.
Several studies have looked at the effects of supplementing the
diet with excess BCAAs to determine if there are any benefits for
exercising athletes. It is known that high levels of BCAAs in the
blood can reduce the amount of serotonin (a neurotransmitter used by
the brain) in the brain. Researchers also have found a link between
serotonin and its ability to cause fatigue including a decrease in
muscle power output1, 2, 3, 4. So, researchers hoped to delay the
onset of fatigue and improve athletic performance by supplementing the
diet of athletes with excess BCAAs5. One study found that consuming a
drink during game time which contained 10 grams of BCAAs improved
alertness and mental performance in a group of soccer players6.
However, a follow-up study found that as much as 18 grams of BCAAs did
not delay the amount of time to fatigue while riding exercise cycles7.
These conflicting results make it difficult to determine if BCAAs can
influence fatigue and indicate that more studies need to be done on
this issue.
Researchers have looked at other effects of BCAAs than simply
fatigue. Several studies showed some very interesting results from
BCAA supplementation. One study found that marathon runners, who must
certainly be the most catabolic of all athletes, had significantly
higher insulin and testosterone when supplementing with 10 grams of
BCAAs8. This result suggests that BCAAs may reduce some of the
catabolic effects associated with intense exercise.
Several promising studies have shown that BCAAs have the ability
to reduce or limit protein breakdown. First of all, supplementation
with BCAAs stimulates insulin secretion9, 10, 11, 12 13, 14, 15. As
little as 800 mg of each of the three BCAAs have been shown to
increase insulin levels 10 fold, with larger amounts of BCAAs causing
far greater increases. This insulin increase will likely inhibit much
of the breakdown of protein which often occurs in muscle cells during
prolonged exercise. So, BCAAs may be able to reduce overtraining
syndrome which is often associated with long duration or intense
workouts. In addition, supplementation with BCAAs have been shown to
suppress the use of amino acids for energy16. If the AAs are not used
for energy, then they are more likely to be retained within the muscle
rather than burned for fuel. Other studies looked at the effect of
BCAAs on swimmers who were in an overtrained state17, 18. Those
swimmers who supplemented with 2.175 grams of BCAAs were less likely
to be in an overtrained state based on several parameters including
lower cortisol, an increase in lean body weight while body fat was
lost, and possibly an enhanced immunity to infection. Another study
found that the protein breakdown that is often associated with hiking
at high altitudes was decreased following supplementation with
BCAAs19. Those receiving the BCAA supplement consumed 5.76 grams of
leucine per day, 2.88 grams of valine per day and 2.88 grams of
Isoleucine per day resulting in a 1.5% gain in lean body mass and a
11.7% decrease in body fat while the placebo group lost both muscle
and fat which is most common for people in catabolic states. One very
interesting study20 looked at protein breakdown where one group of
subjects received supplemental BCAAs while the control group received
supplementation with an equivalent amount of three different essential
AAs (threonine, methionine, and histidine). The researchers found
that the essential AAs increased proteolysis (protein breakdown) by
36% while the BCAAs did not increase proteolysis. Another measure of
proteolysis indicated that BCAAs were 5% better at sparing lean body
mass than the other three essential AAs. Typically, proteins will be
broken down from other regions of the body first, sparing muscle
proteins during exercise. However, BCAAs were able to reduce this
catabolic state. Another study21 found that supplementation with 77
mg/kg (7.7 grams for a 100 kg person) of BCAAs 20 minutes before
exercise results in better nitrogen (AA) retention in muscle and that
BCAAs block the breakdown of muscle proteins. All of these results
are very positive for any athlete hoping to maintain an anabolic,
growing and healthy state while avoiding a catabolic state of
overtraining that can lead to the loss of lean body mass.
What do these results tell us about the biochemical effects of
BCAA supplementation? During exercise, the BCAAs are taken up by
muscle cells to produce more energy. These BCAAs are taken from
proteins in other regions of the body so that the muscles can continue
to work. This loss of BCAAs from other tissues causes a very
catabolic and stressful condition, especially for the immune system.
Supplementing with excess BCAAs can reduce this catabolic and
stressful situation. A further anticatabolic effect is seen in the
hormonal patterns following BCAA supplementation. Some athletes have
shown elevated testosterone levels following BCAA supplementation. It
is also known that BCAAs cause a large insulin response, even larger
than carbohydrates in some situations. These hormonal effects should
also provide a nice anticatabolic effect for a hard-working athlete.
In addition, some studies have found enhanced athletic performance in
endurance athletes following BCAA supplementation. However, these
studies are very preliminary and will require further replication.
Other unknown biochemical mechanisms may play a role in the
anticatabolic effects of BCAAs. Some researchers speculate that some
of the anticatabolic effects of the BCAA leucine actually result from
a breakdown product of leucine which is known as HMB. This is one of
the hottest supplements on the market and its full name is
Beta-hydroxy Beta-methyl glutarylCoA. People are excited about this
product because of a recent study22 showing an increase in lower body
strength and an increase in lean body mass following use of as much as
3 grams of HMB per day. The gains seen were above and beyond a
control group that received a placebo. However, other researchers
will have to replicate this work before it can be asserted that the
anticatabolic effects of BCAAs are brought about by this breakdown
product of leucine. At the present time there is far more research
supporting supplementation with BCAAs than for use of HMB.
BCAAs are found in all animal protein sources with milk being one
of the best natural sources of BCAAs. Whey protein is very high in
BCAAs and is one of the major reasons that athletes prefer
supplementing with whey protein. Whey is a watery part of milk that
separates out as the milk sours and thickens (don't try this at home).
Whey protein is found in cottage cheese along with other milk
proteins. In addition, many companies produce whey protein powders
that can be mixed with water or milk.
In all of these studies the amount of supplemental BCAAs ingested
ranged from 2.2 grams to 18 grams per day. These are BCAAs consumed
above and beyond those obtained from dietary sources and they were
usually consumed all at once or during exercise. In addition to the
BCAAs obtained from dietary sources, athletes would benefit by taking
an additional 10 grams of BCAAs each day. The ratios of the three
BCAAs averaged 40% leucine, 30% valine and 30% isoleucine across all
these studies. There is general agreement that leucine is more
important than the other two, but this does not negate their
importance either. Studies looking at leucine alone and valine alone
have found similar effects on hormonal profiles. More studies are
necessary to determine the importance of each individual amino acid.
Even though the most appropriate ratio of the BCAAs is unknown
athletes would do well to take them in the 40:30:30 ratio. Animal
proteins are typically 15% BCAAs while whey protein is composed of 30%
BCAAs. For those athletes who are prone to store body fat, they
should consume their supplemental BCAAs with other protein sources, or
as a component of whey protein to minimize the effects of insulin.
Those athletes who find it difficult to put on any mass (fat or
muscle) should consume their BCAAs either alone or with a small
quantity of carbohydrates to maximize the effects of insulin. The
BCAAs can be consumed during or prior to exercise.
Every athlete should pay attention to the quantity of BCAAs in
their diet. BCAAs are a simple and effective way to gain an
anticatabolic edge in the fight for muscle growth and improved
strength.
References:
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1988
2. Newshoolme et al., Medical Sports Science Vol. 32: 79-93, 1991
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Edinburgh, 1987
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