All About BCAA

by Ryan
Andrews
, December 15th, 2008.

What are branched chain amino acids?

Amino acids are the building blocks of protein. Branched chain amino acids
(BCAAs) are so called because of their structure, which includes a “side chain”
of one carbon atom and three hydrogen atoms. There are three BCAAs: leucine,
isoleucine, and valine. Of these, leucine is the most heavily researched, and
appears to offer the biggest physiological benefit. (More on that below.)
For the science geeks, these hydrophobic (water-fearing) amino acids are
referred to as “aliphatic” (from the Greek aleiphar, or oil), as their
central carbon attaches to a branched non-cyclic, open carbon chain.


BCAA structure. Source: University of
Illinois

BCAAs provide the basis for protein synthesis and energy production (Harper
AE et al 1984; Patti ME et al 1998; Xu G et al 1998; Anthony JC et al 2001). In
fact, BCAAs can comprise up to one-third of muscle protein (Mero 1999). Because
of their prevalence and involvement in protein synthesis and energy production,
BCAAs are important to many metabolic processes.
However, if BCAAs are going to participate in these processes, they must be
available to the body. This means we have to eat enough BCAAs, and at the right
times, to enable such processes to occur.

Why is adequate BCAA intake so important?

The BCAAs are the only amino acids not degraded in the liver. All other amino
acids are regulated by the gut and the liver before being circulated elsewhere
in the body. However, BCAAs head directly into the bloodstream. This means that
dietary intake of BCAAs directly influences plasma levels and concentrations in
muscle tissue (Layman DK 2003). Interestingly, BCAAs are burned for energy
(oxidized) during exercise, so they’re also an important exercise fuel.
Consuming BCAAs before training can increase uptake into muscle tissue
(Mittleman KD et al 1998). This has many benefits:

  1. BCAA supplementation may lower lactate levels after resistance training and
    improve muscular oxidation.
  2. BCAAs may increase growth hormone (GH) circulation, which may be related to
    anabolic mechanisms causing muscle growth (De Palo EF et al 2001).
  3. BCAA supplementation may decrease serum concentrations of the intramuscular
    enzymes creatine kinase and lactate dehydrogenase following prolonged exercise.
    This can decrease muscle damage and improve recovery (Coombes JS, McNaughton LR
    2000).

Muscle is an important site of BCAA activity. There is an increased cell
concentration and breakdown of BCAAs in muscle tissue (Layman DK 2003). BCAAs
are continuously released from the liver and other internal organs to skeletal
muscle so that the BCAAs can assist in maintaining blood sugar levels. Indeed,
BCAAs may be responsible for up to 40% of blood sugar production during exercise
(Ahlborg G et al 1974; Ruberman NB 1975; see also Layman DK 2003).

Glucose production from amino acids. Image from Medscape.com
Glucose production from amino acids. Image from
Medscape.com

What you should know

Because BCAAs are so important to muscle tissue, and because they help
maintain blood sugar levels, it’s important to get enough to support your
workouts. Consuming a carbohydrate, protein, and amino acid beverage during and
after training can induce an insulin response, which helps transport BCAAs into
cells. However, availability of leucine is more important than insulin. Within
the muscle cell there’s one particular regulatory pathway for protein synthesis
that’s stimulated by insulin, but dependent on leucine (Anthony et al 2000). In
other words, protein synthesis (and hence muscle rebuilding) depends on how much
leucine is available. And since BCAA levels decline with exercise, it makes
sense to supplement with them during and/or after workouts (Mero 1999).
Because it’s so important to have leucine available for protein synthesis, if
you train in a fasted state, or don’t eat after exercise, you’re going to lose
more protein than you rebuild. However, if you eat adequate BCAAs during this
time, especially leucine, you’ll enhance protein synthesis.

For extra credit

For the body to make new proteins, it needs an estimated daily leucine intake
of between 1 to 4 grams/day (FAO/WHO/UNU 1985). That minimum intake needs to be
met before leucine will be able to impact the insulin signaling pathway. But
that’s just a baseline. Actual metabolic use, especially by athletes and people
doing heavy resistance training, may be upwards of 12 grams/day.
There is a theory that BCAAs can limit central fatigue with endurance
athletes, but it doesn’t appear to be supported by current data.
BCAA content of foods (grams of
amino acids/100 g of protein)
Whey protein isolate 26%
Milk protein
21%
Muscle protein 18%
Soy protein isolate 18%
Wheat protein 15%
Source: USDA Food Composition Tables

Summary and recommendations

BCAAs play an important role in:

  • Synthesis of proteins in general
  • Glucose homeostasis (i.e. keeping blood sugar levels constant)
  • Direct regulation of muscle protein synthesis (via insulin signaling
    cascade)

BCAAs’ potential impact on the aforementioned processes depends upon
availability and dietary intake.
Adequate consumption of BCAAs may help manage body fat, spare muscle mass,
and regulate glucose/insulin balance.

How can you put this knowledge to use?

Try adding BCAAs into your workout drink at a rate of 5 g BCAA per hour of
training.
During periods of lower calorie intake, try adding a BCAA supplement every
2-4 hours during the day.

More reading:

Solving
the Post-Workout Puzzle

Recovery
Update

Advanced
Workout Nutrition: Why Are You Still Drinking Gatorade?

References

Anthony JC, et al. Signaling pathways involved in translational control of
protein synthesis in skeletal muscle by leucine. J Nutr 2001;131:856S-860S.
Anthony JC, et al. Orally administered leucine stimulates protein synthesis
in skeletal muscle of postabsorptive rats in association with increased eIF4F
formation. J Nutr 2000;130:139-145.
Ahlborg G, et al. Substrate turnover during prolonged exercise in man. J Clin
Invest 1974;53:1080-1090.
Coombes JS, McNaughton LR. Effects of branched-chain amino acid
supplementation on serum creatine kinase and lactate dehydrogenase after
prolonged exercise. J Sports Med Phys Fitness 2000;40:240-246.
De Palo EF, et al. Plasma lactate, GH and GH-binding protein levels in
exercise following BCAA supplementation in athletes. Amino Acids
2001;20:1-11.
FAO/WHO/UNU. Energy and protein requirements. Report of joint FAO/WHO/UNU
expert consultation. WHO Tech Pep Ser 1985;724:1-206.
Garlick PJ. The role of leucine in the regulation of protein metabolism. J
Nutr. 2005 Jun;135(6 Suppl):1553S-6S. Review.
Harper AE, et al. Branched-chain amino acid metabolism. Annu Rev Nutr
1984;4:409-454.
Layman DK. The role of leucine in weight loss diets and glucose homeostasis.
J Nutr 2003;133:261S-267S.
Mero A. Leucine supplementation and intensive training. Sports Med
1999;27:347-358.
Mittleman KD, et al. Branched chain amino acids prolong exercise during heat
stress in men and women. Med Sci Sports Exerc 1998;30:83-91.
Patti ME, et al. Bidirectional modulation of insulin action by amino acids. J
Clin Invest 1998;101:1519-1529.
Ruberman NB. Muscle amino acid metabolism and gluconeogenesis. Ann Rev Med
1975;26:245-258.
Xu G, et al. Branched-chain amino acids are essential in the regulation of
PHAS-I and p70 S6 kinase by pancreatic beta cells. J Biol Chem
1998;273:28178-28184.

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About dkpilates

Pilates Instructor, Yoga Instructor, Personnel trainer and Group Fitness Instructor. Don teaches Contemporary and the Authentic forms of Pilates, in the later 90's, Don began his study of Yoga. His study of Yoga includes the Hatha, Iyengar, Bikram, and Astanga disciplines. His other areas of interest in fitness include Martial Arts, Spin, Boot Camp Training, and Weight Training. Don has extensive training and certifications from AFFA, IDEA, MadDog, B-Fit and Polestar. Don Continues his of Pilates education with Michelle Larson in Santa Fe New Mexico. His personal philosophy related to fitness is to aid students in a personalized balance of strength, stamina and flexibility. He is dedicated to design a program specifically for his students independent of the season of their life to create functional movement and help them reach their fitness goals.
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2 Responses to All About BCAA

  1. Pingback: All About Recovery | The Core Matrix

  2. Andreas says:

    Nice information. Keep up the great work

    Nutreas BCAA
    http://www.nutreas.de/shop/de/bcaa.html

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