Muscle & Fitness UK – July 2019

JULY 2019/MUSCLE & FITNESS 67

CH 3

NH 2

NH 2

NH 2

CH 3

CH 3

CH 3

CH 3

CH 3 — CH 2

CH— CH 2 — CH— COOH Leucine

Isoleucine

Valine

CH— CH— COOH

CH— CH— COOH

Figure 2. Chemical structure of BCAAs

taken from (3)

Figure 3. List of biological values of

goods taken from http://www.food-info.

net/uk/protein/bv.htm

AMINO-ACIDS

There are known to be a total of 20-22

amino acids (this is currently disputed)

and from these 20-22 amino acids, there

are thousands of varying polypeptide

chain combinations that produce

different proteins for different roles.

These amino acids can be categorised

into 2 categories;

NON- ESSENTIAL – Our body can

produce these

ESSENTIAL (EAAS) (N=9) - Our body

cannot produce these

There are 9 EAAs that must be provided

by our daily nutrition as our body cannot

produce them internally. To help identify

what sources best achieve this, a

biological index (BV) (see figure 3) was

produced that categorised foods from

0-100 on their usefulness when sourcing

these EAAs.

So how does the body make a new

protein? Well, for protein synthesis to

occur, the body does need all 9 EAAs

and non-essential amino acids. Whilst

mainly sourced from foods, the body can

breakdown its own internal pools of

amino-acids to and use them for

generation of new proteins. Whilst there

are 9 EAAs, research has established 3

main amino acids that are more

important for anabolic production of new

proteins. These 3 amino acids are termed

BCAAs and are;

Leucine- Arguably the most important

for MPS. When ingested in extra

amounts within a mixture of EAAs, it can

affect specific intracellular pathways of

muscle protein synthesis. Specifically, it

can regulate the production of ribosomal

protein S6 Kinase (S6K1) and eukaryotic

initiation factor (eIF)4E-binding protein-1

involved within the mammalian target of

rapamycin complex 1 (mTORC1), the main

pathway associated with muscle protein

synthesis (1).

Isoleucine- important within the

bio-synthesis of proteins and recovery

of muscle fibres.

Valine- Holds a stimulatory effect on

MPS; important for tissue repair and

maintaining nitrogen balance.

Product Biological value

Whole egg 93.7

Milk 84.5

Fish 76.0

Beef 74.3

Soybeans 72.8

Rice, polished 64.0

Wheat, whole 64.0

Corn 60.0

Beans, dry 58.0

MARKETING OF BCAAS & EAAS

Because of the researched importance of

these three BCAAs companies began

marketing them as a singular supplement

to enhance muscle protein synthesis and

claim that BCAA products alone will

provide you with the EAAs needed for

stimulating MPS, producing a net

anabolic state and ultimately increasing

muscular growth and repair (2). The

mechanisms above explain why BCAA

products advertise a ratio of leucine:

isoleucine and valine as 2:1:1 (USN, BSN

& Myprotein BCAA products specifically),

but as useful as BCAAs are marketed to

be - and as we know, all 9 essential

amino acids are needed - can leucine,

isoleucine and valine do the job they’re

marketed to do themselves?

ARE THEY USEFUL?

Given the provided evidence, it could

be assumed that BCAAs are an essential

supplement for aiding with muscle

growth and recovery. However, in certain

scenarios current research has found the

opposite to be true. This is due to the

overlooked fact that a new protein

cannot be formed without all 9 EEA’s,

including the marketed 3 main BCAAs.

Therefore, BCAAs alone cannot provide

the necessary 9 EAAs needed to make a

new protein. Furthermore, it is

established that a high concentration of

leucine can actually be harmful to MPS.

Excess leucine causes an increase in the

oxidation rate of isoleucine and valine
for energy, decreasing their availability
for MPS and subsequently, decreasing
overall production. A recent review of
literature by Wolfe, (2017) suggested that
BCAAs fail to produce an anabolic state
for MPS and in fact promote a catabolic
state, increasing muscle protein
breakdown (MPB).
In studies (n=2) where MPS and
MPB have been measured during a
post-absorptive state of BCAA ingestion
(via oral and intravenous sources), where
participants were within a fasted state
(up to 16 hours), the rate of MPS was
decreased. More proteins were being
broken down to produce the EAAs for
PHOTO CREDIT: OSTOCK new muscles from internal sources that