Revista de Medicina Desportiva (English) July 2018 | Page 22

besides some reports of minimal
gastrointestinal symptoms. 6 To date,
only one case has been reported
that associates the ingestion of
whey and creatine e and cholestatic
liver disease. However, there are no
prior cases documented and the
studies in this field have revealed
liver protection associated with the
consumption of whey. The chronic
intake of creatine, associated with
the continuous supplementation of
whey four weeks before the onset of
symptoms, together with the clinical
improvement after abstinence from
these supplements, were the main
reasons to explain the probable rea-
son to cause this clinical situation. 15
Casein
Casein is the major component
of milk proteins, corresponding to
approximately 80% of its protein
composition. As the whey, casein is
a protein with high biological value
and rich in minerals, like calcium
and phosphorus. The casein exists in
the milk in the form of micelle, which
allows it to form a kind of gel or clot
in the stomach. This characteristic
guarantees its efficiency on the nutri-
ent supply, since the clot allows a
sustained and gradual release of the
amino acids to the systemic circula-
tion for several hours, which guar-
antees better use by the body and
greater nitrogenous retention. 16.17
a) Types of supplements
• Casein micellar
• Calcium caseinate
• Isolated
• Concentrated
• Hydrolyzed.
b) Functions
Scientific studies showed that sup-
plementation with casein enhances
maintenance and the muscle mass
formation. 18,19 In 2011, a clinical
trial on supplementation with whey
comparing with casein, on a 1 st divi-
sion Brazilian football team, found
an increase in muscle mass in the
casein group, without changes in
the group that ingested whey. 18 Due
to its high content in branched-chain
amino acids, casein is a strong
ally for the repair and recovery of
miofibrilares lesions resulting from
20 july 2018 www.revdesportiva.pt
physical exercise. 11 Because it is a
slow absorption protein, the casein
holds a strong satiating power, with
considerable thermogenic effect and
lipid oxidation, characteristics that
justify their inclusion on hypocaloric
diets for weight loss. 19
The main benefit of casein intake
is its ability to inhibit muscular
catabolism, which is about 34%. 20
Although it contributes only moder-
ately to muscular protein synthesis,
due to its strong inhibitory power
of catabolism, casein induces more
muscle mass retention than whey,
after seven hours. 11,20,21 So, feeding or
supplementation with casein before
bedtime reveals an excellent way
to avoid protein degradation and
oxidation of amino acids occurring
during the night fast. 11,22 Accord-
ing to a study with 16 young people,
published in 2012 in Medicine Science
In Sports & Exercise, supplementa-
tion with 40gr of casein, 30 minutes
before bedtime, proved to be effective
in stimulating the muscular protein
synthesis and improving the overall
muscle balance during the night
recovery of the physical exercise. 23,24
c) Clinical applications
Clinical trials with the different
components of casein have been
carried out, revealing favorable
results in the following clinical
applications:
• Increase or maintenance of mus-
cle mass 18
• Prevention of sarcopenia
• Systolic and diastolic blood pres-
sure reduction in patients with
hypertension 25,26
• Prevention and treatment of cog-
nitive decline 26
• Prevention of demineralization
and incidence of tooth caries 27 .
d) Side effects
There are no known side effects
of supplementation with casein.
However, due to its high content
in β-casein, its consumption is not
advised to individuals with milk
intolerance. 28
BCAA
The BCAA (Branched-chain amino
acids) are made up of three essen-
tial amino acids: leucine, valine and
isoleucine. Leucine, in addition to
providing substrate, is a key element
in the initiation of protein synthe-
sis. 6,12,14,22 The BCAA, as opposed to
the other amino acids, have their
metabolism in the tissues other than
in the liver (muscles, brain, kidney,
adipose tissue). They are indispensa-
ble elements in the protein synthesis
and degradation, depending on the
context, they can be substrate for
the neoglicogénese and ensure the
maintenance of the body levels of
glutamate-glutamine. The glutamine
has several functions in the body,
notably protein synthesis, mainte-
nance of kidney acid-base balance,
production of glutathione, removal
of ammonia from tissues, etc. 29
The main functions of the BCAA
are the recovery of micro muscu-
lar lesions induced by the physical
exercise and the prevention of mus-
cular catabolism, reasons for which
the consumption is advised before
and after the workout periods. 30 In
addition to these, there are numer-
ous advantages of supplementation
with BCAA, for example, at the level
of central fatigue. The decrease on
the levels of tryptophan transported
to the brain after supplementa-
tion with BCAA slows the feeling
of fatigue during training, allowing
the increase of the intensity and the
performance. 31,32
The BCAA ingested as supplement
are quickly absorbed by the body.
Since they do not suffer a lengthy
digestion process, they are imme-
diately absorbed by the intestine,
causing rapid rising of the circulat-
ing insulin, which ensures an ana-
bolic effect on the muscular protein
synthesis. 33
a) Components
• L-Leucine
• L-Valine
• L-Isoleucine
b) Presentation
• Capsules
• Liquid
• Powder
c) Functions
The BCAA have a wide range of
actions in the body, highlighting the
following:
• Increase and maintenance of body
muscle mass 33