Protein supplements are commonly used by people as
part of a fitness program, and indeed there is good
reason to do so. In fact, protein is one of the most
important substances for the maintenance of good health
and vitality. It is of primary importance in the growth and
development of all body tissues including muscles, blood,
skin, hair, nails and internal organs. Protein is also needed
for the formation of hormones, enzymes and antibodies. In
addition to being the major source of building materials for
the body, protein may be used as a source of heat and energy.
Each gram of protein provides four calories. This energy
function of protein is spared when sufficient fats and carbohydrates
are present in the diet.1 While any protein source
can serve these functions, whey protein provides distinct
advantages as a source of supplemental protein.
WHEY PROTEIN IN GENERAL
Whey, a by-product of cheese manufacturing, contains proteins.
These include alpha-lactalbumin, beta-lactoglobulin,
lactoferrin, serum albumin, lysozyme, and immunoglobulins
A, G, and M2 and relatively large amounts of the amino
acid cysteine.3 Whey also contains carbohydrates, primarily
lactose, and the minerals calcium, sodium, phosphorus,
and potassium.4
Whey protein is derived from whey and tends to provide
a higher concentration of essential amino acids than other
protein sources.5 Also, whey protein typically contains 24
percent branched chain amino acids, which are readily oxidized
as an energy source during stress. In addition, whey
protein is also a source of cysteine, a precursor to the vital
intracellular antioxidant glutathione (GSH),6 which is depleted
by oxidative stress, which occurs during exercise, infections,
trauma, or major surgery.7 In fact, some researchers
think that whey protein may help play a role in cancer
prevention by providing GSH precursors and increasing
levels of GSH in the tissues.8 This is consistent with animal
research showing that protein from whey may protect
against certain cancers.9,10,11
Whey protein varies in the immunoglobulins and other
proteins present, depending on the processing method
used to produce the final form of whey protein.12 These
forms include whey protein isolate, whey protein concentrate,
and hydrolyzed whey protein. This article will focus
on whey protein isolate.
WHEY PROTEIN ISOLATE
Arguably, the best way to process whey protein isolate (WPI)
is via cross-flow ultrafiltration. This process preserves protein
microfractions and separates the protein from whey
without the use of heat or damaging chemicals. As a result
WPI is virtually fat and lactose free, is extremely digestible,
and has a good taste. WPI does not tend to cause gas,
bloating or other gastrointestinal distress.13 Furthermore
whey protein isolate is easily digested and absorbed, and
has received the highest score (1.14) of any protein tested
according to the Protein Digestibility Corrected Amino Acid
Score (PDCAAS), the preferred method for evaluating protein
quality.14
WPI AND BODYBUILDING
Clinical research shows that taking 1.2–1.5 grams WPI
per kilogram of body weight, per day in combination with
strength training for 6–10 weeks increased lean body mass,
strength, and muscle hypertrophy compared to placebo.
15,16,17 In one double-blind study,18 recreational bodybuilders
supplemented their normal diet with WPI (1.5 grams per
kilogram of body weight, per day) or another protein for 10
weeks. The results were that the WPI group experienced a
significant gain in lean mass compared to the other protein
group (11 lbs versus 1.76 lbs) and a significant reduction in
fat mass compared to the other protein group (-3.3 lbs versus
+0.44 lbs). The bodybuilders also achieved significant
improvements in strength.
WPI supplementation also results in higher blood
amino acid concentrations compared to some other protein
sources. This results in greater stimulation of protein
synthesis,19 thus providing the foundations for preservation
and production of muscle mass. Several studies involving
supplementation with whey protein have been shown to be
effective in augmenting the effects of resistance exercise,
particularly when supplementation occurs in the hours surrounding
the exercise training.20 Research in healthy volunteers
showed that consuming 10 grams WPI following exercise
can stimulate muscle protein synthesis, which could
potentially lead to increased muscle hypertrophy.21 Research
also shows that men who ingest 45 grams of WPI had significantly
increased levels of insulin. In research, WPI increased
insulin secretion to a greater extent than HWP.22
WPI AND FAT LOSS
WPI and one of its components, glycomacropeptide (GMP),
were fed to a group of rats, while other rats received a standard
diet. The results were that body-weight gain was 21
percent lower on the WPI diet. GMP has an effect of reducing
fat mass and insulin levels.23 A meal replacement drink
containing 15 grams of WPI enriched with GMP (GMP-WPI)
was given to 72 participants, twice daily for 12 months. The
results were that the participants lost fat weight, and decreased
total and LDL cholesterol, triglycerides, glucose,
insulin, and blood pressure.24 One reason that WPI may be
effective for fat loss is that it is better at creating a sense of
fullness than other types of protein types. In research, feelings
of fullness were greater after consuming WPI.25
WPI AND GSH
Thirty-one healthy subjects given WPI produced increased
levels of GSH. Those who ingested 45 grams daily of WPI
had the highest increase in GSH, 24 percent.26 This increase
in GSH may be part of the reason that, in other research,
WPI enhanced the ability of a chemotherapy drug to destroy
cancer cells.27
WHO NEEDS SUPPLEMENTAL PROTEIN?
While everyone needs protein, there are specific population
groups that could benefit by supplemental protein. In addition
to athletes/bodybuilders (as previously discussed),
this includes pregnant women, those who have undergone
bariatric surgery, young children who are picky eaters, some
adolescent girls and older adults.
PREGNANT WOMEN
The protein RDA for women is 46 grams per day. The protein
RDA for pregnant women is 71 grams per day. That’s
25 grams more per day than non-pregnant women.28 Since
pregnancy is often associated with indigestion and heartburn,
29 it may make sense to supplement protein intake
with an easily digested protein such as WPI.
BARIATRIC SURGERY PATIENTS
Individuals who have undergone bariatric surgery often experience
a reduction in protein intake.30,31 This is problematic
since increasing protein intake to at least 60 grams per
day is recommended to help those who have undergone bariatric
surgery retain more lean mass (i.e., Muscle).32,33 Given
that bariatric surgery may be associated with digestion and
absorption issues (i.e., gastric dumping syndrome),34 the
use of an easily digested protein such as WPI makes sense
for supplementing protein intake.
CHILDREN WHO ARE PICKY EATERS
Research35 has shown that children who are picky eaters
are more likely to consume less than the recommended
amounts of protein (i.e., meat and alternatives) as well
as fruit and vegetables. Furthermore, research36 has also
shown that some top sources of protein for children include
pizza, beef and burgers, which often contribute substantial
saturated fat. WPI is a healthy, low-fat option for supplementing
protein intake in children.
ADOLESCENT GIRLS
According to the National Health and Nutrition Examination
Survey,37 7.7 percent of adolescent females consume
protein levels below their estimated average requirement.
While the reasons for this are not clear, protein supplementation
may have value
.
OLDER ADULTS
Muscle mass and function is progressively lost with aging,
so that by the age of 60 many individuals have reached a
threshold where function begins to be affected. Increasing
protein intake may help. Dietary protein intake helps stimulates
muscle protein synthesis and may lead to improved
muscle mass, strength and function over time, which in
turn may help improve health outcomes in older individuals.
Some researchers suggest that the optimal protein intake
for an older individual is greater than the RDA.38 Since
protein intake tends to decline with age, especially among
7.2–8.6 percent of older women consuming protein levels
below their estimated average requirement,39 this suggestion
has merit.
CONCLUSION
Protein is important for multiple functions in the body, not
the least the repair growth of muscles. As a supplemental
source, whey protein offers several advantages and has significant
research to support its use.
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