Nutrition Performance - Colostrum: The Ultimate Source of Protein?
Athletes engaged in heavy training need more protein than sedentary
people.1,2,3 Protein supplements may be a convenient means for some busy
athletes to secure additional protein in the diet. Many of these products contain
high-quality protein, such as milk or egg protein; they provide a balanced
mixture of protein, carbohydrate and fat for additional calories; and they may
also contain supplemental vitamins and minerals. It’s important to emphasize
that these supplements should be used as an adjunct to an otherwise balanced
nutritional plan, not as a substitute.
Milk proteins are commercially available as whole milk proteins,
caseinates and whey proteins. Milk protein is approximately 80 percent
caseinate and 20 percent whey protein. Recently, bovine colostrum protein has
been marketed as an ultimate source of protein for athletes. Colostrum is the
first milk secreted by cows after giving birth and is a rich source of protein,
carbohydrates, fats, vitamins, minerals and biologically active components such
as antimicrobial molecules, immunoglobulins and growth factors.
Recent data from our laboratory suggest that colostrum protein has a
higher Protein Efficiency Ratio (PER) than calcium caseinate.4 Further, there is
some evidence suggesting colostrum supplementation may increase lean body
mass,5 improve time trial performance in cyclists,6 enhance recovery during
endurance exercise,7 improve sprint performance in hockey players,8 enhance
buffer capacity in female rowers,9 increase peak anaerobic power,10 and
enhance resistance to development of upper respiratory track infection.11
Colostrum and Lean Body Mass
The purpose of a recent study by Dr. Jose Antonio and colleagues was
to determine the effect of eight weeks of colostrum supplementation on body
composition and exercise performance in active men and women.5 Subjects
were randomly assigned to either a placebo (whey protein) group or a colostrum
group (20 grams/day). Each subject participated in aerobic and heavy
resistance training at least three times per week. Body composition was
assessed via dual x-ray absorptometry (DEXA) analysis. Treadmill time to
exhaustion, one repetition maximum strength (bench press), and the total
number of repetitions performed during one set to exhaustion at a submaximal
load for the bench press (50 percent and 100 percent of body weight for women
and men, respectively) were ascertained.
The whey protein group experienced a significant increase in body
weight (mean increase of 2.11 kilograms, or 4.62 pounds), whereas the bovine
colostrum group experienced a significant increase in bone-free lean body mass
(LBM, mean increase of 1.49 kilograms, or 3.28 pounds). However, as pointed
out by Dr. Antonio and coworkers, one must exercise caution with this
interpretation because some investigators have found the coefficient of variation
for lean body mass estimates via DEXA to be as high as 3.1 percent. Certainly,
this is as large as the difference in LBM reported for the colostrumsupplemented
group. Further, there were no changes in any of the other
parameters measured.
Colostrum and Exercise Performance
The purpose of the recent study by Dr. Coombes and colleagues was to
determine the dose effects of colostrum supplementation on cycling
performance.6 Forty-two competitive cyclists were randomly divided into three
groups and were required to consume either 20 grams of colostrum 40 grams
of whey protein; 60 grams of colostrum; or 60 grams of whey protein (placebo).
Two measures were used to assess performance before and after an eightweek
supplementation period. The first measure required subjects to complete
two maximal oxygen uptake (VO2max) tests separated by 20 minutes with the
amount of work completed in the second test used to evaluate performance.
The second performance measure was the time to complete a work-based time
trial following a two-hour cycle at 65 percent maximal oxygen uptake. Subjects
were required to maintain their regular training and keep a food and training
diary over the study period.
After supplementation, the performance enhancement in measure one
was not statistically significantly different in the colostrum groups compared to
the placebo group. In performance measure, two subjects in the 20-gram and
60-gram groups completed the time trial significantly faster post-supplement
compared to pre-supplement. The authors concluded that colostrum
supplementation at 20 or 60 grams per day provided a small but significant
improvement in time trial performance in cyclists after a two-hour ride at 65
percent maximal oxygen uptake. Further, the authors postulated that bovine
colostrum supplementation improves small intestine function and nutrient
absorption leading to enhanced nutrient availability to recovering muscle cells.
More recently, Dr. Jonathan Buckley and colleagues examined the
effects of colostrum supplementation on peak vertical jump power, peak cycle
power, alactic anaerobic work capacity and resistance exercise one-repetition
maximum (1-RM).10 Using a randomized, double-blind, placebo-controlled
parallel design, 51 males completed eight weeks of resistance and plyometric
training while consuming 60 grams per day of colostrum or whey protein. Peak
vertical jump power and peak cycle power were not significantly different
between groups by week four. By week eight, however, peak vertical jump
power and peak cycle power were significantly higher in colostrum condition.
The authors concluded that colostrum supplementation during training
significantly increased peak anaerobic power, but had no effect on alactic work
capacity or 1-RM.
Since colostrum supplementation had no significant effect on 1-RMs in
this study, or in a previous study by Dr. Antonio and co-workers,5 and 1-RM
provides a measure of muscular strength, it’s unlikely that colostrum exerted its
effects by increasing muscle contractile protein content or by recruiting
additional motor units. According to Dr. Buckley and colleagues, it’s more likely
that the increased phosphogenolytic rate may have resulted from an increase in
the relative proportion of fast myosin heavy chain.
Colostrum and IGF-I
Growth hormone is a protein anabolic hormone that produces positive
nitrogen and phosphorous balance, and a fall in the blood urea nitrogen and
amino acid levels. The effects of growth hormone on growth, cartilage and
protein metabolism depend on an interaction between growth and
somatomedins, which are polypeptide growth factors secreted by the liver and
other tissues. The principal (and in humans, probably the only) circulating
somatomedins are insulin like growth factor 1 (IGF-1) and insulin-like growth
factor 2 (IGF-2). IGF-2 is thought to be a less effective anabolic agent than IGF-
1. The majority of studies support the fact that IGF-1 has significant anabolic
and anticatabolic effects, especially when acting with insulin and GH where
there is an adequate amount of certain amino acids. Thus, increasing
endogenous levels of IGF-1 could be useful for maximizing the effects of
exercise on muscle mass and strength.
The purpose of a study by Dr. Antti Mero and colleagues was to examine
the effects of bovine colostrum supplementation on serum IGF-1 concentrations
during strength and speed training period.12 Bovine colostrum supplement
contained 67.6 micrograms per liter of IGF-1. Nine male sprinters and jumpers
underwent three randomized experimental training treatments of eight days
separated by 13 days. The only difference in the treatments was the drink of
125 milliliters consumed per day. Post-exercise increases were noticed for
serum IGF-1 in the 25-milliliter bovine colostrum treatment (125 ml contained 25
ml colostrum) and especially in the 125-milliliter bovine colostrum treatment
(125 ml contained 125 ml colostrum) compared with the placebo (whey protein)
treatment.
However, investigators used a radioimmunoassay that measures both
the IGF-1 and its associated binding proteins. A more appropriate and accepted
procedure is to remove the binding protein before measuring IGF-1.
Furthermore, the negligible change in IGF-1 level could be due to the training
effect. As might be expected and as found in normal physiology, the observed
exercise-associated rise in growth hormone would be mirrored by a rise in
circulating IGF-1. Finally, it should be noted that the initial mean level of IGF-1
was somewhat greater in the placebo group. This means the possibility that
reasons other than colostrum supplementation may have contributed to the
differences in the IGF-1 concentration between the groups.
In follow-up study, Dr. Mero and coworkers examined the effects of
bovine colostrum supplementation on blood and saliva variables and the
absorption of orally administered human recombinant IGF (rhIGF-1) labeled
with 123iodine. Authors concluded that long-term supplementation of bovine
colostrum increases serum IGF-1 concentration in athletes during training.
However, absorption data gives no support to the absorption of intact IGF-1
from bovine colostrum.
We recently examined effects of colostrum supplementation on serum
IGF-1, growth hormone (GH) and testosterone. In order to avoid effects of
exercise, serum concentration of IGF-1, GH and testosterone were measured
initially (day 0) and before the first exercise test (day 11) in all subjects. Serum
IGF-1, GH and testosterone concentrations were within the reference ranges
and no statistically significant changes were seen in response to 11 days
administration of colostrum or placebo (whey protein). Further, the counts of red
blood cells, leukocytes, thrombocytes, hemoglobin, hematocrit, cortisol and
interleukin-6 were within reference limits at the beginning of the experimental
period and did not show significant changes during colostrum or placebo
supplementation.
Colostrum and Upper Respiratory Tract Infection
Colostrum is a rich source of immunoglobulins. Circulating
immunoglobulins protect their host by binding to and neutralizing some protein
toxins; by blocking the attachment of some viruses to cells; by opsonizing
bacteria (making it more susceptible to cell action that absorbs harmful
microorganisms); and by activating proteins in blood plasma that aid in
destruction of harmful bacteria. Immunoglobulin A is the major immunoglobulin
found in mucosal secretions, which constitute the first barrier to the entry of
pathogens into the body. Consequently, the level of secretory immunoglobulin A
contained in mucosal fluids has been shown to correlate highly with resistance
to certain infections caused by viruses, such as upper respiratory tract infection.
Recently, Dr. Mero and colleagues reported that colostrum increases salivary
immunoglobulin A concentrations after two weeks of supplementation.12
Therefore, it is possible that an increase in salivary immunoglobulin A may
protect against the development of upper respiratory tract infection.
Drs. Grant Brinkworth and Jonathan Buckley examined whether
colostrum affected the incidence or duration of self-reported symptoms of upper
respiratory tract infection in adult males. One hundred and seventy-four healthy,
physically active adult males comprised the sample for this study. During the
supplementation period, 93 subjects consumed colostrum, while 81 consumed
whey protein. During the pre-experimental period, there was no significant
difference in proportion of subjects taking the different supplements who
reported symptoms of upper respiratory tract infection.
During the seven-week experimental period, a significantly lesser
proportion of subjects taking colostrum reported symptoms of upper respiratory
tract infection compared with those taking whey protein. Thirty-two percent of
subjects taking colostrum reporting at least one episode of upper respiratory
tract infection, compared with 48 percent who were taking whey protein.
This study provides preliminary evidence that colostrum may enhance
resistance to the development of symptoms of upper respiratory tract infection
in young adult males. However, colostrum appeared to have no effect on the
duration of symptoms once they developed, indicating that it’s unlikely to be
useful as a therapeutic treatment for upper respiratory tract infection once
infection has occurred.
