Flu Season: Exercise & Beta-Glucan Can Help Protect You

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Flu Season is Here: Find Out How Exercise and Beta-Glucan Can Help

Protect You

Source: ProHealthNetwork.com

New study shows direct, beneficial effect of short-term moderate exercise o=

n

susceptibility to upper respiratory tract infection.

November 10, 2003 - (Bethesda, MD) – Americans are lining up for flu shots,=

stocking up on cough and cold medicines, and taking inventory of what

antibiotics they may again need this winter. Despite expansive planning, fe=

w

remember two low-tech staples that can be easily and affordably added to

their first line defenses against the illnesses of the season: exercise and=

oat

fiber Beta-Glucan (É¿-glucan).

Individually, moderate exercise and the soluble oat fiber É¿-glucan increas=

e

immune function and decrease the risk of infection. However, no information=

exists about the possible benefits of combining the two. A new study, using=

an

animal model of induced respiratory infection, looks at the direct effects =

of a

short period of moderate exercise training and consumption of soluble oat

fiber É¿-glucan on the illness (morbidity) and death (mortality) following =

exposure to an upper respiratory tract infection (URTI). The study conclude=

s

that that moderate exercise alone is associated with a significant reductio=

n in

risk.

Background: How It Works

Exercise - It was thought that moderate exercise may enhance resistance to =

infection by activating the release of immunostimulatory factors (such as

growth hormones, prolactin and cytokines), which in turn activate various

immune cell populations.

Exercise bouts of moderate duration (<60 min) and lower intensity (<60

%VO2 max) have been associated with enhanced activity of immune

parameters, including macrophage chemotaxis, oxidative metabolism and

phagocytic activities, as well as increased natural killer (NK) cell activi=

ty.

These cells may constitute an important part of a first-line defense agains=

t

URTI by nature of their phagocytic, cytotoxic and intracellular killing

capacities.

Oat Fiber É¿-Glucan - É¿-Glucans (polysaccharides derived from the cell wal=

l

of yeast, fungi, algae and oats) have been shown to enhance the activities =

of

both the non-specific and specific immune system but have received little

attention in the field of exercise immunology. É¿-Glucan exerts its effects=

through the direct stimulation of macrophage, neutrophil and NK cells via É=

¿-

glucan specific receptor sites. When bound, É¿-glucan activates key cells, =

which set off a cascade of immune defenses that protect the organism from

various viral, bacterial and fungal challenges. The exact mechanisms are at=

least partially dependent on the route of administration; protection follow=

ing

oral administration results primarily from certain effects of ingestion, fo=

r

example.

A New Study

The authors of a new study, entitled " Effects of Moderate Exercise and Oat =

É¿-

glucan on Innate Immune Function and Susceptibility to Respiratory

Infection, " are J.M. , E.A. , A.S. Brown, M.D. Carmichael, A.

Ghaffar and E.P. Mayer, all of the University of South Carolina, Columbia, =

SC.

Their findings are published in the online edition of " Articles in Press " f=

or the

American Journal of Physiology – Regulatory, Integrative and Comparative

Physiology. The journal is one of 14 scientific periodicals published each =

month by the American Physiological Society (APS).

Methodology

The researchers used the following protocol:

Mice: Male CD-1 mice, four weeks of age, were acclimated at the research

facility 3+ days prior to experimentation. They were maintained on a 12:12-=

hour light-dark cycle in a low stress environment and given food (chow) and=

water (oat â-glucan dissolved in water) ad libitum. Separate groups of mice=

were used for each dependent variable: in vivo susceptibility to infection =

(n=

24 per group), macrophage anti-viral resistance (n=18 per group), and natur=

al

killer (NK) cell cytotoxicity (n=12 per group).

Nutrient Treatment: Mice were randomly assigned to one of four groups:

exercise water (Ex-H20), exercise oat É¿-glucan (Ex-OÉ¿G), control water

(Con-H20), or control oat â-glucan (Con-OÉ¿G). Ex-H20 and Con-H20

received tap water for the ten days prior to inoculation/death, while Ex-OÉ=

¿G

and Con- OÉ¿G mice were fed a solution of oat É¿-glucan dissolved in the

drinking water for the 10 days prior to inoculation/death. Oat É¿-glucan wa=

s

not fed to the animals during the 21 days following inoculation.

Treadmill Acclimation and Exercise Protocol: On the second day of oat â-

glucan/water treatment, exercise mice (Ex-H20 and Ex-OÉ¿G) were

acclimated to a treadmill for 20 min/day. The exercise protocol consisted o=

f a

one-hour bout of treadmill running for six consecutive days. Mice in the

control groups (Con-H20 and Con-OÉ¿G) remained in their cages in the

treadmill room during the bouts.

Intranasal Inoculation of and Infection with HSV-1: Intranasal inoculation =

of

Herpes simplex virus type 1 (HSV-1) VR strain was administered. This strain=

in the mouse is an established experimental model of respiratory infection;=

this route was chosen to mimic the typical route of entry for viral infecti=

on.

On the day of the experiment mice (n=24 per group) were exposed to either

control treatment or exercise for one hour and immediately returned to thei=

r

cages. Fifteen minutes later they were anesthetized and inoculated

intranasally with 50 ìL of HSV-1 VR strain. Following infection, the mice w=

ere

returned to their respective cages and monitored twice daily for 21 days fo=

r

signs of morbidity/mortality.

Peritoneal Macrophage Antiviral Resistance: On the day of experiment, mice =

(n=12 per group) were exposed to either control or exercise treatment.

Immediately following exercise or rest they were euthanized. Peritoneal

macrophages were collected, prepared and infected with HSV-1. The virus

was allowed to absorb for 90 minutes and, 72 hours after infection, anti-vi=

ral

resistance was quantified.

NK Flow Cytometric Assay: On the day of experiment, mice (n=12 per group)

were either exposed to control or exercise treatment and euthanized 30 min/=

post-treatment. Spleens were removed and weighed, and blood cells were

immediately lysed. Two parameter flow histograms were conducted.

TNF-É¿ and Statistical Analysis: Blood was collected and plasma assayed for=

TNF-É¿. Statistical analyses were performed for differences in morbidity an=

d

mortality across the 21-day post-infection period. Differences in NK cell

activity, macrophage anti-viral resistance, TNF-É¿, weight gain and fluid

consumption were compared using a two-way analysis of variance.

Results

Highlights of the findings include:

• Morbidity: There were differences in morbidity across the groups over the=

21-day post-infection period. Intranasal administration of HSV-1 following =

short-term moderate exercise training resulted in a decrease in morbidity a=

s

compared with resting controls. Exercise mice (Ex-H20) experienced only a

13% incidence in morbidity while 58% percent of control mice (Con-H20)

exhibited such symptoms. Consumption of oat É¿-glucan for ten days prior to=

inoculation did not further decrease the symptoms of morbidity as there was=

no real difference between the Ex-H20 group (13%) and the Ex-OÉ¿G group

(21%).

• Mortality: Similar effects were found for mortality over the 21-day post-=

infection period among the four groups. Intranasal administration of HSV-1 =

following six days of moderate exercise resulted in a decrease in mortality=

compared to control mice. Ex-H20 mice showed a mortality rate of 8% over

the 21-day period compared with a 46% rate among the Con-H20 mice.

Consumption of oat É¿-glucan for ten days prior to inoculation did not furt=

her

decrease mortality in the exercise animals; there were no significant

differences between Ex-H20 and Ex-OÉ¿G mice. However, oat É¿-glucan

administration did show a trend toward decreasing mortality in the control =

mice, prolonging the survival time of resting animals. Con-H20 mice showed =

a mortality rate of 46% while Con-OÉ¿G mice experienced a mortality rate of=

only 33%.

• Peritoneal Macrophage Anti-Viral Resistance: The intrinsic anti-viral

resistance in mice exercised moderately for six days (Ex-H20) was

significantly greater than in control mice (Con-H20). Oat É¿-glucan

consumption for ten consecutive days did not further enhance the benefits o=

f

exercise. However, resting mice consuming oat É¿-glucan dissolved in the

drinking water for ten days prior to death (Con-OÉ¿G) had a significantly

greater macrophage anti-viral resistance than did resting mice drinking wat=

er

(Con-H20).

• NK Cytotoxicity, TNF-a: Six days of moderate exercise was associated with=

a

very small increase in splenic NK cytotoxicity at effector:target ratios of=

5:1

and 1:1, but not at 20:1 and 80:1, compared with non-exercised controls. Oa=

t

É¿-glucan consumption did not result in any change in NK cytotoxicity. The =

presence of TNF-á was not detectible above 3 pg in any of the groups

following moderate exercise or oat É¿-glucan treatment. Therefore, moderate=

exercise or oat É¿-glucan consumption was not associated with an elevation =

of this cytokine.

Conclusions

These results support the hypothesis that moderate exercise training can

decrease susceptibility to induced respiratory infection in mice. These dat=

a

also provide evidence of a role for macrophages and NK cells as mediators o=

f

this benefit on host protection. While there were no added benefits of oat =

É¿-

glucan in this experiment, it deserves further research to evaluate the pos=

itive

trends observed in both the immune function and infection rates.