"Best Food to Counter Stress-Induced Immune Suppression"
Natural "immunomodulators" are getting more and more popular,
things that might naturally regulate our immune system.
"That popularity, however, often brings
over-optimistic claims and mediocre effects."
Such mythical beasts have been sought after for centuries.
The current market is full of all sorts of supplements
promising the golden fleece: inexpensive, no side-effects,
yet actively boosting our immune system.
Many simply repeat unjustified claims
with hardly any science to support them.
On the other hand, there's beta-glucan,
which has undergone 10,000 scientific studies and clinical trials.
Wait, what?
Beta-glucan is the fiber in nutritional yeast I talked about before,
able to decrease episodes of common illnesses in young children.
But what about in adults?
First of all, why can't they just come up
with a vaccine against the common cold virus?
Because there is no single common cold virus;
there are hundreds of different viruses implicated
in causing cold-like symptoms.
So that's why there is so much interest in finding
a general, nonspecific immune booster, across the board.
Beta-glucan supplementation can increase
the levels of immunoglobulin A in the saliva within four days,
at a daily dose of 400 mg, but not 100 mg.
So the amount found in about 2 teaspoons of nutritional yeast
a day, but not a half teaspoon.
IgA is an antibody that plays a crucial role in the immune function
of our moist membranes, like eyes, nose, and mouth.
One teaspoon's worth didn't do much until they exercised.
Two hours after a strenuous 50-minute bout
of strenuous cycling in a hot, humid environment,
those who had been on the yeast beta-glucan did get that IgA boost.
Beta-glucans failed, however, to boost the antimicrobial
activity of white blood cells taken from subjects
who had been taking like a tablespoon's worth a day.
What we care about, though, are clinical outcomes.
Do those consuming beta-glucans suffer
significantly fewer infections?
OK. How about a double-blind, randomized, placebo-controlled
nutritional study to see if yeast beta-glucan
can improve our immune defense system.
100 people followed for 26 weeks,
50 getting about a tablespoon of nutritional yeast worth
of beta-glucan a day, 50 getting placebo.
They counted how many episodes of the common cold
they got, and there was no significant difference.
Now, if you just look at the first half of the time, during cold season,
there did appear to be fewer infections in the active group,
meaning the beta-glucan group.
But this is what's called a "post-hoc" analysis,
where you go back and look at your data after the fact,
which is frowned upon by the scientific community
because it increases the likelihood
that your findings are just due to chance.
But those who did end up getting sick while on the beta-glucan
did genuinely appear to suffer milder symptoms.
A similar, larger study had similar findings.
Maybe the severity of the colds was lessened,
but in the main analysis, no significant difference
in the number of times people got colds in the first place.
Same in other studies: no significant differences
in the number of symptomatic respiratory infection episodes.
No significant effect on upper respiratory tract infection outcomes,
so overall, pretty disappointing results.
But wait a second.
What about my video about preserving immune function
in athletes with nutritional yeast?
They found a significant drop in cold symptoms
2 weeks and 4 weeks after a marathon at both
1 teaspoon of yeast worth of beta-glucan a day and 2 teaspoons.
Yeah, but they had just run a marathon.
Remember this study where the effect only seemed
to emerge after strenuous exercise?
That's where beta-glucan seems to shine,
counteracting the toll extreme physical exertion
can have on our immune function.
In an athlete, that just may mean some lost practice days
or something, but for soldiers or firefighters maintaining
one's health, even in the context of heavy physical stress,
could be critical.
OK. But that's counteracting the effects of physical stress.
What about mental stress?
Stressful life events can impair our moist membrane defenses,
such that psychological stress has also been shown
to increase susceptibility to the common cold,
getting more colds and worse colds than people under less stress.
So let's see if we can help.
And indeed, in this a study of healthy women
under moderate levels of perceived psychological stress,
those taking about a teaspoon of nutritional yeast a day worth
of beta-glucans for 12 weeks were 60% less likely
to report experiencing symptoms like sore throat,
stuffed or runny nose, or cough,
strongly suggesting that baker's, brewer's,
and nutritional yeast "beta-glucan is able
to counteract the negative effects of stress on the immune system."
And they experienced 41% greater vigor,
which is a measure that encompasses physical energy, mental acuity,
and emotional well-being. So they just felt better, too.
Put all the studies together, and yeast beta-glucans
do appear to have immune strengthening effects, at least in children,
and those under physical or mental stress.