"Preventing Asthma With Fruits and Vegetables" Asthma is the most common
chronic disease in children, and the prevalence is
increasing around the world. Despite this, most research dollars
are spent on adult chronic diseases. One might ask whether this is because
our politicians and senior administrators feel themselves to be more
likely to suffer from the latter, and ignore allergic diseases
because they have their major impact on children and young
adults who don't vote. Imagine how much more effort
would be put into elucidating causes of a disorder
that increased at the same escalated rate in
the middle aged and elderly. Well, finally, an international study
of asthma and allergies in childhood, studying more than a million children
in nearly a hundred countries, making it the most comprehensive survey
of these diseases ever undertaken. What did they find? They found a wide variability
in the prevalence and severity of asthma, allergies,
and eczema. We're talking 20-fold
to 60-fold difference in prevalence of symptoms of
asthma, allergic runny nose, and atopic eczema
around the world. Striking worldwide variations in
the prevalence of allergic symptoms.

What does it
all mean? Well, the large variability
suggests a crucial role of some kind of local characteristics
determining the differences in prevalence between
one place and another. What kind of environmental factors? Like, why does the prevalence
of itchy eyes and runny nose range anywhere from 1% in India, for
example, up to 45% of kids elsewhere? There were some associations with
regional air pollution and smoking rates, but the most significant
associations were with diet. Adolescents showed a
consistent pattern of decreases in symptoms of wheeze
(current and severe), allergic rhinoconjunctivitis
and atopic eczema, associated with increased
consumption of plants. The more their calories and
protein came from plant sources, the less allergies
they seemed to have. In general, there seems
to be an association between an increase
in asthma prevalence and decreased consumption of
fresh fruits, green vegetables, and other dietary
sources of antioxidants, helping to explain why the prevalence
of asthma and respiratory symptoms is lower in populations with high
intake of foods of plant origin. Intakes of high fat and sodium,
and low fiber and carbohydrates are linked with asthma, while traditional and vegetarian diets
are associated with lower rates.

For example, if you
look closer within India, in a study of more
than 100,000 people, those who consumed meat, for example,
daily or even occasionally, were more likely to report asthma than
those who were strictly vegetarian, which meant also
avoiding eggs. Eggs have been associated,
along with soda, with an increased risk of respiratory
symptoms and asthma in schoolchildren, whereas consumptions
of soy foods and fruits were associated with reduced
risk of respiratory symptoms. In fact, removing eggs from
the diet, along with dairy, may improve lung function
in asthmatic children in as little
as eight weeks. So maybe it's a combination of eating
less animal foods and more plants.

High vegetable intake, for example,
has been found protective in children, cutting the odds of
allergic asthma in half. And fruit showed a consistent
protective association for current and severe wheeze and
runny nose in adolescents, and for current and severe asthma,
allergies, and eczema for children. But why? I've talk about the endocrine-
disrupting industrial pollutants building up in the meat supply that may
increase the risk of allergic diseases, but the increase in asthma
may be a combination of both a more toxic environment
and a more susceptible population. "The dietary changes which have
occurred over recent years may have led to a reduction in
these natural antioxidant defenses, resulting in a shift of the antioxidant
status of the whole population and leading to increased susceptibility
to oxidant attack and airway inflammation." In adults, for example, the risk
of airway hyper-reactivity may increase seven-fold
among those with the lowest intake of
vitamin C from plants foods, while the lowest intake of saturated
fats gave a 10-fold protection, presumably because of saturated fats
have a role in triggering inflammation.

“The protective effect of plant-based
food may also be mediated through effects on
intestinal microflora." It turns out the differences in
the indigenous intestinal flora might affect the development and priming
of the immune system in early childhood. Kids with allergies,
for example, tend to be less likely to
harbor lactobacilli, the good bacteria that's
found in fermented foods and also just naturally
on fruits and vegetables. And lactobacillus probiotics may
actually help with childhood asthma, which may all help
explain why children raised on largely
organic vegetarian diets may have lower prevalence
of allergic reactions. Infants raised in this way tend
to have more good lactobacilli in their guts compared
to controls, though they were also more likely
to have been born naturally, breastfed longer, and not
given as many antibiotics, so you really can't tell if it's the
diet until you put it to the test… which we'll
explore next..

Video Transcript – As found on YouTube