"Fiber vs. Low FODMAP for SIBO Symptoms"
If you test more than a thousand patients suffering from
irritable bowel-type symptoms such as excess gas, bloating,
diarrhea, abdominal pain for longer than six months,
who don't appear to have anything more serious going on, such as
inflammatory bowel disease, a significant percentage were found
to be suffering from lactose intolerance: intolerance to the milk sugar lactose.
In infancy we have an enzyme in our small intestines that
digests milk sugar, but most of us understandably lose it after weaning.
Although a genetic mutation has led to the persistence of the enzyme
in a minority of adults, about 75% of the world's population
malabsorb lactose and have lactose intolerance after age 30.
A third, though, were diagnosed with SIBO:
Small Intestinal Bacterial Overgrowth.
The evidence for SIBO and IBS symptoms is shrouded in controversy,
predominantly because of the fact that the breath tests used
in clinical practice to diagnose SIBO are not valid,
as I explored in the last video. And it's not even clear
what the implications are of having more versus less bacteria growing
in your small intestine since the number don't seem to correlate with symptoms.
It turns out it's not the number, but the type.
It's the kind of bugs you have growing in your small intestine.
So it's small intestinal microbial dysbiosis, not overgrowth in general,
but the wrong kind of growth that appears to underlie
symptoms associated with functional gastrointestinal disorders
like irritable bowel syndrome.
How can you prevent this from happening?
Well, the symptoms appeared be correlated to a significant drop
in the number of Prevotella species. Remember them?
Prevotella are healthy fiber feeders, suggestive of a higher fiber intake
in healthy individuals, while the bugs found more in symptomatic patients
ate sugar, which may reflect a higher dietary intake of sugars.
Yes, but correlation doesn't mean causation.
To prove cause and effect you have to put it to the test,
which is exactly what they did.
Switching a group of healthy individuals who habitually ate a higher fiber diet
to a more typical standard American low fiber diet with lots of sugar
produced striking results within just seven days.
First, 80% developed new gastrointestinal symptoms
out of the blue, such as bloating and abdominal pain that resolved
on resumption of their more healthful, habitual higher fiber diet. And the
diet related changes in the small intestinal microbiome were predictive
of symptoms and linked to an alteration in intestinal permeability;
in other words, they developed a leaky gut within seven days.
And while some went from SIBO positive to SIBO negative,
or SIBO negative to SIBO positive,
it didn't matter, since the number of bacteria growing
didn't correlate with symptoms. It was the type of bacteria growing.
And no wonder their guts got leaky. Short-chain fatty acid levels plummeted.
Those are the magical by-products that our good gut bugs make from fiber,
which play an important role in intestinal barrier integrity,
meaning keeping our gut from getting leaky. So while
we don't have sound data that something like a low FODMAP diet
has any benefit for SIBO-symptom patients,
there have been more than a dozen randomized controlled trials
putting fiber to the test, and overall there was a significant improvement
in symptoms among those randomized to increase their fiber intake.
That may actually help explain why high-fiber, plant-based diets
may prevent so many common diseases — the effect such diets have
on the composition and metabolic activity of our microbiome.
Our good gut bugs take the plant residues like fiber
and produce health-promoting and cancer-suppressing metabolites
like those short-chain fatty acids which have profound
anti-inflammatory properties.
All the evidence points to a physiological need
for about 50 grams of fiber a day,
which is the amount contained in the traditional African diet
and associated with the prevention of westernized diseases.
That's approximately twice what's typically recommended
and three times more than what most people are getting day-to-day.
Perhaps it should be no surprise we need so much.
Even though we split from chimpanzees millions of years ago,
there's still broad congruency in the composition
of our respective microbiomes to this day.
While they're still eating their 98-99% plant-based diets to feed their friendly
flora with fiber, we've largely removed fiber-rich foods from our food supply.