the metabolic and cognitive effects of a poor diet.
A Gut-Brain Terrorist
Unsurprisingly, ground zero for many of the problems
associated with sugar is the gut. Fructose in particular,
whether from processed sugary foods or excessive fruit
sugar, impairs its own absorption when it is consumed in
large amounts. While this may sound vaguely positive, the
excess fructose left to linger in the gut can create many
unpleasant symptoms, from bloating and cramps to diarrhea
and symptoms of irritable bowel syndrome (IBS). As gnarly
as this sounds, high intestinal fructose concentration can
also interfere with tryptophan absorption.^24 Tryptophan is
an essential amino acid that we must get from our diets, and
it is the direct precursor to the neurotransmitter serotonin,
which is important for healthy mood and executive function.
This may be why fructose malabsorption is associated with
symptoms of depression.^25
The gut lining is the precious matrix across which we
absorb nutrients from food. It also helps keep intestinal
bacteria in the gut where it belongs. The last thing you’d
want to do is poke holes in your gut lining, but this is what
concentrated fructose seems to be able to do. The technical
term for this is increased intestinal permeability, which is
when the gut lining allows the leakage of inflammatory
bacterial components from the gut into circulation. The
seepage of these bacterial components into your blood is a
major driver of systemic inflammation, and it can induce