readings> peptide poisoning
Here is a shocking little factoid of which the neurologist might want
to take note. Meat, fat and sugar made up ten percent of our diet a
century ago. Now that figure has soared to 60 percent.
Why should this second great change in human eating habits (the first
being the agricultural revolution 10,000 years ago) be of any
particular interest to neurologists? Well, have you seen the headlines
screaming: “Tenfold rise in autism in ten years”,
“Six percent of US children now on drugs for
hyperactivity”, “Dyslexia triples to affect
one-in-five”?
Although official confirmation remains hard to come by, many in the
frontline of child care feel we are facing a modern plague of
developmental brain disorders. They say it's not just a matter of
better diagnosis, or the creation of new borderline classifications
like PDD-NOS (pervasive developmental disorder not otherwise
specified!). Something really is up. And perhaps not just with kids as
adult complaints, such as migraines and chronic fatigue syndrome, and
even outright psychiatric conditions like post-natal psychosis,
obsessive-compulsive disorders and depression, all seem on the rise.
What could be the reason? One X-Files style answer is that our changed
diet is largely to blame. Not to put too fine a point on it, our brains
are being poisoned by undigested milk and wheat. The plague is the
terrible result of a clash between our incomplete evolutionary past and
our polluted, disrupted, junk food present.
This "opioid excess" theory has been doing the rounds since at least
the 1970s. But recently people have begun to find it more credible. The
hypothesis is that the human digestive system evolved for a stone age
diet – tubers, berries and lots of lean meat. At the end of
the last ice age we settled down to be farmers. Suddenly, grain and
milk products became the new staples and hurriedly we had to develop a
matching set of digestive enzymes. The consequence of this rushed
evolution is a wide genetic variation in how well people can cope with
the proteins in these foods. An incomplete breakdown can leave the gut
awash in opioid-like peptide fragments such as casomorphine and
gliadomorphine.
The second part of the story is that these peptides fragments float
through to the brain where their close resemblance to neuropeptides and
nerve growth factors create all kinds of neurological mayhem. In a
mature adult brain, the effects may range from mild immune system
disruption to serious psychiatric disturbance. In the infant brain,
autism and other developmental syndromes may result.
Now here is the rub. Believers in the rogue peptide theory have to
explain how these largish molecules manage to penetrate the body's
natural defences - the three barriers of the gut lining, the immune
system and then the particularly tight protection of the blood-brain
barrier itself. Many have dismissed the opioid excess story on these
grounds alone. Then even those willing to grant the theory a basic
plausibility find themselves balking because such a confusing range of
penetration mechanisms have been suggested.
Is it organophosphate pollution from our environment eroding the
membranes of the gut and brain, causing them to spring leaks? Or
perhaps a genetic incompetence of some key protective mechanism, such
as the sulphate transferase system? Or maybe an overgrowth of thrush
(the yeast, candida) creating holes in the intestine? Or a lack of
essential fatty acids and trace elements like zinc and selenium doing
the same to the choroid plexus? Or - most notoriously - the MMR
(measles, mumps and rubella) triple vaccine inflaming the gut and
perhaps brain membranes. All these and more have their proponents.
When this maze of suggested causal pathways is then being linked to an
equally various range of neurological and immunological disorders - did
I remember to mention schizophrenia, multiple sclerosis, Gulf War
syndrome and allergy-proneness? - you can see the problem. The rogue
peptide story is an aetiological mess and no serious medical
practitioner would touch it with a barge pole.
And yet something does seem to be going on here. It is hard to deny the
increase in autism and other allied complaints. Or that our kids are
eating a heck of a lot of junk food these days (yes, and their busy
parents too). If indeed peptides are poisoning our brains, then it is
going to take some pretty committed scientific detective work to
untangle all the strands of the tale. However this does seem
one wacky theory that deserves a proper hearing.