A chemical once produced in the manufacture of white bread may play a role
in the increased incidence of some neurological diseases, according to the preliminary
findings of a team of UBC researchers.
“We think we’ve found a smoking gun,” says Christopher Shaw, an associate
professor of Ophthalmology. “There is a very suspicious correlation between
the characteristics of this substance and those known to be toxic to the nervous
system.”
The incidence of neurological diseases, notably amyotrophic lateral sclerosis
(ALS), has been on the upswing during the last 50 years.
Shaw and fellow researchers think the culprit may be methionine sulfoximine
(MSO), a toxic byproduct of nitrogen trichloride, which was used to bleach unprocessed
wheat flour. By 1950 the process was banned in the United Kingdom and the United
States. Canada stopped using it in 1968.
In the late 1940s, scientists discovered that dog biscuits made from bleached
flour produced canine epilepsy. A risk for humans via white bread was suspected,
but the exact toxic effects of MSO had not been investigated until neuroscientist
Shaw and colleagues from the University of Tampere in Finland and Dalhousie
University began their investigation last month.
Scientists have known since 1976 that MSO acts to inhibit the production of
two molecules critical to the healthy functioning of the nervous system, glutathione
and glutamine. Cells in the nervous system are particularly sensitive to a decline
in either of these two molecules.
It was not known, however, if the compound had a direct effect on neurons.
Shaw, research associate Jaswinder Bains and Physiology PhD candidate Bryce
Pasqualotto have found that MSO over-stimulates neurons. In a phenomenon known
as excitotoxicity, MSO directly turns on a toxic cascade of events which can
lead to neuron death, says Shaw.
“This appears to be the worst possible toxin you can imagine for the nervous
system because it strikes in so many different ways at the same time,” he says.
Because it is eliminated from the body over time, MSO cannot be detected in
patients now suffering from neurological disease.
“We know people have been exposed to a toxin but we’re still uncertain of
the impact,” says Shaw. “My main concern is what the MSO story tells us about
the presence of other toxins in processed foods. It’s probably not the only
thing out there.”
Shaw became interested in MSO while researching the effect on neurons of other
chemical compounds which can be excitotoxic. Similarities between them and MSO
sparked his curiosity in the decades-old story.
“I think this is the tip of an iceberg,” says Shaw. “Many products in the
supermarket have been processed with chemicals that are not listed on the package.”
The team’s preliminary findings have been accepted for publication in the
journal Medical Hypotheses.
Their work is funded by the Amyotrophic Lateral Sclerosis Association.
UBC spin-off Precision Biochemicals Inc. provided chemicals used in the research.
