Artificial butter flavouring ingredient diacetyl (DA) boosts the damaging effects of an abnormal brain protein linked to Alzheimer's disease, say researchers.
Robert Vince and colleagues Swati More and Ashish Vartak explain that DA has been the focus of much research recently because it is linked to respiratory and other problems in workers at microwave popcorn and food-flavouring factories.
DA gives microwave popcorn its distinctive buttery taste and aroma. DA also forms naturally in fermented beverages such as beer, and gives some chardonnay wines a buttery taste.
Vince's team realized that DA has an architecture similar to a substance that makes beta-amyloid proteins clump together in the brain - clumping being a hallmark of Alzheimer's disease.
So they tested whether DA also could clump those proteins.
DA did increase the level of beta-amyloid clumping. At real-world occupational exposure levels, DA also enhanced beta-amyloid's toxic effects on nerve cells growing in the laboratory.
Other lab experiments showed that DA easily penetrated the so-called "blood-brain barrier", which keeps many harmful substances from entering the brain. DA also stopped a protective protein called glyoxalase I from safeguarding nerve cells.
"In light of the chronic exposure of industry workers to DA, this study raises the troubling possibility of long-term neurological toxicity mediated by DA," the researchers said.
The study has been published in ACS' journal Chemical Research in Toxicology.