Diacetyl is a natural byproduct of fermentation. It occurs naturally in alcoholic beverages (especially Chardonnay wines) at low levels and is added to some foods to give them a butter or butterscotch flavor. Butter substitutes like margarine often contain significant amounts of diacetyl.
In a recent edition of the journal Chemical Research in Toxicology, researchers looked at the effect of this butter substitute on the aggregation of β-amyloid, one of the main processes associated with the development of Alzheimer’s disease. In an experimental laboratory model, the authors found that diacetyl had a size and structure that easily allowed its entrance into the brain (i.e. it crosses the blood-brain barrier). Diacetyl was found to accelerate or speed up the formation of β-amyloid. This chemical also made β-amyloid more resistant to breakdown by natural processes within the brain. All of these features suggest that diacetyl promotes the development of Alzheimer’s disease.
I think I’ll stick to real butter on my popcorn from now on.