The study – published in Chemical Research in Toxicology – reveals evidence that the food ingredient diacetyl (DA) intensifies the damaging effects of beta-amyloid protein clumping that is linked to Alzheimer's disease. The industry favorite – found in products including margarines, snack foods, sweets, baked goods, some types of microwave popcorn, pet foods, and certain alcoholic beverages – is known for its distinctive buttery taste and aroma.
“Diacetyl is ubiquitous in the modern human diet and is present often as an added flavorant,” say the researchers, led by Professor Robert Vince, from the University of Minnesota in the US.
Vince and his colleagues say the study findings, which suggest occupational exposure to DA could be linked to the development of Alzheimer’s, could raise concern about chronic exposure of workers in industry to the food flavoring ingredient.
“We have now shown that DA potently enhances beta-amyloid toxicity toward neuronal cells in culture at concentrations that are normally found in body compartments upon occupational exposure,” say the researchers.
“Whether toxic levels of diacetyl are achieved in various body compartments upon mere (over)consumption of DA-containing food substances is an unanswered but an important question,” they add.
Diacetyl has already been the focus of a plethora of recent research, thanks to its links to respiratory and other problems in workers at microwave popcorn and food-flavoring factories.
Concerns about diacetyl were initially raised after researchers from the Netherlands linked the industrial use of the flavourant with the debilitating lung disease bronchiolitis obliterans syndrome (BOS).
The team, from the Universiteit Utrecht, the Netherlands, examined a population of workers at an unnamed chemical plant that produced diacetyl, and found a cluster of BOS – which leads to inflammation and obstruction of the lungs through rapid thickening or scarring of the small airways.
Since then, many studies have linked the butter flavour to the development of the lung disease, say the researchers: “While the effects on the respiratory system upon inhalation of diacetyl have been studied, the chronic repercussions of diacetyl exposure on neuronal tissue are hitherto unknown,” they explained.
Vince's team realised that diacetyl has a structure similar to that of a substance that makes beta-amyloid proteins clump together in the brain. Such clumping is a hallmark of Alzheimer's disease, and increases the risk of developing the condition, they noted.
Therefore, the researchers tested whether exposure to DA also could enhance the clumping of beta-amyloid proteins – finding that the flavourant increased clumping at levels achievable from real world occupational exposure.
DA was also found to enhance beta-amyloid's toxic effects on nerve cells growing in the laboratory, while other experiments showed the compound easily penetrated the blood-brain barrier which generally keeps harmful substances from entering the brain.
"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," said the researchers.
Source: Chemical Research in Toxicology
Published online ahead print, doi: 10.1021/tx3001016
“The Butter Flavorant, Diacetyl, Exacerbates β-Amyloid Cytotoxicity”
Authors: Swati S. More, Ashish P. Vartak, Robert Vince