Mixed messages from scientists about the advantages or disadvantages of coffee are almost a weekly event. New research published this week shows that coffee made from roasted coffee beans has antibacterial activities against certain micro-organisms, including Streptococcus mutans (S. mutans), a major cause of dental caries.
Scientists from two Italian universities conducted laboratory tests that showed some coffee molecules prevent adhesion of S. mutans on tooth enamel. Their findings were published in the February 27 issue of the Journal of Agricultural and Food Chemistry, the publication of the American Chemical Society.
"All coffee solutions have high anti-adhesive properties due to both naturally occurring and roasting-induced molecules," said the study's lead author, Gabriella Gazzani of the University of Pavia. She and researchers at the University of Ancona analysed samples of green and roasted arabica and robusta coffee from different countries.
"All of the tested samples inhibited S. mutans adsorption and showed inhibitory activity ranging from 40.5 per cent to 98.1 per cent," according to the research article. However, the article adds that "all green [unroasted beans] coffee samples were significantly less active than the corresponding roasted coffees".
The researchers examined caffeine and non-caffeine samples of ground and instant coffee, and found that it had a slightly higher level of inhibitory activity against S. mutans. As for caffeine and decaf, the results seem to indicate that "caffeine is not involved in the anti-adhesive properties of coffee solutions", according to the article.
The data from the study suggests that trigonelline, a water-soluble compound in coffee that contributes to the aroma and flavour of the beverage, "may have the major responsibility for coffee's anti-adhesive activity".
While the study findings appear encouraging, Dr Gazzani and her colleagues are circumspect. "In the absence of animal model data, caution is advised in the interpretation of the in vivo significance of our present results."
"Nevertheless," the researchers concluded, "we can hypothesise that due to both antibacterial and anti-adhesive activity, coffee might reduce S. mutans colonisation of [the] tooth surface and might be effective in preventing S. mutans-induced tooth decay."