How the bacteria in your mouth could be the reason you dislike broccoli
Brussels sprouts, broccoli, and cauliflower – all members of the Brassica family – are inarguably healthy vegetables. They also have infamously bitter and pungent characteristics that some people find deeply unpleasant.
The classic bitter taste of Brassica vegetables is commonly thought to be due to compounds called glucosinolates. When we chew a big mouthful of broccoli or cauliflower these molecules are converted into a chemical called isothiocyanate, which is responsible for the pungent flavor many struggle to overcome.
But new research is indicating another process may be influencing some people’s undesirable response to these vegetables. Brassicas also contain a compound called S-methyl-L-cysteine sulfoxide (SMCSO), which, when mixed with another enzyme present in the vegetables, produces sulfurous odors.
The enzyme that mixes with SMCSO to produce these stinky smells is also produced by bacteria in the oral microbiome, and different people have different levels of this particular oral bacteria. So a team of Australian researchers set out to investigate whether levels of sulfurous odors produced by bacteria in saliva can be associated with subjective preferences of Brassica vegetables.
The researchers recruited 98 child/parent pairs for the study. Saliva samples from all the subjects were mixed with cauliflower powder and the subsequent volatile gases produced were analyzed.
The study found significant variations in the levels of sulfur volatiles produced from sample to sample, but children did generally display similar levels of sulfur volatiles as their parents, suggesting they shared comparable oral microbiomes.
A distinct correlation was found between a strong dislike of Brassica vegetables in children and high levels of sulfur volatiles produced by their saliva. Interestingly, this association was not seen in parents with similar volatile sulfur profiles, indicating a possible tolerance to bitter or pungent flavor profiles accruing with age.
A positive interpretation of these findings is that people can potentially learn to appreciate, or even enjoy, Brassica vegetables regardless of their oral microbiome composition. Damien Frank, lead author on the study from Australia’s CSIRO, says it is reasonable for children to be resistant to these vegetables if they are producing confronting levels of volatile gases in their mouth while eating.
"Basically this gas is associated with the smells of farts and the smells of decomposing animals," Frank told ABC News. ”I think it would be quite scary [for kids] if you are getting a lot of this weird sulfur taste in your mouth."
The new study was published in the Journal of Agricultural and Food Chemistry.
Source: American Chemical Society