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Can’t stand broccoli or sprouts? Your oral microbiome, not your fussy habits, may be the reason

Written by Aisha Al-Janabi (Assistant Editor)

Maybe your broccoli and cheese casserole won’t be a hit with all your family this Thanksgiving, not due to questionable cooking but because of bacteria in saliva that produce sulfurous gases.

Everyone is unique, and everyone’s oral microbiomes are as well. Different amounts of bacteria are present in different people’s saliva which could leave a disgusting taste after eating broccoli for some. Cauliflower, broccoli and the festive favorite Brussel sprouts are part of the Brassica family of vegetables. Perhaps due to their unpopularity, these veg have previously been studied and found to contain S-methyl-L-cysteine sulfoxide (SMCSO).

Bacteria in saliva produce enzymes that will react with SMCSO to produce sulfurous gases that would put anyone off their veg. Researchers from the Commonwealth Scientific and Industry Research Organisation (North Ryde, Australia) recently studied how these enzymes differ in the saliva of children and adults, and if this influences vegetable preferences and avoidance.


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Raw and steamed broccoli and cauliflower were mixed with saliva samples and gas chromatography-olfactometry-mass spectrometry was used to detect and characterize any volatile compounds produced.

Similar amounts of gaseous sulfurous compounds were found in the saliva of parent-child pairs analyzed, indicating similar enzyme levels and oral microbiome characteristics. However, large differences were observed between individuals, perhaps explaining why some people don’t like these vegetables.

The participants of the study, 98 parent-child pairs between six and eight years old, were also asked about their likes and dislikes of Brassica vegetables. A correlation was observed between children whose saliva produced more of these sulfurous compounds when reacting with Brassica vegetables and a dislike of broccoli and cauliflower. However, this was less apparent in adults, who may have learned to eat broccoli and ignore their tastebuds over the years.

So, this Thanksgiving if an overbearing family member is trying to force feed you cauliflower, tell them you are listening to your bacteria and stick to pumpkin pie, pecan pie or mac and cheese – anything without the Brassica veg!