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Grandkids Hate Broccoli? There's a Scientific Reason Why

Study puts blame on oral microbiome

Child states angrily at broccoli and carrots on a plate

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En español | If your grandchildren can’t stomach broccoli, cauliflower, cabbage or Brussels sprouts, it may be because of an abundance of a certain type of bacteria living in their saliva, researchers in Australia say.

A study appearing in the American Chemical Society’s Journal of Agricultural and Food Chemistry suggests that distaste for these vegetables — particularly among children — is driven by an unpleasant odor created as these Brassica vegetables are chewed.​

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It seems that a certain type of bacteria abundant in some people’s saliva breaks down a compound in these chemicals called S-methyl-ʟ-cysteine sulfoxide, producing a volatile chemical called dimethyl trisulfide that the researchers say has a “pungent, rotten, sulfur odor.” Children ages 6 to 8 whose saliva produced high amounts of sulfur volatiles disliked raw Brassica vegetables the most, according to the study, which included 98 child-parent pairs in Australia.

​​For the study, researchers measured levels of sulfur volatiles that resulted after mixing fresh saliva from the volunteers with pulverized raw cauliflower. While they found large differences in the levels across the samples, parents and children shared similar levels, likely due to having similar microbiomes, the study speculates.​​ Although a link between high levels of sulfur volatiles and childhood dislike of Brassica vegetables was found, the same was not true for their parents. The researchers suggest that over time, the adults may simply have learned to tolerate the flavor.​

Peter Urban is a contributing writer and editor who focuses on health news. Urban spent two decades working as a correspondent in Washington, D.C., for daily newspapers in Connecticut, Massachusetts, Ohio, California and Arkansas, including a stint as Washington bureau chief for the Las Vegas Review-Journal. His freelance work has appeared in Scientific American, Bloomberg Government and