There’s a scientific reason why kids dislike broccoli and cauliflower

NORTH RYDE, Australia — Children and vegetables are not exactly a match made in heaven. In fact, many parents will probably admit getting their kids to eat greens like broccoli, cauliflower, and Brussels sprouts can be next to impossible. While some may think children are just being picky, a new study finds there’s an actually scientific explanation for why kids dislike these vegetables. A team in Australia says a youngster’s tastes may come down to the organisms in their saliva.

Brassica vegetables, such as broccoli, cauliflower, cabbage, and Brussels sprouts, are the enemies of many children and even some adults as well. Even former president George H.W. Bush famously declared his dislike for broccoli. Now, scientists know what’s likely behind this.

The study finds bacteria in the mouth can mix with certain enzymes in these veggies — producing an unpleasant and sulfurous odor. Specifically, Brassica vegetables contain a compound called S-methyl-ʟ-cysteine sulfoxide. It produces a potent smell when it interacts with the same enzyme coming from bacteria in a person’s oral microbiome.

Blame the parents!

Ironically, the study finds parents should actually blame their own microbiome if their kids don’t like eating broccoli. Previous studies show that the levels of this odor-producing compound vary from adult to adult. However, parents and their children typically have very similar microbiome makeups in their saliva.

With that in mind, researcher Damian Frank and a team working at Australia’s national science agency (CSIRO) examined how both adults and their children react to Brassica vegetables depending on their microbiome makeup. First and foremost, the team discovered that children with higher levels of these volatile compounds in their saliva causes them to dislike broccoli, cauliflower, and other Brassica vegetables.

What are people smelling from these veggies?

Researchers used a process called gas chromatography-olfactometry-mass spectrometry to identify the main odor-active compounds in raw and steamed cauliflower and broccoli. From there, 98 child-parent pairs rated the odors they smelled coming from these greens. Each of the children were between the ages of six and eight years-old.

Dimethyl trisulfide ranked as the most unpopular odor coming from raw broccoli and cauliflower among both kids and their parents. Study authors say this compound smells rotten, sulfurous, and putrid.

After this test, researchers mixed saliva samples from the group with raw cauliflower powder. The team discovered large differences in the production of sulfur volatile compounds between participants, but very similar results when comparing parents and their kids.

Surprisingly, the parents of children with high levels of volatile compounds in their saliva did not hate broccoli and cauliflower as much as their youngsters did. Frank’s team believes this is probably because the adults in the study have learned to tolerate the flavor of Brassica vegetables over time. Researchers conclude that the findings provide new insight into how the human microbiome interacts with certain foods.

Now, when a child says “yuck” while eating a plate of broccoli, parents will understand their kids are really telling the truth!

The study appears in the Journal of Agricultural and Food Chemistry.