Are your genes responsible for your aversion to certain foods?
I’m sure many of you have been told that you have your mother’s eyes or your grandfather’s dimples. These traits have been shown to be genetic. But what if I told you that your distaste for some foods might also come from your parents?
No, I don’t mean that your parents had a bad childhood experience with split pea soup so they never served you green peas and always talked about how gross they were – although that could certainly color your views. A group of scientists recently published a study that suggests an enzyme produced by mouth bacteria could be to blame for the bitter taste some people experience when eating broccoli. We will get into that story, but first let’s talk a little bit about our sense of taste.
How do we taste things?
The sensation of taste occurs from a combination of signals that travel from the mouth and the nose, linking up in the brain to complete the final flavor you perceive. The journey from sticking a cookie in your mouth to tasting it begins on your tongue. Taste buds are the master taste organ. Many of us think the bumps on our tongue are taste buds, but that is not entirely accurate. The taste buds live under those bumpy structures, which are called papillae.
Our taste buds contain many sensory receptors that are connected to nerve fibers. There are five specialized kinds of sensory receptors, and each kind detects one of five basic tastes: sweet, sour, salty, bitter, and savory. When chewed food is mixed with saliva it washes over the taste buds. Chemical substances in the food bind the appropriate sensory receptor and it, in turn, tells taste bud cells that a specific taste has been detected.
After a taste bud cell is notified that food has been detected, it signals proteins in the cell to produce a tiny electrical current. Nerves within the tongue detect the electrical impulse and pass it on to more nerves, which signal more nerves. The impulse travels from the tongue all the way to the taste center of your brain, which is called the gustatory cortex. It is here that the signal from your mouth combines with the signal from your nose to tell you what taste you perceive, sweet, salty, bitter, sour, or savory.
Does your genome influence your hatred for certain foods?
The basic taste system is the same for all humans, but we don’t all taste things the same. Many factors can influence how people perceive certain tastes. The number of taste buds on an individual’s tongue determines how strongly they can taste certain flavors and profiles. There are also genetic predispositions for aversion to certain foods. For example, you may be one of the many people who think cilantro tastes like soap. This phenomenon is due to variation in a group of olfactory-receptor genes that allows you to strongly perceive molecules called aldehydes in the cilantro which have a soapy flavor. This genetic variation can be passed from parent to child.
However, it turns out that the microbes that live in our mouths might also influence our sense of taste. Our mouths are filled with tiny microscopic organisms that live together in a group called a microbiome, similar to our gut microbiomes which we recently discussed in another Shareable Science article. Some microbes produce enzymes and other molecules that can influence how food tastes are perceived.
Broccoli and other cruciferous vegetables in the Brassica family (which also includes cauliflower, cabbage, and Brussels sprouts) possess an enzyme called cysteine sulfoxide lyase. When the vegetable is mechanically disrupted, for example by chewing, the enzyme is released and breaks down a compound called S-methyl-L-cysteine sulfoxide (SMCSO) into unpleasant, sulfurous odor molecules.
Bacteria naturally present in some people’s mouths can further increase the production of odor molecules, potentially affecting the in-mouth flavor of Brassica veggies. Several previous studies in adults suggest that the level of cysteine sulfoxide lyase enzyme activity in a person’s spit determines how much SMCSO breaks down, and therefore, how many odor molecules get produced. This influences how Brassica vegetables taste to adults.
Similar studies had not been done with children until now. A research team used a process called gas chromatography-olfactometry-mass spectrometry to identify the main odor compounds in raw and steamed broccoli and cauliflower. They asked 98 pairs of parents and their children between the ages of six and eight years old to rate the key odor molecules based on pleasantness and intensity. Children rated most of the odors more intense than adults.
Saliva was also collected from each of the pairs and mixed with raw cauliflower powder to analyze the production of sulfurous odor molecules over time. Levels of these odor molecules were similar in parents and children, which might be why these vegetables are turn offs for both generations, especially when the levels are high. The finding also suggests shared oral microbiomes. Along these same lines, a separate publication recently found that the oral microbiome of infants was more similar to their mothers than to unrelated female adults, suggesting that moms are indeed sharing and influencing the types of bacteria found in their children’s mouths.
Children whose saliva produced high amounts of sulfur volatiles hated raw Brassica vegetables the most. This was not seen in adults, but they likely learned to tolerate the flavor over time. These findings may also explain why some people like Brassica vegetables and others do not. So next time someone politely turns down your broccoli au gratin or roasted Brussels sprouts, keep in mind that it’s not necessarily a comment about your cooking. It may simply be their genetics and oral microbiome making that call.
To schedule a media interview with Dr. Neil Lamb or to invite him to speak at an event or conference, please contact Nikki Rohling by email at [email protected] or by phone: Office (256) 327-9417 | Cell (256) 937-8210