• Samantha Schofield

The genetics of tastebuds: does coriander actually suck?

Taste preferences affect us every day, whether it's asking for no coriander or extra pickles. Many people’s favourite foods are inedible to others! Is there a genetic component for food preferences? Can you grow out of being fussy eating? Are people who hate coriander just looking for attention or does it taste like soap? All will be revealed!

How do we taste things?

The tongue is responsible for the majority of our tasting, along with the help of saliva and our noses. The belief that different areas of the tongue are responsible for different tastes is actually a myth. In reality, the tongue is covered in tiny bumps called papillae. The sides of the papillae are home to our taste buds and within the taste buds, all snuggled together, are all our taste receptors. We have sweet, sour, salty, bitter and umami (savoury) taste receptors. When we eat food, the chemical compounds in the food activate our taste receptors and the receptors send signals to the brain.

Taste receptors are thought to be essential to survival for early humans (and animals), by helping the brain choose nutrient-rich food and stay clear of poison in order to survive. Sweet and umami foods are commonly nutrient-rich and when consumed their respective taste receptors sends a chemical message to the brain to say “hey this is good stuff”. Bitter and sour tastes are commonly associated with being toxic and dangerous if ingested. So our body usually rejects a lot of bitter and sour tastes. Unfortunately, this doesn’t seem to be the case for beer, another reason why I think beer is gross. Salty tastes are linked to sodium balance in the body, when animals have low sodium, they tend to have a higher salty appetite. Taste is also helped by the olfactory system, which has sensors located up our nostrils. As we chew food, the smell wafts up to our nostrils and triggers the olfactory system, sending even more messages to the brain.

Does genetics have anything to do with tastebuds?

As we know, taste receptors are essential in how we perceive food and if we down a whole packet of chips without realising. Taste receptor genes have been studied in both humans and mice extensively. Studies found individual variation in taste receptor genes correlated with differences in taste responses. So, some people’s taste receptor genes could make them more sensitive to bitter tastes than others who don’t care how bad beer tastes. But taste isn’t just straightforward genetics of liking or not liking bitter foods. Food preference and taste perception are what we call a complex trait, which means its influenced by both genetic and environmental factors. Many genes contribute to bitter taste perception and they all interact! So, we can’t look at one gene and say “yes this person would froth an espresso”. Plus, if you’ve been brought up tasting bitter foods (which are the environmental factors), that changes how you perceive bitter too. And this isn’t even considering the olfactory system’s response to foods, in which there are over 400 functional olfactory genes that can all contribute to how we taste and smell foods.

People can also be classified into super-tasters, tasters and non-tasters. And this is not a complex trait as it's caused by three small SNPs (which means 3 tiny changes in our DNA)! Whether you’re a supertaster or not can be figured out by a classic Punnett square stuff that we know and love. Supertasters taste certain flavours a lot stronger than other tasters and account for 25% of the Australian population. 50% are normal tasters and 25% are non-tasters (who don’t as strong reactions to food).

Can you grow out of being a fussy eater?

As a previously fussy eater, I always wondered how people liked the taste of foods I hated. One study review found that children preferred sweet food when compared to adults. A possible explanation is that kids require more calories to grow. As we said before, sweet foods are usually calorie and nutrient-rich. So really, it could be evolution’s fault that kids gulp down red cordial and act insane in Coles when I’m just trying to shop in peace. Kids across the board also agreed bitter and sour was their least favourite taste.

Taste sensitivity to certain tastes also changes with age. Kids have a higher concentration of taste receptors, making them more sensitive to sweet and bitter foods. The bitter foods warn them of poison and tell the brain the food is disgusting. This explains why certain foods can taste so much more intense to young kids. Broccoli isn’t the end of the world Lil Jimmy, you might like it someday. Adults also lose a lot of taste receptors as they age, which is consistent with adults liking foods with strong flavours.

So, what's the deal with coriander?

Ahh, the world’s most controversial herb and it’s not even illegal! Coriander’s name has been dragged through the mud as people say it tastes like soap or dirt. Justice for coriander!!!!! While not proven, it is suspected people hate coriander because of smell, rather than taste. A genome-wide association study analysed the genes of over 14,000 participants. Of the participants who answered that coriander tastes like soap, there was a strong association with one SNP. This SNP is near a cluster of genes that affects the olfactory (smell) system and within that cluster is an olfactory receptor gene. So, it's most likely the smell of coriander that’s got everyone freaking out.

Taste used to help us stay alive and now it sees me sculling my 3rd coffee of the day without a care in the world. Whether you’re a super-taster or a broccoli denier, everyone tastes different! Ooh, that didn’t sound right…

Sources and further reading