Despite their health benefits, the bitterness of foods such as broccoli can put people off. New research finds that the taste perception of these foods can change the more they are eaten.

Australians do a poor job when it comes to eating vegetables with just seven per cent getting five (for women) to six (for men) serves of vegetables each day. Eating more of these foods can be challenging when they often have an unpleasant, bitter taste making it difficult to promote the health benefits of vegetables.

This is in stark contrast to the fat, sugar, and salt-heavy obesogenic diets typical of many Western countries and where taste plays a key role in the desirability of these foods.

Taste though, is not a fixed sensation, with sensitivity and perception able to change over time. One mechanism that can change taste is through proteins found in saliva. Food is dissolved in saliva and from there is exposed to over 1,000 different proteins. In humans, salivary protein profiles are related to taste sensitivity and food preference. Salivary protein profiles are different in children with limited food selections compared to children with no such eating difficulties

Amazingly, what is eaten can change the make-up of the salivary proteins which can then alter the sense of taste. The modification of bitter tastes could be a defence system by salivary proteins to allow altering of the characteristics of the food.

In new research looking at bitter taste perception, rats were trained to detect decreasing levels of bitterness in water with quinine added to it. Quinine is what gives tonic water its bitter taste. The rats were then put on diets containing bitter chemicals designed to alter their salivary proteins or a control diet.

The rats exposed to salivary protein-inducing diets had higher detection thresholds for bitter taste meaning they were less sensitive to it. So over time and with a change in salivary proteins, the bitter taste of the water declined.

Implications

Bitter foods can be unpalatable but they are also very healthy foods to eat. This new research helps to show that bitterness can be an acquired taste. Increasing exposure to bitter foods by eating more of them can change the taste perception of these foods meaning they’ll taste better. Just give it a little time.

Last Reviewed: 26/07/2020

© Norman Swan Medical Communications.



References

For reference: Martin LE et al. Bitter-induced salivary proteins increase detection threshold of quinine, but not sucrose. Chemical Senses 2019;44:379-388.

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