Bitterness Taste Receptors
Taste is a crucial determinant of food selection. Taste sensitivity can influence preference in dietary habits, particularly in children. Modification in bitter taste receptors alters taste perception and, as a result, an individual will have increased sensitivity to bitter tastes. They will therefore avoid bitter foods, such as vegetables, and instead may have a preference for sweet foods.
What is the TAS2R38 gene?
The TAS2R38 gene encodes a bitter taste receptor that recognises phenylthiocarbamide (PTC), a bitter compound very similar to the bitter glucosinolates found in brassica vegetables.
What is the effect of genetic variation at the TASR38 gene?
Genetic variation at the TAS2R38 gene affects an individual’s sensitivity to bitter foods. Individuals with two alleles find foods containing PTC more bitter than individuals with one allele and individuals with no SNP cannot taste PTC. Genetic variation at TAS2R38 accounts for up to 85% of the variation in PTC tasting ability by altering the G-protein binding sites on the receptor that it codes for.
Sensitivity to bitterness affects dietary choices and has been linked to increased sugar preference, especially in children.
Why is it important to be aware of bitter sensitivity in children?
Children with bitter sensitivity have a preference for sweet foods because other non-sweet foods taste too bitter to them. Research found that children with sensitivity to bitter tastes consumed more sweet snacks that those with no sensitivity. This preference for sweet foods increases their risk of obesity.
Increased sensitivity to bitterness is also associated with increased child neophobia. Child neophobia results in rejection of new unfamiliar foods, which in turn leads to a diet with little food variety, especially in young children.
Does sensitivity to bitterness change with age?
Children are much more sensitive to bitterness than adults, suggesting that innate bitter sensitivity may be modified during life.
Why did the ability to taste bitter substances evolve?
Humans are exquisitely sensitive to bitterness and can detect bitter compounds at concentrations several orders of magnitude lower than the other basic tastes.
The ability to taste bitter substances is believed to have evolved in humans to avoid food that contains toxins, which are usually bitter. Therefore, higher sensitivity to bitterness was advantageous in the human evolution as it decreased an individual’s risk of consuming toxins which would be harmful to their health.