Taste Gene Could Be Behind Your Child's Poor Eating Habits

Fussy children refusing to eat their regular meals or anything which we consider to be healthy is very common in almost all households. Mothers usually complain about the poor eating habits of their children, which leads to a mini warlike situation in the dinning area. Parents try all the methods like distracting the child, bribing, scolding, running after the kids with a plate in hand etc. But unfortunately, all these methods are not longstanding and cannot cultivate healthy eating habits in our kids. At the end of every meal, parents land up thinking how to make their children eat a proper nutritious balanced diet.

We often forget that the food choice of kids also depends on a number of physiological, environmental, and socio-cultural factors like any other adult. They also have preferences like any adult, for example, some like very spicy food, whereas some it like sweet. It is a real tough task for parents to understand the taste demands of their children and prepare food according to their taste.

The word “Taste” usually means all the sensations arising from the oral cavity. A special chemosensory gustatory system is involved in giving us the perception of taste. Small tissue elevations known as gustatory papillae are located on the upper surface of the tongue, oropharynx, larynx, epiglottis, and the upper esophagus. The gustatory papillae contain taste buds, organized with the receptors of taste (taste receptor cells/ TRCs). The taste stimuli in food are usually generated by the water soluble chemicals in food. The apical ends of the TRCs, exposed to the oral cavity, interact with these taste stimuli to produce the sensation of taste. Signals of the interactions with the taste stimuli are sent to the brain through cranial nerves. The wide representation of taste information in the brain is very essential to raise our appetite and stimulate behavioral responses to taste stimuli (Bachmanov & Beauchamp, 2009).

Taste receptors function as chemoreceptors, which interact with taste stimuli and give us the perception of taste. Some criteria set to label a molecule as a taste receptor are as follows-

• They should be expressed in taste receptor cells.
• Specific ligand to the taste receptors should be identified.
• Changes in taste receptors should lead to alterations in the perception of taste (Bachmanov & Beauchamp, 2009).

Currently, human taste sensations are divided into five qualities: bitter, sour, salty, sweet, and umami (representing the stimulus generated by the amino acid glutamate, generally used to describe meaty, savory flavor) and accordingly different taste receptors have also been identified. Some of the approved taste receptors include T1R and T2R receptors which belong to a super-family of G protein–coupled receptors. Amongst these trans-membrane proteins,

• T1R receptors are associated with sweet and umami taste perception.
• T2R receptors are associated with the perception of bitter taste.
• PKD1L3 and PKD2L1 are ion channels which act as sour taste receptors.
• CD36 is an integral membrane protein which recognizes the putative fat taste.
• Epithelial sodium channels and TRPV1 are together associated with the perception of salt taste (Bailo, et al. 2009).

The association between genes and taste preferences was first discovered in 1931 when a chemist named Arthur Fox accidentally discovered that he could not detect the bitter taste of PTC (phenylthiocarbamide). Later, genetic modeling studies have suggested that there are two different alleles or two common forms of the PTC gene. The sensitivity to PTC is inherited and depends upon which alleles have been inherited from parents. This study was further supported when a group of psychobiologists conducted their genetic testing on a group of 143 children and their mothers. These psychobiologists not only concluded that PTC gene is responsible for the bitter taste, but also that the preferences for sweet tasting food was higher in children having two bitter-sensitive regions of a gene (Psychobiologists Find Genetic Component in Children's Food Preference, 2005). Similarly, other genes coding for different taste receptors also show variations among different individuals of a population.

There are two main hypotheses which describe how these taste genes are interpreted by our brain. The first one is the labeled-line theory, according to which the signal from the taste receptor cells is directly carried to the neurons without any modification. This signal is read by the brain as a specific quality. This means that the TRCs make a one-to-one connection with brain. The second one is cross-fiber or pattern hypothesis. According to this hypothesis, the brain captures the information in the form of a complex pattern of nerve firing and tries to interpret from this complex pattern. The coding of primary tastes by the brain is individualized, which makes the perception of taste very specific for each person (Reed, et al. 2006).

Genetic variation in taste receptors has been correlated with food choices and dietary habits in different individuals, which ultimately has an impact on the nutritional and health status of an individual. Apart from genetic factors, environment and socio-cultural factors also influence food selection. The main objective of this article was to throw light on the scientific factors related to the poor eating habits of children. The author of this article feels that if parents are able to understand the taste preferences of their children and provide nutritious food according to their taste, the job is mostly done.

Bachmanov, A,A & Beauchamp, G, K. (2009). Taste Receptor Genes. Annu Rev Nutr. 27, 389–414.

Bailo, BC., Toguri, C., Eny, K,M., & Sohemy, A, E. (2009), Genetic Variation in Taste and Its Influence on Food Selection. A Journal of Integrative Biology. 13(1).

Psychobiologists Find Genetic Component in Children's Food Preference. (2005). Retreived on 15^th Feb. 2013. from http://www.sciencedaily.com/videos/2005/0508-the_taste_gene.htm

Reed, D,R. Tanaka, T and McDaniela, A, H. (2006). Diverse tastes: Genetics of sweet and bitter perception. Physiol Behav. 88(3): 215–226.