Can our genes influence what we like to eat?

Teachable moment in classrooms:

1. cellular basis of life chapter – concept of one gene, one protein
2. cellular basis of life chapter – concept of gene mutation leading to protein malfunction
3. special senses chapter – taste receptors are in taste buds
4. special senses chapter – role of G-proteins in sweet, bitter and savory taste receptors

The news item:  Recently this news article appeared online:

Bitter or Savory, Taste Genes Could Influence Your Diet

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The article states that a study was conducted to link previously described gene variations to the five basic taste types: sweet, sour, bitter, salty and savory. People with high sensitivity to bitter flavor ate fewer whole grains.  People with high sensitivity to savory flavor ate fewer vegetables. People with high sensitivity to sweet flavor had lower triglyceride levels.

So, Why Do I Care??  Changing ones diet have been part of many non-invasive prevention of diseases, and also part of maintaining a healthy lifestyle after surgery or after the start of new medication. However, changing ones diet is a challenging task, because of the stubborn food preferences we all develop. If those food preferences can be linked to genetic function, then dietary changes could be guided to accommodate those gene-influenced food preferences, and to give patients dietary prescriptions that we find easier to follow.

Plain English, Please!!!  First, let’s talk about the cells that detect tastes. On the surface of your tongue there are hundreds of small bumps called papilla, and inside each of those bumps sit taste receptor cells that detect chemicals around them. When those receptor cells detect taste-related chemicals, the cells then release neurotransmitters to start a nerve impulse in the axons of cranial nerve VII or IX.

Second, let’s talk about how taste receptors detect tastes. The five types of taste receptor cells are sensitive to different taste-causing chemicals (tastants). The “sour” receptor cells are sensitive to hydrogen ions, and the “salty” receptor cells are sensitive to sodium ions. For both of those receptors the chemicals have to enter the receptor cell to cause a release of neurotransmitters. The “bitter” receptor cells (detect small organic molecules), the “sweet” receptor cells (detect simple sugars), and the “savory” receptor cells (detect some amino acids) are using receptor proteins on the outer surface of the cell. When a tastant physically binds, stick to the receptor protein, then a signal is sent to the inside of the receptor cell, and that causes the release of neurotransmitters. Imagine that a tastant molecule is a finger, and the receptor protein is a doorbell. Once the finger touches the doorbell, a signal is sent into the house, the taste receptor cell.

Third, let’s talk about how the sensitivity of sweet, bitter, and savory receptor cells might change to bring about altered sensitivity to flavors. The doorbell in a house always sounds the same. However, imagine that changes in the house would make the doorbell ring louder in some houses, or ring for a longer time. Inside the receptor cell (the house) genetic mutations may change the protein components of the signaling routes, and that may cause a stronger reaction, a longer release of neurotransmitters, or the release of more neurotransmitters. That is why researching genetic markers (evidence of genetic mutation) may correlate with altered sensitivity to flavors.