Why chili pepper feels hot while Mint feels cold?

Have you ever wondered why eating a chili pepper burns your mouth and makes you feel hot while sucking up a mint brings cool sensation in your mouth??

 

This can simply be explained owing to “receptors”. Receptors are protein-molecules that recognize and responds to chemical signals. In case of a hot chili, there is an active ingredient in the pepper called capsaicin. This capsaicin binds to a special class of receptors found in the tongue, mouth, and skin called vanilloid receptors 1 “VR1 receptors”.

This binding cause the sensory neuron to depolarize (sodium ions rush inside and the neuron becomes more positive) sending a signal to the brain indicating the presence of spicy stimuli.

What we should mention is that VR1 receptors weren’t designed to detect capsaicin – they were found to bind spicy food by accident- Their main function is to rather detect heat, a process known as thermoreception. They are activated by temperatures higher than 42 °C or by acids to prevent us from consuming harmful compounds or burning ourselves.

You may have noticed, that eating a large amount of spicy food by time won’t increase the burning sensation, but on the contrary will make you feel nothing! That is because the receptors will eventually stop responding so strongly to the compound, a phenomenon called “capsaicin desensitization”. That is why you can find capsaicin in patches and creams used to alleviate pain.

 

On the other hand, as capsaicin activates “VR1 receptor” we have menthol in mint which binds and activates transient receptor potential cation channel subfamily M member 8 (TRPM8).

This TRPM8 is an ion channel that regulates the movement of ions across the membrane, and only certain stimulants can open it, like the cold temperatures or menthol binding to it, allowing Na+ and Ca2+ ions to enter the cell. This entry changes the electrical charge within the neuron and signals the brain to interpret a sensation of cold!

Now you know why sensation can differ according to the activated receptor.

 

Here are some extra benefits of both compounds:

Capsaicin

  • For osteoarthritis, rheumatoid arthritis and fibromyalgia, as well as certain kinds of joint pain.
  • It decreases the amount of psoriasis breakout on the skin.
  • Helps in weight-loss by speeding metabolism, burning fat and suppresses appetite.
  • Acts as a potent anti-inflammatory.

 

Menthol

  • Reduces stomach aches, Apply a little amount of the oil on the stomach helps ease stomach pain.
  • Menthol treats irritable bowel syndrome. Due to its ability to prevent or treat gas and bloating.
  • In certain medications used to treat sunburns, as it provides a cooling sensation.
  • Inhaling steam from a hot bowl of water, in which menthol has been added, can refresh the mind and ease mental fatigue.

 

 

References:

http://pharmrev.aspetjournals.org/content/51/2/159

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2430674/

 

 

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