A 2009 study suggested that genes may play a big role in how sensitive people are to pain, especially when it comes to spicy foods. Scientists looked at five specific SNPs in the GCH1 gene that are linked to pain sensitivity. They tested 39 healthy volunteers by putting a strong capsaicin cream on their skin to see how much it hurt.

The GCH1 gene encodes for GTP cyclohydrolase, which is implicated in shaping pain responses in rodents and humans and regulates the production of BH4, an essential cofactor for the synthesis of dopamine, serotonin, and nitric oxide. People with certain genetic variants variations in GCH1 reported feeling less pain from the capsaicin. In fact, when they looked at all five SNPs together, they could explain about 35% of the differences in how much pain people felt. This study suggests that specific genetic variants in the GCH1 gene (such as SNPs rs3783641-T and rs752688-C) could have a big impact on how spicy food feels to you. 

In another 2017 study, researchers looked at how a genetic variant known as 1911A>G  (rs8065080) in the TRPV1, the capsaicin receptor gene, can affect an individual’s sensitivity to heat and pain, especially when they are exposed to capsaicin, the fiery component in chili peppers.

They studied 25 healthy people with different variants in this genetic locus:  nine had the most common version (AA), eight were heterozygotes (AG), and eight were homozygous for the variant(GG). They tested how these different gene versions affected how sensitive people were to heat and pain before and after applying capsaicin.

They found that people with the less common alleles (GG) felt less warmth and pain after capsaicin was applied compared to those with the common allele version (AA or AG). This suggests that the variant  1911A>G  (rs8065080 T>C)    might affect how our bodies respond to capsaicin and spicy food.

These two studies show that genes can influence how people experience spicy sensations, and understanding these genetic differences could be important for both patients with pain syndromes and in studies using capsaicin as a model for pain in healthy volunteers.

In a more recent but similar 2020 study, scientists explored how genetic variation might affect people’s sensitivity to coughing triggered by inhaling capsaicin. They focused once again on the TRPV1 gene, which plays a role also in cough response when activated by capsaicin.

They tested 20 healthy volunteers to see how sensitive they were to capsaicin-induced coughing and then analyzed their DNA to look for variations in the TRPV1 gene. They found that individuals with certain combinations of TRPV1  SNPs were more sensitive to capsaicin-induced coughing.

Specifically, they identified four combinations of gene variants (315M or rs222747-C, 585I or rs8065080-T, 469I or rs224534-A, and 91S or rs222749-A) that were associated with increased sensitivity to capsaicin-induced coughing. Interestingly, having at least two of these variations, such as 91S combined with 315M or 91S combined with 585I, was enough to affect cough sensitivity.

These findings suggest that our genetic makeup, specifically variations in the TRPV1 gene, can influence how sensitive we are to coughing triggered by capsaicin. Understanding these genetic differences could help explain why some people are more prone to coughing in response to spicy stimuli.