TAS2R38 rs673849: Understanding Your Bitter Taste Genetics
The rs673849 variant is a functional genetic marker within the TAS2R38 gene, which encodes a receptor responsible for detecting bitter compounds. This variant is part of a three-SNP haplotype that determines whether an individual is a 'taster' or 'non-taster' of specific bitter substances like PTC and PROP.
What each genotype means
High bitter sensitivity
You carry two copies of the C allele at rs673849, an intronic variant in TAS2R38 that is in high linkage disequilibrium with the functional coding alleles defining the taster form of the receptor. Research indicates individuals with this genotype are significantly more likely to perceive intense bitterness from phenylthiocarbamide (PTC), 6-n-propylthiouracil (PROP), and bitter cruciferous vegetables like broccoli and Brussels sprouts. However, overall vegetable intake and dietary habits vary widely among individuals due to cultural, culinary, and non-genetic factors.
Carried by approximately 25% to 35% of individuals across global populations, with slightly higher frequencies observed in East Asian ancestries.
Intermediate bitter sensitivity
You carry one copy of the C allele and one copy of the T allele at rs673849. In population studies, heterozygous individuals frequently report an intermediate sensitivity to bitter compounds like phenylthiocarbamide (PTC) and glucosinolates found in Brassica vegetables. Because bitter perception exhibits co-dominant or partially dominant patterns, your sensitivity to specific bitter foods may fall between non-tasters and strong tasters.
This is the most common genotype globally, occurring in roughly 45% to 50% of people across diverse ancestral backgrounds.
Low bitter sensitivity
You carry two copies of the T allele at rs673849, which typically tags the non-taster form of the bitter taste receptor TAS2R38. Studies show that individuals with this genotype often perceive little to no bitterness from compounds such as phenylthiocarbamide (PTC) and may be less sensitive to the natural bitterness of certain green vegetables. Keep in mind that individual taste preferences are influenced by multiple taste receptors as well as dietary experience.
Found in approximately 18% to 25% of individuals globally, though frequencies can vary among specific ancestral groups.
What is the rs673849 Variant?
The rs673849 variant is a single nucleotide polymorphism (SNP) located within the TAS2R38 gene on human chromosome 7. This gene provides instructions for creating a G protein-coupled receptor found on the surface of taste receptor cells. While rs673849 is a key marker, it does not act alone; it functions as part of a three-SNP haplotype alongside other variants. These combined genetic changes result in amino acid substitutions that alter the shape of the receptor protein. Depending on the specific combination of these variants, the receptor may be highly sensitive to bitter compounds or essentially non-functional. This genetic architecture is the primary reason why individuals perceive the intensity of bitter tastes, such as those found in certain vegetables or chemical compounds like phenylthiocarbamide (PTC), so differently.
The Role of the TAS2R38 Gene
The TAS2R38 gene belongs to a family of 25 functional genes responsible for human bitter taste perception. Its primary role is to detect glucosinolates and thiourea-containing compounds. Evolutionarily, the ability to taste bitterness served as a protective mechanism, helping humans identify potentially toxic substances in nature. Today, this gene influences more than just taste; it is linked to food preferences, dietary choices, and even body composition. Because the receptor is also expressed in other tissues, such as the respiratory tract, some research suggests it may play a role in innate immunity and susceptibility to upper respiratory infections. However, the most well-established function remains its role in the oral cavity, where it dictates the intensity of the bitter signal sent to the brain when consuming specific foods.
Research and Associations
Scientific research has consistently shown a strong correlation between TAS2R38 haplotypes and the ability to taste PTC or PROP. Individuals carrying the 'PAV' haplotype (proline-alanine-valine) are typically 'tasters' who find these compounds intensely bitter, while those with the 'AVI' (alanine-valine-isoleucine) haplotype are often 'non-tasters.' The evidence for this association is robust and widely replicated across diverse populations. Beyond taste, studies have explored links between these genotypes and smoking behaviors, alcohol consumption, and even longevity, though these associations are often more complex and can vary significantly by ancestry. It is important to note that while these statistical associations exist, they do not imply a direct cause-and-effect relationship for every individual. Genetic predisposition is only one factor among many, including environment and culture, that shapes human behavior and health outcomes.
Population Frequency and Diversity
The frequency of TAS2R38 haplotypes varies significantly across global populations, reflecting different evolutionary pressures and dietary environments. For instance, studies analyzing diverse cohorts have found that the prevalence of the functional PAV haplotype and the non-functional AVI haplotype differs between African, European, and Asian populations. In some groups, the AVI/AVI diplotype is quite common, while in others, the PAV/PAV or PAV/AVI combinations predominate. These variations mean that the proportion of 'tasters' versus 'non-tasters' is not uniform worldwide. Understanding these frequency differences is crucial for researchers studying the genetic basis of taste, as it highlights how human populations have adapted to their local food sources over thousands of years. Because of this variability, genetic findings in one population may not always translate directly to another.
What You Can Do With This Information
Knowing your TAS2R38 genotype can be an interesting way to understand your personal sensory experience, such as why you might find certain vegetables like broccoli or Brussels sprouts particularly bitter compared to others. However, this information should be viewed as a fun insight into your biology rather than a medical diagnostic tool. You cannot use this genetic data to diagnose health conditions or determine specific nutritional requirements. If you are concerned about how your taste preferences affect your diet, weight, or overall health, the best approach is to consult with a registered dietitian or a healthcare provider. They can help you develop a balanced eating plan that accounts for your personal preferences and health goals. Always remember that genetics is not destiny; your environment and lifestyle choices play a significant role in your long-term health.
How common is this variant?
The frequency of TAS2R38 haplotypes is highly variable across global populations, with some ancestries showing a higher prevalence of the non-functional AVI haplotype compared to others.
Frequently asked questions
Does my TAS2R38 genotype mean I am a picky eater?
While your genotype influences how intensely you perceive bitter tastes, it does not strictly dictate your food preferences. Many factors, including culture, upbringing, and repeated exposure to foods, play a major role in shaping what you enjoy eating.
Can I change my bitter taste perception?
Your genetic receptor structure is fixed, but your perception can be influenced by your environment. Repeated exposure to bitter foods can sometimes lead to increased tolerance or preference for those flavors over time.
Is being a 'non-taster' bad for my health?
No, being a 'non-taster' is simply a natural variation in human biology. It is not a medical condition and does not inherently indicate poor health or nutritional status.
Should I get tested for this variant?
Genetic testing for TAS2R38 is generally for personal interest rather than clinical necessity. If you are curious about your taste genetics, you can explore it through direct-to-consumer testing, but it is not required for medical management.
Sources & further reading
Educational information only, last refreshed 10/10/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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Val262Ala substitution in TAS2R38 forming the middle polymorphic site of the classic AVI/PAV taste sensitivity haplotype.
One of the three classical missense variants defining the PAV bitter taster haplotype for phenylthiocarbamide and cruciferous vegetables.
Key missense polymorphism contributing to phenylthiocarbamide (PTC) and propylthiouracil (PROP) bitter taste taster status.
Functional marker affecting bitter taste perception of phenylthiocarbamide (PTC).
A key SNP in the TAS2R38 gene (part of the PAV/AVI haplotype) determining sensitivity to bitter compounds like PTC and PROP.
Third position marker (Val296Ile) completing the classic PAV/AVI haplotype determining sensitivity to the bitter glucosinolates found in raw brassica vegetables such as Brussels sprouts and kale.