Tastes threshold and obesity
Tastes sensitivity and food choice
Variations in taste receptor genes give rise to differential taste perception. Low perception of some tastes not only affect our preference towards certain foods, but also alter our metabolism.
These genetic risk factors can promote obesity. Get Gene-Informed, and you might have some useful insights that will help you control cravings and weight gain.
Taste is often cited as the factor of greatest significance in food choice, and has been described as the body’s ‘nutritional gatekeeper’. Taste perception can be affected by age, sex, and factors like age of first exposures, culture and genetic factors.
Obesity is known to decrease taste perception for most tastes. On the other hand, lower taste perception increase the risk for obesity.
Variations in taste receptor genes can give rise to differential perception of sweet, sour, bitter, salty, umami, and fatty taste.
Gene: TASTE RECEPTOR, TYPE 2, MEMBER 38 (TAS2R38)
Genomic coordinates (GRCh38): 7:141,972,630-141,973,772
Low ability to taste bitter taste has been associated with BMI.
The TAS2R38 gene encodes for a taste receptor sensitive to bitter compounds. It is also active as a sensor in the gastrointestinal tract, involved in regulation of metabolism.
Variants in this gene change both our taste response to bitter substances, and our postprandial (after meal) response to nutrients. About a third of the population carry a genetic makeup that lowers their sensitivity to bitter taste and sharp foods. Studies found that this genetic setup is associated with overeating.
Individuals with such a genotype tend to feel more hunger and have higher leptin levels (a hormon promoting sense of hunger).
Gene: TASTE RECEPTOR TYPE 1, MEMBER 2 (TAS1R2)
Genomic coordinates (GRCh38): 1:18,839,598-18,859,660
Individuals with an increased sweet perception tend to have a lower preference for sugar than less taste-sensitive individuals.
Sweet taste perception is affected by age, sex, obesity, environmental factors like age of first exposures to sweet, culture and more. In addition, sweet taste sensitivity has a strong genetic factor.
The TAS1R2 is expressed in taste buds, in the gastrointestinal tract, pancreas, and hypothalamus and may act through these pathways to affect food intake through a glucose-sensing mechanism.
Individuals carrying the variant form of the gene are at higher genetic risk for over-consumption of sugars. Individuals with the common genotype tend to eat relatively less carbohydrates, but also eat less fruit and less fibers in their diet.
Gene: Cluster of differentiation 36 (CD36)
Genomic coordinates (GRCh38):7:80,602,187-80,679,276
Fat is the most energy dense of the nutrients, containing over twice the energy per gram of carbohydrates and proteins.
Fat contributes to a wide range of textural and flavor aspects of foods. As we all know, high-fat foods are highly palatable and often overconsumed in the Western diet.
Individuals who show reduced oral fat perception may consume higher fat foods to compensate for a weak oral signal of fat’s presence. As a result, these individuals may be more likely to overeat and become obese.
Our taste-sensitivity is eroded as we eat more and more fats. Most obese individuals have lowered sensitivity to fat-taste.
Another major factor for losing sensitivity to fat taste is a genetic predisposition towards impaired oral fat-sensing.
The CD36 gene is a fatty acid translocase and oral fat sensor that contribute to the gustatory sensation of long-chain fatty acids, as well as dietary fat preferences.
One of the primary roles of CD36 is to help transport fatty acids across cell membranes
It was found that a homozygous (carrier of two copies) of the CD36 variant are 3 to 5 times less sensitive of taste and texture of fats and oils.
This figure shows that homozygous individuals could not tell the difference between a low (5% fat) and high salad dressing (35%, and even 55%).
The homozygous genotype leads to reduced expression of CD36. This results in lowered sensitivity to fat taste, and low ability to discriminate between high-fat and low-fat content.
Individuals with this genotype tend to have higher preferences for added fats, oils, and spreads (like margarine). individuals who show reduced oral fat perception may consume higher fat foods to compensate for a weak oral signal of fat’s presence. As a result, these individuals may be more likely to overeat and become obese. In the same manner, the sensitivity of fatty acid receptors within the small intestine may be impaired, leading to overconsumption due to reduced satiety signaling.