Genetics govern sensitivity to taste of fat in food
MedWire News: People with a variant of the Cluster of Differentiation 36 (CD36) gene are more sensitive to the presence of fat in foods than others, say US researchers.
"The ultimate goal is to understand how our perception of fat in food might influence what foods we eat and the quantities of fat that we consume," commented study author Nada Abumrad, from Washington University School of Medicine in St Louis, Missouri, in a press statement.
"In this study, we've found one potential reason for individual variability in how people sense fat. It may be, as was shown recently, that as people consume more fat, they become less sensitive to it, requiring more intake for the same satisfaction."
CD36 is a glycoprotein receptor that mediates traffic and uptake of lipids between cells. It has been proposed as a potential fat taste receptor in rodents and other species.
To test whether a functional mutation in CD36 (rs1761667) influences fat tasting ability in humans, co-author Marta Pepino, also from Washington University School of Medicine, and colleagues recruited 21 obese (body mass index of 30 kg/m2 or more) individuals with different genotypes for this single nucleotide polymorphism.
In total, six individuals had an AA, seven an AG, and eight a GG genotype for rs1761667. Carriage of the A allele was associated with significantly lower expression of the CD36 protein than was carriage of allele G.
As reported in the Journal of Lipid Research, Pepino and team found that on tasting solutions containing combinations of oleic acid and triolein in different cups, participants who were homozygous for the G allele of rs1761667 were eight times less likely to detect the presence of the fats than those who were homozygous for the A allele. People with the AG genotype had intermediate fat tasting ability between those with the AA and GG genotypes.
"We did the same three-cup test several times with each subject to learn the thresholds at which individuals could identify fat in the solution," explained Pepino. "If we had asked, 'does it taste like fat to you?' that could be very subjective. So we tried to objectively measure the lowest concentration of fat at which someone could detect a difference."
Of note, when participants were given orlistat, which inhibits lipase in the mouth and digestive system in general, their ability to taste triolein was improved, but their ability to taste oleic acid was unchanged.
"Diet can affect sensitivity to fat, and in animals, diet also influences the amount of CD36 that's made," said Pepino.
"If we follow the results in animals, a high-fat diet would lead to less production of CD36, and that, in turn, could make a person less sensitive to fat. From our results in this study, we would hypothesize that people with obesity may make less of the CD36 protein. So it would seem logical that the amounts of the protein we make can be modified, both by a person's genetics and by the diet they eat."
Abumrad concluded: "What we will need to determine in the future is whether our ability to detect fat in foods influences our fat intake, which clearly would have an impact on obesity."
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By Helen Albert