Salad with creamy delicious dressing (credit: nuchylee)
Super slim model Kate Moss once said, “nothing tastes as good as skinny feels.” Could it be that Ms. Moss just doesn’t taste the true deliciousness of fatty foods?
A recent study by Keller et al. suggests that people vary in how they perceive both fat content and creaminess of foods and that these perceptual differences are based, at least in part, on differences in the coding of a single gene, the CD36 fat translocase.
In this study 317 African Americans were given three cups of Italian salad dressing which varied in fat content (5%, 35%, and 55%). We’ll get to why they tested African Americans later; I don’t know how they chose Italian dressing. The participants then taste-tested the dressing in a red lit room (so the dressings all looked identical) and rated the oiliness, creaminess, and fat content of each dressing. They also filled out a questionnaire where they rated how much they liked different foods, including what the authors termed “added fats and oils” foods (like sour cream, margarine, full-fat salad dressing) and other high fat foods (bacon, doughnuts, salami, cake). When I came to this part of the article I started getting really hungry.
Delicious donuts (credit: Piyato)
Researchers also sequenced portions of the CD36 gene of all the participants and found intriguing relationships between the genotype (the DNA sequence of an individual) of individual participants and the perceptions of the creaminess and fat content of the salad dressing. Specifically, people who had the A/A genotype at one position in the CD36 gene (rs1761667) thought all the salad dressing samples were creamier, regardless of fat content, than did people with the G/G or G/A genotype. The A/A group also showed a higher ‘liking’ rating for the ‘added fats and oils’ food group than the other genotypes. This makes sense to me; more creamy=more delicious. None of the groups was very good at differentiating among the three dressings in terms of either creaminess or fat content, and the A/As were particularly bad.
Genetic differences at another site, rs1527483, were associated with the perceived fat content of the dressing samples. People with the the C/T and T/T genotypes thought all of the salad dressings were fattier compared to the people with the C/C genotype. The C/T and T/T people also tended to have lower body mass indices (body weight adjusted for height), and the authors suggest that these people may be hypersensitive to the taste of fat.
Boy eating cream puff (Credit: Stuart Miles)
These results suggest that two people can taste the same food but experience the taste quite differently, depending on the sequence of their CD36 genes. Fatty acids are known to bind to the CD36 protein, but the exact mechanisms for how this leads to the perception of fattiness or creaminess are unknown—although mice completely lacking this gene don’t prefer “fatty water” over regular water like normal mice do.
Limitations of this study, as discussed by the authors, include the fact that the authors chose to study African Americans specifically because, as a group, they are at a higher risk for metabolic disease and because there are known CD36 genotype variants in this group. It is unknown how the effects of this study would generalize to other ethnic groups. Additionally, the authors did not ask the participants how much they liked the different salad dressings, which could have been interesting.
What I find particularly fascinating about this study is that, if we generalize the findings, people who perceive food as especially creamy have increased cravings for fatty and oily foods, whereas people who perceive food as fatty have a lower body weight (and presumably lower cravings for fatty foods, although the authors don’t state this). Does this suggest that a creamy taste is more appealing than a fatty taste? Does this pass your sniff (err, taste) test?
Keller KL, Liang LCH, Sakimura J, May D, van Belle C, Breen C, Driggin E, Tepper BJ, Lanzano PC, Deng L and Chung WK. (2012) Common Variants in the CD36 Gene Are Associated With Oral Fat Perception, Fat Preferences, and Obesity in African Americans. Obesity. PMID: 22240721