Why do we eat what we eat? People enjoy eating foods that are not just appealing to their taste buds, but more importantly, that are not unappealing to them. Whether it’s disgust over the taste of cilantro or intolerance to a food group altogether, the science behind food preferences is complex. Factors including allergies, genetics, socioeconomical influences, and even the gut microbiome have been implicated in determining what we eat. Genetics specifically remains a poorly understood contributor to diet, although recent research has shed light onto several genetic variations in individuals that can play a role in determining which foods we prefer to consume.
A popular example of a highly polarizing food item affected by genetics is cilantro. Those who detest this innocuous leafy herb describe its taste as soapy or bitter – not a taste you want in your next bowl of noodles. This unpalatable flavour comes from the presence of aldehydes in cilantro leaves. Caucasians that possess a single nucleotide polymorphism (SNP) mutation in a set of olfactory receptor genes tend to experience this phenomenon more frequently, suggesting that variants of these olfactory receptors are responsible for the disagreeable taste of cilantro due to differential binding to aldehydes.
Cilantro isn’t the only example where an individual’s sense of smell can affect their dietary choices. Asparagus is known to leave a foul odour in urine after consumption, a by-product of asparagusic acid metabolism that generates pungent sulfuric compounds as a waste product. Yuck! However, some people are in luck. SNPs in olfactory receptor genes on chromosome 1 have been associated with the curious inability to smell asparagus in urine, a condition known as asparagus anosmia. Over 50% of Caucasians possess altered olfactory receptors that evade the putrid stench left behind by asparagus, possibly influencing one’s decision to include these green stalks in their diet.
Along with our sense of smell and taste, the ability to metabolize food is also an important determinant in what we eat. Enzymes that aid in the digestion of common foods, such as dairy or alcohol, are often found lacking or dysfunctional in some populations. For example, SNPs in the regulatory region of the lactase gene, which is typically downregulated after infancy, are postulated to contribute to the retention of lactase into adulthood and the ability to consume dairy products without intestinal discomfort. This phenomenon is more common in populations with pastoral ancestors that drank animal milk. Similarly, SNP variants of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) contribute to alcohol tolerance. Acetaldehyde, a by-product of alcohol metabolism via ADH, results in nausea and flushing as it builds up in the body. Individuals with “fast” ADH variants or inactive ALDH variants (which normally breaks down acetaldehyde) tend to drink less alcohol due to the bodily discomfort caused by this toxic by-product.
Although the foods and drinks we consume are heavily influenced by the environment we are raised in, it is clear that our genetic makeup can play a significant role in our dietary decisions. Gene variants can cause certain foods to be unpleasant – if a meal tastes nasty or gives you the runs, chances are you won’t eat it again. However, at what level genes determine what we enjoy eating still requires further research. As scientific groups continue to investigate the genetics behind food preferences, it will be interesting to uncover how much of our diet is directly affected by our biological code.
References
1. Eriksson, N., Wu, S., Do, C. B., Kiefer, A. K., Tung, J. Y., Mountain, J. L., Hinds, D. A., & Francke, U. (2012). A genetic variant near olfactory receptor genes influences cilantro preference. Flavour, 1(1). https://doi.org/10.1186/2044-7248-1-22
2. Markt, S. C., Nuttall, E., Turman, C., Sinnott, J., Rimm, E. B., Ecsedy, E., Unger, R. H., Fall, K., Finn, S., Jensen, M. K., Rider, J. R., Kraft, P., & Mucci, L. A. (2016). Sniffing out significant “pee values”: Genome Wide Association Study of Asparagus Anosmia. BMJ, i6071. https://doi.org/10.1136/bmj.i6071
3. Anguita-Ruiz, A., Aguilera, C. M., & Gil, Á. (2020). Genetics of lactose intolerance: An updated review and Online Interactive World Maps of phenotype and genotype frequencies. Nutrients, 12(9), 2689. https://doi.org/10.3390/nu12092689
4. Tolstrup, J. S., Nordestgaard, B. G., Rasmussen, S., Tybjærg-Hansen, A., & Grønbæk, M. (2007). Alcoholism and alcohol drinking habits predicted from alcohol dehydrogenase genes. The Pharmacogenomics Journal, 8(3), 220–227. https://doi.org/10.1038/sj.tpj.6500471
5. Edenberg, H. J. (2007). The Genetics of Alcohol Metabolism: Role of Alcohol Dehydrogenase and Aldehyde Dehydrogenase Variants. Alcohol Research & Health, 30(1), 5–13.
6. Chester, L. (2021, October 14). How genes influence food choices, obesity. Boston University. Retrieved June 13, 2022, from https://www.bu.edu/articles/2021/how-genes-influence-food-choices-obesity/ 7. Merino, J., Dashti, H. S., Sarnowski, C., Lane, J. M., Todorov, P. V., Udler, M. S., Song, Y., Wang, H., Kim, J., Tucker, C., Campbell, J., Tanaka, T., Chu, A. Y., Tsai, L., Pers, T. H., Chasman, D. I., Rutter, M. K., Dupuis, J., Florez, J. C., & Saxena, R. (2021). Genetic analysis of dietary intake identifies new loci and functional links with metabolic traits. Nature Human Behaviour, 6(1), 155–163. https://doi.org/10.1038/s41562-021-01182-w
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