Do Our Genes Make Us Like Eating Crap We Know Is Bad for Us?

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Do you have trouble sticking to a healthy eating plan? As spring arrives, do you realize that you might not fit society’s accepted version of a “beach body”? You’re not alone. And according to some new research on how your genes affect the foods you seek out, it’s not your fault. You’re not weak-willed, you’re just genetically predisposed to prefer certain foods. So like, just relax. And let’s talk about why this is the case.

In a presentation at the Experimental Biology Conference in Chicago on Saturday, Silvia Berciano, a predoctoral researcher in genomics and nutrition at Tufts University, shows how our genes can predispose us to preferring certain types of foods, foods that aren’t always the best for us. This can make it really hard to stick to diets. Fortunately, this research could help develop better diets in the future, diets that we’re more likely to stick to.

“I am a geneticist by training, and I have always been very interested in human behavior and the genetics of human behavior,” Berciano tells Inverse. This is how she got into this particular area of study, combining these two elements to help us understand the ways our genes affect our behaviors. Berciano is particularly interested in this research because she knows the positive impact that diet can have on health, especially in terms of neutralizing genetic risks. But she worries that some diets are setting people up to fail.

“I was wondering, ‘Will personalized diets reach their full potential in the future, helping us stay healthier for longer, if people cannot adhere to their diets?’” she says. “Changing our habits, changing our behaviors, is probably one of the hardest things that we can ask someone to do.”

This new research could shed some light on the genetics underlying why it’s so hard to change our dietary behaviors.

To complete this study, Berciano and her colleagues used data from 818 people who completed a diet history questionnaire created by the National Cancer Institute. Then they examined these test subjects’ genomes at 38 different points that scientists have found to be associated with a handful of psychological and behavioral traits, including stress, addiction, depression, impulsivity, novelty-seeking, and aberrant eating. What they found were some interesting correlations between eating habits and what are known as single nucleotide polymorphisms — the most common types of genetic variations among people.

SNPs at five of the 38 tested locations are associated with specific receptors in the brain, and the researchers found statistically significant correlations between these genes and particular eating habits. In addition to finding that certain genes are associated with preferences for salty foods and fats, they found one for vegetables and high fiber intake.

Notably, the researchers also found that people whose genes showed a lower number of oxytocin receptors in the brain — oxytocin is the hormone associated with human bondingeat more chocolate and have significantly higher body mass indices, which in turn has its own set of negative health outcomes. And while Berciano and her colleagues have not proven the mechanism for this outcome, she has a working hypothesis that could explain the observed effect.

“Eating chocolate can promote oxytocin as well as dopamine secretion in the brain, subsequently inducing a pleasurable feeling,” she says. “Individuals who carry the genetic variant that results in a defective receptor need to eat more to get the same reward as those who don’t have the defective receptor.” She says that if these people can find ways to improve oxytocin secretion without gorging on chocolate, such as engaging in therapies involving social interactions, then perhaps they don’t have to be slaves to their genes.

Berciano says the correlations they found between genes and diet are very strong — p values below 0.05.

“We are very confident here that we have new findings that can be applied to creating better personalized diets,” she says.

Personalized medicine is still in its early stages, but Berciano says that advances in genetic testing will continue to help us gain a deeper understanding of how our interactions with the world, including diet and other environmental factors, affect our gene expression. The next step? Test more people.

“We are in the process of validating these findings in a different population,” she says. This is important because the current study was done on mostly Caucasian subjects, and genetic differences among ethnic groups could provide important insights into personalized diets in the future.

Abstract: Food preferences and cognitive control influence dietary habits thus affecting compliance with dietary advice and the risk of chronic diseases. A complex mix of genetic and environmental, cultural and social factors drives these preferences. Therefore, efforts to improve diet and behavior at the individual level should take into consideration this distinct combination of genetic and environmental factors, specifically addressing the psychological component of food consumption with the goal of facilitating long-term compliance with dietary interventions. Objective: To investigate the association between behavioral candidate genes, food preferences and anthropometric traits. Population and Methods: For this purpose we used data from the Genetics and Lipid Lowering Drugs and Diet Network (GOLDN) Study including two genetically homogeneous sites (Minneapolis, Minnesota, and Salt Lake City, Utah). In the current study, 818 participants (404 men and 414 women) of European ancestry were included in our analyses. Single nucleotide polymorphisms (SNPs) within 38 loci (1359 SNPs) selected on the basis of previous associations with several behavioral and psychological traits (i.e., stress, addiction, depression, impulsivity, novelty-seeking, aberrant eating) were extracted from the original genome genotype data that was generated from the Genome-Wide Human SNP Array 6.0 (Affymetrix). Information about dietary intake was collected with the use of a diet-history questionnaire, which was developed by the National Cancer Institute. Results: Multiple nominally significant associations (p<0.05) were observed between genetic variability at the selected loci and the consumption of specific foods and nutrients. However, after adjustment for multiple comparisons, significant associations (Padj<0.05) were observed for the FTO locus with vegetable and total fiber intake; the CREB1 and GABRA2 loci were associated with salt intake; and the SLC6A2 with total fat and monounsaturated fatty acids. Finally, chocolate intake was associated with variation at the OXTR locus. The most significant association with anthropometric traits was found for OXTR and waist circumference. Conclusion: Our data indicate that genes implicated in behavioral and psychological traits drive a significant component of an individual’s food preferences and dietary habits. This information will contribute to a better understanding of eating behavior and facilitate the implementation of personalized dietary advice that should result in better compliance and more successful prevention and therapy of chronic disorders.
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