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Genetic variant influences eating habits on girls

Girls with the seven-repeat DRD4 gene may present different eating behavior, depending on socioeconomic environment in which they live
Genetic variant influences eating habits on girls

When interacting with the environment, the gene determines if girls prefer to eat greasy food or to have a healthier diet. Picture by: Joseph Molieri/ Bread for the World

Author: Carolina Golenia

A study conducted by UFRGS and Canadian universities McGill McMaster and University of Toronto discovered that some girls have a genetic variation which may influence in their eating habits. The DRD4 VNTR gene with seven repetitions and its interaction with the environment  determine if girls prefer to eat greasy food or to have a healthier diet.

The DRD4 gene is found in around 20% of the population and it is commonly associated with  obesity, especially in women. The study indicates that girls with the gene and a low income background showed higher levels of body fat compared to girls without this  gene  from the same socioeconomic background. On the other hand, girls with the same genetic variant who came from high income families consumed less fat when compared to other girls from the same social class. “That suggests that it is not the gene itself, but how it makes people more sensitive to environmental conditions, which makes people’s eating decisions more or less healthy in relation to fat and, as a consequence it impacts on the risk of obesity over the years”, says Laurette Dubé, one of the researchers involved in the study.

During the study, the researchers used food diaries kept by the parents of around two hundred 4 year-old children from Montreal and Hamilton, in Canada.  Thus, they calculated fat, protein, and carbohydrates percentages the children consumed, as well as their Body Mass Index (BMI). Saliva sample were collected to verify who among the children had the seven-repeat DRD4 gene. The families’ income was used as a reference to measure socioeconomic environment  quality in which the children were  being  raised and also as an indirect indication of the food environment ( as availability of fruits and vegetables or presence of fast-food restaurants in their neighbourhood, for example).

Recent studies suggest that certain genes, DRD4 included, work as plasticity alleles. It means that those who have that genetic variant may be more influenced by the environment than those who do not.  Thus, depending on the environment, certain neurobehavioral disorders may be more or less likely to happen. Since people with the 7r- DRD4 gene were described as having higher risk of developing obesity, scientists questioned if it would also work as a plasticity allele, which is also environment dependant.

“We hypothesized that the higher fat intake  previously described on girls with the 7r DRD4 allele  could be altered by the social environment -  and we proved it can be so, once the preference for fat increases or decreases according to the socioeconomic level. That is important because it takes the  attention from the allele - previously considered ‘guilty’ for the higher preference for fat - to the environment,  as  the effect of this allele changes according to the way the child was raised”, says Patrícia  Pelufo Silveira, UFRGS Medicine Faculty Professor.

On the other hand, the researchers noticed that the same effect did not happen among boys. They suggested that, from an evolutionary perspective, it might have been more important for girls  to be able  to easily gain  weight  in adverse conditions so they could guarantee reproduction. Another possibility is that, at age four, it might be too early to notice any effect  in boys, since boys and girls gain weight  differently along childhood and they may have distinct behavioral responses to hunger and satiation. “What we can tell from the results is that the genetic variant influences alimentary preferences differently according to the environment, but we do not know how it influences our choices”, comments Silveira.

“The results reinforce how important it is to abandon a “one-size-fits-all” approach to childhood obesity prevention.  We must move towards targeted approaches that focus on  populations that are particularly susceptible to genetics factors, as much as to environmental ones -  individuals biologically vulnerable under adverse conditions  are those who are more likely to have a positive response to such conditions”, emphasizes Laurette.

Scientific Article

Silveira, Patricia P. et al. Genetic differential susceptibility to socioeconomic status and childhood obesogenic behavior: why targeted prevention may be the best societal investment. Jama Pediatrics. Published online February 01, 2016.

 

Original text in Portuguese available at: http://www.ufrgs.br/secom/ciencia/variante-genetica-influencia-habitos-alimentares-de-meninas/

Translated by Ana Nachtigall, supervised by Professor Márcia Moura da Silva (UFRGS)

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