From the latest issue of Food, Nutrition & Science.
We’ve all been there. Offering our children sides of broccoli and carrots only to be met with refusal, followed by an adorable “can we have dessert now?” plead. As a parent, it’s hard to know if your child is truly disgusted by the healthy item in question, or if all that exhausting negotiating – the promise of sweets in exchange for eating those vegetables – has created a snack-craving monster. Turns out, it just might be a little bit of both.
While genetic and environmental effects are both significant in predicting food preferences in children, the environment has a larger influence on energy-dense foods like snacks, dairy and starches, according to a recent report from University College London and published in the American Journal of Clinical Nutrition. The report also found that genetics have a stronger influence on nutrient dense foods like fruits, vegetables and protein.
“The findings of this study show that while the home environment is very influential, particularly in shaping children's liking for energy dense snacks and starchy foods, the extent to which children like some other foods such as fruits, vegetables and protein foods is highly heritable. However, it is important to remember that just because genes are involved in determining preferences doesn't mean that we can't intervene to change liking for these foods,” says Dr. Alison Fildes, study author.
When thinking about the development of children's food preferences, there has been a strong focus on the early home-food environment, particularly among health professionals. But what about the fussy child who seems to hate vegetables? Previous research has shown that there actually are genes related to taste sensitivity (like preferences or aversions to bitter, sweet, umami and even fat), yet there have been few genetic studies looking at specific foods. This study delves into specifics, looking at how environment and genes relate to both energy and nutrient dense preferences.
Data for this study came from Gemini – a cohort of UK twins (twin studies enable researchers to observe which variation in a population can be explained by genetic or environmental factors) born in 2007 – and looked at preferences for 114 foods. Vegetables were the least liked, followed by dairy, protein and starch. Not surprisingly, snacks (chocolate, cookies, ice cream and chips) were the most liked. Genetics were found to only have a moderate influence on starch, snacks and dairy. Vegetable preferences and protein, on the other hands, were strongly influenced by genetics. Meanwhile the shared home environment had a significant influence on preferences for snacks, starches and dairy and only moderate influence on fruits, vegetables and protein.
Fildes points out that we know humans are born with innate preferences for sweet and energy dense foods, and in the past, when food availability was relatively scarce, it was adaptive to prefer energy-rich foods. But in the current food environment, where energy-rich snack foods are readily available, these preferences have obvious negative repercussions. We also know that there is individual variation in the extent to which people like snack foods (and other foods), and it is this variation that was the focus of the research.
“While most children will display an inborn preference for sweet and salty snack foods, our study also found that a large amount of the individual variation in liking for these foods (the extent to which liking varies from child to child) is explained by environmental factors. Research has shown the more we are exposed to certain foods, the more we like them, and our findings suggest this is especially true for snack foods. The early food environment is particularly important for the development of food preferences and by making snack foods freely available in the home, or regularly offering them to young children, we are reinforcing these less healthy preferences,” says Fildes.
Even though parents may be correct in perceiving some of their children’s preferences to be innate, the influence of inherited food preferences does not mean environmental interventions are insignificant – especially when it comes to energy-dense snacks. Researchers therefore recommend that both parents and health professionals tackle this issue in different ways for different types foods.
“Just because a child may be genetically predisposed to dislike certain foods doesn't mean their preferences can't be changed. Children can learn to like rejected or novel foods by repeatedly tasting them and it can take up to 10 to 14 tries of a food before acceptance is increased,” says Fildes.
Fildes suggests retailers emphasize that the home food environment is very important for the development of children's food preferences. However, Fildes adds that we should avoid “blaming” parents when children are fussy and refuse to eat vegetables and fruits as these behaviors are likely to be at least partially genetically determined. Instead, parents should be supported and given guidance on techniques to increase children's liking for commonly rejected foods, such as vegetables.
“While restricting children's access to energy dense snack foods is important to prevent strong preferences for these foods, simply increasing availability of vegetables might not be sufficient to increase some children's liking, meaning additional intervention might be necessary,” Fildes adds. “The key message to parents is not to give up but to persist in offering rejected foods again and again.”