The science of getting your kids to eat more vegetables

So yum!
So yum!
Image: Reuters/Andres Stapff
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Parenting in the information age can be maddening. Data and opinions are everywhere, but helpful advice often feels in short supply. In our Mom and Scientist series, Quartz journalists Jenny Anderson, a mother of two, and Akshat Rathi, a scientist, tackle challenging topics by balancing complex science against real-life experience.

According to a 2004 study, 19% of four- to six-month-olds are picky eaters, with that figure rising to 50% by age 19 to 24 months. Toddlers are notoriously resistant to anything new, but food intake surveys show that the dislike of vegetables is widespread, starts early, and persists through childhood.

But we also know that the best predictor of whether kids will eat food is whether they like it. So how do we get them to like vegetables—or at least, anything other than chicken nuggets and Cheerios?

The good news is that there is a science to it, and it’s encouraging. In the past decade, researchers have developed some easy and robust techniques to help shape a kid’s food preferences.

The flavor window

Studies show infants have a “flavor window.” It likely opens at four months and closes around 18 months. Hit it, and your kids might be like cauliflower as much as they like cake.

2014 study was one of the first to show that a flavor window exists. Researchers at the University of Birmingham found that kids were most likely to accept a new vegetable they hadn’t tasted—pea purée—between four and six months of age.

2015 study went one step further. It recruited 139 infants about six months old from three countries—the UK, Greece, and Portugal—who had never had solid food. In one group the parents were advised to introduce their kid to five different vegetables, one a day, and repeat that cycle three times, for a total of 15 days. The other group were given no such advice but asked to note the first day the kid was introduced to solid food.

On the 15th day after being introduced to solid food, infants from both groups were made to taste artichoke puree. Artichoke wasn’t part of the vegetable program, but children who had undergone the program were much more likely to enjoy it than the others. (The difference was most marked in British kids, which researchers speculated might be down to cultural differences: Greek and Portuguese parents in the control group may have been more likely to introduce new foods anyway than UK parents were.)

This provides two awesome lessons. Giving a child new foods repeatedly during the flavor window makes it more likely that they will like those foods. And liking those foods makes them more willing to try other new foods.

This doesn’t mean mothers shouldn’t breastfeed. The World Health Organization recommends breastfeeding for the first six months. ”Mothers can follow that advice because breastmilk has a varied taste profile,” says Bee Wilson, author of First Bite: How We Learn to Eat. What the mother eats, the baby gets a taste of, through the milk.

“The trouble arises when mothers choose to move on to formula milk (which is mostly sweet). That’s when I would recommend that mothers also start introducing their kids to new foods,” says Wilson. That’s also what most doctors recommend. 

Wilson highlighted the flavor window in her book. She says that, if parents can get their kids to eat more vegetables in the earliest stages of the window, from four to seven months, they will endow their kids with a liking for vegetables for life. But that flavor window slowly starts closing—making most children neophobic, or afraid of new food, by about 18 months of age.

Exposure and persistence

Many of us might have missed that window, or tried it and found it slammed shut. Jenny introduced her two kids to the exact same foods at the exact same ages; one ate everything, the second spat just about everything out.

The good news is that even after the flavor window closes, it can still be pried open. The key is exposure and persistence. And the trouble is most parents just aren’t persistent enough. According to the previously mentioned 2004 study, more than 90% of caregivers offered kids food they did not like only three to five times before giving up. In a 2007 survey of mothers and infants in southern Germany, 85% of mothers reported their infant refused to eat at least one vegetable. Among those mothers:

  • 6% said they immediately decided their infant didn’t like it
  • 33% decided after two meals
  • 57% decided after three to five meals
  • and just 4% continued trying for longer.

Another 2007 study suggests that sticking it out just a little longer can yield results. In a trial of 49 infant-mother pairs (the kids’ average age was 7 months), Andrea Maier of the University of Burgundy explored whether kids who had already expressed a dislike for a vegetable could develop a taste for it.

The answer: yes they could. When offered the disliked vegetable purée (the ones she tested included carrot, pumpkin, green beans, peas, artichoke, and zucchini-tomato) at eight meals on alternating days, eventually more than 70% of the infants ate it and liked it. Nine months later, 63% of the original group still did.

Other studies have supported Maier’s work. They conclude that toddlers can be made to like a new food by introducing it 5-10 times. Kids aged 3-4 may need to try it 15 times before developing a taste for it. But the flavor window may never completely shut.

Do rewards work?

That’s all well and good, but what about the kids who won’t try the vegetable even once, much less 15 times? Jenny has one of these.

One method researchers suggest is called “tiny tastes,” where the child is asked to eat a pea-sized morsel of a new food. Even licking counts. Do this again and again.

If that doesn’t work, try “Plate A/Plate B.” Give the child a tiny portion of a new food on plate A, and a normal portion of a food he or she likes on plate B. Then ask the child to eat a bite from plate A first and then from plate B next.

If all else fails, there is always bribery—but not the way you usually use it. Cake for some peas? It’s a terrible idea that breeds bad habits and immediately undoes all the good of the nutrients from the vegetables. The reward should not involve food, but, say, stickers or game time. (This is not the best option, but let’s just say one of the authors of this story has definitely reverted to this. Many times.)

It goes without saying that setting an example is critical, and is among the best ways to influence your kids’ eating habits. If you scoff at brussels sprouts, good luck getting your child to eat them.

Finally, if nothing works, you can always blame genetics. Researchers at University College London used data from a long-term study of 2,400 pairs of identical and non-identical twins to study food preferences. When the twins were three, the researchers sent out extensive food questionnaires to the parents asking them to identify their kids’ preferences for six food groups: fruits, vegetables, protein foods, dairy foods, carbohydrates, and snacks. They found that around half of children’s liking for fruits, vegetables and protein foods was attributed to genetics; the rest was due to environmental factors like what foods parents ate and kept in the home.

Which means it’s time to toss the Oreo stash—but if your home is a flawless shrine to organic everything, and your kid still won’t touch a green bean, it may not be your fault. It’s just their (and your) genes.