Do babies naturally hate Kale?

A new study about kale-hating fetuses captured the imagination in popular media recently. The research, published in Psychological Science, scanned about 100 pregnant women using 4D (3D made into a video) ultrasound after exposing them to vegetables, and showed more smiling fetuses after exposure to carrots, and more “cry-faces” after mom-to-be ate kale. The ability to code 4D ultrasounds and visualize the curve direction of the corner of a fetus’ mouth in the third trimester results in stunning images – cuteness factors in to make these findings more shareable, and that’s perhaps why this study made it into the Today show.

These aren’t surprising findings though. 

Many pregnant women say that their fetus reacted to certain foods they ate, perked up soon after they had a dose of their favorite flavor, and also liked the same food as a baby.

These anecdotes are supported by theoretical plausibility and some evidence. We know that a fetus develops taste buds early on in pregnancy, that the nose passages (where the organ of smell resides) are open, and inhale amniotic fluid by the end of the second trimester.  Even though the flavor and aroma receptors are not fully developed, and the fetal brain interpretations of the senses are immature, exposure to the content of the amniotic fluid does occur. We have evidence that flavor molecules, originating from mom’s diet, are present in amniotic fluid. There are also studies that show that exposure to certain flavors in pregnancy increases the chance the baby will like these flavors better once they’re introduced to new foods, in the second half of their first year of life.

As to the babies displeased with mom’s food choice: prenatal exposure may lead to better acceptance of kale later in life, and that’s something on which "future studies need to follow up,” the researchers conclude.

It’s never too early

Humans are innately fond of sweet food. But natural preference is just a starting point, as we’re creatures of instinct, but also of habituation and learning. As with many natural tendencies, a parent’s role is to modulate these in order to form healthy, adaptable behaviors in their kid. And since when it comes to food only 1 in 10 kids eat enough veggies, focusing on acquiring a flavor preference for veggies could be very beneficial.

These smiling and frowning 4D ultrasound babies are a reminder that it’s never too early: Mom’s diet during pregnancy, and if she’s breastfeeding, after birth, exposes the baby to the flavor of veggies from the very beginning, well before they eat their first pureed tomato. 

Food habits are one of these things in which timing really matters, as there’s a window of greatest opportunity to take advantage of. Generally, a baby’s first 20 months are the time they’re most open to new flavors and textures – bear in mind that babies are usually fed nothing but milk until age 6 months. Acceptance of new foods decreases after that, food neophobia (dislike of the unfamiliar) peaks at age 5 years, after which interest in new flavors and textures usually recovers.

Say yes to vegetables

Taking advantage of the high adaptability of the very young makes for a good head start with loving your veggies. 

A review, in Appetite, looked at 46 relevant scientific studies – 25 interventional studies and 21 observational ones – on promoting intake of vegetables in kids under 3 years of age. 

Repeated exposure (for 8-10 repeats) was the focus of 27 studies. All 21 experimental studies find that recurrent exposure increases intake, usually by at least about an ounce a day, and that the younger the baby, the greater the gains in veggie consumption. The 6 observational studies confirm the same trends. Some of these studies had up to 6-month follow up, demonstrating that repeated exposure led to a stable uptick in veggies.

Pay attention to the amount of repeats in these studies: Although there is a chance of success by the third exposure, it usually takes many repeats to change a baby’s mind and by the eighth exposure about 70 percent of babies will like a veggie they previously disliked. The persuasive power of repetition works on a baby the way it works on us – hence the repetitive messages and ads we shown.

And bear in mind that many things we eventually love to eat are an acquired taste – think coffee, cheese that smells like sweaty feet, garlic, hot sauce  and wine.

Exposure to a variety of veggies also seems to increase veggie intake in young kids in the 15 studies examining this strategy. When variety is piled on to repeated exposure the advantages are magnified.

Setting a veggie-loving example also helps. Parents who eat vegetables in the presence of their kids tend to have kids that eat vegetables. Three observational studies in the above review confirm that setting a good example of eating and enjoying vegetables is associated with higher frequency and intake in their young kids. And that makes sense: Most kids eventually eat their parents’ diet.

It’s never too late to fall for veggies. Try to do so yourself if it hasn’t happened to you yet; there’s lots of flavor and beauty to explore in the veggie kingdom. The finest chefs in the world are demonstrating their newly found veggie infatuation through vegetable tasting menus – why, Eleven Madison Park recently retained its 3 Michelin star status after going plant-based. Serve veggies in a positive, calm, fun, no pressure way. It also follows common sense that better-tasting, nicely prepared veggies will be better liked.

Soon enough, your kids may like kale.

Dr. Ayala