Do people pretend to like kale because it’s trendy? Or is the purported ‘super food’ an acquired taste like olives … or hay?
A world-first experiment has found that fussy eating begins in the womb, and that late-stage unborn babies tend to give kale the thumbs down.
To be precise, foetuses have been recorded on 4D ultrasound screwing up their faces and looking very unhappy when exposed to kale’s flavour, such as it is.
The image in 4D ultrasound is continuously updated and reveals foetal movement in real time, whereas 2D and 3D ultrasounds capture a still image.
The finding was part of an experiment from Durham University that “recorded the first direct evidence that babies react differently to various smells and tastes while in the womb”.
The study was led by Durham University’s Foetal and Neonatal Research Lab, and included scientists from Aston University, Birmingham, and the National Centre for Scientific Research, University of Burgundy, France.
One hundred pregnant women, aged 18 to 40, were scanned at 32 weeks and 36 weeks of pregnancy, “to see foetal facial reactions to the kale and carrot flavours”.
The mothers were given a single capsule containing about 400 milligrams of carrot or 400 milligrams kale powder about 20 minutes before each scan.
They were asked not to consume any food or flavoured drinks one hour before their scans.
The mothers also did not eat or drink anything containing carrot or kale on the day of their scans to control for factors that could affect foetal reactions.
Facial reactions seen in both flavour groups were compared with foetuses in a control group who were not exposed to either flavour.
The scans revealed that “just a small amount of carrot or kale flavour was enough to stimulate a reaction”.
The scientists found that “foetuses exposed to carrot showed more ‘laughter-face’ responses while those exposed to kale showed more ‘cry-face’ responses”.
The researchers believe that what pregnant women eat “might influence babies’ taste preferences after birth and potentially have implications for establishing healthy eating habits”.
An amniotic fluid buffet
Given that we experience flavour through a combination of taste and smell, how would flavour work in a watery environment?
In foetuses, the researchers say, it is thought that this might happen through inhaling and swallowing the amniotic fluid in the womb.
“A number of studies have suggested that babies can taste and smell in the womb, but they are based on post-birth outcomes while our study is the first to see these reactions prior to birth,” said lead researcher Beyza Ustun, a postgraduate researcher at Durham.
“As a result, we think that this repeated exposure to flavours before birth could help to establish food preferences post-birth, which could be important when thinking about messaging around healthy eating and the potential for avoiding ‘food-fussiness’ when weaning.”
The researchers have begun a follow-up study with the same babies post-birth to see if the influence of flavours they experienced in the womb affects their acceptance of different foods.
Research co-author Professor Jackie Blissett, of Aston University, said: “It could be argued that repeated prenatal flavour exposures may lead to preferences for those flavours experienced postnatally. In other words, exposing the foetus to less ‘liked’ flavours, such as kale, might mean they get used to those flavours in utero.
“The next step is to examine whether foetuses show less ‘negative’ responses to these flavours over time, resulting in greater acceptance of those flavours when babies first taste them outside of the womb.”