Womb to WEAN:Weaning and Exploring Acceptance of New Tastes
Research type
Research Study
Full title
Womb to WEAN: Weaning and Exploring Acceptance of New Tastes
IRAS ID
245551
Contact name
Jacqueline Wallace
Contact email
Sponsor organisation
University of Dundee
Duration of Study in the UK
2 years, 6 months, 28 days
Research summary
Research Summary
Children have an innate preference for sweet and salty foods and dislike for bitter foods which creates a challenge in today’s food environment where we have unlimited access to sweet and salty, energy-dense, nutrient-poor foods; and often the foods which are most beneficial for our health, such as bitter vegetables, are rejected. However, there is a body of evidence to support the benefits of flavour exposure in utero and through breastmilk via the Mother’s diet to alter infants’ taste preferences.
Research investigating the effects of fetal flavour exposure has primarily been conducted in animals with a single target flavour – however this unnatural consumption pattern along with differences in the development of the chemosensory system mean the results are not readily generalizable to humans. A prospective study in humans is needed to assess the influence of the perinatal diet as a whole, particularly fruit and vegetable consumption, on infants’ taste preferences at weaning in order to, potentially, provide proof of concept and inform nutritional guidelines. Pregnant women in their third trimester will be exposed to a diverse range of fruit and vegetable-based foods as part of a 24day intervention, and their habitual consumption assessed. The hypothesis is that an intervention to increase maternal intake of fruit and vegetables in late pregnancy will enhance the diversity of fetal flavour exposure and make infants more likely to accept these flavours. This will be assessed via taste acceptance tests when the infants begin weaning. These will be carried out in the infants home environment and involve measuring the amount consumed, rate of feeding and perceived liking of vegetable-based (plain and bitter) and fruit-based (sweet) purees. The influence of perinatal nutrition on the development/activity of the infants gut microbiota, a key indicator of later health, will be determined in stool samples collected from nappies.Summary of Results
There is evidence that flavour learning via the maternal diet begins in the womb but studies in humans are limited and confined to a single strong flavour exposure. The primary objective was therefore to investigate the effects of an intervention which increases the diversity of fruits and vegetables consumed by mothers in the final third of pregnancy on their infants’ acceptance of novel fruits and vegetables, particularly those with a bitter profile, at weaning Seventy-nine pregnant women were recruited and ate soups/sauces with or without bitter vegetables for 24-days from ~30 weeks gestation in addition to their usual diet. Relevant demographics, habitual diet and monthly milk-feeding status were assessed by questionnaires/24h diet recalls. Infant taste-tests were videoed by the mothers in their own homes at the outset of weaning. Potato puree was offered first until babies were competent at eating, then taste-tests were conducted using potato, apple, broccoli, and spinach purees. Sixty-three mother-infant dyads completed this aspect (some were unable to do so due to travel restrictions imposed on the study team during the first lockdown - Covid-19). Four independent assessors observed the first ten spoons per test using a previously validated behaviour and facial expression coding system developed for feeding infants. This involved recording the baby’s positive and negative behaviours before the test puree was tasted and the negative expressions once the food was tasted. Food acceptance behaviour and the amount eaten were also recorded, and all of this provided an independent assessment of the infants overall liking of the different test purees which was compared with the mother’s assessment of her infant’s liking.
Mothers proved to be highly effective at conducting the taste tests in the home environment and there was strong agreement between the researcher’s independent assessments of infant liking compared to that of the mothers. Few differences in the babies’ response to the potato, apple or broccoli purees were observed but the response to the bitter spinach puree test was striking and highly significant. The babies liking of spinach was correlated with the level of bitter flavour exposure achieved via their mothers’ diet in the womb. This proved to be case for mothers whose normal intake of bitter vegetables was already high, and for mothers who were receiving more bitter vegetables than normal while eating the intervention foods. Furthermore, these effects were independent of the babies bitter tasting genotype. Thus, prenatal exposure to bitter flavours during late pregnancy via the maternal diet can positively influence infants’ acceptance of bitter tasting vegetables at weaning, subsequently laying the foundations for healthy eating habits.
The maternal diet, along with other perinatal factors, may influence the development of the infant gut microbiota providing a further potential avenue for health improvement, hence exploring this was the secondary objective. Development of the infant gut microbiota was assessed in faecal samples collected at five time-points from one to nine months postnatal by 16S rRNA gene sequencing. This was achieved in two thirds of the study population. Collection of these age-sensitive samples ceased for the remaining volunteers during the first lockdown. In spite of this reduction in sample availability we were able to demonstrate that maternal pre-pregnancy body mass index (BMI) and diet quality in terms of frequency and diversity of fruit and vegetable intake modestly influenced the development of the infant microbiota but other perinatal factors such as mode of delivery and milk-feeding type had a greater impact. In general, a healthier microbiome characterised by low bacterial diversity and a dominance of beneficial bacteria was observed in vaginally delivered, exclusively breastfed babies. The differences due to mode of delivery were transient and by nine months postnatal the differences due to breastfeeding were somewhat attenuated indicating that solid food introduction was beginning to influence the microbiota profile by this stage. While the data tentatively suggest that babies born from mothers with a healthy pre-pregnancy BMI and good quality diet in terms of fruit and vegetable intakes may be more likely to have a healthy gut microbiota, larger studies are needed to better isolate these factors while taking other major influences such as breastfeeding status and mode of delivery into account.
Indeed, the choice to breastfeed may have further reaching benefits via the types of foods introduced to babies. Mothers are generally the main gatekeepers of the range of first-foods offered and their own dietary habits and milk-feeding choices may impact their approach to weaning. Weaning diaries indicated that breastfeeding mothers and those in the healthy BMI category offered more types of bitter vegetables to their infants during the first three months of weaning, whilst the overall diversity of fruits and vegetables offered was positively associated with the average portions per day habitually consumed by mothers. Furthermore, women with a more diverse diet in terms of fruits and vegetables were less likely to offer their infant’s non-core foods such as cakes and biscuits.
Thus maternal diet and lifestyle choices beginning during pregnancy and extending into the postnatal period provide interconnected routes to optimise healthy eating and gut health in infants.REC name
East of Scotland Research Ethics Service REC 1
REC reference
18/ES/0060
Date of REC Opinion
5 Jun 2018
REC opinion
Further Information Favourable Opinion