With enjoyment representing an important predictor of children’s fruit and vegetable consumption and the naturally sweet tastes of fruit already leading to ready acceptance, researchers have assessed how familiarity can increase ‘harder-to-achieve’ vegetable acceptance
The study, led by University College London (UCL) and published in the British Journal of Nutrition, aimed to investigate the impact of advising parents to introduce a variety of single vegetables as first foods on infants’ subsequent acceptance of a novel vegetable.
Carried out in the UK, Greece and Portugal, it suggests that repeatedly offering infants a variety of vegetables during weaning increases their vegetable consumption and appreciation.
“Innate preferences for sweet tastes and dislike of sour or bitter tastes mean that fruit is readily accepted, but that liking for vegetables may be harder to achieve,” the report’s authors explain. “However, innate preferences can be modified through pre- and postnatal experiences.
“Flavours become more acceptable as they grow in familiarity and there is unequivocal evidence in young children that intake and liking for unfamiliar foods can be increased through repeated exposure, i.e. providing repeated opportunities to taste small quantities of the food.”
Between February 2011 and July 2012 mothers of four- to six-month-old infants in the UK, Greece and Portugal were randomised to either a control group, who received country-specific ‘usual care’, or an intervention group, who received guidance on introducing five vegetables (one per day) as first foods repeated over 15 days. The latter were encouraged to offer a range of colours and flavours with a focus on green vegetables such as broccoli, peas and spinach. They were told not to mix them together or with other flavours.
One month later, the infants’ consumption and liking (maternal and researcher rated) of an unfamiliar vegetable – artichoke purée – were assessed. Primary analyses were conducted for the full sample with secondary analyses conducted separately by country. No significant effect of the intervention was found for vegetable intake in the three countries combined.
However, sub-group analyses showed that UK intervention infants consumed significantly more novel vegetables than control infants. UK mothers and researchers rated infants’ vegetable liking higher in the intervention than in control conditions, with intervention infants eating on average 16g more artichoke purée than control infants.
“The UK findings provide support for previous research showing repeated exposure to vegetables during complementary feeding can impact positively on infants’ vegetable acceptance and daily changes in the variety of vegetables consumed increase acceptance of a novel food,” the report notes.
In Portugal and Greece, there was no significant intervention effect on infants’ vegetable intake or liking. The authors suggested the differing outcome between countries possibly reflects cultural variations in existing weaning practices. Recent research has revealed that Portuguese school children, for instance, have among the highest levels of vegetable intake in Europe.
However, the UK results suggest in countries where vegetables are not common first foods, advice on introducing a variety of vegetables early in weaning may be beneficial for increasing vegetable acceptance.
Current recommendations in the UK are to introduce fruits, vegetables and baby rice or cereal as first foods, but the information provided to mothers is inconsistent, according to the report, and the advice available may vary by local health authority.
Between the ages of four and seven months, the report says infants are highly receptive to new flavours and textures, requiring fewer exposures than older children to increase acceptance.
“Exposing children to the taste of commonly rejected foods, such as vegetables, may be most effective in early infancy before the onset of food neophobia or pickiness (a normal developmental stage during the second year of life),” it points out. “Since food preferences develop early and have been shown to track through later childhood and into adulthood, early intervention is likely to reap the greatest benefit.”
A variety is most important
But while repeated exposure to a single vegetable flavour increases infants’ acceptance, the researchers say the speed with which they acquire preferences means that a lack of sufficient variety might result in a ‘monotony’ effect – the infant becoming bored with the taste.
“Daily changes in the vegetables offered to infants during the transition to solid foods have been shown to lead to immediate increases in preference and intake, and a generalisation of the effect to acceptance of novel tastes.”
In a group of formula-fed infants, the effect of offering a variety of different vegetables versus carrots alone, or potatoes alone over a period of nine days was evaluated. Infants in both the variety and carrot groups significantly increased their intake of carrots compared with infants fed potatoes, but only the infants exposed to a variety of tastes ate more of a novel food at the end of the exposure period.
It has been suggested that the variety of vegetables from meal to meal offered to weaning infants is more important than the overall number of vegetables offered. For example, increased intake of novel foods was observed in weaning-age infants experiencing daily changes in the vegetables offered compared with infants fed three vegetables, each for three consecutive days (18), which suggests that the beneficial effect of variety is maximised by daily changes. In addition, a more varied diet during the weaning period has been linked to greater dietary diversity in later childhood.
The report’s authors claim that the benefits of repeated and varied exposure early in the complementary feeding period have been previously described, suggesting promising opportunities for increasing children’s vegetable intake.
However, they are quick to point out that no studies to date have tested the procedures in the form of an easily disseminable intervention comprising simple, practical guidance to parents for introducing a variety of vegetables as first foods.
Furthermore, no previous study of variety exposure in infants has included a no-treatment control group in which mothers receive only the current standard weaning advice offered by their national health service.
Finally, although the existing weaning recommendations and practices vary across Europe, no study to date has examined cross-cultural differences in the effectiveness of such an intervention.