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Background and aim Most children do not eat the recommended amount of vegetables. Their low vegetable intake may be attributed to their low preference for vegetables. Since the first years of life is a sensitive period in the development of taste preferences, and since taste preferences track over time, we started a longitudinal intervention study to investigate the effect of starting weaning with repeated exposure to vegetable purées on vegetable intake and liking during the first 2 years of life. The primary aim of this thesis was to investigate whether starting weaning with vegetables compared to weaning with fruit had an effect on the intake and liking of vegetables on the short and on the long term. The secondary aim was to investigate whether starting weaning with vegetables compared to weaning with fruit, influenced the preferences for sweet taste and daily intake of sugar. Methods First, we conducted an intervention study (n = 101) that investigated the effects of repeated exposure to either vegetable purées (vegetable groups) or fruit purées (fruit groups) on infants’ acceptance of vegetable or fruit purées during the first 18 days of weaning. Intake of the purées and mothers’ rated liking were measured in the lab. From a subsample (n = 60), we also measured liking by analysing the infants’ facial expressions and behaviour after consuming green beans purée in the lab. In two follow-up studies, when the infants were 12 (n = 84) and 23 months of age (n = 81), the long-term effect of the intervention was measured on intake and mothers’ rated liking of the purées in the lab. Additionally, infants’ daily vegetable intake was assessed with 3-day food records at both follow-ups. At the second follow-up, also the influence of starting with vegetables or fruits on children’s preferences for sweet and salty tastes (n = 81), were measured with sweetened and salted water solution and by calculating their daily mono- and disaccharides intake from the 3-day food records. Additionally, a systematic review investigated the current status of knowledge about effective strategies to increase vegetable intake in children younger than 3 y. Results The studies showed that the group of children who were repeatedly exposed to vegetables increased their vegetable intake from 24 ± 28 g to 45 ± 44g (p < 0.001), while the children who were repeatedly exposed to fruit increased their fruit intake from 46 ± 40 g to 66 ± 42 g (p < 0.05) . Interestingly, the first vegetable intake in the fruit group, which was directly after the 18 days of exposure to fruit purées, was as low as the first vegetable intake of the children in the vegetable group at day 1. This indicates that the repeated exposure to fruit did not influence the children’s vegetable intake. These results were confirmed by the results of the facial expressions, showing a decrease in negative facial expressions after repeated exposure to green beans. At the follow-ups, when the infants were 12 and 23 months of age, no differences between the vegetable and fruit groups in green beans or apple purée were found in the lab. Daily intake of vegetables at 12 months of age, was 38% higher (p = 0.02) in the vegetable group (75 ± 43 g) than in the fruit group (54 ± 29 g). At 23 months of age, no significant difference in daily vegetable intake was found between the groups. Also the 23 month olds’ preference for sweet water solutions and their daily mono- and disaccharides intake did not differ between groups. Finally, the systematic review of literature showed that counselling of the parents on healthy eating and nutrition did have a positive long-term effect on their children’s’ vegetable intake, although the effect was relatively small. The review further showed that repeated exposure was the most studied and also the most effective strategy, since all studies reported an increase in intake after repeated exposure to a vegetable. Also exposure to a variety of vegetables showed to have a positive effect on the intake of a new vegetable. Conclusion Weaning with repeated exposure to vegetables has a positive influence on vegetable intake until at least 12 months of age. |
