Impact of a “vegetables first” approach to complementary feeding on later intake and liking of vegetables in infants: a study protocol for a randomised controlled trial

BACKGROUND: Vegetables as first complementary foods for infants may programme taste preferences that lead to improved vegetable intake in children. Yet few studies have investigated the impact of a ”vegetables first” approach to complementary feeding, especially in New Zealand. The purpose of this randomised control trial is to investigate the effect of starting complementary feeding with vegetables only on infants’ later intake and liking of vegetables, compared to those starting with fruit and vegetables. METHODS/DESIGN: One-hundred and twenty mother-infant pairs living in Auckland, New Zealand, will be randomised to receive either vegetables only (intervention) or fruit and vegetables (control) for 28 days, starting from the first day of complementary feeding at around 4–6 months of age. Infants will be presented with a brassica (broccoli), followed by a green leafy vegetable (spinach) and sweet fruit (pear) at 9 months of age. The primary outcome measures of intake of each food will be assessed using a weighed food diary. Secondary outcome measures of overall intake, liking and wanting of vegetables will be assessed using a food frequency questionnaire, liking tool and video coding tool, respectively, at 9, 12, and 24 months of age. Infant growth and iron status will be assessed as part of health screening and monitoring at baseline, post intervention and 9 months of age. Other biological samples to be collected include infant stool samples, vitamin D (mother and infant), iron status (mother), and mothers’ diet. DISCUSSION: This randomised, controlled trial will be the first to our knowledge to investigate a “vegetables first” approach to complementary feeding on infants’ liking and intake of vegetables in New Zealand. Comparison against standard practice (fruit and vegetables as first foods) should complement other trials underway, such as the Baby’s First Bites and Nordic OTIS trial. Results may contribute to the evidence supporting complementary feeding guidelines in New Zealand and worldwide. TRIAL REGISTRATION: Australian New Zealand Clinical Trial Registry ACTRN12619000737134. Registered on 16 May 2019. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13063-021-05374-7.