Eating fruit and vegetables (FV) offers important health benefits for children and adolescents, but their average intake is low. To explore if negative trends with age exist as children grow, this study modelled differences in FV consumption from childhood to young adulthood. A pseudo-panel was constructed using years 1–4 (combined) of the Rolling Programme of the UK National Diet and Nutrition Survey (NDNS) (2008/2009–2011/2012). Intake of FV in the NDNS was recorded using 4-d unweighted food diaries. The data consisted of 2131 observations of individuals aged 2–23 years. Age-year-cohort decomposition regression analyses were used to separate age effects from year and cohort effects in the data. Total energy intake was included to account for age differences in overall energy consumption. Fruit intake started to decrease from the age of 7 years for boys and girls, and reached its lowest level during adolescence. By 17 years, boys were consuming 0·93 (P=0·037) less fruit portions compared with the age of 2 years. By 15 years, girls were consuming 0·8 fruit portions less (P=0·053). Vegetable intake changed little during childhood and adolescence (P=0·0834 and P=0·843 for change between 7 and 12 years, boys and girls, respectively). There was unclear evidence of recovery of FV intakes in early adulthood. Efforts to improve FV intake should consider these trends, and focus attention on the factors influencing intake across childhood and adolescence in order to improve the nutritional quality of diets during these periods.