The free fruit scheme in schools, introduced by the UK government in 2004, may confer no long term benefit, says a study in the Journal of Epidemiology and Community Health.
The scheme cost £42 million to set up and has received a further £77 million to keep it going.
Initially mooted in the government's blueprint for the NHS in 2000, the scheme was introduced to improve young children's diets in a bid to cut the risks of cancer and cardiovascular disease in later life.
The average UK consumption of fruit and vegetables is three portions a day - two less than the recommended amount. And it is lower among those living in deprived areas and among children.
The authors assessed the impact of the School Fruit and Vegetable Scheme (SFVS) on 3700 children from 98 schools in the north of England during 2004.
All the children were between 4 and 6 years of age, covering reception and years 1 and 2 classes.
A specially devised measure for children was used to assess dietary and nutrient intake.
The results showed that the scheme initially boosted intake by half a portion and slightly increased levels of beta carotene and vitamin C.
But these increases had waned seven months later and had disappeared completely by year 3, when pupils, aged 7 to 8, are no longer eligible for the scheme.
There were no changes in salt, fat or overall energy intake among the children. And fruit and vegetable intake actually fell at home, possibly because parents thought their children were getting their quota at school.
The authors highlight certain difficulties associated with the scheme. The range of fruit and vegetables on offer is fairly narrow, because of health and safety concerns the time needed for preparation, they say.
For long term impact, they suggest that the scheme needs to be more structured and targeted, with involvement from the whole school as well as peers and parents.
The fruit and vegetable message also needs to be carried forward at all meal times and throughout a child's education, they add.