Half the mothers in a Mintel survey were classed 'unperturbed parents', taking little or no interest in what their children eat for lunch.
The responses from more than 700 British mothers of children aged five to 16 suggests that health food manufacturers targeting children are facing a significant education barrier among parents.
Just one in four 'persisting parents' aim to give their children the best food they can, found the report. The remaining parents are 'pampering parents' who pander to the demands of their 'fussy' children.
The findings contrast with children's attitudes. As many as 71 per cent of 11 -16 year olds agreed that 'it is important to eat a balanced diet' and only one in ten seven to 16 year olds find buying health foods a strange concept.
"Although the 'fat epidemic' in children is spreading and the problem of childhood obesity is widely acknowledged, it would appear that there is a clear acceptance of the basic principles of healthy eating and not overindulging among today's children," said Amanda Lintott, consumer analyst at Mintel.
"But recognising the importance of healthy eating is only half the battle, as children now need to be encouraged to put this in to practice."
This could be difficult as just two in five mothers (42 per cent) surveyed said they always pack a lunch for their child or children.
But manufacturers could encourage more parents to pack their children's lunchboxes by providing convenient, healthy options designed just for this purpose, suggests the report 'Children's Packed Lunches'.
Currently sandwiches and crisps and snacks rank as the two most popular packed lunch items, while fresh fruit at 47 per cent is the third most frequently packed food item, proving more popular than sweet biscuits and cakes.
Fizzy drinks at 5 per cent rank among the least favoured lunch choices and are far less popular than still fruit drinks (39 per cent). Other healthier fillers include unprocessed cheese, raw vegetables and dried fruit.
"Looking at what children now take in their packed lunches, the results are reassuringly healthy. For many parents packing a lunch is the only way that they feel that they are setting down some dietary guidelines for their children," said Lintott.
Food manufacturers in the UK under pressure from the government to help stem the rise in childhood obesity could attract greater sales by providing convenient, healthy options for parents to use in lunch boxes.