Parents must eat more fruit and vegetables to improve their children's eating habits, it is claimed.
Fruit and veg are essential to a healthy diet
The finding follows a study showing the amount of healthy foods consumed by children is directly related to their parents' choices.
The study, by Cancer Research UK, found a third of children's diets deficient in fruit and vegetables.
Research carried out by University College London suggests regular family meals may encourage a better diet.
Scientists found that more than a third of children under six are not eating fruit and vegetables on a daily basis.
However, the more often parents ate fruit and vegetables, the more likely it was their children would have a correspondingly high intake.
The earlier children are introduced to fruit and vegetables, the more frequently they eat them, according to the study.
It also found that family meal times are associated with more frequent intake of vegetables, but not fruit.
The World Health Organization (WHO) recommends adults eat at least five servings of fruit and vegetables a day.
The health benefits of such a diet include a reduced risk of obesity, cancer, heart disease, strokes and diabetes.
WHO guidelines also advocate five portions of fruit and vegetables for children, although the portions may be smaller for younger children.
Cancer Research UK's Lucy Cooke, who led the project, said the charity's research also showed that children who had been breast fed as babies ate vegetables and fruit more often than bottle-fed babies.
She said: "The most influential aspect of a young child's environment is likely to be the family and the eating habits of parents are very important.
"Research has suggested that parents can influence their children's eating habits by controlling meal time routines.
Five portions of fruit and veg should be eaten daily
"Regular family meals are related to healthier dietary patterns and a higher intake of fruit and vegetables in older children.
"Our study underlines the potential importance of parents' own eating habits in encouraging their children to eat a healthy diet."
The study findings were based on questionnaires sent to 22 nursery schools in north London.
Parents were asked questions, including whether the children in the family ate the same food as grown-ups and whether the family ate at the same time and in the same place.
Professor Robert Souhami, director of clinical and external affairs at Cancer Research, said: "This research is particularly valuable in that it clearly shows what a key role parents play in influencing their children's eating habits.
"If the grown-ups opt for fast food TV dinners they can't expect the children to relish regular helpings of fruit and vegetables."
Most parents accept responsibility for their children's diet, but believe the food industry has a role to play, according to another survey.
They firmly believe all processed foods should contain less salt, sugar and other additives and there should be clearer labelling of such products to help parents make the right choices.
The survey, carried out by the website netmums.com, quizzed 400 parents across the country on issues surrounding children's eating habits.
Netmums founder Siobahn Freegard said: "Just a little symbol on the packaging to say it is healthy, would avoid the need to look at the composition of foods.
"There would need to be some sort of regulations to say that foods aimed at children couldn't contain more than what the experts say are healthy amounts of sugar and salt etc.
"If labels on packages could say they passed the test then we would probably go for those items in the supermarket."
More than three quarters of those taking part in the survey said it was difficult at times to work out what food was healthy.
When asked whether simple labels on packages would help, 98% said yes and 98% of parents said the food industry should reduce levels of salt, sugar, fat and additives in food sold to children generally.