Changes in a family's income do not affect the healthiness of their children's diet, according to a new report. 

Researchers found that a drop in family income does not trigger a decrease in the amount of fruit and vegetables their children eat. The finding challenges the idea that the healthiness of a diet is directly linked to income levels. 

The study, which used data from the Growing Up In Scotland survey, compared the diet of about 3000 children at the age of two and then again at age five. It also tracked the income of their parents over the same period.

The diets of young children in Scotland deteriorated between the ages of two and five for all, regardless of a family's income level, the University of Edinburgh study found. 

By the age of five all children are likely to eat fewer vegetables and to have more sweets and sugary drinks than at the age of two. This may be because children become better able to demand and reject foods as they grow, according to researchers. 

When the children were two, less than one in ten (8.1 per cent) drank soft drinks more than once a day. By the age of five, this increased to three in 10 (28.7 per cent). Similarly, aged two, one in 20 (6.4 per cent) of the children never ate vegetables, but this rate increased nearly five times (27.9 per cent) by the time they turned five.

Children's diets deteriorated when parents believed that they were going through financial hardships.

For parents whose financial situation changed from 'feeling comfortable' to 'finding it difficult 'to cope as their offspring grew from age two to age five, children ate fewer varieties of fruit and vegetables, and ate crisps and sweets more often.

Among families whose income did not change, children from families with a low income were more likely to have poorer diets to begin with. This group also had diets improve the most from age 2 to age 5. Two in ten (20.5 per cent) of these children lowered their sweet consumption compared with only one in 10 (11.2 per cent) in high-income homes.

Dr Valeria Skafida, report author and Research Fellow at the Centre for Population Health Sciences, said: "Changes in how parents felt about money were more strongly linked to their children's diets than their actual incomes. This could be because income is not evenly distributed within the home, or because it is perception of poverty rather than measured poverty that determines food choices."

These findings are published in the Journal of Epidemiology and Community Health