The government plans to conduct its first nationwide survey on how family income affects children's health as concerns grow about the nation's growing child poverty problem, officials said.
More than 16 percent of children aged 17 or younger live in households that earn less than half the average income in Japan, the worst figure ever.
The child poverty ratio is much higher in single-parent families, where it soars to around 55 percent.
The health ministry expects the findings to help the government devise measures to more effectively support children who have poor diets, the officials said Saturday.
The survey will be conducted in September as part of the ministry's decennial national nutrition survey on preschool children and will cover 3,000 households with children 5 or younger. The results will be reported by next March.
The ministry will ask each household for details on its composition, parental education levels, income and mothers' occupational status to see how social and economic conditions influence child nutrition.
There will also be questions about how often parents feed their children confectionery, instant food or fast food and with whom their children eat their meals.