The effects of malnutrition on growth of toddlers and preschoolers by socioeconomic status are not well known. This study aimed to examine the effects of dietary intake on growth outcomes in toddlers and preschoolers by household income level.

The study population was a total of 1,687 children aged 1 to 5 years that participated in the KNHANES from 2009 to 2011. Growth of children was assessed by height for age (HFA) and weight for height (WFH). Children were classified into three groups according to children's HFA and WFH compared to the 10^th and 90^th percentiles of the 2007 Korean Children and Adolescent Growth Standard. Average monthly household income was divided into quartile groups. Dietary intake data were obtained by using the one day 24-hr recall method. Risks of inadequate intake of nutrients and unfavorable growth were estimated by using a multiple logistic regression model adjusted for sex, age, region, and energy intake.

The low HFA group (< 10^th percentile) had significantly lower intakes of energy, carbohydrate, and thiamin as compared with the high group (≥ 90^th percentile). For WFH status, vitamin C intake was lower in the low group than in the high group. Household income level was related to WFH status but not HFA. Children from lower income households were more likely to have high WFH than those from higher income households ( P for trend = 0.038). Household income status was also significantly related with risk of inadequate intake of micronutrients such as thiamin ( P for trend = 0.032) and vitamin C ( P for trend = 0.002), showing higher odds of inadequate intakes in children from lower income households.

Children from lower income households were prone to be overweight and to have inadequate intakes of micronutrients such as thiamin and vitamin C. To reduce nutritional and health disparities, collective action in the public sector is required from early life.