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Identifying nutrition risk among U.S. infants and children with limited financial resources
Inadequate nutrition in childhood can inhibit optimal growth and development, and is also associated with increased risk of chronic diseases later in life. Children living in households with limited financial resources may face a number of challenges to meet nutrient needs through unhealthy eating patterns, which may lead to health inequalities throughout the life-course. Therefore, improving low-income children’s diet would be an effective strategy for their health promotion and disease prevention, and potentially for narrowing health inequalities. The essential step for an efficient intervention would be to identify the unique nutrition risk that low-income children have. Therefore, the overarching aim of research in this dissertation was to identify nutrition risk of U.S. infants and children with low income or food insecurity, or participating in federal nutrition assistance programs using data from nationally representative surveys. An additional aim was to assess whether the inclusion of micronutrient intake from dietary supplements impacts micronutrient inadequacy in children.
For low-income infants and young children up to the age of 5 years, the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) provides tailored food packages to improve dietary intake that may be inadequate due to economic constraints. Therefore, it is expected that nutrient intake of WIC participants would be more like those of higher-income nonparticipants and higher than those of lower-income nonparticipants who are likely to be eligible for WIC. The results from the Feeding Infants and Toddlers Study 2016 data analysis supported the hypothesis for several nutrients of concern, although WIC participants were more likely to exceed the recommended limits for sodium and added sugars compared to higher-income nonparticipants. However, higher-income nonparticipants were more likely to use dietary supplements than both WIC participants and lower-income nonparticipants, which can impact total nutrient intake (i.e., nutrient intake from all sources).
Systematic differences in dietary supplement use by income and WIC participation were also observed in a nationally representative sample of children aged 18 years and younger from the 2011-2014 National Health and Nutrition Examination Survey (NHANES). Dietary supplement use was lower among children in low-income families compared to those in higher-income families. Among children in low-income families, those participating in WIC were less likely to use dietary supplements compared to nonparticipants. In addition, food insecurity and the Supplemental Nutrition Assistance Program (SNAP) participation were associated with lower use of dietary supplements. Overall, one-third of children used any dietary supplements, mostly multivitamin-minerals, with primary motivations for use as “improve” or “maintain” health.
The following analysis of the 2011-2014 NHANES data showed that the inclusion of dietary supplements in nutrient intake assessments may lead to wider disparities in dietary intake by food security. This study also demonstrated the dose-response relationship between food security status and mean adequacy ratio, a summary measure of micronutrient adequacy. The mean adequacy ratio, inclusive of dietary supplements, was the highest in high food-security group (mean of 0.77), lower in marginal and low food security group (mean of 0.74), and the lowest in very low food security group (mean of 0.66), based on classification by food security among household children. However, the mean adequacy ratio does not reflect the usual intake (i.e., a long-term, habitual intake).
Therefore, another analysis of the 2011-2016 NHANES data estimated total usual nutrient intake of U.S. children 18 years and younger by food security status, using the National Cancer Institute method that adjusts for random error by statistical modeling. The results suggested that food insecurity was associated with higher risks of inadequate intakes for some nutrients, such as vitamins D and E and magnesium among boys and girls and vitamin A and calcium among girls only. Poor overall dietary quality and excessive sodium intake were of concern, regardless of food security status.
Collectively, the results from the studies in this dissertation add value to the evidence base about the adverse association of low income level and food insecurity status with dietary intake and extend the finding to include nutrient intakes from dietary supplements, which widens the disparity in nutrition risk. These findings highlight a need for interventions to reduce nutrient inadequacies and improve dietary quality among children across all socioeconomic levels, but especially among those with low income or food insecurity.