Diet, Growth Patterns in Infants Tied to Socieodemographics

Diana Phillips

October 15, 2014

Maternal sociodemographic factors significantly influence dietary patterns among US infants, which in turn affects infant growth and development, new research has shown.

In a study evaluating dietary patterns in infants at 6 and 12 months of age, mothers with non-Hispanic black race/ethnicity, lower education, and low household income were more likely to feed their infants foods high in sugar, fat, and protein. This diet is linked to fast gain in infant adiposity and slower growth in length, Xiaozhong Wen, MD, PhD, from the State University of New York at Buffalo, and colleagues report in an article published online October 13 in Pediatrics.

Using data from the longitudinal Infant Feeding Practices II study, the researchers analyzed the dietary patterns of 1555 infants at age 6 months, 1445 infants at age 12 months, and 530 infants at both 6 and 12 months. They identified four distinct dietary patterns at 6 months: high sugar/fat/protein, formula, high dairy/regular cereal, and infant guideline solids (vegetables, fruits, baby cereal, and meat). At 12 months, formula/baby cereal and high dairy replaced formula and high dairy/regular cereal, respectively.

"Consistent with our previous knowledge, these dietary patterns varied substantially by maternal education and race/ethnicity," the authors report. Specifically, at age 12 months, a high score on the "high sugar/fat/protein" pattern was correlated with low household income, maternal non-Hispanic black race/ethnicity, and low education, whereas a high score on the "infant guideline solids" pattern was correlated with high household income, maternal non-Hispanic white race/ethnicity, and high education.

"Maternal education seems to be an important correlate for infant dietary patterns, as mothers who had a low education level tended to feed their infant with 'High sugar/fat/protein' diet at age 12 months," according to the authors. "Mothers of low education level might lack the needed nutrition knowledge for their infant, which could cause them to practice unhealthy infant feeding, which emulates their own poor personal dietary choices."

The investigators also observed an association between enrolment in the Women, Infants, and Children (WIC) program and high scores on the "formula" pattern at 6 months and the "formula/baby cereal" pattern at 12 months. "Infant formula is on the list of WIC-eligible food and is free to low-income households," the authors write. "After adjusting for WIC enrolment and other sociodemographics, we found that infants from low-income households were more likely to be fed 'High sugar/fat/protein' diet, possibly because of the relatively low price of these foods and family dietary habit," they hypothesize.

With respect to infant growth, both "high sugar/fat/protein" and "high dairy/regular cereal" patterns were associated with a smaller increase in sex-specific length-for-age z score and with a greater increase in body mass index (BMI) z score from age 6 to 12 months, both of which were statistically significant, the authors write, noting that the "formula" pattern was also associated with a greater increase in BMI z score. The "infant guideline solids" pattern was not associated with changes in length-for-age or BMI z scores, they report.

The association between "high sugar/fat/protein" and "high dairy/regular cereal" diet patterns and greater increase in weight–length z score, an indirect measure for adiposity, "may be attributable to the excessive caloric intake from these high-energy-density foods," the authors state. "High protein intake by infants could lead to accelerated growth and increased adipose tissue ['the early protein hypothesis'], possibly by stimulating secretion of insulin-like growth factor 1 and cell proliferation." This is a concern, they stress, because of the association between rapid infant weight gain, especially fat mass gain, and obesity later in life.

Although there is not enough evidence to support a recommendation of a definitive, optimal dietary pattern for US infants, a combination of prolonged breast-feeding and gradual introduction of infant guideline solids is promising for infants after 6 months, the authors write. "Our advice to parents is to introduce 'Infant guideline solids' gradually after age 6 months so that these solids will not completely replace breastfeeding [which should be continued until at least 12 months]."

This work was supported by the Department of Pediatrics, State University of New York at Buffalo.

Pediatrics. Published online October 13, 2014. Abstract

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