Can Families Eat Better Without Spending More? Improving Diet Quality Does Not Increase Diet Cost in a Randomized Clinical Trial among Youth with Type 1 Diabetes and Their Parents

Abstract

Background: Although cost is a frequently cited barrier to healthful eating, limited prospective data exist.

Objective: To examine the association of diet cost with diet quality change.

Design: An 18-month randomized clinical trial evaluated a dietary intervention.

Participants and setting: Youth with type 1 diabetes duration ≥1 year, age 8.0 to 16.9 years, receiving care at an outpatient tertiary diabetes center in Boston, MA, participated along with a parent from 2010 to 2013 (N=136). Eighty-two percent of participants were from middle- to upper-income households.

Intervention: The family-based behavioral intervention targeted intake of whole plant foods.

Main outcome measures: Diet quality as indicated by the Healthy Eating Index 2005 (HEI-2005) (which measures conformance to the 2005 Dietary Guidelines for Americans) and whole plant food density (cup or ounce equivalents per 1,000 kcal target food groups) were calculated from 3-day food records of youth and parent dietary intake at six and four time points, respectively. Food prices were obtained from two online supermarkets common to the study location. Daily diet cost was calculated by summing prices of reported foods.

Statistical analyses performed: Random effects models estimated treatment group differences in time-varying diet cost. Separate models for youth and parent adjusted for covariates examined associations of time-varying change in diet quality with change in diet cost.

Results: There was no treatment effect on time-varying diet cost for either youth (β -.49, 95% CI -1.07 to 0.08; P=0.10) or parents (β .24, 95% CI -1.61 to 2.08; P=0.80). In addition, time-varying change in diet quality indicators was not associated with time-varying change in diet cost for youth. Among parents, a 1-cup or 1-oz equivalent increase in whole plant food density was associated with a $0.63/day lower diet cost (β -.63, 95% CI -1.20 to -0.05; P=0.03).

Conclusions: Improved diet quality was not accompanied by greater cost for youth with type 1 diabetes and their parents participating in a randomized clinical trial. Findings challenge the prevailing assumption that improving diet quality necessitates greater cost.

Trial registration: ClinicalTrials.gov NCT00999375.

Keywords: Diet cost; Diet quality; Families; Intervention; Type 1 diabetes.

Figure 1

Participant flow through a randomized clinical trial of a behavioral nutrition intervention in youth with type 1 diabetes (participants are youth-parent dyads) ^aLongitudinal analyses include all available data from each subject through withdrawal or study completion Adapted with permission from: Nansel TR, Laffel L, Haynie D, Mehta S, Lipsky L, Volkening L, Butler D, Higgins L, Liu A. Improving dietary quality in youth with type 1 diabetes: randomized clinical trial of a family-based behavioral intervention. International Journal of Behavioral Nutrition and Physical Activity 2015; 12:58.

Figure 2

Effect of a behavioral nutrition intervention on diet cost in 136 youth with type 1 diabetes and parents participating in a behavioral nutrition efficacy trial^{a a}Bars represent 95% confidence intervals.