Exploring the Socioeconomic Disparities in the Association Between Organic Food Consumption and Obesity in the Sister Study

Objectives: We examined the relationship between organic food consumption, weight gain, and the risk of obesity in the Sister Study and investigated how this association differs by individual and neighborhood socioeconomic status. Methods: We analyzed data from 37,079 eligible participants aged 35-74 years who enrolled in the Sister Study (2003-2009) and reported their organic food consumption frequency. An organic diet score (ODS) was calculated, assigning scores from 0 to 3 based on reported consumption frequency of produce, meat, and dairy as follows: (0) never, (1) less than half the time, (2) about half of the time, and (3) more than half of the time. We evaluated the association between ODS and incident overweight (BMI ≥ 25 kg/m2), obesity (BMI ≥ 30 kg/m2), and weight gain (relative weight change) over a mean of 11.3 years of follow-up until 2019. We explored effect modification by individual and neighborhood socioeconomic status, measured by the Area Deprivation Index (ADI). A generalized log-linear model with robust error variance was used to estimate multivariable adjusted relative risks and 95% confidence intervals. Results: At baseline, 61% of participants reported consuming organic food in the last year. After adjusting for confounders, consumption of organic food was inversely associated with gaining 5 kg or more (RR 0.95; 95%CI 0.91-0.99, a BMI increase of 10% or more (RR 0.93; 95% CI 0.88-0.97), incident overweight (RR 0.90; 95% CI 0.83-0.98), and incident obesity (RR 0.84; 95% CI 0.77-0.92). Higher ODS (≥4) was associated with gaining 5 kg or more (RR 0.86; 95%CI 0.80-0.91; Ptrend< .001), a BMI increase of 10% or more (RR 0.85; 95%CI 0.79-0.92; Ptrend< .001), incident overweight (RR 0.76; 95% CI 0.68-0.86; Ptrend< .001), and incident obesity (RR 0.69; 95% CI 0.60-0.79; Ptrend< .001). The inverse association between higher ODS and risk of incident obesity was stronger for women with lower area deprivation (RR: 0.61; 95% CI 0.48-0.77, Pinteraction=0.11), higher education (RR: 0.62; 95% CI 0.51-0.75, Pinteraction=0.02), and higher income (RR: 0.63; 95% CI 0.50-0.79, Pinteraction=0.02). Conclusions: Organic food consumption may be associated with lower risk of obesity; the association was strengthened among participants of higher individual and neighborhood socioeconomic status.