Dietary Patterns during Adulthood among Lesbian, Bisexual, and Heterosexual Women in the Nurses' Health Study II.

Background: Lesbian and bisexual women are at greater risk of being obese than heterosexual women; however, there is little research on dietary intake among lesbian and bisexual women.

Objective: This study estimated differences in dietary quality and intake during adulthood comparing heterosexual women to lesbian and bisexual women.

Design: Biennial mailed questionnaires were used to collect data from a cohort between 1991 and 2011. Heterosexual-identified women were the reference group.

Participants/setting: More than 100,000 female registered nurses in the United States, aged 24 to 44 years, were recruited in 1989 to participate in the Nurses' Health Study II. More than 90% of the original sample are currently active in the study. About 1.3% identified as lesbian or bisexual.

Main Outcome Measures: Dietary measures were calculated from a 133-item food frequency questionnaire administered every 4 years. Measures included diet quality (Alternative Healthy Eating Index-2010 and Dietary Approaches to Stop Hypertension); calorie, fat, and fiber intake; and glycemic load and index.

Statistical Analyses: Multivariable adjusted repeated measures linear regression models were fit.

Results: On average, lesbian and bisexual women reported better diet quality (P<0.001) and diets lower in glycemic index (P<0.001) than heterosexual women. In the whole cohort, diet quality scores increased as participants aged, and were lower among women living in rural compared to urban regions. Comparisons in dietary intake across sexual orientation groups were generally similar across age and rurality status. However, differences between lesbian and heterosexual women in Alternative Healthy Eating Index-2010 were larger during younger compared to older ages, suggesting that diet quality estimates among sexual orientation groups converged as women aged.

Conclusions: Lesbian and bisexual women reported higher diet quality than heterosexuals. More research examining how diet affects risk for chronic conditions, such as diabetes, among sexual minorities is needed. Physical activity, sedentary behavior, disordered eating behaviors, and psychosocial and minority stress should be explored as potential contributors to higher rates of obesity among sexual minority women.