BACKGROUND: Social isolation is linked to survival and health. However, dietary effects of social activities, and gender differences, over time are unknown. METHODS: A prospective study of adults (45+y) reporting daily fruit or vegetable (F/V) intake (at wave 1) from the Canadian Longitudinal Study on Aging (CLSA). Multivariable mixed logistic regression assessed changes in social isolation or breadth of social participation (wave 1 to 2) in relation to adverse changes in F/V (non-daily intake) at wave 3 in women and men. RESULTS: Women who remained socially isolated between waves 1 and 2 had 85% higher odds of non-daily vegetable intake (OR 1.85 [95% CI: 1.32, 2.59]) and over twofold higher odds of non-daily fruit intake (2.23 [1.58, 3.14]), compared to reference (not isolated at waves 1 and 2). Higher odds of non-daily F/V intake were also observed for women who changed from isolated at wave 1 to not isolated at wave 2. Women and men who had less diverse social participation at waves 1 and 2 had 28-64% higher odds of non-daily F/V intake, compared to their counterparts with diverse social participation at both waves. Higher odds of non-daily fruit were also seen for women who had diverse social participation at wave 1 but reduced their diversity at wave 2 (1.35 [1.12, 1.62]). CONCLUSIONS: Results showed persistent social isolation impacted changes in F/V among women only, while limited breadth of social participation affected F/V intake in both genders. Further longitudinal research on the complexities of social engagement and eating behavior is warranted.