Associations of Mediterranean Diet Adherence, Dietary Glycemic Index, and Antioxidant Intake With Acne Vulgaris: A Case–Control Study in Young Adults

Background Dietary patterns, glycemic characteristics, and oxidative balance have been implicated in acne vulgaris, although findings remain inconsistent. Aim This study evaluated the associations of Mediterranean diet adherence, dietary glycemic index (GI), and dietary antioxidant score with acne vulgaris in young adults. Methods This case–control study included 279 participants (115 acne/164 controls). Dietary intake was assessed using three‐day food records, and Mediterranean diet adherence was evaluated with the Mediterranean Diet Adherence Screener (MEDAS). Individual MEDAS components were compared using Holm adjustment. Two forced‐entry multivariable logistic regression models assessed associations with acne status while adjusting for age, BMI, sex, education, and vitamin/mineral supplementation. Results Participants with acne had lower MEDAS scores than controls (5.97 ± 2.22 vs. 7.02 ± 2.12; p < 0.001), whereas dietary GI did not differ between groups (57.57 ± 4.99 vs. 57.74 ± 7.13; p = 0.821). Dietary antioxidant scores were higher in the acne group (3.74 ± 2.53 vs. 3.02 ± 2.46; p = 0.019). After Holm correction, only the vegetable and butter/cream/margarine criteria remained significantly different. Failure to meet these criteria was independently associated with higher odds of acne (aOR = 3.242 and 2.413, respectively). Higher MEDAS scores were inversely associated with acne (aOR = 0.806; 95% CI: 0.710–0.915), while higher dietary antioxidant scores showed a modest positive association (aOR = 1.126; 95% CI: 1.008–1.258). Dietary GI was not independently associated with acne (aOR = 1.049; 95% CI: 0.685–1.607). Conclusions Lower Mediterranean diet adherence was associated with higher odds of acne vulgaris, whereas dietary GI was not independently associated. The positive association observed for dietary antioxidant score should be interpreted cautiously given the case–control design and potential residual confounding.