Influence of Vitamin E Intake on Sexual Function and Depressive Symptoms in Young Women with Euthyroid Autoimmune Thyroiditis Undergoing Vitamin D Therapy: A Pilot Study.

Euthyroid autoimmune thyroiditis (Hashimoto's disease) has been shown to negatively affect female sexual health; however, this adverse impact appears to be mitigated by vitamin D therapy. Emerging research suggests that vitamin E may reduce susceptibility to autoimmune thyroiditis and that supplementation could contribute to improved sexual health outcomes. The present study aimed to investigate whether vitamin E status influences the effects of exogenous vitamin D on female sexual function and depressive symptoms in individuals with this condition. This pilot study included three cohorts of young women with Hashimoto's disease, matched for age, thyroid antibody titers, and 25-hydroxyvitamin D levels, all exhibiting normal TSH and free thyroid hormone concentrations. The cohorts differed in vitamin E intake: below the recommended daily allowance (group 1), adequate intake (group 2), and high intake (exceeding 400 IU daily; group 3). All participants received vitamin D at a daily dose of 100 µg for six months. Serum hormone levels, thyroid antibody titers, and calculated indices of thyroid homeostasis were evaluated at enrollment and at the conclusion of the study. Female sexual function and depressive symptoms were also evaluated at both time points using validated instruments: the Female Sexual Function Index (FSFI) and the Beck Depression Inventory-II (BDI-II). At enrollment, group 2 scored higher than the other cohorts in the sexual desire and arousal domains. Vitamin D supplementation increased serum 25-hydroxyvitamin D in all groups. The decrease in antibody titers was most pronounced in group 2, and only in this group did vitamin D enhance thyroid secretory capacity and increase testosterone levels. In group 2, treatment led to improvements across all FSFI domains and the total score. In group 1, positive effects were limited to the lubrication and lack of pain/discomfort domains, whereas group 3 showed no changes in sexual function. Improvements in female sexual function correlated with vitamin E intake, reductions in antibody titers, and increases in testosterone levels. Significant improvements in depressive symptoms, as measured by the BDI-II, were observed exclusively in group 2. Adequate vitamin E intake is essential to achieve the full effects of vitamin D on female sexual function and mood in young euthyroid patients with Hashimoto's disease.