The association between dietary diversity and patterns in Chinese university students with abnormal uterine bleeding: a cross-sectional study

Background: Abnormal uterine bleeding (AUB) is a common gynecological issue during reproductive years. Researches on how dietary diversity and patterns influence AUB in Chinese university students are limited, with some studies not clearly defining irregular menstruation. This research investigated the incidence of AUB according to the International Federation of Gynecology and Obstetrics criteria and sought to identify preventative factors via online questionnaires.

Methods: Food intake was assessed via factor analysis. This study analyzed the relationships among the dietary diversity score (DDS), dietary patterns, and AUB via univariate and multivariate binary logistic regression models and generalized additive models.

Results: The sample consisted of 698 students, with 434 (62.2%) having experienced AUB. Among them, 87 (20.05%) reported abnormal frequency, 250 (57.60%) reported irregular menstrual cycle, 41 (9.45%) reported prolonged duration, and 268 (61.75%) reported abnormal flow volume. A 1-unit increase in the DDS was linked to a 22% lower risk of AUB (odds ratio 0.78, 95% CI: 0.67, 0.90). A high DDS (≥ 6) was consistently associated with a lower risk of AUB across all the models. Using a two-piecewise linear regression model and recursive algorithm, a nonlinear, reverse L-shaped relationship was identified between the "low fat plant-based" dietary pattern factor score (FAC4) and AUB, with an inflection point of 1.45. Before this point, FAC4 had a protective effect on AUB (odds ratio 0.42, 95% CI: 0.21, 0.84).

Conclusions: Our study underscores the importance of a varied diet as a preventive measure for AUB, utilizing a DDS to quantify the relationship between dietary diversity and AUB. According to our findings, higher dietary diversity and moderate adherence to a "low fat plant-based" dietary pattern may be significant protective factors against AUB in university students.