Effect of medical nutrition therapy on premenstrual syndrome, mental well-being, cognitive flexibility, gastrointestinal symptoms, and biochemical parameters in women: an 8-week intervention study

Premenstrual syndrome (PMS) is a common condition that substantially impairs physical, psychological, and social functioning among women of reproductive age. Although medical nutrition therapy has been proposed as a promising non-pharmacological approach, evidence regarding its simultaneous effects on psychological well-being, cognitive flexibility, gastrointestinal symptoms, and metabolic health remains limited. Therefore, this study evaluated changes in these multidimensional outcomes following an 8-week individualized medical nutrition therapy intervention in women with PMS. This exploratory, 8-week, single-center, single-arm pre-post intervention study was conducted between November 2023 and January 2024. Forty-four overweight or obese women aged 25–49 years with PMS received individualized medical nutrition therapy. Within-participant changes from baseline to week 8 were evaluated using paired analyses. The principal outcome was the PMSS total score; WEMWBS, CFI, GSAS, anthropometric measurements, and biochemical parameters were evaluated as exploratory outcomes. PMSS scores decreased from 116.11 ± 26.81 at baseline to 96.52 ± 21.07 at week 8 (mean change = − 19.59 points when expressed as week 8 minus baseline; 95% CI, − 22.25 to − 16.93; p < 0.001). Improvements were also observed in WEMWBS, CFI, and GSAS scores. Several metabolic and anthropometric outcomes changed between baseline and week 8; however, these secondary findings were exploratory and were not adjusted for multiple comparisons. In this uncontrolled exploratory study, individualized medical nutrition therapy was associated with within-participant changes in PMS symptoms, psychological well-being, cognitive flexibility, gastrointestinal symptoms, and metabolic outcomes. Because there was no comparison group, the observed changes cannot be attributed to the intervention alone. Adequately powered randomized controlled trials with objective adherence assessment are required to confirm these preliminary findings.