Abstract
Premenstrual syndrome (PMS) and polycystic ovary syndrome (PCOS) are common hormonal disorders in reproductive-aged women. Conventional treatments often have side effects, highlighting the need for natural alternatives such as seed cycling, a dietary strategy involving flax, pumpkin, sesame, and sunflower seeds consumed in specific phases of the menstrual cycle. This systematic review evaluated studies from 2015 to 2025 (PubMed, Scopus) on seed cycling or its components in women aged 15-49 years with PMS or PCOS diagnosed using standardized criteria. Eligible designs included randomized controlled trials, cohort, case-control, observational, quasi-experimental, and case series. Non-human studies, reviews, opinion pieces, conference abstracts, and studies outside the age range or before 2015 were excluded. The PRISMA 2020 guidelines were followed, and the Quality Assessment with Diverse Studies Tool assessed risk of bias. Primary outcomes included changes in hormonal markers (e.g., estrogen, progesterone, LH/FSH ratio, testosterone), symptom scores for PMS, and metabolic parameters (e.g., BMI, lipid profile, insulin resistance). Ten studies (n = 635) with low to medium risk of bias reported that seed cycling, particularly flax and sesame seeds, was associated with improved menstrual regularity, reduced PMS symptom severity, favorable modulation of sex hormone levels, and improvements in metabolic profiles. While findings suggest that seed cycling is a low-cost, safe, and potentially effective adjunct for managing PMS and PCOS, the conclusion is based on small sample sizes and moderate-quality evidence, underscoring the need for larger randomized controlled trials and standardized intervention protocols.