The research, published in the journal Phytotherapy Research, was presented at the Fertility Society of Australia Annual Conference 2017 in Adelaide and the European Society of Human Reproduction and Embryology (ESHRE) Annual Meeting in Geneva.
The study involved 122 women aged 18 to 44 years old from across New South Wales, Queensland and Victoria, all of whom had been medically diagnosed with PCOS.
The herbal intervention included a fixed formulation of five ingredients: cinnamon (Cinnamomum verum), llquorice (Glycyrrhiza glabra), St John's Wort (Hypericum perforatum), and peony (Paeonia lactiflora) with Tribulus terrestris.
A common, under-recognised and increasingly prevalent hormonal disorder, PCOS affects one in five young Australian women and one in four Australian indigenous women.
Symptoms of PCOS include menstrual irregularity, excessive levels of male hormones (hyperandrogenism), weight gain, difficulties with fertility, ovarian cysts, and metabolic and psychological disorders.
"Lifestyle modification is the current first line-intervention. However, as many as seven in 10 women with PCOS use additional complementary medicines, and approximately two out of five use herbal medicine.
"Hence, we sought to test the most commonly used herbal interventions," said lead author and National Institute of Complementary Medicine (NICM) adjunct research fellow Dr Susan Arentz.
"We conducted a randomised controlled trial over three months to determine the clinical effectiveness of combining a herbal medicine treatment with a lifestyle intervention, compared with lifestyle alone for improved menstrual regularity in overweight women with PCOS," said Dr Arentz.
Participants in both groups improved, but women in the group receiving herbal medicine and lifestyle intervention reported a greater improvement in menstrual regularity (32.9%).
The average menstrual cycle length was 43 days shorter in the combination group compared to those in the lifestyle-only study group, with over half (55%) completing the trial with normal menstrual length (23 to 34 days) against 24% in the control group.
Secondary outcomes were also significantly improved for women in the combined group for (BMI), pregnancy rates, hormones, glucose metabolism, blood pressure, and quality of life. The study also showed statistically significant reductions in depression, anxiety and stress scores.
The trial's co-supervisor, gynaecologist and UNSW Sydney associate professor Jason Abbott, said PCOS may affect both fertility and long-term health, including an increased risk of some cancers, and the disease needs to be treated throughout a woman's life.
"Many women do not want to take medications or may have considerable side effects from medications, and a scientific approach that utilises lifestyle changes and effective complementary and alternative medications is more suited to the changing needs of a woman with PCOS," he said.
"This trial demonstrated that this combination of approaches may alter the gynaecological outcomes for women to improve fertility and may have more long-term effects, including a risk-reduction for cancer, by normalising the menstrual cycle," he added.
Future studies with placebo controls will examine the specific clinical effects of each component of the intervention and the sustainability of the outcomes.