16S rRNA Amplicon Sequencing (Illumina MiSeq)

Valentin Borzan et al. (2023) · BMC endocrine disorders

This phase IV, double-blind randomized controlled trial with 180 participants (ProPCO-RCT) explored whether a multi-strain probiotic supplement can improve hormone and metabolic markers in women with Polycystic Ovary Syndrome (PCOS), a condition affecting up to one in five women that combines irregular periods, excess androgen (male hormone) activity, and polycystic ovaries. The trial's premise builds on prior findings that women with PCOS have a less diverse gut microbiome, which past research has linked to higher testosterone and greater insulin resistance. The study also examines equol, a compound gut bacteria make from soy isoflavones that has anti-androgenic properties, framing the gut microbiome as a possible lever on PCOS hormone levels. Participants (ages 18-45, meeting standard Rotterdam PCOS diagnostic criteria) were split into three groups of 60: a seven-strain probiotic sachet, a matching placebo, or open-label metformin (a standard PCOS drug), each taken daily for six months. The probiotic-versus-placebo comparison was blinded and allocation-concealed; the metformin group was not blinded. Measurements included blood hormone panels, an oral glucose tolerance test, a hirsutism (excess hair growth) score, body measurements, gut permeability and stool-microbiome testing (via genetic sequencing), and symptom and mood questionnaires, taken at the start and repeated at six months. As a protocol paper, this publication describes the trial's design rather than its findings — the primary comparison (change in free testosterone, probiotic versus placebo) had not yet been unblinded or analyzed at the time of publication. The one concrete number reported comes from the research group's earlier, smaller pilot study: 10 women taking the same probiotic for three months saw their free testosterone drop by a median of 0.3 pg/ml (range 1.7 down to 2.5 up), a result the team used to calculate that 60 participants per group would give the trial 80% power to detect a larger, expected 0.6 pg/ml reduction. The full trial adds metformin as a benchmark and follows participants for twice as long as most prior probiotic-PCOS studies the authors cite, several of which reported androgen and metabolic improvements with about 60 participants total. Because the results are not yet in, the paper's value lies in its design: registered with clinical trial authorities (ClinicalTrials.gov NCT04593459), ethics-approved, and built to isolate a probiotic's effect from both an inert placebo and an established drug. The authors describe it as the first trial to test a probiotic against both comparators in PCOS. The protocol also flags a limitation the authors state plainly: recruitment began before the COVID-19 pandemic, and the trial's long six-month intervention window may make some participants unable to fully follow the schedule, which is why the statistical plan pre-specifies analyzing everyone as originally assigned. Readers looking for evidence of probiotic effectiveness in PCOS will need the trial's later results publication, not this one.

Varol Tunali et al. (2026) · Gut microbes

This 12-month follow-up study revisited 121 adults with irritable bowel syndrome (IBS, a common gut condition causing pain, bloating, and altered bowel habits) who had completed a 6-week randomized trial comparing two dietary approaches: a standard low-FODMAP diet (LFD, which restricts fermentable carbs known to trigger IBS symptoms) and a microbiome-guided personalized diet (PD, built from each person's own gut-bacteria profile using a machine-learning algorithm). The goal was to see whether the benefits people got in the first 6 weeks actually lasted a full year, and whether either diet changed the gut microbiome (the community of bacteria living in the digestive tract) over that time. Participants, recruited at four Turkish gastroenterology clinics, were followed with symptom, quality-of-life, and mood questionnaires plus stool samples for gut-bacteria testing at 6 and 12 months after their original 6-week diet ended (nobody's diet plan was updated again after the start). Seventy people who got the personalized diet and 51 who got the low-FODMAP diet were included at the start of follow-up, though many dropped out over the year, leaving 40 and 29, respectively, providing data at 12 months. Both diets worked well at first, cutting symptom-severity scores by roughly 100 points within 6 weeks. But by 12 months the picture diverged: people on the personalized diet kept most of that improvement (still about 78 points better than baseline), while people on the low-FODMAP diet had drifted back close to where they started. About 63% of the personalized-diet group still counted as meaningful responders at 12 months, compared with about 35% of the low-FODMAP group. The personalized-diet group also showed steadier gains in quality of life and in anxiety and depression scores. On the microbiome side, gut-bacteria diversity rose more and stayed higher in the personalized-diet group throughout the year, though the two groups' overall bacterial makeup looked similar by 12 months, and no single type of bacteria reliably separated the two diets. The takeaway is that tailoring a diet to someone's own gut bacteria may help IBS relief last longer than a standard restrictive diet, which seemed to lose its effect without further guidance. That said, the researchers are careful to call these findings hypothesis-generating rather than proven: many participants dropped out, everyone knew which diet they were on, and the gut-bacteria testing used here cannot show which bacterial genes or byproducts, if any, actually drove the improvement. Larger, purpose-built trials are needed before personalized, microbiome-guided diets become a routine part of IBS care.