How Oestra Chooses Supplements for Your Personalized Plan

If you've ever typed "best supplement for PCOS" into a search bar, you already know what comes back: a ranked list of ten. Inositol at number one, then berberine, then NAC, then a vitamin you've never heard of, all promising the same vague "hormonal balance." The problem isn't that the supplements on those lists are wrong. It's that a ranked list can't answer the only question that matters — which of these is worth your time and money, given how your PCOS — now PMOS, after the 2026 Lancet consensus — actually shows up.

That's the decision Oestra's assessment is built to make with you, instead of leaving you to guess in the supplement aisle. Here's how it works, and the evidence underneath it.

From your answers to a plan: a rule engine, not a guess

When you take the free 5-minute assessment, you answer questions about your symptoms and your day-to-day — cycles, skin and hair, energy, weight, sleep, stress, how you eat, whether you're trying to conceive. Those answers feed a deterministic, doctor-designed rule engine: a defined set of evidence-based rules, not a black-box guess. Deterministic means the same answers always produce the same plan, for reasons we can point to — the logic is transparent and built from the clinical evidence, not a trend.

Your results are free; the full report then builds your supplement picture in two tiers: a foundation most people with PMOS benefit from, and targeted additions chosen for your specific picture — all passed through safety filters before anything reaches your plan.

The foundation tier: inositol

Inositol is the closest thing to a sensible default, which is why it anchors the foundation. A 2023 meta-analysis found myo-inositol non-inferior to metformin for restoring menstrual cycles, with markedly better tolerability — roughly 1.79 times the cycle-regularity rate of placebo, without metformin's stomach trouble. The form the evidence keeps pointing to is a 40:1 blend of myo- to D-chiro-inositol — the ratio the body maintains naturally — most studies use around 2 g of myo-inositol twice daily.

It earns the foundation slot because it acts on the shared root — insulin signalling — that runs underneath most presentations of PMOS. If you only ever take one thing, the evidence points here. It isn't universal: its effect may be largest where insulin resistance is prominent, and more moderate in lean PMOS, where the metabolic signal is subtler.

The targeted tier: added when your answers call for it

Once the foundation is in place, the engine adds targeted support only where your assessment points to a specific need. A few of the rules, and the evidence behind them:

• When androgen symptoms are prominent (acne, unwanted hair, the high-testosterone picture): spearmint has the most direct anti-androgen evidence. A 2010 randomised trial of 42 women found two cups of spearmint tea daily for 30 days significantly lowered free and total testosterone; a larger 2024 trial over 12 weeks saw testosterone fall around 15%. Zinc and omega-3s may be reasonable companions.
• When the picture is strongly metabolic (weight that won't move, marked insulin resistance): berberine is the one to know. A comparison trial found it broadly comparable to metformin on several insulin markers. It's potent — the engine treats it like a medication, not a vitamin, and it's one of the first things the safety filters check.
• Where SHBG runs low (more common in Asian populations — when SHBG is low, more of your testosterone is biologically active even if the total reads normal): the lever is usually improving insulin sensitivity rather than chasing a specific pill, so inositol and lifestyle tend to do more here than a shelf of bottles.

Notice what the engine is not doing: it isn't sorting you into a fixed box. It reads the signals your answers actually carry and matches evidence to them — which is why two people with the same diagnosis can leave with different plans.

The safety filters: what never makes it in

Before any plan is finalised, it passes through hard filters — these override the evidence rules, not the other way around:

• Allergies and intolerances — anything flagged is excluded outright.
• Trying to conceive, or possibly pregnant — supplements that aren't considered pregnancy-safe, or that matter around conception (berberine and NAC especially), are held back for a conversation with your doctor rather than added to a plan.
• Vegetarian and vegan — forms and sources are matched to how you eat.

These aren't caveats buried in the copy; they're rules the engine applies before you ever see the plan.

How long before you can judge it

This is where most people give up too early, and it matters more than any single supplement choice.

Egg development takes roughly 90 days — a follicle ovulating this month started maturing about three months ago. So a supplement acting on ovulation or egg quality simply cannot show its full effect in two weeks; it's biologically too soon. This is the 90-day rule, and it's a genuinely useful frame for expectations. Roughly:

• Energy and cravings: 2 to 4 weeks
• Menstrual cycle: 2 to 3 months — one study found cycles restored in about 88% of inositol users by month three
• Acne and hair: 4 to 6 months, because these track skin and hair cell cycles, not blood levels

If you've given a supplement a fair, consistent three months and seen nothing, that's real information — a signal to revisit the driver you're targeting, rather than keep pushing the same thing.

What we'd be careful about

A few honest cautions, because the supplement aisle rarely offers them.

Spearmint lowers androgens slowly and mildly. If your androgenic symptoms come on suddenly or severely, that's not a cue to drink more tea — it's a reason to see a clinician, because rapid-onset hyperandrogenism can point to something else.

Berberine and NAC are the two most likely to interact with medication or matter around conception — which is exactly why the safety filters flag them. If you're on any medication, or trying to conceive, they belong in a conversation with your doctor.

And be wary of dramatic claims built on animal studies. The spearmint-and-flaxseed combination, for instance, looks promising in rodents and has very little human evidence yet. Promising isn't proven — and we'd rather tell you that than sell you the gap.

Where to start

The useful move isn't buying the top supplement on a list — it's letting an evidence-based, doctor-designed process decide what actually fits you, then giving it an honest three months.

Our free 5-minute assessment reads your symptoms and lifestyle and shows you where you stand, without asking for anything in return. From there, Oestra turns that result into a detailed personalized report you can keep — the foundation and targeted supplements chosen for you, filtered for safety — plus a 14-day plan built around your real life. It's the day-to-day lifestyle layer alongside whatever medical care you choose — never a replacement for it.

Citations

• Teede HJ, et al. Renaming polycystic ovary syndrome. The Lancet. 2026 May.
• Myo-inositol versus metformin for menstrual regularity in PCOS (meta-analysis). 2023.
• Grant P. Spearmint herbal tea has significant anti-androgen effects in PCOS: a randomised controlled trial. Phytotherapy Research. 2010.
• Najafi M, et al. Androgen modulation through spearmint tea in PCOS and non-PCOS populations. Journal of the Academy of Nutrition and Dietetics. 2024.
• Berberine versus metformin on insulin resistance markers in PCOS (randomised comparison). 2012.