Vitamins and Supplements for PCOS: What Science Actually Says

If you’ve ever searched for “PCOS supplements,” you’ve probably been buried under endless advice, miracle claims, and half-truths. At TribElle, we believe you deserve better: straight answers, backed by science, in plain English.

Here’s what the research actually says about vitamins and supplements in PCOS — what helps, what doesn’t, and how to take them so they actually work for you.

🌞 Vitamin D: The Sunshine Vitamin

Many women with PCOS have low vitamin D — and that matters. Low levels have been linked to worse insulin resistance, higher testosterone, and irregular cycles.

✨ The science:

• A review of 11 clinical trials found vitamin D supplementation improved insulin resistance and lowered testosterone levels in women with PCOS (Nutrients, 2018).

• A larger review in 2025 confirmed improvements in blood sugar and cholesterol — including lower fasting glucose, insulin, triglycerides, and LDL cholesterol (BMC Endocrine Disorders, 2025).

🕒 Best time to take it: With a meal that contains fat. Morning or midday is ideal (high doses at night can affect sleep).

🍊 Inositol: Promising but Not a Silver Bullet

Inositols (myo- and D-chiro) are natural compounds that help with insulin signalling. Many women with PCOS don’t process them properly, which can fuel insulin resistance and irregular cycles. That’s why inositol supplements have been studied as a possible way to restore balance.

✨ The science:

• A Cochrane review (2019) of 13 trials found that while inositol may improve ovulation and reduce testosterone, the quality of evidence was low to moderate, and more large-scale studies are needed.

• A 2024 systematic review by Monash University echoed this: results look promising, but the evidence base is still limited and inconsistent.

📖 Read the Monash systematic review summary (JCEM, 2024)

🕒 Best time to take it: Inositol is water-soluble, so timing with food doesn’t matter. Splitting the dose (morning + evening) may help keep levels steady across the day.

👉 TribElle takeaway: Inositol shows promise for improving cycles and hormone balance in some women with PCOS, but it’s not a one-size-fits-all solution. More research is needed, and individual results vary.

🥑 Omega-3s: Good Fats for Hormones & Metabolism

Omega-3 fatty acids (EPA and DHA from fish oil or algae) are well known for their benefits on heart and metabolic health. For women with PCOS, the focus is on whether they can improve insulin resistance and cholesterol balance.

✨ The science:
A meta-analysis of randomised controlled trials found that omega-3 supplementation improved insulin resistance, lowered cholesterol and triglycerides, and boosted adiponectin — a hormone that helps the body respond to insulin.
(Reproductive Biology and Endocrinology, 2018).

🕒 Best time to take it: With your main meal (especially one containing fat) to maximise absorption. Evening doses may also help reduce “fish burps.”

👉 TribElle takeaway: Omega-3s show strong evidence for improving metabolic markers in PCOS. While more research is needed on hormone balance, they’re a safe, supportive option many women find helpful.

🌿 Vitamin E: Antioxidant Support

Vitamin E is a strong antioxidant. For women with PCOS, oxidative stress plays a role in worsening hormone imbalances and insulin resistance.

✨ The science:

• A 2020 trial found women taking vitamin E had lower LH and testosterone, higher progesterone, and healthier cholesterol levels (PubMed, 2020).

🕒 Best time to take it: With food that contains fat. Works well when paired with vitamin C.

🍃 Vitamin B12 & Folate: Smart Support When You’re on Metformin

Metformin is commonly used to manage PCOS, but one important thing to know is that it can lower vitamin B12 levels over time. That’s why many clinicians recommend monitoring B12 if you’re on long-term metformin.

✨ The science:

• Research shows that women with PCOS on metformin are more likely to develop low vitamin B12 compared with those not taking it.

• Studies also highlight that adding B-vitamins and folate can support healthy homocysteine levels (a marker linked to cardiovascular and metabolic health).

• Folate co-supplementation alongside metformin has been shown to support vascular health markers and improve metabolic balance. (PubMed, 2010)

🕒 Best way to take it:

• Vitamin B12: morning, either on an empty stomach or with a light meal.

• Folate: any time of day, as it’s water-soluble and well absorbed.

👉 TribElle takeaway: If you’re on metformin, it’s worth checking your B12 levels periodically and asking your clinician whether adding folate makes sense for you. These small steps can help protect your long-term health and energy.

🔩 Zinc: Small But Mighty

Zinc helps with insulin sensitivity, skin health, and hair.

✨ The science:

• A comprehensive review in a reputable nutrition journal found evidence suggesting that zinc supplementation may improve markers of insulin resistance and support healthier lipid profiles in women with PCOS (Nutrients 2020).

🕒 Best time to take it: On an empty stomach if you can tolerate it. If it upsets your stomach, take it with a small evening meal (but avoid dairy or coffee at the same time).

✨ The TribElle Take

Supplements won’t cure PCOS. But the right ones, taken in the right way, can ease symptoms, support hormones, and improve long-term health.

The best evidence is for:
✔️ Vitamin D
✔️ Omega-3s
✔️ Vitamin B12 + Folate

👉 Remember: everyone’s body is different. Supplements work best alongside medical care, nutrition, movement, and sleep.

⚠️ Important Note

This blog is for general information only. Supplements are not licensed medicines for PCOS in the UK. Research is ongoing, and results vary. Always speak to a healthcare professional before starting anything new.