Does vitamin K2 help with depression in PCOS?
An 8-week placebo-controlled trial found a small improvement
Vitamin K2 and mood in PCOS: an 8-week placebo-controlled trial found a small improvement in depression scores with daily menaquinone-7.
In this story
Mood is one of the least-studied parts of PCOS, so it's a nice thing to see a trial take it on directly. Researchers in Shiraz gave 84 women with PCOS either a daily vitamin K2 capsule (a form called menaquinone-7) or an identical placebo for eight weeks, without anyone knowing who got which. Depression scores dipped in the K2 group and held steady in the placebo group, a difference that was statistically significant. The change was small, about two points on a 63-point scale, and on average both groups stayed in the mild range throughout. So think of this as an early, encouraging signal rather than a mood fix, and as the first time anyone has tested this question in PCOS at all.
The numbers that matter
The placebo group moved +0.2 over the same eight weeks.
Can we actually trust this?
Yes, as an early signal. The design is sturdy: women were randomly assigned, the K2 and placebo capsules were made specifically for this trial to look, smell, and weigh the same, and neither participants nor researchers knew who was taking which. Adherence was checked with daily text messages and by counting returned capsules, around 90% of women followed the protocol completely, diet and activity were tracked so they couldn't quietly explain the result, and nobody reported side effects. The caveats are about how much weight the finding can carry. Eighty-four women over eight weeks is a small, short trial. Depression wasn't the question the trial was built around; the sample size was calculated for blood sugar, which was reported in a separate paper. The K2 group also started with higher depression scores than the placebo group, by about three points, and the analysis didn't adjust for that, so part of the drop may be the higher group naturally settling back. And the trial was registered after the data had already been collected. None of that erases the result. It just means this is a first step worth building on, and the authors say as much themselves.
Does this apply to you?
This study is most relevant if:
- You have PCOS diagnosed by Rotterdam criteria
- You're between 18 and 40
- Your BMI is around 26 to 27
- You don't have diabetes, thyroid disease, or high blood pressure
- You're not taking blood thinners, or supplements and medications that affect blood sugar, cholesterol, bone, or ovarian function
These women were recruited from an infertility clinic and weren't selected for depression, so the study speaks to everyday mood rather than to treating a diagnosed condition.
Why this matters
When PCOS care focuses on cycles, weight, and hormones, mood tends to get left for last, if it comes up at all. This trial is the first to ask whether vitamin K2 might help with depression in women with PCOS, and it tested that properly, with a placebo and blinding, instead of relying on a survey or an animal study. The answer it found is modest: a small shift, in women who were mostly in the mild range to begin with. But modest isn't nothing, and a small, cheap, well-tolerated nutrient showing a measurable nudge in a controlled trial is exactly the kind of finding that earns a bigger follow-up study. The more hopeful takeaway is broader than K2 itself. Your mood is a legitimate part of PCOS, researchers are starting to treat it that way, and every trial like this one makes it a little harder for anyone to wave it off.
If you want to try this
- Check with your doctor first, especially about blood thinners.
Vitamin K directly affects how anticoagulants like warfarin work, which is why the trial excluded anyone taking them. This is the one conversation that genuinely matters before starting.
- Know what the dose was.
One capsule of 90 micrograms of menaquinone-7 a day, for eight weeks. That's a modest amount, and it's the only dose this trial tested.
- Note where you're starting.
The change here was small, and small changes are easy to miss from memory. Jotting down how your mood feels now gives you something real to compare against in two months.
- Give it the full eight weeks.
Mood was measured at the start and the end, with nothing in between, so there's no evidence about when any change begins.
- Keep your existing support in place.
This trial looked at everyday mood in women who weren't being treated for depression. If low mood is weighing on you, a supplement can sit alongside real support, not replace it, and talking to a clinician or someone you trust is always a good step.
FAQ
- Does vitamin K2 help with depression in PCOS?
- In this trial, eight weeks of daily vitamin K2 lowered depression scores slightly compared with a placebo, and the difference was statistically significant. The change was about two points, and participants mostly started and finished in the mild range, so it's best read as an early signal. It's the first trial to test this in PCOS, and larger studies are needed to confirm it.
- Why would vitamin K affect mood in women with PCOS?
- Researchers don't know yet, but they have a few ideas. Insulin resistance is common in PCOS and has been linked to depression, and vitamin K may improve insulin sensitivity. It also appears to calm inflammation and support proteins that help brain cells grow and communicate, both of which are involved in mood. None of these pathways was measured in this trial, though, and the same research team found in an earlier paper that K2 didn't change fasting blood sugar in women with PCOS. So the "why" is still an open question.
- What is menaquinone-7 (MK-7)?
- Menaquinone-7 is one form of vitamin K2. Vitamin K comes in two natural forms: K1 (phylloquinone) and K2 (menaquinone). Vitamin K is best known for its role in blood clotting, and researchers are also studying its effects on insulin sensitivity, inflammation, and brain health.
- How much vitamin K2 was used in the study?
- Participants took one 90-microgram capsule of menaquinone-7 daily for eight weeks. The comparison group took an identical-looking placebo capsule.
- Is vitamin K2 safe to take?
- No side effects were reported during this eight-week trial. The study excluded women who were pregnant or breastfeeding and anyone taking blood thinners like warfarin, since vitamin K interacts with them. Checking with your doctor before starting is the best way to make sure it fits with anything else you take.
How Sachi can help
A two-point shift in mood is real, but you would never notice it day to day. Mood moves around with sleep, stress, your cycle, and a hundred other things, which makes gradual change almost impossible to judge from memory. Sachi tracks your mood over time, so the pattern becomes visible: whether things are slowly improving, what tends to coincide with your harder weeks, and what your baseline actually looks like.
That record is useful whether or not you ever try vitamin K2. It turns "I think I've been feeling better lately" into something you can see, and it gives you something concrete to bring to a conversation with your doctor. Some of this is live today and some is still being built. You can follow along or join the beta at sachi-health.com.
Study at a glance
Reference
Tarkesh F, Namavar Jahromi B, Hejazi N, Hoseini G (2022). Effect of vitamin K2 administration on depression status in patients with polycystic ovary syndrome: a randomized clinical trial. BMC Women's Health , 22, 315. https://doi.org/10.1186/s12905-022-01825-8
Cite this issue
Sachi Health. (September 22, 2026). Does vitamin K2 help with depression in PCOS? An 8-week placebo-controlled trial found a small improvement. The PCOS Brief. https://www.sachi-health.com/blog/the-pcos-brief-issue-32
Further reading from The PCOS Brief
Thomson RL, Buckley JD, Brinkworth GD (2016). Perceived exercise barriers are reduced and benefits are improved with lifestyle modification in overweight and obese women with polycystic ovary syndrome: a randomised controlled trial. BMC Women's Health, 16, 14. https://doi.org/10.1186/s12905-016-0292-8 — Read our plain-English summary.
Patten RK, McIlvenna LC, Moreno-Asso A, Hiam D, Stepto NK, Rosenbaum S, Parker AG (2023). Efficacy of high-intensity interval training for improving mental health and health-related quality of life in women with polycystic ovary syndrome. Scientific Reports, 13, 3025. https://doi.org/10.1038/s41598-023-29503-1 — Read our plain-English summary.
Kogure GS, Lopes IP, Ribeiro VB, Mendes MC, Kodato S, Furtado CLM, Silva de Sá MF, Ferriani RA, Lara LAS, dos Reis RM (2020). The effects of aerobic physical exercises on body image among women with polycystic ovary syndrome. Journal of Affective Disorders, 262, 350-358. https://doi.org/10.1016/j.jad.2019.11.025 — Read our plain-English summary.