Researchers studied 70 women with PCOS (a common hormone condition) who didn’t have enough vitamin D. Half received birth control pills plus vitamin D supplements, while the other half received only vitamin D. After three months, both groups showed improvements in sexual function and desire. Interestingly, adding birth control pills didn’t provide extra benefits beyond the vitamin D alone. The study suggests that vitamin D supplementation might be a simple way to help women with PCOS feel better and improve their sexual health, without necessarily needing additional medications.

The Quick Take

  • What they studied: Whether taking vitamin D supplements and birth control pills together could help women with PCOS feel better sexually, compared to just taking vitamin D alone.
  • Who participated: 70 women with PCOS who had low vitamin D levels. The study took place in Iran from January to April 2019. The women were split into two equal groups of 35 each.
  • Key finding: Women who took vitamin D showed better sexual function at 3 months (P=0.01) and 6 months. Adding birth control pills didn’t make the results any better than vitamin D alone. Sexual desire improved more in the group taking only vitamin D.
  • What it means for you: If you have PCOS and low vitamin D, taking vitamin D supplements may help improve your sexual health and overall quality of life. You may not need to add birth control pills specifically for this benefit, though your doctor might recommend them for other reasons related to PCOS.

The Research Details

This was a randomized controlled trial, which is considered one of the strongest types of medical research. Researchers randomly assigned 70 women with PCOS and vitamin D deficiency into two equal groups. Both groups received vitamin D supplements (50,000 IU per week) for 12 weeks. The key difference was that one group also received low-dose birth control pills while the other group received a placebo (fake pill) that looked identical. Neither the women nor the researchers knew who was getting the real birth control pills—this is called “double-blind” and helps prevent bias. The researchers measured sexual function using a standard questionnaire called the Female Sexual Function Index (FSFI) and checked vitamin D levels at the start, 3 months, and 6 months.

This study design is important because it allows researchers to isolate the effects of vitamin D from the effects of birth control pills. By randomly assigning women to groups and using placebos, the researchers could be more confident that any improvements came from the treatments themselves, not from other factors. The double-blind approach prevents expectations from influencing the results.

This study has several strengths: it used random assignment, included a control group with a placebo, and was double-blind. However, the sample size was relatively small (70 women), and the study only lasted 6 months. The research was conducted in Iran, so results may vary in other populations. The study focused specifically on women with both PCOS and vitamin D deficiency, so findings may not apply to all women with PCOS.

What the Results Show

Both groups showed improvement in sexual function scores after receiving vitamin D supplements. At the 3-month mark, sexual function improved significantly (P=0.01), and this improvement continued at 6 months. The improvements were seen across multiple areas of sexual health. Importantly, the group that received birth control pills along with vitamin D did not show better results than the group receiving only vitamin D. This suggests that vitamin D was the main factor driving the improvements, not the birth control pills. Sexual desire specifically showed greater improvement in the group taking only vitamin D compared to the group taking both vitamin D and birth control pills at both the 3-month (P=0.009) and 6-month (P=0.01) marks.

The study also measured depression using the Beck Depression Inventory, as depression can affect sexual function. While the abstract doesn’t detail these results, the researchers assessed mood changes alongside sexual function improvements. The vitamin D levels increased in both groups as expected from supplementation. The two groups were well-matched at the start of the study, with no significant differences in weight or other demographic characteristics, which strengthens the comparison between groups.

Previous research has shown that women with PCOS often experience sexual dysfunction and that vitamin D deficiency is common in PCOS. This study builds on that knowledge by testing whether correcting vitamin D deficiency could improve sexual health. The finding that vitamin D alone may be sufficient (without adding birth control pills for this specific purpose) is somewhat surprising and suggests that vitamin D deficiency itself may be a key factor in sexual dysfunction for these women. This aligns with growing evidence that vitamin D plays a role in sexual health beyond its traditional bone health functions.

The study had a relatively small sample size (70 women), which limits how much we can generalize the findings. The study only lasted 6 months, so we don’t know if benefits continue longer-term or if they fade over time. All participants were from Iran, so results may differ in other populations with different genetics and lifestyles. The study only included women with PCOS who also had vitamin D deficiency, so these results may not apply to women with PCOS who have normal vitamin D levels. Additionally, the study didn’t track whether women continued taking the supplements after the study ended or how that affected long-term outcomes.

The Bottom Line

If you have PCOS and low vitamin D levels, vitamin D supplementation appears to be a reasonable option to discuss with your doctor for improving sexual health and quality of life (moderate confidence level). The typical dose used in this study was 50,000 IU per week. However, you should have your vitamin D levels tested before starting supplements and work with your healthcare provider to determine the right dose for you. Birth control pills may still be recommended for other PCOS-related reasons, but this study suggests they may not provide additional sexual health benefits beyond vitamin D supplementation alone.

This research is most relevant for women with PCOS who have been found to have low vitamin D levels and are experiencing sexual dysfunction or reduced sexual desire. Women with PCOS who have normal vitamin D levels may not see the same benefits. Men and women without PCOS should not assume these findings apply to them. If you’re pregnant, planning to become pregnant, or breastfeeding, discuss vitamin D supplementation with your doctor before starting.

Based on this study, you might expect to notice improvements in sexual function within 3 months of starting vitamin D supplementation. The improvements continued through 6 months, suggesting that benefits may build over time. However, individual results vary, and some women may see changes sooner or later than others. It’s important to be patient and consistent with supplementation while working with your healthcare provider to monitor your progress.

Want to Apply This Research?

  • Track your vitamin D supplementation daily (dose and date taken) and rate your sexual desire and satisfaction weekly on a scale of 1-10. Note any changes in mood or energy levels, as these can affect sexual health. Record your vitamin D blood test results when available to monitor improvement in deficiency status.
  • Set a daily reminder to take your vitamin D supplement at the same time each day (such as with breakfast) to build consistency. If using an app, log your supplement intake immediately after taking it. Create a weekly check-in where you reflect on any changes in sexual desire or satisfaction, and share these observations with your healthcare provider at follow-up appointments.
  • Use the app to track vitamin D intake over 3-month periods, with a goal of assessing changes at the 3-month and 6-month marks (similar to the study timeline). Set reminders for blood work to recheck vitamin D levels every 3-6 months. Create a trend report showing your sexual health ratings over time to identify patterns and share with your doctor. Monitor for any side effects or changes in mood that might affect sexual health.

This research summary is for educational purposes only and should not replace professional medical advice. The findings apply specifically to women with PCOS who have vitamin D deficiency. Before starting any vitamin D supplementation or making changes to your birth control, consult with your healthcare provider. Individual results vary, and what works for one person may not work for another. If you experience any adverse effects or have concerns about your sexual health, contact your doctor immediately. This study was conducted over 6 months in a specific population, so long-term effects and applicability to other groups are not fully established.