Researchers reviewed 18 studies to understand whether vitamin D levels affect ovarian cancer risk and survival. Most studies found that women with low vitamin D levels were more likely to develop ovarian cancer and had worse outcomes if diagnosed. However, a couple of large studies disagreed with these findings. The evidence suggests vitamin D may play a role in ovarian cancer development and progression, but scientists need more research to be completely certain. This is important because vitamin D is something people can potentially control through diet, supplements, and sun exposure.

The Quick Take

  • What they studied: Whether women with low vitamin D levels have a higher chance of getting ovarian cancer and whether low vitamin D means worse outcomes if someone is diagnosed with the disease.
  • Who participated: The review analyzed 18 different research studies involving ovarian cancer patients and healthy women. The studies used different research methods including comparing cancer patients to healthy people and laboratory experiments with cancer cells.
  • Key finding: Most studies (6 out of 9 case-control studies) showed that women with ovarian cancer had lower vitamin D levels than healthy women. Studies looking at survival rates found that women with adequate vitamin D levels lived longer after diagnosis.
  • What it means for you: If you’re a woman, maintaining healthy vitamin D levels may help reduce ovarian cancer risk and improve outcomes if diagnosed. However, this doesn’t mean vitamin D is a cure or complete prevention—more research is needed. Talk to your doctor about your vitamin D levels and whether supplementation is right for you.

The Research Details

This was a systematic review, which means researchers searched medical databases (PubMed, CINAHL, Cochrane, and Scopus) for all studies published since 2008 that looked at vitamin D and ovarian cancer. They included different types of studies: some that followed women over time (cohort studies), some that compared cancer patients to healthy women (case-control studies), and laboratory experiments using cancer cells. The researchers then analyzed all these studies together to see what the overall evidence showed.

The review included 18 studies total. Nine were case-control studies (comparing women with cancer to women without), several were cohort studies (following women over time), and some were laboratory experiments. By combining results from multiple studies, researchers could see if there was a consistent pattern across different research approaches.

A systematic review is valuable because it combines evidence from many studies rather than relying on just one. This approach helps identify patterns and gives a more complete picture of what the research shows. Since ovarian cancer is serious and vitamin D is something people can potentially control, understanding this connection could help with prevention and treatment strategies.

The strength of this review depends on the quality of the individual studies included. The fact that most studies pointed in the same direction (lower vitamin D = higher cancer risk) is encouraging. However, two large studies found no connection, which suggests the relationship may be more complicated than it first appears. The mix of different study types (some comparing groups, some in laboratories) provides different kinds of evidence but also makes it harder to draw firm conclusions.

What the Results Show

Most case-control studies (6 out of 9) found that women diagnosed with ovarian cancer had lower vitamin D levels compared to women without cancer. This suggests low vitamin D might be connected to developing the disease. The studies that looked at survival rates after diagnosis found encouraging results: women with adequate vitamin D levels had better survival rates than those with low levels.

Laboratory experiments with cancer cells showed that vitamin D appeared to slow down cancer cell growth and reduce how quickly the cancer progressed. These lab results support the idea that vitamin D might protect against ovarian cancer.

However, the cohort studies (which follow women over time) showed mixed results, similar to the case-control studies. This means some found a connection between low vitamin D and cancer risk, while others didn’t.

Two large, carefully designed studies (called nested studies) found no significant connection between low vitamin D levels and the development of ovarian cancer. This contradicts most other findings and suggests the relationship may not be as straightforward as it appears. These conflicting results highlight that more research is needed to fully understand the connection.

This review builds on previous research suggesting vitamin D plays a role in cancer prevention. The findings align with studies on other cancers showing vitamin D may have protective effects. However, the mixed results—with some large studies finding no connection—suggest that vitamin D’s role in ovarian cancer may be more complex than initially thought. The evidence is stronger than for some other potential risk factors but weaker than for well-established ones like family history.

The biggest limitation is that the studies included used different methods and measured vitamin D in different ways, making it hard to compare results directly. Some studies were small, which means their findings might not apply to larger populations. The two large studies that found no connection raise questions about whether the positive findings might be due to chance or other factors. Additionally, most studies were observational (watching what happens) rather than experimental (testing if vitamin D actually prevents cancer), so we can’t prove that low vitamin D causes cancer—only that they’re connected.

The Bottom Line

Based on this review, maintaining adequate vitamin D levels appears to be associated with lower ovarian cancer risk and better outcomes if diagnosed (moderate confidence level). General recommendations include: getting 10-30 minutes of midday sun exposure several times per week, eating vitamin D-rich foods like fatty fish and fortified dairy, and discussing vitamin D supplementation with your doctor. However, vitamin D should be viewed as one part of overall cancer prevention, not a standalone solution.

Women of all ages should be aware of this research, especially those with family history of ovarian cancer, those at higher risk, or those concerned about cancer prevention. Women already diagnosed with ovarian cancer may want to discuss vitamin D levels with their oncology team. This research is less relevant for men, though vitamin D has other health benefits for everyone. Anyone considering supplements should consult their healthcare provider first.

If you start optimizing vitamin D levels, it’s not a quick fix. Cancer prevention is a long-term process. You might notice improved energy and mood from adequate vitamin D within weeks, but any protective effect against cancer would develop over months to years. If already diagnosed with cancer, vitamin D status may influence outcomes, but this should be discussed with your cancer care team.

Want to Apply This Research?

  • Track your vitamin D intake sources weekly: record sun exposure time (in 10-minute increments), vitamin D-rich foods consumed, and any supplements taken. Note the date and estimated vitamin D amount from each source.
  • Set a weekly reminder to spend 15-20 minutes in midday sun (with appropriate sun protection) and add one vitamin D-rich food to your meals (salmon, fortified milk, egg yolks, mushrooms). Log these activities in the app to build consistency.
  • Schedule annual vitamin D blood level checks with your doctor and log the results in the app. Track any health changes, energy levels, and mood alongside vitamin D intake. Create a trend report every 6 months to see if your vitamin D levels are improving and correlate with how you’re feeling.

This review suggests an association between vitamin D levels and ovarian cancer risk, but it is not medical advice. Vitamin D should not be considered a treatment or cure for ovarian cancer. If you have concerns about ovarian cancer risk, family history of cancer, or are currently diagnosed with ovarian cancer, please consult with your healthcare provider or oncologist. Any decisions about vitamin D supplementation should be made in consultation with your doctor, as excessive vitamin D can have health risks. This information is for educational purposes only.