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Can Vitamin D Reduce the Likelihood of Cancer?

Written by Ana Aleksic, MSc (Pharmacy) | Last updated:
Evguenia Alechine
Puya Yazdi
Medically reviewed by
Evguenia Alechine, PhD (Biochemistry), Puya Yazdi, MD | Written by Ana Aleksic, MSc (Pharmacy) | Last updated:

In addition to its immune-balancing activity, emerging research suggests that maintaining healthy vitamin D levels might reduce the likelihood of cancer. Is vitamin D really all that powerful? Read on to uncover what the latest research says.

Vitamin D & Cancer Protection Snapshot

  • Vitamin D may help prevent cancer by strengthening the immune system
  • Normal vitamin D levels may make it harder for cancer cells to form and grow (limited research)
  • Despite promising results, the effects of vitamin D on cancer prevention are still uncertain

The majority of published studies found that sufficient vitamin D levels protect against cancer and the risk of dying [1].

Vitamin D and its byproducts inhibit the spreading of cancer and cancer cell growth. It also induces cancer cell death.

As a result, it reduces the potential for the cancerous cell to survive [2, 3, 4, 5].

The body naturally makes vitamin D when exposed to sunlight. Getting regular, moderate sun exposure is a safe way to maintain normal vitamin D levels during the summer months.

Vitamin D is also found in certain foods, such as fatty fish like salmon and sardines. Additionally, many vitamin D supplements are available on the market.

Taken at the recommended doses, vitamin D supplements are considered safe. However, taking too much can be harmful. Vitamin D supplements may also interact with prescription medications. Remember to talk to your doctor before supplementing!

Vitamin D may help prevent cancer by strengthening the immune response, but its cancer-preventive effects are still being researched.

Next, let’s take a look at what scientists have discovered about its effects on different cancer types in experimental settings.

Vitamin D & Breast Cancer

Women with a high dietary intake of this vitamin and regular exposure to sunlight had a significantly lower incidence, recurrence, and risk of dying from breast cancer [6, 7].

Intake of 2,000 IU/day of Vitamin D is associated with a reduction of 50% in the incidence of breast cancer [8].

Low vitamin levels were also associated with faster progression of metastatic breast cancer [8, 9, 10, 11, 12, 13].

On the other hand, some studies did not show an association between higher vitamin D intakes and lower breast cancer risk in postmenopausal women. In one, daily supplementation with 1,000 mg of calcium combined with 400 IU of vitamin D3 had no effect on breast cancer incidence [14, 15].

In breast cancer cells, estrogen production and aromatase enzyme activity decreased, while the production of androgens (testosterone, DHT) increased [16].

Breast cancer patients must maintain adequate levels of this vitamin to minimize medical complications associated with its deficiency including bone loss, falls, fractures, and infection. However, they should not supplement with vitamin D unless recommended by a doctor [17, 18, 19].

Some studies suggest that women who get more sun and eat foods high in vitamin D are less likely to get breast cancer, while other studies found no link. Large-scale studies should clarify these findings.

Vitamin D & Colon and Prostate Cancer

Epidemiological studies reported that higher blood levels of vitamin D are associated with a lower risk of colorectal cancer [1, 20, 21].

According to a single study, daily intake of 1,000 – 2,000 IU/day of this vitamin could reduce the incidence of colorectal cancer by 50% [22].

Additionally, the risk of dying from prostate cancer goes down in people who get more UVB, the principal source of Vitamin D [23, 24].

Vitamin D deficiency may increase the risk of initiation and progression of prostate cancer [25, 26].

In prostate cancer cells, vitamin D deficiency increases the production of androgens (testosterone and dihydrotestosterone) [27], which increases the growth of prostate cancer.

According to limited research, maintaining higher vitamin D blood levels may aid in colon cancer prevention. Deficiency might increase prostate cancer risk. More research is needed.

Vitamin D & Pancreatic and Ovarian Cancer

In one study, higher intakes of vitamin D were associated with lower risks for pancreatic cancer. Doses of 600 IU/d or more of this vitamin lowered the risk of pancreatic cancer by 41%. However, this study only looked at associations over a period of time. Clinical studies need to determine whether vitamin D actually reduces pancreatic cancer risk or not [28].

Another group of researchers found that low vitamin D levels are common in ovarian cancer patients and have been associated with a lower overall survival rate [29].

On the other hand, ultraviolet B (UVB) radiation — known for promoting vitamin D production in the skin — was associated with a lower risk of ovarian cancer in one study. Despite these promising findings, it’s still far too early to say whether vitamin D helps prevent ovarian cancer [30].

It’s still uncertain whether vitamin D can help prevent pancreatic or ovarian cancer, though early studies hint at its potential.

More About Vitamin D


While a growing body of evidence seems to indicate that vitamin D might play a role in a myriad of medical conditions, most of the evidence for these roles comes from in vitro, animal, and epidemiological studies. Randomized clinical trials are considered to be more definitive [31, 32].

In conclusion, make sure to talk with your doctor about the risks and benefits of supplementing with vitamin D, especially if you are worried about your risk of cancer.


Vitamin D helps balance the immune response. The body requires it for optimal well-being. Emerging research suggests that people with low vitamin D levels might be at an increased risk of various types of cancer–such as breast, prostate, ovarian, and colon cancer. Studies have shown that vitamin D might make it harder for cancer cells to grow and divide, possibly by keeping the immune system alert. It’s a good idea to keep your levels within the normal range by getting enough sun and dietary vitamin D sources. However, clinical data are lacking to back up supplementation for cancer prevention.

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About the Author

Ana Aleksic

Ana Aleksic

MSc (Pharmacy)
Ana received her MS in Pharmacy from the University of Belgrade.
Ana has many years of experience in clinical research and health advising. She loves communicating science and empowering people to achieve their optimal health. Ana spent years working with patients who suffer from various mental health issues and chronic health problems. She is a strong advocate of integrating scientific knowledge and holistic medicine.


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