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Table of Contents
How They Are Linked
Breast Cancer Risk
Cancer Progression
Recommended Dose
There is debate over the connection between vitamin D and estrogen-positive (ER-positive) breast cancer. Although the findings are far from certain, a few early studies suggested thatvitamin D deficiencycan increase the risk of breast cancer or lead to poorer outcomes.
Vitamin D supplements, in turn, may reduce the risk, particularly in postmenopausal females who are often vitamin D deficient. They may also lower the risk ofrecurrencewithER-positive breast cancer(but not ER-negative breast cancer).
EatingWell / Eric Brockob
A Note on Gender and Sex TerminologyVerywell Health acknowledges thatsex and genderare related concepts, but they are not the same. To accurately reflect our sources, this article uses terms like “women” and “female” as the sources use them.
A Note on Gender and Sex Terminology
Verywell Health acknowledges thatsex and genderare related concepts, but they are not the same. To accurately reflect our sources, this article uses terms like “women” and “female” as the sources use them.
How Vitamin D and Cancer Are Linked
Vitamin D plays a role in cancer insofar as it activates receptors—called vitamin D receptors (VDR)—found on nearly all cells in the body, including the breasts and lungs. Researchers have found that VDR plays two vital roles in this regard:
Cancer is largely associated with the termination of apoptosis. Rather than dying as they are supposed to, mutated cancer cells will start to multiply out of control, effectively becoming “immortal” as they increase in size and start to invade other tissues.
Vitamin D and the Risk of Breast Cancer
A large body of studies have strongly linked vitamin D deficiency to the risk of breast cancer. A 2023 analysis in theJournal of Clinical Oncologystrongly supports this, particularly in postmenopausal women (who have already undergonemenopause).
According to the study, which reviewed the medical records of nearly 150,000 females over age 40, postmenopausal females with vitamin D deficiency are 45% more likely to develop breast cancer than those with normal vitamin D levels.
Premenopausal women (those who have yet to undergo menopause) are also at risk but to a lesser magnitude. Compared to premenopausal women with normal vitamin D levels, those with vitamin D deficiency are 18% more likely to develop breast cancer.
The current body of research suggests an inverse relationship between vitamin D and breast cancer risk, meaning that low levels of vitamin D are linked to a higher risk of cancer, and high levels of vitamin D are linked to a lower risk of cancer.
Vitamin D and Cancer Progression
To date, the evidence of this remains mixed. While studies conducted at Stanford University showed that vitamin D deficiency in mice was linked to the rapid onset of metastasis, epidemiologic studies in humans have not been so cut and dry.
This is due in part to the fact that vitamin D deficiency is extremely common in women with breast cancer, affecting as many as 94% to varying degrees at the time of diagnosis.
It is hard, therefore, to determine the exact role that vitamin D plays in the onset ofmetastatic breast cancerand at what level vitamin D supplementation may or not be therapeutic.
ER-Positive vs. ER-Negative Breast Cancer
As a result, vitamin D plays a greater role in the prevention of ER+ cancer cells simply because they have more VDR receptors on them.
On the flip side, vitamin D deficiency plays a greater role in the onset of ER- breast cancer andtriple-negative breast cancerdue to the paucity of VDR. (Triple-negative cancers are those without estrogen,progesterone, andHER2 receptors.)
The benefits of vitamin D may also extend to the risk of recurrence of ER+ breast cancer. Because of the high expression of VDR on ER+ cancer cells, vitamin D can significantly reduce the risk of recurrence for these types of cancer. The same is not seen with ER- breast cancer.
Recommended Dosage of Vitamin D
Given the relationship between vitamin D and breast cancer, it would seem reasonable to suggest thatsupplementscan lower the risk of cancer and potentially slow the progression of the disease. But at what dose?
A 2024 review of studies in the journalNutrientsanalyzed 16 high-quality studies and concluded that vitamin D blood levels over 40.26 ng/mL can exert a protective effect against breast cancer.
With respect to disease progression, there is no data to suggest what dose of vitamin D may or may not be therapeutic. Even so, the general aim would be to achieve and maintain optimal vitamin D levels with diet and supplements.
According to the National Institute of Health, the daily vitamin D requirements from all sources—measured in international units (IU) and the equivalent micrograms (mcg)—are as follows:
For people with cancer, a form calledvitamin D3 (cholecalciferol)is preferred over vitamin D2 (ergocalciferol) as it is better able to raise and sustain vitamin D levels.
Vitamin D is also beneficial because it helps keep bones strong. This is important because all threearomatase inhibitorsused to prevent recurrence and certain chemotherapy drugs used to treat cancer can cause bone loss and weakening.
Regular sun exposure—generally between 10 to 30 minutes, several times per week—can also bolster vitamin D levels. However, this may not be possible as certain chemotherapy drugs are known to causephotosensitivity. Speak with your cancer specialist.
Food Sources of Vitamin DCertain foods are rich sources of vitamin D, including:Fatty fish, such as trout, salmon, tuna, mackerel, and sardinesFish liver oilsBeef liverEgg yolksShrimpMushroomsFortified milk or milk alternativesFortified breakfast cerealFortified orange juiceFortified yogurt
Food Sources of Vitamin D
Certain foods are rich sources of vitamin D, including:Fatty fish, such as trout, salmon, tuna, mackerel, and sardinesFish liver oilsBeef liverEgg yolksShrimpMushroomsFortified milk or milk alternativesFortified breakfast cerealFortified orange juiceFortified yogurt
Certain foods are rich sources of vitamin D, including:
Summary
Vitamin D deficiency is linked to an increased risk of breast cancer and breast cancer recurrence, especially with estrogen-negative breast cancer. On the other hand, optimal vitamin D levels may reduce your risk of estrogen-positive breast cancer or its recurrence. Some studies suggest that vitamin D blood levels over 40 ng/mL have a protective effect.
12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Kuhn T, Kaaks R, Becker S, et al.Plasma 25-hydroxyvitamin D and the risk of breast cancer in the European prospective investigation into cancer and nutrition: a nested case-control study.Int J Cancer,2013 Oct 1;133(7):1689-700. doi:10.1002/ijc.28172
Academy of Nutrition and Dietetics.Vitamin D breast and cancer risks.
Torres A, Camaselle C, Otero P, Simal-Gandara J.The impact of vitamin D and its dietary supplementation in breast cancer prevention: an integrative review.Nutrients.2024;16(5):573. doi:10.3390/nu16050573
Mackey JD, Young P, Zimmerer R, Miles B.Vitamin D deficiency as a risk factor for breast cancer development.J Clin Oncol.2023;41(Suppl_16). doi:10.1200/JCO.2023.41.16_suppl.10559
Atoum M, Alzoughool F.Vitamin D and breast cancer: latest evidence and future steps.Breast Cancer (Auckl). 2017;11:117822341774981. doi:10.1177/1178223417749816
National Cancer Institute.Vitamin D deficiency may promote spread of some breast cancers.
National Institutes of Health Office of Dietary Supplements.Vitamin D Fact Sheet for Health Professionals.
Office of Dietary Supplements.Vitamin D: fact sheet for health professionals.
Breastcancer.org.Vitamin D.
Drucker AM, Rosen CF.Drug-induced photosensitivity: culprit drugs, management and prevention.Drug Saf. 2011;34(10):821-37. doi:10.2165/11592780-000000000-00000
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