Having a low level of vitamin D is linked with breast cancer. Making sure you have a healthy level of Vitamin D is a great way to stay well and may reduce your risk of breast cancer.

What is Vitamin D and how do we get it?

Vitamin D is naturally present in some foods (e.g. oily fish such as salmon, sardines, herring and mackerel, and egg yolks), added to others (e.g. breakfast cereals and non-dairy milk) and available as a dietary supplement.

But your main source of vitamin D is sunlight. When the sun’s rays interact with skin, vitamin D synthesis is triggered.

Vitamin D is a nutrient you need for good health. It helps the body absorb calcium, one of the main building blocks for strong bones.

How could vitamin D lower breast cancer risk?
In some studies, vitamin D has been found to slow or prevent the development of breast cancer. It also has anti-inflammatory benefits and decreases oestrogen synthesis. It is also important for a properly functioning immune system and may help protect against cancer spreading.

How much vitamin D should you have?

Your vitamin D level depends on several lifestyle habits, e.g. how much time you spend outdoors, what you eat, what medications you take, but also on your age and skin type.

Most people in the northern hemisphere can make enough vitamin D from being out in the sun daily for short periods with their forearms, hands or lower legs uncovered and without sunscreen, from late March to the end of September.

During winter and autumn, you need to get vitamin D from your diet because the sun is not strong enough for the body to make enough.

We recommend you get vitamin D from food sources rather than supplements, but if you can’t, consider taking a daily supplement containing 10 micrograms of vitamin D (400 IU).

Ensuring adequate levels of vitamin D could be beneficial in reducing breast cancer risk. To detect a vitamin D deficiency, a laboratory blood test is necessary

While you can’t get too much vitamin D through sunshine, you can get too much vitamin D through supplements, which can lead to health problems.  Getting more than 4,000 IU per day (100 micrograms/day) increases the risk of harmful health effects, for example, kidney damage.

Making sure you have healthy levels of vitamin D is important for breast cancer prevention, but also good for your general.

BCUK recommends you be mindful about your vitamin D status and if you have any concerns get your levels checked by your GP, so you can determine if you need to take in more vitamin D either through sun exposure, or if this isn’t possible, though food or supplements.

Check out our Prevention Hub for my breast cancer prevention tips.


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  1. National Institutes of Health. Vitamin D. 2020. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/ [Accessed 5 Feb. 2021].
  2. NHS. How to get vitamin D from sunlight. NaN. https://www.nhs.uk/live-well/healthy-body/how-to-get-vitamin-d-from-sunlight/ [Accessed 1 Feb. 2021].
  3. National Institutes of Health. Vitamin D. 2021. https://ods.od.nih.gov/factsheets/VitaminD-Consumer/ [Accessed 5 Feb. 2021].
  4. Atoum M. et al., 2017. Vitamin D and Breast Cancer: Latest Evidence and Future Steps. Breast cancer : basic and clinical research 11: 1178223417749816. https://journals.sagepub.com/doi/pdf/10.1177/1178223417749816.
  5. Voutsadakis, I. A. et al., 2021. Vitamin D baseline levels at diagnosis of breast cancer: A systematic review and meta-analysis. Hematology/oncology and stem cell therapy: 1 14: 16–26. https://pubmed.ncbi.nlm.nih.gov/33002425/.
  6. Estébanez N. et al., 2018. Vitamin D exposure and Risk of Breast Cancer: a meta-analysis. Scientific reports: 1 8: 9039. https://www.nature.com/articles/s41598-018-27297-1.
  7. McDonnell, S. L. et al., 2018. Breast cancer risk markedly lower with serum 25-hydroxyvitamin D concentrations ≥60 vs <20 ng/ml (150 vs 50 nmol/L): Pooled analysis of two randomized trials and a prospective cohort. PloS one: 6 13: e0199265. https://pubmed.ncbi.nlm.nih.gov/29906273/.
  8. O’Brien, K. M. et al., 2017. Serum Vitamin D and Risk of Breast Cancer within Five Years. Environmental health perspectives: 7 125: 77004. https://pubmed.ncbi.nlm.nih.gov/28728134/.
  9. Lukaszuk, J. M. et al., 2017. 25(OH)D status: Effect of D3 supplement. Obesity science & practice: 1 3: 99–105. https://onlinelibrary.wiley.com/doi/full/10.1002/osp4.85.
  10. Krishnan, A. V. et al., 2011. Mechanisms of the anti-cancer and anti-inflammatory actions of vitamin D. Annual review of pharmacology and toxicology 51: 311–336. https://pubmed.ncbi.nlm.nih.gov/20936945/.
  11. Vuolo L. et al., 2012. Vitamin D and cancer. Frontiers in endocrinology 3: 58. https://pubmed.ncbi.nlm.nih.gov/22649423/.
  12. Carlberg C. et al., 2020. An update on vitamin D signaling and cancer. Seminars in cancer biology. https://www.sciencedirect.com/science/article/pii/S1044579X20301140.
  13. NHS. Vitamins and minerals – Vitamin D – NHS. NaN. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/ [Accessed 9 Feb. 2021].
  14. Marcinowska-Suchowierska E. et al., 2018. Vitamin D Toxicity-A Clinical Perspective. Frontiers in endocrinology 9: 550. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6158375/.
  15. Harvard Health. Taking too much vitamin D can cloud its benefits and create health risks – Harvard Health. 2017. https://www.health.harvard.edu/staying-healthy/taking-too-much-vitamin-d-can-cloud-its-benefits-and-create-health-risks [Accessed 10 Jun. 2021].

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