Vitamin D

Vitamin D is a group of fat-soluble pro-hormones. These are substances that have negligible hormonal activity on their own but our body can convert them into hormones. Vitamin D primarily helps our body to optimally use calcium and phosphorus. While the main source of Vitamin D is exposing your skin to direct sunlight, there are some foods that offer it too. Vitamin D2 (ergocalciferol) and Vitamin D3 (cholecalciferol) are the two most important forms of Vitamin D to humans. 

Here is a quick look at the foods that naturally provide Vitamin D:

There are Vitamin D dietary supplements available too.

Vitamin D and Cancer

  • Vitamin D intake might protect against breast or colorectal cancers and even affect markers for prostate cancer. 
  • However, Vitamin D alone does not prevent or treat cancer. 
  • It also contributes to the hormone regulation and might help regulating the immune system. 
  • Enhances the effects of radiation.
  • In certain cancers, it can improve muscle strength and reduce pain.


  • Regression in cervical intraepithelial neoplasia grade 1.
  • In combination with naproxen, Vitamin D showed slowing of the rate of rise of prostate-specific antigen in men.
  • Deficiency of Vitamin D has adverse effects on elderly patients with diffuse large B-cell lymphoma (DLBCL).
  • It has the potential to improve the outcome of breast cancer treatment.
  • Deficiency of Vitamin D can promote the spread of some breast cancers.
  • Patients suffering from metastatic prostate cancer experience improved muscle strength and lowering pain by treating Vitamin D deficiency.
  • In an animal study, Vitamin D was found to reduce the risk of breast cancer.
  • A study found reduced risk of colorectal cancer in women undergoing estrogen therapy.
  • Women with a history of non-melanoma skin cancer were found to have a lower risk of melanoma after Calcium and Vitamin D intake.

Key Points

  • Vitamin D is made by our bodies when skin is exposed to  sunlight and is also available in a few foods and in supplements.
  • Vitamin D deficiency is associated with some cancers, inflammation and several other health conditions.
  • Vitamin D is widely available in supplements and is generally considered safe at doses up to 4,000 IU/day.  
  • Consider having your doctor check your vitamin D levels to determine if there is a deficiency and to prescribe a dosage if needed.
  • A few adverse effects and interactions with drugs are noted. Individuals with disorders of calcium metabolism, gastrointestinal disease, kidney disease, heart disease or liver disease should consult a physician before use.


  • Nutrilite Alfalfa Calcium Plus 90 N Tablets (Combination Of Calcium, Magnesium & Vitamin D) – Amazon Link
  • Solgar Vitamin D3 Cholecalciferol Softgels – 120 Softgels – Amazon Link
  • iOTH iDaily D Vitamin D3 1000 IU Lavish Dose Of Sunshine – 100 Softgels – Amazon Link

References & More Information

  1. Credit: Beyond Conventional Care Therapies
  2. Integrative Oncology Cancer Care
  3. WebMD. Does Vitamin D Help Protect Against Cancer? 
  4. Vitamin D Council. What is Vitamin D? 
  5. Office of Dietary Supplements. Vitamin D Fact Sheet for Consumers. National Institutes of Health. February 11, 2016. 
  6. Memorial Sloan Kettering Cancer Center. About Herbs: Vitamin D
  7. Beyond Conventional Cancer Therapies. Vitamin D.
  8. National Cancer Institute: Vitamin D and Cancer Prevention.
  9. Vahedpoor Z, Jamilian M et al. Effects of long-term vitamin D supplementation on regression and metabolic status of cervical intraepithelial neoplasia: a randomized, double-blind, placebo-controlled trial. Hormones & Cancer. 2017 Feb;8(1):58-67.
  10. Srinivas S, Feldman D. A phase II trial of calcitriol and naproxen in recurrent prostate cancer. Anticancer Research. 2009 Sep;29(9):3605-10.
  11. Bittenbring JT, Neumann F et al. Vitamin D deficiency impairs rituximab-mediated cellular cytotoxicity and outcome of patients with diffuse large B-cell lymphoma treated with but not without rituximab. Journal of Clinical Oncology. 2014 Oct 10;32(29):3242-8.
  12. Chiba A, Raman R et al. Serum vitamin D levels affect pathologic complete response in patients undergoing neoadjuvant systemic therapy for operable breast cancer. Clinics in Breast Cancer. 2017 Dec 11. pii: S1526-8209(17)30324-5.
  13. NCI Staff. Vitamin D deficiency may promote spread of some breast cancers. National Cancer Institute. April 14, 2016. 
  14. Van Veldhuizen PJ, Taylor SA, Williamson S, Drees BM. Treatment of vitamin D deficiency in patients with metastatic prostate cancer may improve bone pain and muscle strength. Journal of Urology. 2000 Jan;163(1):187-90.
  15. Krishnan AV, Swami S, Feldman D. Equivalent anticancer activities of dietary vitamin D and calcitriol in an animal model of breast cancer: importance of mammary CYP27B1 for treatment and prevention. Journal of Steroid Biochemistry and Molecular Biology. Jul 2013;136:289-295
  16. Ding EL, Mehta S, Fawzi WW, Giovannucci EL. Interaction of estrogen therapy with calcium and vitamin D supplementation on colorectal cancer risk: reanalysis of Women’s Health Initiative randomized trial. International Journal of Cancer. 2008 Apr 15;122(8):1690-4.
  17. Tang JY, Fu T et al. Calcium plus vitamin D supplementation and the risk of nonmelanoma and melanoma skin cancer: post hoc analyses of the women’s health initiative randomized controlled trial. Journal of Clinical Oncology. 2011 Aug 1;29(22):3078-84.
  18. Natural sources of Vitamin E by Doctors Beyond Medicines

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