Vitamin D

Vitamin D is a hormone created by the body when skin is exposed to ultraviolet rays in sunlight. It is found naturally in a small number of foods and can also be taken as a fat-soluble dietary supplement.

How do experts use vitamin D?

Both medical groups and integrative experts provide recommendations for vitamin D in treating people with cancer. Learn more about the approaches and meanings of recommendations: Integrative Oncology Programs and Expert Guidelines ›

Clinical practice guidelines

More guidelines, specific to medical professionals, are in Are you a health professional?

This 2011 guideline suggests defining vitamin D deficiency as 25(OH)D levels below 20 ng/mL, insufficiency as 25(OH)D of 21–29 ng/mL, and sufficiency starting at 30 ng/mL.

These guidelines suggest that all adults who are vitamin D deficient be treated with 50,000 IU of vitamin D₂ or vitamin D₃ once a week for 8 weeks or its equivalent of 6000 IU of vitamin D₂ or vitamin D₃ per day to achieve a blood level of 25(OH)D above 30 ng/ml, followed by maintenance therapy of 1500–2000 IU per day.

The 2017 guidelines regarding breast cancer patients evaluates vitamin D₂ as having insufficient evidence to recommend using for pain.

Researchers from these organizations found insufficient evidence to recommend vitamin D to treat aromatase inhibitor-related joint pain.

Published protocols, programs, and approaches

Vitamin D is used in programs, approaches, and protocolsa package of therapies combining and preferably integrating various therapies and practices into a cohesive design for care from these integrative oncologists, drawing from both scientific research and observations from years or even decades of treating people with cancer.

Lise Alschuler, ND, FABNO, and Karolyn Gazella

Approaches are described for certain cancer types, or along with certain conventional therapy treatments, or for particular conditions such as insulin resistance.

Uses of vitamin D:

Keith Block, MD

Uses of vitamin D:

Dr. Block says that off-label use of calcitriol, which is the most active form of vitamin D, is of particular interest in prostate cancer. Preclinical evidence shows clear benefit and early clinical evidence to date is promising but not yet conclusive.²Ben-Eltriki M, Deb S, Guns ES. Calcitriol in combination therapy for prostate cancer: pharmacokinetic and pharmacodynamic interactions. Journal of Cancer. 2016 Jan 15;7(4):391-407.

Dr. Block cautions against giving alpha-tocopherol alone, as this may deplete the body of other important components of vitamin E.

Raymond Chang, MD, FACP

Gerald M. Lemole, MD; Pallav K. Mehta, MD; and Dwight L. McKee, MD

Uses of vitamin D:

Barbara MacDonald, ND, LAc

Gurdev Parmar, ND, FABNO, and Tina Kaczor, ND, FABNO

Uses of vitamin D:

David Servan-Schreiber, MD, PhD

Nasha Winters ND, FABNO, LAc, DiplOM, and Jess Higgins Kelley, MNT

Dosing

Sun exposure

You make vitamin D when your skin is exposed to relatively intense sunlight. People with light skin can produce sufficient vitamin D with less than 15 minutes of exposure to the sun around noon on a summer day. The time needed increases among people with darker skin, up to two hours for people with very dark skin.

The farther the sun is from directly overhead, the less efficiently you’ll produce vitamin D. A rule of thumb is that you produce vitamin D only if your shadow is shorter than you are.⁶Vitamin D and Cancer with William B. Grant, PhD. Moss Report Podcast. June 22, 2022. Viewed September 12, 2022. People who live far from the equator may not make any vitamin D in the winter, even when exposed to sunlight at noon.⁷Raman R. How to safely get vitamin D from sunlight. Healthline. April 28, 2018. Viewed September 12, 2022.

Supplements

Vitamin D measurements: 40 IU=1 microgram

The National Academies Health and Medicine Division (formerly the Institute of Medicine) recommends a daily dietary allowance of vitamin D of 600 IU/day (increasing to 800 IU/day at age 71) with the upper level intake at 4,000 IU/day starting at age nine for healthy individuals.⁸Institute of Medicine. Dietary Reference Intakes for Calcium and Vitamin D (chapter 7). 2011. Viewed November 2, 2021. Higher doses may be needed among people treated with steroids.⁹Albert Einstein College of Medicine. Oral steroids linked to severe vitamin D deficiency in nationwide US study. ScienceDaily. September 30, 2011. Viewed March 6, 2019.

Who benefits from supplements?

Taking vitamin D supplements provides benefits mostly among people who have low vitamin D blood levels. A large study found that vitamin D supplementation showed the strongest benefits regarding cancer mortality among people with vitamin D deficiency (less than 12 ng/mL or 30 nmol/L) or insufficiency (from 12 to 20 ng/mL or 30 to 50 nmol/L), with little or no benefit among people who already had sufficient vitamin D levels (above 20 ng/mL or 50 nmol/L).¹⁰Brenner H, Jansen L, Saum KU, Holleczek B, Schöttker B. Vitamin D supplementation trials aimed at reducing mortality have much higher power when focusing on people with low serum 25-hydroxyvitamin D concentrations. Journal of Nutrition. 2017 Jul;147(7):1325-1333. 

A combined analysis of studies found a daily dose of up to 3000 IU per day of  vitamin D increased serum 25(OH)D among women with polycystic ovary syndrome, but higher intake than that did not lead to clear increases in serum levels.¹¹Cochrane KM, Bone JN, Williams BA, Karakochuk CD. Optimizing vitamin D status in polycystic ovary syndrome: a systematic review and dose-response meta-analysis. Nutrition Reviews. 2024 Sep 1;82(9):1176-1186. 

Large or small doses?

Smaller frequent doses may be better than an occasional high dose, such as a single bolusa single, large dose of a substance, such as a drug, nutrient, or insulin, within a short period of time dose. A combined analysis of studies found lower risk of death from cancer as a whole among people treated with a daily vitamin D supplement compared to controls (3 studies) but no evidence of an effect on risk from an infrequent large-bolus dose (3 studies).¹²Keum N, Chen QY, Lee DH, Manson JE, Giovannucci E. Vitamin D supplementation and total cancer incidence and mortality by daily vs. infrequent large-bolus dosing strategies: a meta-analysis of randomised controlled trials. British Journal of Cancer. 2022 Sep;127(5):872-878. Another study found that postmenopausal women with stage 1–3a breast cancer treated with either 600 IU or 4000 IU vitamin D₃ daily for 6 months showed the same effects on aromatase inhibitor-associated musculoskeletal symptoms. The large dose did not provide more benefit.¹³Shapiro AC, Adlis SA et al. Randomized, blinded trial of vitamin D₃ for treating aromatase inhibitor-associated musculoskeletal symptoms (AIMSS). Breast Cancer Research and Treatment. 2016 Feb;155(3):501-12.
On the other hand, postmenopausal women treated with 50,000 IU vitamin D₃ weekly for 12 weeks followed by 2000 IU daily for 40 weeks saw higher increases in their serum vitamin D levels compared to 800 IU daily for 52 weeks during adjuvant aromatase inhibitor therapy.¹⁴Niravath P, Hilsenbeck SG et al. Randomized controlled trial of high-dose versus standard-dose vitamin D₃ for prevention of aromatase inhibitor-induced arthralgia. Breast Cancer Research and Treatment. 2019 Sep;177(2):427-435. The unanswered question is whether those higher increases in vitamin D levels were beneficial.

Dosage has not been standardized for use in cancer care, but recommendations are available from these sources:

Natural Medicines Database ›

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Beer TM, Hough KM et al. Weekly high dose calcitriol and docetaxel in advanced prostate cancer. Seminars in Oncology. 2001;28(4 Suppl 15):49–55.

Also see published programs and approaches (above).

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