If you are a patient of mine, you’ve had your vitamin D tested. In my practice, it is mandatory, and I would like to share why I feel this way. I’m almost crazy about it. If you have cancer, or have a history of cancer, you should have your vitamin D levels tested at least once per year, and I’ll help you correct any deficiency you may have.
Humans obtain vitamin D from the sun through their skin. Depending on cultural habits, skin colour and altitude, different regions of the world have higher rates of vitamin D deficiency, like here in Canada. We can also get vitamin D through liquid fish oil or gel cap supplements.
How vitamin D influences cancer processes was first discovered in 1981. As you will read below, vitamin D has a major role in the immune system. Vitamin D sufficiency has been correlated with better responses to chemotherapy and radiation, lower recurrence rates, and even lower mortality rates. This has been found in many different cancers, including breast, pancreatic, colon, melanoma, esophageal, gastric, lymphoma and glioblastoma.
WHAT DOES VITAMIN D DO IN THE BODY?
Generally, vitamin D is important for regulating the immune system. It is classically known for increasing calcium absorption and having positive effects on bone structure. It has antiviral activity, helps fight infections, and decreases inflammation. It has been found in clinical trials to be beneficial for the treatment of psoriasis, type I diabetes, MS, inflammatory bowel disease, rheumatoid arthritis and even COVID.
With respect to cancer, it regulates the cell cycle causing cellular arrest, decreases the growth of rapidly dividing cells (which happens in cancer!) and is involved in cell death, called apoptosis. It also decreases signalling cascades in cells that are involved in the invasion and migration of cancer cells, leading to decreased metastasis. Let’s look at some of the research below.
VITAMIN D DECREASES MORTALITY IN AGGRESSIVE CANCERS
The following recent studies have looked at the link between vitamin D levels and survival:
- a shorter overall survival was found in patients with non-small cell lung cancer who had vitamin D deficiency (1);
- a meta-analysis of 7718 patients with colorectal cancer showed a 33% decreased risk of mortality with higher vitamin D levels (2);
- in mantle cell lymphoma, vitamin D deficiency was associated with worse progression-free survival and overall survival (3);
- vitamin D deficiency was correlated to increased risk for progression and mortality in melanoma (4);
- a review of 303 women with breast cancer found increased mortality rates when women were vitamin D deficient, regardless of lymph node status, stage or subtype (5);
- 5-year survival rates were significantly longer in stage I-III GI cancers (esophageal, gastric, colorectal) when vitamin D levels were optimal (6);
- statistically significant longer survival was found in pancreatic cancer (7) and glioblastoma (8) with higher vitamin D levels;
- the VITAL trial followed 25,871 people with cancer over a 5 year period, and found that people who supplemented with vitamin D on a daily basis had decreased cancer-specific mortality (9).
VITAMIN D DECREASES SIDE EFFECTS AND INCREASES RESPONSE TO CHEMOTHERAPY
The following studies have looked at how vitamin D may improve response to chemotherapy, as well as how it may decrease side effects:
- having sufficient vitamin D levels correlates to a higher likelihood of having a pathologic complete response to chemotherapy in locally advanced breast cancer (10);
- vitamin D deficiency correlates with an increased risk of radiation-induced proctitis (11);
- low vitamin D is associated with chemotherapy-induced peripheral neuropathy (12);
HOW TO TEST YOUR VITAMIN D LEVELS
You can ask your family doctor, or I can give you a requisition. It is a simple blood test. The federal recommendations are that everyone should supplement with 2000 IU of vitamin D per day. However, if your vitamin D levels are quite low, this may not be enough to raise your blood levels to where we want it. Testing it is the only way to know exactly how much you need to take.
As stated previously, optimizing vitamin D levels is critically important and one of the easiest nutrients to test and correct if needed. If you have cancer or have a history of cancer, I recommend getting your vitamin D tested at least once yearly. Please contact me if you are overdue for your vitamin D screening test.
Dr. Jessa
(1) Mak et al. Cancer Biomark, 2017;18(3):297-303.
(2) Maalmi et al. Nutrients, 2018;10(7):896.
(3) Xu et al. J Cancer Res Clin Oncol, 2020;146(4):1003.
(4) Slominski et al. Lab Invest, 2017;97(6):706.
(5) Thanasitthichai et al. Asian Pac J Cancer Prevention, 2019;20(10):3101.
(6) Yonaga et al. Nutrients 2019;11(10):2547.
(7) Yuan et al. J Clin Oncol, 2016;34(24):2899.
(8) Elmaci et al. Metab Brain Dis, 2019;34(3):687-704.
(9) Br J Cancer, 2020; 123(8): 1205.
(10) Viala et al. BMC Cancer, 2018;18:770.
(11) Int Radiat Oncol Biol Phys, 2015;92(3):613.
(12) J Clin Med, 2022;11(2): 355.
