image of a spilled bottle of vitamin pills

Can Low Levels of Vitamin D Increase Cancer Risk?

As many as seven in 10 Americans may have low vitamin D levels. In Midwestern states such as Illinois and Wisconsin, vitamin D deficiency is even more common. Although the findings are mixed, some research suggests that having enough vitamin D may help lower the risk of getting certain kinds of cancer for some groups.

“Vitamin D deficiency is common in the United States, wherever you are,” says Michael Walker, N.D., a naturopathic oncology provider at City of Hope® Cancer Center Chicago. “It’s often said that vitamin D helps the immune system, but of course the immune system is like a military with countless ways of orchestrating its activity and response to threats.”

Some observational studies have found links between the risk of developing certain kinds of cancer and lower levels of vitamin D, which may be linked to the role this nutrient plays in our immune health.

This article covers what we know — and don’t know — about how vitamin D and cancer risk may be related, including topics such as:

If you or a loved one has recently been diagnosed with cancer and are looking for a second opinion, call us 24/7 at (877) 524-4673.

Why Is Vitamin D Deficiency Higher in the Midwest?

We get some of the vitamin D we need from foods such as fatty fish and eggs. But most of it comes from ultraviolet-B radiation, from natural sunlight. When ultraviolet-B rays hit our skin, they turn cholesterol in our bodies into vitamin D-3.

“The role vitamin D plays in various parts of the immune system has been pretty well recognized,” Walker says. This nutrient acts almost like a hormone, managing and regulating a variety of processes, including those related to:

  • Bone density
  • Thyroid function
  • Our immune system’s ability to fend off infection
  • Depression and some other mental health disorders
  • Dental health
  • Heart function and health

Although vitamin D deficiency is common across the United States, it is more likely to affect Americans who live in the northernmost states and the Midwest. Why? Because sun is harder to come by. Even a sunny winter day in Wisconsin, for example, offers less strong ultraviolet-B rays, making it harder to get the sun exposure we need to produce enough vitamin D.

For most people, this is about 20 minutes of sunlight. But for some, it may be longer.

“Skin pigmentation may likely be a factor impacting the amount vitamin D produced with sun exposure. That is, darker skin may need a higher relative ‘dose’ of sunlight,” Walker adds. “However, people with lower vitamin D levels in the blood seem to have a higher response to sunlight.”

Cancer and Vitamin D: What’s the Link?

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Michael Walker, N.D., a naturopathic oncology provider at City of Hope® Cancer Center Chicago


While research into the link between cancer risk and vitamin D has had mixed results, “supplementation of vitamin D may help reduce the risk of developing some cancers in some people,” Walker says. Some of the most notable positive findings from observational trials are:

  • Adequate vitamin D levels may reduce the risk of getting colorectal or bladder cancer.
  • Sufficient levels of vitamin D are generally associated with lower risk of dying from cancer.

But those are just associations: they don’t prove cause and they are certainly not the be all end all,” says Walker — especially given that other studies have found little or no link between cancer risk and vitamin D deficiency. These mixed results could be the result of the demographics of the people taking part in the study, their geographic location or other variables.


Vitamin D Deficiency Treatment

If you’re worried about vitamin D deficiency, your primary care doctor is able to check your levels with a simple blood test. If you are deficient, he or she may recommend daily vitamin D supplements.

For people with cancer, more factors should be considered. Vitamin D may be appropriate for some cancer patients, but not all. Discussing your options with your care team is key, Walker says.

“The value of treatment at City of Hope Chicago is that you get regular follow up with everyone in the team,” Walker says. “That means that not only do you get a personalized care plan at your initial visit, but it’s always updated based on changes in symptoms, clinical condition or treatment. Someone’s health status is completely dynamic.”

Another lesser-known benefit: Vitamin D may help some types of cancer therapies work as effectively as possible.

“This has been seen in treatments using monoclonal antibodies for at least the past decade and is most well demonstrated in people with non-Hodgkin and B cell lymphomas,” says Walker.

Illinois Cancer Screening

It’s best to follow your primary doctor’s or oncologist’s recommendations for cancer screening. For some people, monitoring vitamin D levels may play a role in screening recommendations, too.

“If someone has very low levels of vitamin D, which is associated with bone health, fatigue, autoimmune disease and cancer, then maybe monitoring more is worth it,” Walker says.

But given that there are natural therapies with both positive and negative potential, “these therapies need to be evaluated on an appropriate basis, and appropriate depends on a patient’s clinical situation and treatment.”

If you or a loved one has recently been diagnosed with cancer and are looking for a second opinion, call us 24/7 at (877) 524-4673.