The Role of Vitamin D in African American Prostate Cancer
- Vitamin D has a different role in the bodies of African American men compared to white men.
- The actions of vitamin D in African American men may explain some of the racial differences in risk for aggressive prostate cancer.
- African Americans run higher risk for vitamin D deficiency than their white counterparts, which could play a role in cancer risk.
Campbell and his colleagues, including Clayton Yates, PhD, of Tuskegee University and Lara Sucheston-Campbell, PhD, of Ohio State University, have followed the path of vitamin D through the body to try to find the answer. Decades ago, researchers tried (and failed) to find a link between vitamin D and prostate cancer survival. But, Campbell says, “In our preliminary studies, we saw a potential footprint of the actions of vitamin D receptor in prostate cancer.”
Today, Campbell, Yates, and Sucheston-Campbell have begun to tease out a relationship between vitamin D and prostate cancer. Their work underscores racial disparities in clinical research and may begin to unravel racial disparities in the cancer itself.
First, a Primer on Vitamin D
Your body needs vitamin D to function. A protein in your body called vitamin D receptor helps your body use the vitamin D that it gets from food and sunlight. After various reactions that take place as your body takes up vitamin D, Vitamin D receptor attaches to sections of your DNA and regulates the activity of certain genes. It can turn those genes on or off to control various processes in the body.
Focusing In on Vitamin D
This new research adds to evidence that there’s something about the way vitamin D is processed in the body that drives some of the racial differences in prostate cancer.
Researchers analyzed the prostate cells of a group of healthy white men and African American men and also prostate tumor cells of a group of white men and African American men with prostate cancer.
What they found in the healthy cells was that vitamin D receptor attaches to different sections of DNA in white men than it does in African American men. What’s more, it attaches in more places in African American men. That means that in African American men, vitamin D receptor controls more genes and different genes than it does in white men. In particular, vitamin D receptor seems to regulate genes associated with inflammation and with sleep patterns (circadian rhythm) in African American men. Inflammation is believed to have a role in many cancers. The role of circadian rhythms is less understood.
Prostate cancer in African American men seems to weaken vitamin D receptor’s ability to bind to cells. So the protein regulates fewer genes in the prostate tumors of African American men than in the healthy prostate cells of African American men. But, it still regulates some 600 genes in African American men’s prostate cancer compared to none in white men’s prostate tumors.
Vitamin D and Prostate Cancer – A Complicated History
So, what does it all mean?
The study certainly does not suggest that African American men should load up on vitamin D – by sunbathing or eating foods that have been fortified with the stuff – in order to avoid prostate cancer. “Though it probably wouldn’t hurt,” Campbell says.
But, what the study does do is point one more finger at vitamin D as a possible accomplice in the rates of aggressive prostate cancers among younger African American men.
Getting here hasn’t been easy.
What researchers already knew is that African Americans are more prone to vitamin D deficiency than their white counterparts.
Decades ago, laboratory studies suggested that giving men vitamin D in addition to regular cancer medications would make their prostate cancer less aggressive and less deadly. But, when the concept made it to human clinical trials, it didn’t bear out.
Looking back though, Campbell says, “Presumably, the older clinical trials were probably largely conducted on European-American men, who for whatever reason, perhaps weren’t vitamin D deficient, so vitamin D didn’t work in those trials.” Still today, people of color are vastly under-represented in medical research.
In the early 2000s, however, the idea of a role for vitamin D in cancer came up again. Some data suggested that vitamin D-related processes in the body played a part in the more aggressive breast cancers seen in some African American women.
“So this directed attention once again to looking at vitamin D receptor in cancer – only this time in the context of health disparities,” Campbell says.
The recent VITAL Study also pointed to unique actions of vitamin D in African Americans. The trial tracked 25,871 older adults for just over five years. Researchers wanted to see whether a daily vitamin D pill would reduce risk of cancer and heart disease. While the group as a whole didn’t see any reduction in cancer risk after taking vitamin D, the African Americans in the group did. But, once again, there were too few of them in the study to confirm these results with certainty.
Is it possible that a lifetime of vitamin D deficiency in some African Americans accumulates to put the wheels in motion for more aggressive types of prostate cancer to develop?
Campbell, Yates and Sucheston-Campbell will continue to explore this question in their future research. Their next steps are to explore the relationship between sleep patterns and prostate cancer risk. “There’s some data out there about prostate cancer risks and altered circadian rhythm,” he says. “But, it’s pretty subtle, so that’s where we’re going next.”
Close the Gap
Disparities in treatment and survival rates for Black cancer patients are a grim fact of life in the U.S. However, over the past two years, SurvivorNet has focused on raising awareness around this persistent racial gap.
The “Close the Gap” initiative is working to improve survival rates for all people diagnosed with cancer – regardless of race. We are pleased to have NYU Langone and The Perlmutter Cancer Center as partners in this effort, as the fight for equality carries on.