- Vitamin D is essential for bone health but may also carry other health benefits.
- Experts are seeking to understand the anticancer impact of vitamin D and why these effects may occur.
- A recent literature review highlighted how an active form of vitamin D may help prevent colorectal cancer and improve survival in people with colorectal cancer.
The impact of
A recent literature review of 50 studies and over 1 million participants explored the actions of vitamin D and its relationship to colorectal cancer.
The results suggest that vitamin D may help decrease the risk of colorectal cancer and improve survival for people with colorectal cancer.
The review also explores some of the mechanisms involved, components like proper intake levels, and areas for future research.
The findings were published in Nutrients.
This review notes that worldwide, colorectal cancer is the third most common type of cancer for women and the second most common cancer type for men.
The authors of this review examined vitamin D’s anti-cancer properties, focusing on colorectal cancer, and discussed vitamin D’s physiological actions. They did a comprehensive literature search on three databases. Their analysis included 50 cohort studies and data from over 1.3 million participants.
Researchers explain that vitamin D helps the immune system, such as by helping to decrease inflammation. It also has specific anti-cancer effects, such as supporting programmed cell death and stopping uncontrolled cell growth.
Vitamin D may help prevent colorectal cancer, and vitamin D deficiency may increase the risk of colorectal cancer.
Levels of serum vitamin D may be of particular importance. They cite studies that found that higher levels of serum vitamin D were related to better survival from colorectal cancer. Higher vitamin D could also limit colorectal cancer recurrence. The authors suggest that the evidence supports that higher vitamin D improves post-treatment survival and decreases mortality from colorectal cancer.
Vitamin D via diet vs. supplements
Dietary vitamin D intake also appeared to have beneficial effects on colorectal cancer. Several studies support that higher vitamin D consumption reduces the risk of colorectal cancer. In particular, one meta-analysis found that people with the highest intake of dietary vitamin D had a 25% decreased risk for colorectal cancer.
Supplementation with vitamin D may also decrease the risk of colorectal cancer and improve survival. One study in metastatic colorectal cancer participants also found that receiving vitamin D supplementation led to prolonged progression-free survival. Vitamin D intake might also decrease the risk of adenomas and polyps.
However, other studies did not find a significant relationship between vitamin D levels and the incidence of colorectal cancer. Some did not find that dietary vitamin D consumption had a significant association with colon cancer. Others found that vitamin D supplementation did not appear to decrease colorectal cancer risk in women.
Another study suggested that people’s body mass index or nutritional status could play a role in vitamin D’s effects since the study had different outcomes based on weight and BMI. Another found that vitamin D supplementation may not improve relapse-free survival in gastrointestinal cancer.
Still, another found that vitamin D supplementation did not significantly affect progression-free survival or overall survival in participants who had metastatic colorectal cancer. Finally, some studies found that vitamin D supplementation did not significantly decrease colorectal adenomas or serrated polyps risk.
Researchers further discuss several ways vitamin D exerts its anti-cancer properties in colorectal cancer.
Vitamin D, in its active form, is called calcitriol. Calcitriol helps decrease the inflammation that occurs with colorectal cancer and stops the formation of new blood vessels that can supply blood to cancer. It helps induce cell death and stop cancer cell growth.
Finally, it also helps regulate a pathway called the Wnt/β-Catenin pathway, ultimately helping decrease tumor invasiveness and stabilize cell-cell adhesion.
Preclinical studies also suggest that calcitriol helps with cellular differentiation, regulates critical genes, and affects the microenvironment of tumors.
The authors further note that supplementing with vitamin D appears to help improve the gut microbiota and the intestinal barrier and decrease inflammation. These components may all help prevent colorectal cancer.
Researchers highlight that vitamin D also influences the immune system’s function and helps decrease inflammation. It also suppresses certain T-helper cells that contribute to the development of colorectal cancer and helps to stop the proliferation of cancerous cells.
The review discusses other mechanisms that may mediate vitamin D’s protective components, such as its interactions with specific proteins.
The authors also suggest that vitamin D may have synergistic effects, helping to improve the work of other cancer treatments. It might also have particular benefits when combined with other nutrients of a healthy diet.
Overall, the review highlights the potentially substantial benefits of vitamin D.
Wael Harb, MD, a board-certified hematologist and medical oncologist at MemorialCare Cancer Institute at Orange Coast and Saddleback Medical Centers in Orange County, CA, who was not involved in the study, noted the following to Medical News Today:
“For patients with [colorectal cancer], ensuring adequate vitamin D levels may help support immune surveillance and potentially improve outcomes when used alongside standard therapies. Importantly, this review highlights the need for personalized approaches, as individual vitamin D requirements can vary based on genetics, baseline levels, and comorbidities.”
“If future prospective trials confirm these findings, vitamin D screening and supplementation could become a routine part of colorectal cancer prevention strategies — particularly in high-risk populations or regions with widespread deficiency.”
— Wael Harb, MD
This review also discusses several aspects of vitamin D. Vitamin D deficiency is a concern, and multiple factors can contribute. For example, during winter, people have less exposure to the sun, and people in lower-income countries may have limited access to food and supplement sources of vitamin D.
The review further describes vitamin D’s other biological effects. The review cites evidence that vitamin D plays a role in calcium and phosphorus metabolism, immune function, nerve cell communication support, cardiovascular health, decreasing risk for respiratory infections, maintaining thyroid hormone levels, blood sugar regulation, and even aging mitigation.
This review notes that people can consume dietary sources of vitamin D, consume a diet with high calcium and fiber, exercise, manage weight, and get enough sun exposure to help decrease the risk of colorectal cancer. Supplementation might also be helpful for people who are at risk of low vitamin D.
The review notes that around 2,000 IU of vitamin D a day “is the optimal minimum dose for adults of normal weight.” They also recommend screening people at risk for deficiency and for doctors to discuss the benefits of vitamin D with their patients.
However, it is also important to note that
This review does have limitations. First, the researchers acknowledge that the way vitamin D actually affects colorectal cancer treatment and prevention is not totally clear.
They note that there aren’t many large-scale, randomized clinical trials yet. This could be a helpful component of future research. Future research can also help determine the best dosing and form of vitamin D supplements to have the maximum effect on cancer outcomes. It will be helpful to explore components like how people’s genetics, lifestyle choices, and use of other treatments play a role in vitamin D’s effects on cancer.
Reviewers’ choices of databases and inclusion criteria could have affected the results and their applicability. For example, the research only looked at studies with adults, so it’s unclear how the results might apply to children. All the included studies had limitations, so gathering more data will remain critical.
Finally, it’s important to take this review in the context of other findings about vitamin D and other components that protect against colorectal cancer risk.
Woi Kim, MD, a colorectal surgeon with Memorial Hermann & UTHealth Houston, who was also not involved in the study, said:
“The experimental lab data and analysis by the many cited studies certainly support a convincing argument for their theory of the role of vitamin D in colorectal cancer prevention and treatment outcomes. However, this theory requires testing to demonstrate meaningful effects for us clinically.”
