Vitamin D: Recognised for its Essential Role in Bone Health and Calcium Regulation

*By Dr. Devan

Vitamin D, often called the “sunshine vitamin,” has long been recognized for its essential role in bone health and calcium regulation. However, modern research has expanded our understanding of this remarkable nutrient, revealing its profound influence on immunity, inflammation, and cell biology. Among its most compelling roles is its protective effect against cancer.

The Biology of Vitamin D

Vitamin D is synthesized in the skin when exposed to sunlight, specifically ultraviolet B (UVB) rays. It can also be obtained through dietary sources such as fatty fish, fortified dairy, and supplements. Once in the body, it undergoes conversion to its active form, calcitriol (1,25-dihydroxyvitamin D), which acts as a hormone.

Calcitriol binds to vitamin D receptors (VDRs) present in nearly every tissue of the body, regulating the expression of hundreds of genes. This gene modulation extends far beyond calcium balance — it touches upon immune regulation, cell growth, and differentiation.

How Vitamin D Protects Against Cancer

Regulation of Cell Growth and Apoptosis

Cancer begins when normal cells escape the rules of controlled growth. Vitamin D restores order by promoting apoptosis (programmed cell death) in abnormal cells and by slowing uncontrolled cell proliferation. This reduces the likelihood of mutations accumulating into malignancy.

Inhibition of Angiogenesis

For tumors to grow, they must develop their own blood supply — a process called angiogenesis. Vitamin D suppresses this process, effectively “starving” potential tumors before they can spread.

Strengthening Immune Surveillance

Vitamin D enhances the activity of immune cells such as T-lymphocytes and natural killer cells. These cells act as the body’s sentinels, identifying and destroying abnormal or precancerous cells before they become dangerous.

Reduction of Chronic Inflammation

Chronic inflammation is a well-established risk factor for many cancers, including colon, liver, and pancreatic cancer. Vitamin D dampens inflammatory pathways, lowering the background risk environment in which cancers thrive.

Genetic and Epigenetic Regulation

By interacting with VDRs, vitamin D influences genes responsible for DNA repair and stability. This protective mechanism ensures that genetic errors are corrected promptly, reducing the risk of malignant transformation.

Evidence from Research

Colorectal Cancer: Numerous studies have shown that individuals with higher vitamin D levels have a significantly lower risk of developing colorectal cancer. Supplementation has been linked to improved survival rates in diagnosed patients.

Breast Cancer: Women with adequate vitamin D status have been found to have lower risks of breast cancer, especially postmenopausal women.

Prostate Cancer: The evidence is mixed, but some studies suggest that sufficient vitamin D reduces aggressive prostate cancer risk.

Pancreatic and Lung Cancer: Lower vitamin D levels are consistently observed in patients, though causation is still being explored.

While not a cure, vitamin D is increasingly recognized as a powerful preventive factor and a potential adjunct in cancer management.

Vitamin D Deficiency and Cancer Risk

Vitamin D deficiency is widespread, affecting nearly 1 billion people globally. Modern indoor lifestyles, sunscreen use, and geographic factors all contribute to insufficient sun exposure. Alarmingly, the same populations most deficient in vitamin D often show higher incidences of certain cancers.

Safe Levels and Supplementation

Experts generally recommend maintaining blood levels of 25-hydroxyvitamin D between 30–50 ng/mL for optimal health and cancer protection. While sun exposure is the most natural source, supplementation of 1000–2000 IU daily is often necessary, particularly in regions with limited sunlight.

Conclusion

Vitamin D is more than a vitamin; it is a guardian of cellular integrity, a modulator of immunity, and a quiet but powerful protector against cancer. Ensuring adequate levels is not merely a lifestyle choice but a preventive strategy of profound importance.

In the fight against cancer, prevention is as crucial as treatment. By honoring the gift of sunlight, consuming nourishing foods, and supplementing when needed, we can harness the protective shield of vitamin D — a natural ally in safeguarding human health.

*Dr Devan is a Mangaluru-based ENT specialist and author.