Association of Serum Vitamin B12 and Vitamin D Levels With Colorectal Cancer: A Cross-Sectional Study From Eastern India.

Background Colorectal cancer (CRC) is one of the leading causes of cancer-related mortality worldwide, with increasing incidence in developing countries such as India due to changing dietary habits and sedentary lifestyles. Epigenetic alterations, particularly DNA methylation, play an important role in colorectal carcinogenesis and are influenced by micronutrients involved in one-carbon metabolism, such as vitamin B12. Vitamin D, on the other hand, regulates cell proliferation, apoptosis, differentiation, and immune responses through vitamin D receptor-mediated pathways. However, studies evaluating the association of serum vitamin B12 and vitamin D levels with CRC have shown inconsistent findings, especially in the Indian population. This study aimed to assess the association of serum vitamin B12 and vitamin D levels with newly diagnosed, treatment-naïve CRC patients in a tertiary care center in eastern India. Materials and methods This was a cross-sectional analytical study conducted in the Departments of Biochemistry and Surgical Oncology at Rajendra Institute of Medical Sciences, Ranchi, Jharkhand, India, from January 2024 to February 2025 after obtaining Institutional Ethics Committee approval. A total of 244 participants were enrolled, including 122 newly diagnosed, histopathologically confirmed CRC patients and 122 age- and sex-matched healthy controls. Serum vitamin B12 and 25-hydroxyvitamin D levels were measured using an automated chemiluminescent microparticle immunoassay (CMIA) system. Data were analyzed using the Mann-Whitney U test, chi-square test, and logistic regression analysis, with p < 0.05 considered statistically significant. Results There was no statistically significant difference in age or gender distribution between cases and controls. Serum vitamin B12 levels were significantly higher in CRC patients compared to controls (median 579 pg/mL vs. 367.5 pg/mL; p < 0.001). Around 39.3% of CRC patients had high vitamin B12 levels (>883 pg/mL), compared to 5.7% of controls. Conversely, serum vitamin D levels were significantly lower in CRC patients (median 17.95 ng/mL vs. 21.85 ng/mL; p < 0.001), with 60.7% of cases showing vitamin D deficiency compared to 42.6% of controls. Logistic regression analysis demonstrated a statistically significant positive association between vitamin B12 and CRC (OR = 1.001; p < 0.001) and a significant inverse association between vitamin D and CRC (OR = 0.953; p < 0.001). Conclusion Our study demonstrated significantly elevated serum vitamin B12 levels and significantly reduced vitamin D levels in CRC patients compared to healthy individuals. Vitamin B12 showed a weak positive association, whereas vitamin D demonstrated a significant inverse association with CRC, suggesting a possible protective role of vitamin D in colorectal carcinogenesis. These findings highlight the potential role of these micronutrients as biomarkers in CRC; however, further large-scale longitudinal studies are required to establish causality and clinical applicability.