Objectives: Tobacco use remains a leading cause of preventable diseases, adversely impacting numerous physiological processes, including vitamin metabolism. Vitamin B12 deficiency, essential for cellular function and DNA synthesis, is particularly concerning in smokers due to their exposure to harmful tobacco constituents. This research examines the association between smoking habits, nutritional health and salivary vitamin B12 levels, with an emphasis on the broader public health implications of smoking-induced nutritional deficiencies. Method: This cross-sectional study involved 240 participants, equally divided into 120 smokers and 120 non-smokers. Salivary samples were collected under standardized conditions and vitamin B12 concentrations were measured using the ELISA technique. A 24-hour dietary recall assessed nutritional adequacy, categorized into four levels: excellent, adequate, barely adequate and not adequate. Statistical analyses were conducted using the Mann-Whitney U test to compare vitamin B12 levels and chi-square tests to evaluate the relationship between smoking and dietary adequacy. Results: Smokers exhibited significantly lower salivary vitamin B12 levels compared to non-smokers, with mean ranks of 107.27 and 133.73, respectively (Mann-Whitney U = 8787.5, p = 0.003). Nutritional scores highlighted that smokers had poorer dietary quality, with a higher prevalence of inadequate diets. A significant association between smoking and nutritional adequacy was identified (chi-square value = 12.790, p = 0.005). These findings suggest smoking negatively impacts both vitamin B12 levels and dietary habits. Conclusion: This study highlights that smokers experience significantly lower salivary vitamin B12 levels and poorer dietary adequacy compared to non-smokers. The findings emphasize the need for targeted nutritional interventions, dietary education and public health strategies tailored to mitigate smoking-induced nutritional deficiencies. Future research should explore the interaction between smoking, other micronutrients and the potential benefits of dietary supplementation for smokers..