2025 Volume 83 Issue 3 Pages 87-120
Although vitamin deficiency is primarily considered to be overcome in Japan, vitamin insufficiency, milder than deficiency, still increases the risk of various diseases. Biomarkers play an important role in the nutritional assessment of vitamins and must be understood based on their roles: status and function. Two reference values must be discriminated: the reference range and cut-off value. This review addresses the basic issues, underlying pathophysiology, associated disease risk, and recent evidences. However, clinical and epidemiological studies are limited in Japan and are therefore urgently required.
Attention must be given to the difference between evidence-based nutrition (EBN) and evidence-based medicine (EBM). In addition, the discrepancy in results between observational and intervention studies is of great importance. Unlike drugs, vitamins are present in the body prior to intervention. Therefore, the intervention effects are significant in deficient subjects, but small in sufficient subjects, and most subjects in the large-scale intervention studies are those with vitamin sufficiency. Overall, more significant intervention effects and higher disease incidence are associated with fewer individuals required.
Nutrient interventions, including vitamins, have a smaller effect than drug treatments. Although nutritional therapy is suitable for primary prevention in patients with low-to-moderate disease risk, the disease incidence is low in such populations, and numerous individuals are required for significant intervention effects. These issues have not been discussed in Japan, and issues such as the evaluation of EBN and observational studies should be addressed.
