Vitamins don’t directly “create” energy; they support metabolic pathways, so deficiencies can feel like severe low energy. B vitamins—especially B12, B6, and folate—matter for blood formation and nervous system function; deficiency can cause marked fatigue. Iron (not a vitamin) is a major factor because it enables oxygen transport. Vitamin D may influence musculoskeletal comfort and well-being. The best approach is symptom- and lab-guided correction rather than high-dose guesswork.