B vitamins are often called 'energy vitamins', but they do not provide energy. They're more like detachable tool heads for enzymes: without them, the metabolic pathways for carbohydrates, fats, and amino acids can't run.
The 8 members (B1 · B2 · B3 · B5 · B6 · B7 · B9 · B12) + choline (semi-member):
| Vitamin | Active form | Core function |
|---|
| B1 | TPP | sugar → mitochondria (PDC) |
| B2 | FAD/FMN | electron carrier |
| B3 | NAD/NADP | redox double-account |
| B5 | CoA | acyl carrier |
| B6 | PLP | amino acid intersection |
| B7 | Biotin | carboxylation (adds CO₂) |
| B9 | THF/5-MTHF | one-carbon carrier |
| B12 | MeCbl/AdoCbl | methylation + MUT |
Most B vitamins are water-soluble with little storage, but that doesn't mean massive supplementation is required — as long as total energy is adequate and the diet is diverse, deficiency is uncommon.