The eight B vitamins function collectively as coenzymes in the metabolic pathways that convert carbohydrates, fats, and proteins into ATP, the cellular energy currency. Without adequate B vitamins, these conversion processes are rate-limited at multiple steps. The result is fatigue that is not explained by poor sleep or low activity levels, but by a biochemical bottleneck in the energy production machinery.
The B Vitamins and Their Food Sources
- B1 thiamine: required for pyruvate dehydrogenase, the enzyme that links glycolysis to the Krebs cycle; found in pork, whole grains, legumes, and nuts
- B2 riboflavin: required for FAD and FMN coenzymes in the electron transport chain; found in dairy, eggs, liver, and leafy greens
- B3 niacin: required for NAD and NADP, the cofactors involved in over 400 enzymatic reactions including energy metabolism; found in meat, fish, whole grains, and nuts
- B5 pantothenic acid: required for coenzyme A synthesis; found in liver, eggs, avocado, mushrooms, and legumes
- B6 pyridoxine: required for amino acid metabolism and glycogen phosphorylase; found in poultry, fish, potatoes, and non-citrus fruits
- B9 folate: required for DNA synthesis and methylation; found in dark leafy greens, legumes, avocado, and eggs
- B12 cobalamin: required for methylation and neurological function; found exclusively in animal foods; supplement if vegan
Refined Grains and B Vitamin Depletion
The refining of grains removes the bran and germ, stripping out most of the B vitamins naturally present in the whole grain. Most refined grain products are subsequently fortified with some B vitamins, but not all, and not at the same proportions as in the original grain. A diet based on refined grain products and ultra-processed foods is systematically depleted in B vitamins. Switching to whole grains, legumes, eggs, and animal protein from a refined food diet often produces rapid improvement in energy levels through restoration of B vitamin-dependent metabolic function.