Vitamin B1 , also known as thiamine, is a water-soluble nutrient your body needs every day. Since your body can’t make it on its own, it must come from food. Once absorbed, thiamine is converted into its active form, thiamine pyrophosphate (TPP), which powers your cells to produce energy. Why Vitamin B1 Matters TPP helps your body turn food into energy, especially carbohydrates, fueling high-energy organs like the brain, heart, and nerves. Without enough thiamine, you may not