High-potency and fast-acting energy and nervous system support! Feeling tired or low on energy? Vitamin B-12 can help. Vitamin B-12 is a vitamin that is involved in the synthesis of DNA and RNA, form healthy red blood cells, and turn the food we eat into energy to power our metabolism. Natrol® Vitamin B-12 5000mcg Fast Dissolve delivers high-potency B-12 to boost natural energy levels and support the nervous system. Fast-dissolve is a delivery method that allows vitamin B-12 to quickly dissolve in your mouth and can be swallowed without liquids.