Vitamin B12 is a dietary supplement that contributes to normal energy metabolism, to the reduction of tiredness and fatigue, to the normal functioning of the nervous system, the immune system and to normal psychological function. The body accumulates between 2 and 5 mg of vitamin B12, half of it in the liver. A deficiency in dietary intake can cause symptoms after years of a deficient diet. This delay depends on age (it is much faster in children) and on individual genetic and physiological factors. No plant food has been proven to provide enough B12 in an assimilable form and this is essential for the nervous system and energy metabolism. Hence the interest of this nutritional supplement for people who follow a vegetarian diet. Dosage: Take 1 capsule daily, preferably on an empty stomach. Precautions: Do not exceed the expressly recommended daily dose.