The nutritional reference consumption for an adult ranges from 2 to 3 µg per day.
Supplement B12 is believed to be risk-free when used orally in volumes that do not extend past the recommended dietary allowance (RDA). There have additionally been studies that showed no adverse effects of servings above the RDA. The RDA for supplement B12 in pregnant females is 2.6 µg per day as well as 2.8 µg during lactation periods. There is inadequate reputable data available about the protection of consuming higher amounts of supplement B12 during pregnancy.
The Vegan World, the Vegetarian Source Group, and the Physicians Committee for Responsible Medicine, with others, suggest that vegans either constantly eat foods fortified by having B12 or take an everyday or weekly B12 supplement. Fortified breakfast cereals are an especially important source of vitamin B12 for vegetarians as well as vegans. In addition, grownups age 51 and earlier are recommended to consume B12 fortified food or supplements to fulfill the RDA, since they are a human population at an increased hazard of deficiency.