One review recommended that those with vitamin B12 deficiency take 1 mg of vitamin B12 daily for a month, followed by a maintenance dose of 125–250 mcg per day ( 21). Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. Advertising & Sponsorship

Although not commonly recommended as part of a healthy diet, fortified cereals can be a good source of B vitamins, especially B12. Food fortification is the process of adding nutrients that are not originally in the food. Therefore, the Recommended Dietary Allowance (RDA) for vitamin B12 during pregnancy is 2.6 mcg. This level can be met through diet alone or with a prenatal vitamin ( 1). Breastfeeding people Vitamin B12 has many roles in your body. It supports the normal function of your nerve cells and is needed for red blood cell formation and DNA synthesis ( 1). Most milk and dairy products such as cheese, yoghurt and cream contain relatively high levels of vitamin B12. Recommended vitamin B12 dosages Taking 100mg or less a day of thiamin supplements is unlikely to cause any harm. Riboflavin (vitamin B2)swelling (inflammation) in your intestines because of conditions like Crohn’s disease and coeliac disease In a large review, vitamin B12 supplements had no effect on depressive symptoms in the short term but may help prevent relapse over the long term ( 23). Taking high doses of nicotinic acid supplements can cause skin flushes. Taking high doses for a long time could lead to liver damage. For females with a vitamin B12 deficiency and levels below 150 mg/dL the risk was five times higher, compared to those with levels above 400 mg/dL ( 7). summary

Vitamin B12: Fact sheet for professionals. Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional. Accessed Jan. 9, 2021. Older people are more susceptible to vitamin B12 deficiency. While relatively few younger adults are deficient in B12, up to 20% of adults over the age of 60 have less than optimal blood levels of this nutrient ( 10, 11).Some people believe that certain plant-based foods are good sources of vitamin B12. These foods include: A 3.5-ounce (100-gram) serving of trout fillet offers about 312% of the DV for vitamin B12 and 1,171 mg of omega-3 fatty acids ( 23). You’ll usually take cyanocobalamin tablets every day to prevent or treat vitamin B12 deficiency. However, you may also need vitamin B12 injections at first to boost your levels. That said, being low in vitamin B12 doesn’t always lead to megaloblastic anemia, and many people may only experience mild symptoms like fatigue ( 11). Vitamin B12, like all B vitamins, is water-soluble, which means the body expels what it does not use. Its main job is to maintain healthy nerve cells, support proper brain function, and assist in the production of DNA and RNA.