Vitamin B12 (cobalamin) is a water-soluble vitamin that your body needs to form red blood cells, support nerve function, and synthesize DNA. Animal foods supply it naturally, so vegetarians and vegans face a higher risk of low intake.
This vitamin fuels energy metabolism and helps keep nerve tissue healthy. People also take it when blood work shows low levels, especially older adults and anyone with absorption trouble tied to conditions like pernicious anemia or gastric bypass.
Tablet, sublingual, spray, and injectable forms are common. Most users take it in the morning, with or without food. Sublingual or methylated versions can help when absorption is a concern.
High doses are generally well tolerated, but anyone with a known deficiency should follow a doctor’s guidance. Some medicines, including metformin and proton pump inhibitors, can interfere with B12.