Vitamin B12 supports nerve and blood health and this explains its benefits, potential risks and signs you're getting enough

Vitamin B12 is a water‑soluble vitamin important for making red blood cells and for central nervous system function. People who eat little or no animal products or who have conditions that impair absorption are often checked with blood tests before clinicians recommend oral supplements or injections.

Many people review vitamin B12 when diet, age or medical conditions affect intake or absorption. Vitamin B12 (cobalamin) helps produce red blood cells, supports DNA synthesis and contributes to central nervous system health. Animal products are the main natural dietary sources, and fortified foods or specific plant products can provide B12 in some cases. Medical evaluation, commonly including a blood test, is typically used to determine whether supplements or injections are appropriate. Key points: - Chemical forms: B12 occurs as methylcobalamin, adenosylcobalamin, hydroxocobalamin and synthetic cyanocobalamin; some forms are used in foods and supplements while others (like hydroxocobalamin) are used for injections. - Body functions: B12 supports red blood cell production, DNA synthesis and the myelin that surrounds nerve fibers, and it is involved in biochemical pathways that affect mood and cognition. - Common sources: Meat, fish, shellfish and dairy are primary sources; fortified foods and nutritional yeast are alternative sources for some people following plant-based diets. - Deficiency signs reported: Fatigue, weakness, numbness or tingling in hands or feet, balance or coordination changes, memory or reasoning difficulties, and anemia are associated with low B12 levels. - Groups often evaluated: People who follow strict vegetarian or vegan diets, older adults, and those with gastrointestinal conditions that impair absorption (for example, inflammatory bowel disease) are among groups described as at higher risk. - Treatment considerations: Oral supplements are commonly used when absorption is intact; injections or other medical administration are reported for cases with impaired absorption; injection side effects listed include skin reactions, headache, itching, diarrhea and nausea, and a blood test is commonly performed before treatment decisions. Summary: Vitamin B12 deficiency can lead to anemia and neurological symptoms and is linked in reports to changes in mood or cognition. Clinicians commonly use blood testing to assess levels and then determine whether oral supplements or medically administered doses are advised. Undetermined at this time.