Vitamin B12

The Vitamin B12 test measures the level of cobalamin, an essential nutrient your body needs to make red blood cells, maintain healthy nerve function, and support DNA synthesis.

Unlike many vitamins, B12 is found almost exclusively in animal-based foods like meat, fish, eggs, and dairy, which makes vegetarians and especially vegans particularly vulnerable to deficiency unless they supplement.

B12 also requires a specific stomach protein called intrinsic factor for proper absorption in the gut, so certain digestive conditions, weight-loss surgeries, or long-term use of acid-reducing medications can impair absorption even when dietary intake seems adequate.

Because B12 deficiency can cause irreversible nerve damage if left untreated for too long, timely blood testing and treatment are important whenever deficiency is suspected.