Vitamin B12 (Cobalamin) Test

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.

Why B12 deficiency is common in India

Vitamin B12 is found only in animal foods (milk, curd, eggs, meat, fish), so vegetarians and vegans are especially prone to deficiency. Metformin, acid-reducing medicines, gut surgery, autoimmune gastritis and older age also reduce absorption.

Symptoms and risks

Low B12 can cause fatigue, pale skin, tingling and numbness in hands and feet, balance problems, memory difficulty, low mood, mouth ulcers and megaloblastic anaemia. If untreated, nerve damage can become permanent, so early correction matters.

Treatment

Treatment is by B12 injections or high-dose tablets, depending on severity and cause, often followed by long-term maintenance. Your doctor may also check homocysteine or methylmalonic acid when levels are borderline.