Our test measures levels of the biologically-active component of vitamin B12 - thought to be the best early indicator of vitamin B12 deficiency. Around 70% of the vitamin B12 in your blood is inactive, which means it isn't available for your body to use. The human body can store several years' worth of vitamin B12. However, if you have pernicious anaemia, are vegetarian or vegan, or have recently had gastric bypass surgery - you are at a greater risk of deficiency.
Even if you get enough vitamin B12 in your diet, if your body doesn't absorb it properly, you can become deficient in vitamin B12. People who may have absorption problems include the elderly, people with low stomach acid (including those taking PPIs), people who drink excessive alcohol, and people with inflammatory bowel conditions like Crohn's or Coeliac disease.