Vitamin B12, also known as Cobalamin, is an essential water-soluble micronutrient.
Almost all vitamin B12 comes from animal foods, such as meat and dairy products. It is naturally abundant in animal foods including meat, poultry, eggs, dairy and shellfish. In general, B12 is not found in vegetarian or vegan food sources, unless these have been fortified. Those on a plant-based diet might therefore benefit from supplementation with B12. For those that consume a balanced diet containing meat, most will receive enough dietary B12 to meet their Estimated Average Requirement (EAR).
However, deficiency is B12 is not solely a plant-based dieting concern, as the absorption of B12 is dependent upon several processes within the gut, including the production of intrinsic factor (IF). Intrinsic factor is produced in the stomach, and conditions like gastritis or gastric surgery can interfere with IF production. Additionally, B12 absorption can be affected by disease of the small bowel, bacterial overgrowth or intestinal diseases such as Crohn's disease which can result in B12 deficiency. Elderly adults have been shown to have a higher incidence of B12 deficiency potentially due to decreased intake of animal products, and/or difficulty in chewing food which can contribute to malabsorption.
Medications can also pose problems. Proton Pump Inhibitors (PPIs) that regulate the secretion of gastric acid production can lead to an impaired release of B12 from food proteins leading to deficiency. Metformin, a drug used to lower glucose levels for diabetics, has also been shown to lower vitamin B12 levels in serum.
For those following a plant-based diet, incorporating fortified foods into the diet is important to help ensure adequate intake levels are reached and for some people, supplementation with vitamin B12 may be an essential part the daily routine to achieve sufficient intake.
Source:
1. Australian Health Survey: Usual Nutrient Intakes, 2011-12 financial year [Internet]. Australian Bureau of Statistics. 2021 [cited 17 May 2021]. Available from: https://www.abs.gov.au/
2. Frontiers in Nutrition: Vitamin B12 Intake from animal foods, biomarkers, and health aspects
https://www.ncbi.nlm.nih.gov/