Vitamin B12 is an essential nutrient required for red blood cell formation, nerve function, and DNA synthesis. Unlike most nutrients, B12 is produced by bacteria rather than plants or animals.

Historically, humans obtained B12 by consuming small amounts of soil on unwashed plant foods or from animals that absorbed or produced B12 in their guts while grazing.

In today’s modern food system, plants are thoroughly washed and most animals are farmed indoors, so B12 is no longer reliably present in the diet naturally. Many farmed animals are supplemented with B12 or cobalt to ensure their products contain this nutrient.

For these reasons, anyone following a plant-based diet—or who rarely or never eats meat—is advised to take a B12 supplement.

Additionally, metformin, a common medication for type 2 diabetes, can reduce B12 levels over time. People taking metformin should have their B12 checked regularly and discuss an appropriate supplement dose with a healthcare professional.

Click here for more information on B12 supplementation.