Fermented vegetables and fruits as vitamin B12 sources: An overview

There is a trend towards the consumption of plant foods, especially from the public that aims to reduce meat consumption. Plant-based food diets may have low source of vitamin B12 as plants do not produce them. A possible alternative to mitigate this is the consumption of fermented vegetables and fruits. Therefore, we aimed to provide an overview of the work being done with fermented vegetables and fruits, and show evidence that it is possible to obtain the necessary daily amount of vitamin B12 for human health and maintenance. Vitamin B12, also known as cobalamin, acts as a cofactor for the enzyme methionine synthase and methylmalonylCoA mutase in eukaryotes. The dietary reference values for adult men and women range between 2 and 4 μg/day; however, the requirement may increase depending on special recommendations. The main causes for vitamin B12 deficiency are autoimmune conditions (e.g., pernicious anaemia), malabsorption, and dietary insufficiency. One of the commonly adopted measures to deal with vitamin deficiency is supplementation. It is also possible to obtain food enriched with vitamin B12 through fermentation. Different plant materials and microorganisms can be used to produce fermented products and enhance traditional products, such as tempeh, to increase vitamin B12 concentration in the final product. The bioaccessibility and bioavailability of vitamin B12 in fermented vegetables and fruits are important factors to be considered, and demand more studies. The intake of soy fermented foods, such as tempeh, tofu, and cheonggukjang was associated with cognitive enhancement and neuroprotective effects. In addition to fermented vegetables and fruits, other non-animal sources of vitamin B12 that deserve great attention are algae and mushrooms. Since fermentation can produce considerable amounts of vitamin B12, fermented vegetables and fruits are feasible alternative sources for the intake of this vitamin.