Vitamin B12 sources in food
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Animal-Based Food Sources of Vitamin B12
Vitamin B12 is primarily found in animal-derived foods. The richest sources include meat (especially organ meats like liver and kidney), fish, shellfish, dairy products, milk, and eggs. Among these, ruminant meats and their offal contain the highest concentrations, while dairy products and eggs have lower amounts. The bioavailability of B12 from animal foods is generally high, with absorption rates ranging from about 42% in fish to up to 89% in sheep meat. However, B12 in eggs is less well absorbed compared to other animal products. The vitamin is stable in milk but can be reduced in meat by processing and cooking methods. Animal foods remain the most reliable sources for meeting daily B12 requirements, which are about 2–4 micrograms for adults, with higher needs during pregnancy and lactation247910.
Plant-Based and Non-Animal Sources of Vitamin B12
Plants do not naturally produce vitamin B12, as it is synthesized only by certain bacteria and archaea. However, some plant-based foods can contain B12 due to microbial contamination or fermentation. Notably, certain types of edible seaweed, such as dried purple laver (nori), have been found to contain substantial and bioactive amounts of B12, making them a suitable option for vegetarians and vegans. Some mushrooms, like shiitake and white button mushrooms, may also contain small amounts of B12, but the levels are generally low and variable12458.
Fermented Foods as Vitamin B12 Sources
Fermented plant foods can be a source of vitamin B12 due to the action of B12-producing bacteria during fermentation. Examples include fermented soy products like tempeh, certain types of sauerkraut, pickled parsley juice, and some other lactic acid-fermented vegetables. However, the B12 content in these foods can vary widely, and not all fermented products contain significant amounts. Some studies have found that only specific products, such as sea-buckthorn jam and pickled parsley juice, provide enough B12 to help prevent deficiency. The bioavailability and stability of B12 in these foods depend on the fermentation process and storage conditions136.
Fortified Foods and Supplements
For those who avoid animal products, fortified foods are a practical and reliable source of vitamin B12. Common fortified foods include breakfast cereals, plant-based milks, nutritional yeast, and some breads. These products are enriched with crystalline B12, which is well absorbed by the body. Fortification is especially important for vegans, vegetarians, and elderly individuals who are at higher risk of deficiency2589.
Inactive Forms and Bioavailability Concerns
It is important to note that not all B12-like compounds in food are biologically active in humans. For example, most edible blue-green algae (cyanobacteria) contain pseudovitamin B12, which is inactive and cannot prevent deficiency. Cooking and storage can also degrade B12 in foods, reducing its effectiveness. Therefore, relying on unverified plant sources or certain algae supplements is not recommended for meeting B12 needs245.
Conclusion
Animal-based foods remain the most reliable and concentrated sources of vitamin B12. Some plant-based foods, such as certain seaweeds and fermented products, can provide B12, but their content and bioavailability are inconsistent. For individuals who do not consume animal products, fortified foods and supplements are the safest and most effective ways to ensure adequate vitamin B12 intake and prevent deficiency12345678+2 MORE.
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