Vitamin b12 foods
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Vitamin B12 Foods: Sources and Bioavailability
Animal-Based Vitamin B12 Sources
Meat and Dairy Products
Vitamin B12 is predominantly found in animal-based foods, synthesized exclusively by microorganisms and accumulated in animal tissues. Excellent sources include meat, dairy products, fish, and shellfish. Among these, offal such as liver and kidney contain the highest concentrations of B12, while dairy products have lower quantities . The bioavailability of B12 from animal sources varies, with fish, sheep meat, and chicken meat showing absorption rates of 42%, 56%-89%, and 61%-66%, respectively . However, B12 in eggs is poorly absorbed, with less than 9% bioavailability .
Ruminant Animals
Ruminant animals like cattle and sheep acquire B12 through a symbiotic relationship with bacteria in their stomachs. This makes their meat and milk good sources of B12 for humans . The concentration of B12 in bovine milk remains stable regardless of breed, feed, season, or lactation stage, but it can vary in meat based on the animal's diet and the cut of meat .
Plant-Based Vitamin B12 Sources
Seaweeds and Algae
Certain types of seaweeds, such as dried purple laver (nori), contain substantial amounts of B12, making them suitable for vegetarians 210. However, most edible blue-green algae (cyanobacteria) contain pseudovitamin B12, which is inactive in humans and thus not a reliable source 24.
Mushrooms
Some mushrooms, like white button and shiitake, also contain B12, although the amounts can vary. For instance, white button mushrooms have about 2×10^-3 mcg/20g dry weight, while shiitake mushrooms contain between 0.79 to 1.12 mcg/20g dry weight .
Fermented Foods
Fermented vegetables and fruits can be a viable source of B12. Fermentation processes involving specific microorganisms can enhance the B12 content in plant-based foods, making them a feasible alternative for those on plant-based diets . Soy-based fermented foods like tempeh and tofu have been associated with increased B12 levels and potential cognitive benefits .
Fortified Foods and Supplements
Fortified Breakfast Cereals
For vegans and the elderly, fortified breakfast cereals are a particularly valuable source of B12. These cereals are often enriched with crystalline B12, which is readily absorbed by the body .
B12-Enriched Vegetables
Efforts are being made to produce B12-enriched vegetables through various agricultural techniques. These fortified vegetables could provide an additional source of B12 for those who do not consume animal products .
Conclusion
Vitamin B12 is essential for human health, and its deficiency can lead to serious clinical consequences. While animal-based foods remain the most reliable sources of B12, certain plant-based foods like seaweeds, mushrooms, and fermented products can also contribute to B12 intake. Fortified foods and supplements offer additional options, especially for vegetarians, vegans, and the elderly. Ensuring a varied diet that includes these sources can help meet daily B12 requirements and prevent deficiency.
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