High vitamin b12 foods
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High Vitamin B12 Foods: Sources and Bioavailability
Animal-Based Foods Rich in Vitamin B12
Meat and Dairy Products
Animal-based foods are the primary sources of vitamin B12, which is synthesized exclusively by microorganisms and then accumulated in animal tissues. Among these, ruminant-derived foods such as meat and dairy products are particularly rich in vitamin B12. Offal, such as liver and kidney, contains the highest concentrations of this essential nutrient, while dairy products have lower but still significant amounts 37. The bioavailability of vitamin B12 from these sources varies, with fish, sheep meat, and chicken meat showing absorption rates of 42%, 56%-89%, and 61%-66%, respectively .
Fish and Shellfish
Fish and shellfish are also excellent sources of vitamin B12. However, it is important to note that certain types of shellfish may contain inactive forms of the vitamin, such as pseudovitamin B12, which are not bioactive in humans . Despite this, the bioavailability of vitamin B12 from fish remains high, making it a valuable dietary source .
Eggs
Eggs contain vitamin B12, but the absorption rate is relatively low compared to other animal products, with less than 9% of the vitamin being absorbed . Therefore, while eggs can contribute to vitamin B12 intake, they are not the most efficient source.
Plant-Based Foods Containing Vitamin B12
Seaweeds and Algae
Certain types of seaweeds, such as dried purple laver (nori), are notable plant-based sources of vitamin B12. Nori contains substantial amounts of the vitamin and is considered the most suitable source for vegetarians 45. However, most edible blue-green algae (cyanobacteria) contain pseudovitamin B12, which is inactive in humans and thus not a reliable source 15.
Mushrooms
Some mushrooms, including white button and shiitake, contain measurable amounts of vitamin B12. The content varies, but these mushrooms can contribute to the daily intake of the vitamin, especially in vegetarian diets .
Fortified Foods
Fortified foods, such as breakfast cereals and soy products, are valuable sources of vitamin B12 for vegetarians and vegans. These foods are often enriched with crystalline vitamin B12, which is bioactive and can help meet daily nutritional requirements .
Factors Affecting Vitamin B12 Bioavailability
Cooking and Storage
The bioavailability of vitamin B12 can be affected by cooking and storage. Thermal treatment and prolonged storage can degrade the vitamin, reducing its biological activity 13. Therefore, it is essential to consider these factors when preparing and storing vitamin B12-rich foods.
Intrinsic Factor-Mediated Absorption
The human gastrointestinal system has evolved to selectively absorb active forms of vitamin B12 through an intrinsic factor-mediated mechanism. This system can become saturated at high intake levels, which means that the bioavailability of the vitamin decreases with increasing intake per meal 15.
Conclusion
Vitamin B12 is an essential nutrient primarily obtained from animal-based foods such as meat, dairy, fish, and shellfish. While plant-based sources like seaweeds and mushrooms can contribute to vitamin B12 intake, they are less reliable due to the presence of inactive forms. Fortified foods offer a valuable alternative for vegetarians and vegans. Understanding the factors that affect the bioavailability of vitamin B12, such as cooking, storage, and absorption mechanisms, is crucial for optimizing dietary intake and preventing deficiencies.
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