How much b12 in eggs
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Vitamin B12 Content in Eggs
Overview of Vitamin B12 in Eggs
Eggs are a significant source of vitamin B12, an essential nutrient crucial for various bodily functions, including red blood cell formation and neurological health. The vitamin B12 content in eggs can vary based on several factors, including the diet of the laying hens and the form in which the eggs are consumed.
Vitamin B12 Concentration in Egg Yolks
Research indicates that the concentration of vitamin B12 in egg yolks is influenced by the dietary intake of the hens. Hens fed diets with varying levels of vitamin B12 showed corresponding changes in the vitamin B12 content of their eggs. Specifically, egg yolk vitamin B12 concentrations ranged from 1.3 to 2.6 micrograms per 100 grams of yolk, depending on the dietary supplementation levels1. This suggests that the nutritional status of the hens directly impacts the vitamin B12 content in the eggs they produce.
Bioavailability of Vitamin B12 from Eggs
The bioavailability of vitamin B12 from eggs can vary significantly. Studies using labeled vitamin B12 have shown that the absorption rate of vitamin B12 from eggs ranges from 13.2% to 57.7%, with an average of about 30.2%4. The form in which the eggs are consumed also affects absorption; for instance, boiled and fried eggs have higher absorption rates compared to scrambled eggs7. Additionally, the total amount of vitamin B12 consumed inversely affects its bioavailability, with higher doses resulting in lower absorption efficiency5.
Impact of Storage on Vitamin B12 Content
The storage of eggs can lead to a reduction in their vitamin B12 content. Eggs stored for extended periods, such as twelve months, have been shown to lose a significant portion of their vitamin B12 content3. This highlights the importance of consuming fresh eggs to maximize vitamin B12 intake.
Nutritional Contribution of Eggs to Daily Vitamin B12 Requirements
Eggs are a valuable source of vitamin B12, contributing approximately 20% of the average adult's daily requirement per serving4. This makes them an important dietary component for maintaining adequate vitamin B12 levels, especially for individuals who may have limited sources of this nutrient in their diet.
Conclusion
Eggs are a rich source of vitamin B12, with their content influenced by the diet of the laying hens and the form in which the eggs are consumed. While storage can reduce the vitamin B12 content, fresh eggs remain a significant contributor to daily vitamin B12 intake. Understanding these factors can help optimize dietary strategies to ensure adequate vitamin B12 consumption.
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Most relevant research papers on this topic
Vitamin profiles of eggs as indicators of nutritional status in the laying hen: vitamin B12 study.
Egg yolk vitamin B12 concentrations rapidly respond to dietary changes in vitamin B12 levels, indicating the laying hen's vitamin B12 status.
Non-RCT
Animal StudyYolk of the Century Egg (Pidan) Contains a Readily Digestible Form of Free Vitamin B12.
The century egg yolk contains a readily digestible form of free vitamin B12, with 52% formed during gastric digestion, while no free vitamin B12 was detected in the egg white.
The Vitamin B12 Content of Fresh and Stored Shell Eggs
Shell eggs stored for 12 months lose vitamin B12, but not choline or biotin, indicating nutrient loss during cold storage.
14C-Cobalamin Absorption from Endogenously Labeled Chicken Eggs Assessed in Humans Using Accelerator Mass Spectrometry
Chicken eggs enriched with 14C-B12 show high bioavailability and provide 20% of the average adult daily B12 requirement, making them a good source of vitamin B12.
Non-RCT
Very Rigorous JournalPercent bioavailability of vitamin B12 from eggs is inversely proportional to egg total B12 consumed
Eggs are a good source of vitamin B12, but there is a substantial fall in efficiency of absorption within the normal range of intake, reflecting the limit of the physiological absorptive mechanism for B12.
Vitamin Profiles of Eggs as Indicators of Nutritional Status in the Laying Hen: Diet to Egg Transfer and Commercial Flock Survey
Egg vitamin content is correlated with dietary status in chickens, suggesting that vitamin B12 fortification is easily accomplished in commercial flocks.
Vitamin B12 Absorption from Eggs
Boiling and frying eggs improves vitamin B12 absorption, while scrambled whole eggs have less than half the absorption of crystalline 57Co B12.
Non-RCTAnimal StudyA Comparison of Production Performance, Egg Quality, and Cecal Microbiota in Laying Hens Receiving Graded Levels of Vitamin B12
Dietary supplementation with 100 or 400 g/kg of vitamin B12 improves eggshell quality, metabolism, and gut health in laying hens, without significantly affecting production performance.
RCTAnimal Study