Do eggs have vitamin d
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Vitamin D Content in Eggs: A Comprehensive Overview
Introduction to Vitamin D in Eggs
Eggs are one of the few natural food sources rich in vitamin D, containing both cholecalciferol (vitamin D3) and 25-hydroxyvitamin D3 (25(OH)D3). The latter is particularly potent, being five times more effective at increasing serum 25(OH)D concentrations, the major circulating form of vitamin D1 3 4.
Impact of Egg Consumption on Vitamin D Levels
Dose-Response Effect of Egg Consumption
A study conducted on young Australian adults demonstrated that consuming 7 eggs per week for 12 weeks effectively attenuated the wintertime decline in circulating vitamin D concentrations. The study found that while the control group experienced a significant decrease in serum 25(OH)D levels, those consuming 7 or 12 eggs per week maintained their vitamin D levels1.
Vitamin D-Enhanced Eggs
Another randomized controlled trial investigated the effect of consuming vitamin D-enhanced eggs on winter serum 25(OH)D levels in adults aged 45-70 years. The study found that participants who consumed 7 vitamin D3-enhanced or 25(OH)D3-enhanced eggs per week had significantly higher post-intervention serum 25(OH)D levels compared to the control group, which did not consume enhanced eggs2.
Methods to Enhance Vitamin D Content in Eggs
Dietary Fortification
Feeding hens with higher levels of vitamin D3 and 25(OH)D3 can significantly increase the vitamin D content in egg yolks. Studies have shown that eggs can be fortified to contain between 100 and 500 IU of vitamin D, meeting the recommended daily requirements for children and adults3 4 7.
UVB Exposure
Exposing hens or liquid egg products to UVB light is another effective method to enhance the vitamin D content in eggs. Free-range farming, where hens have access to sunlight, has been shown to produce eggs with three to four times higher vitamin D3 content compared to indoor farming6 9.
Stability of Vitamin D in Eggs
Storage and Cooking Effects
The stability of vitamin D metabolites in eggs is influenced by storage conditions and cooking methods. Studies indicate that 25(OH)D3 retains 72-111% of its concentration after various cooking methods, while vitamin D3 retains 50-152%. This suggests that 25(OH)D3-enriched eggs remain a potent dietary source of vitamin D even after cooking10.
Conclusion
Eggs are a valuable source of vitamin D, particularly when hens are fed vitamin D-enriched diets or exposed to UVB light. Consuming eggs, especially those enhanced with vitamin D, can help maintain adequate vitamin D levels, particularly during winter months. This makes eggs an important component of a diet aimed at preventing vitamin D deficiency.
Sources and full results
Most relevant research papers on this topic
Dose–Response Effect of Consuming Commercially Available Eggs on Wintertime Serum 25-Hydroxyvitamin D Concentrations in Young Australian Adults: a 12-Week Randomized Controlled Trial
Consuming 7 commercially available eggs per week for 12 weeks effectively attenuates wintertime decline in circulating vitamin D concentrations in young Australian adults, with 12 eggs per week providing no additional benefits.
RCT
Very Rigorous JournalVitamin D-enhanced eggs are protective of wintertime serum 25-hydroxyvitamin D in a randomized controlled trial of adults.
Consuming 7 vitamin D-enhanced eggs per week significantly improves winter vitamin D status in adults aged 45-70 years.
RCTVery Rigorous JournalVitamin D fortification of eggs for human health.
Higher levels of vitamin D3 and 25(OH)D3 in egg yolks can meet recommended daily requirements for adults and children without negatively impacting production parameters.
Non-RCT
Animal StudyNaturally enhanced eggs as a source of vitamin D: A review
Naturally enhanced eggs can contribute to increased vitamin D intake by increasing the content through feeding, exposing hens to UVB, and exposing liquid egg products to UVB.
Literature ReviewDietary Whole Egg Consumption Attenuates Body Weight Gain and Is More Effective than Supplemental Cholecalciferol in Maintaining Vitamin D Balance in Type 2 Diabetic Rats.
Whole egg consumption is more effective than supplemental cholecalciferol in maintaining vitamin D balance, reducing weight gain, and improving body composition in type 2 diabetic rats.
RCTAnimal StudyVery Rigorous JournalFree-range farming: a natural alternative to produce vitamin D-enriched eggs.
Free-range farming is an efficient method to produce vitamin D-enriched eggs, with outdoor and indoor/outdoor hens exposed to sunlight resulting in higher vitamin D3 content compared to indoor hens.
RCTAnimal StudyEffect of vitamin D2- and D3-enriched diets on egg vitamin D content, production, and bird condition during an entire production period.
Vitamin D3 supplementation in hens' diets increases egg yolk vitamin D content more effectively than vitamin D2, while both supplements enhance vitamin D3 content in egg yolks without affecting production parameters or hen condition.
Highly CitedThe Vitamin D Content of Certain Egg and Egg Oil Products
Irradiation can increase the vitamin D content of egg and egg oil products, but the vitamin D content of egg yolks remains unchanged.
Effect of production system, supermarket and purchase date on the vitamin D content of eggs at retail.
Free range and organic eggs have higher vitamin D3 concentrations than indoor eggs, and accurate labeling is crucial for consumers to understand variations in vitamin D concentrations in eggs.
Observational Study