Vitamin d content in eggs
Pro Research Analysisby 
Searched over 200M research papers
Vitamin D Forms in Eggs: Vitamin D3 and 25-Hydroxyvitamin D3
Eggs naturally contain two important forms of vitamin D: vitamin D3 (cholecalciferol) and 25-hydroxyvitamin D3 (25(OH)D3). The 25(OH)D3 form is especially valuable because it has about five times the biological activity of vitamin D3, making eggs a potent source of vitamin D for human nutrition 138.
Natural Vitamin D Content in Eggs
The vitamin D content in eggs can vary widely. Standard commercial eggs typically contain about 4–5 µg/100 g of vitamin D3 and 1–1.3 µg/100 g of 25(OH)D3 in the yolk . The total vitamin D activity in non-enriched eggs is generally lower than in eggs that have been specifically fortified or enhanced .
Factors Affecting Vitamin D Levels in Eggs
Hen Diet and Sunlight Exposure
The amount of vitamin D in eggs is strongly influenced by the hen’s diet and exposure to sunlight or ultraviolet B (UVB) light. Hens fed higher levels of vitamin D3 or 25(OH)D3 produce eggs with significantly increased vitamin D content, with some studies showing eggs can contain between 100 and 500 IU of vitamin D depending on the supplementation level 134. Exposing hens to UVB light, either naturally (free-range, organic systems) or artificially, also boosts the vitamin D content in eggs, with free-range and organic eggs generally having higher vitamin D3 levels than eggs from indoor systems 239.
Production System and Seasonal Variation
Eggs from free-range and organic systems have higher vitamin D3 concentrations (about 57 µg/kg) compared to indoor eggs (about 40 µg/kg), likely due to increased sunlight exposure for the hens. There are also seasonal variations, with higher 25(OH)D3 concentrations observed in certain months, such as July and September .
Fortification and Processing
Eggs can be further enriched with vitamin D by adjusting the hen’s feed or by exposing liquid egg products to UVB light. Feeding hens with vitamin D3 is more effective than UVB exposure for increasing egg vitamin D content, but regulatory limits on feed vitamin D levels can restrict the maximum achievable content . Both dried and frozen processed eggs retain similar vitamin D levels as fresh eggs, making them reliable sources in food manufacturing .
Stability of Vitamin D During Storage and Cooking
Vitamin D in eggs, especially 25(OH)D3, remains relatively stable during storage and common cooking methods such as boiling, frying, scrambling, poaching, and microwaving. The retention of vitamin D3 and 25(OH)D3 after cooking ranges from 50% to over 100%, depending on the method, and enriched eggs maintain higher vitamin D activity compared to standard eggs .
Impact on Human Vitamin D Intake
Consuming vitamin D-enriched eggs can help maintain or improve vitamin D status in humans, especially during winter months when sunlight exposure is limited. Regular consumption of seven vitamin D-enhanced eggs per week has been shown to prevent the typical winter decline in serum 25(OH)D levels in adults . Naturally or artificially enhanced eggs can thus play a significant role in addressing vitamin D insufficiency in the population 1310.
Conclusion
Eggs are a valuable natural source of vitamin D, containing both vitamin D3 and the more potent 25(OH)D3. The vitamin D content in eggs can be significantly increased through hen diet, sunlight or UVB exposure, and fortification strategies. These enhancements do not negatively affect egg quality or production. Consuming vitamin D-enriched eggs is an effective way to boost dietary vitamin D intake and support overall health, especially in populations at risk of deficiency.
Sources and full results
Most relevant research papers on this topic