While there have been a considerable number of studies on the impact of additional vitamin D in the diets of hens on the resulting egg vitamin D content, the effect of consumption of such vitamin D-enhanced eggs on vitamin D status of healthy human subjects has not been tested in a RCT.

The aim of this study was to investigate the effect of consumption of vitamin D3 versus 25-hydroxyvitamin D3 biofortified eggs on winter serum 25(OH)D in adults using a 8-wk randomized controlled trial. This research will provide new data on the potential of vitamin D enriched eggs as a food-based strategy for prevention of vitamin D deficiency.

Inclusion Criteria:

- consenting white men and women aged 45-70 years

Exclusion Criteria:

• consumption of vitamin D-containing supplements throughout the study. planning to take a winter vacation (during the course of the 8-wk intervention) - to a location at which either the altitude or the latitude would be predicted to result in significant cutaneous vitamin D synthesis from solar radiation
• planning to use tanning facilities of any type.
• a severe medical illness,
• allergy to egg products,
• medically advised to limit egg intake in relation to managing hypercholesterolemia,
• hypercalcaemia,
• known intestinal malabsorption syndrome,
• excessive alcohol use,
• the use of medications known to interfere with vitamin D metabolism