Impact of dietary calcium on vitamin D dietary requirements and bio-fortified food solutions for vitamin D deficiency

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Hayes, Aoife
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University College Cork
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Recent re-evaluations of Dietary Reference Intakes/Values (DRI/DRVs) for vitamin D on either side of the Atlantic have established intake requirements at the 97.5th percentile between 10 and 20 µg/d, and between 7.5 and 10 µg/d at the 50th percentile. However, national nutrition surveys indicate that mean habitual intakes of vitamin D in young and adult populations are typically in the range 3-7 µg/d. DRV/DRIs for vitamin D are established on the premise that the needs of all other nutrients are being met, however, the US Dietary Guidelines Committee has again recently identified both vitamin D and calcium as nutrients of public health concern. Furthermore, the US-based Institute of Medicine in their DRI report on calcium and vitamin D highlighted that the relationship between habitual calcium intakes and vitamin D activation and catabolism was a key knowledge gap. Vitamin K nutritional status may also be of concern at a population level. Thus, the main objectives of this PhD thesis were i) to address key knowledge gaps in terms of calcium-vitamin D interactions in the body and how these may influence dietary vitamin D requirements, ii) to devise evidence-based and sustainable food-based solutions (particularly, bio-fortification approaches) for the prevention of vitamin D deficiency, and iii) to estimate the mean daily intake of phylloquinone and its adequacy in Irish adults. This thesis provides key new data which will be of use to various regulatory bodies in their future revisions of DRI/DRVs. In addition, considering the pressing need for creative food-based solutions to bridge the gap between current intakes and these vitamin D recommendations, the present work contributes to our understanding of bio-fortified foods, as one subset of such food-based solutions, and provides the first RCT proof of efficacy for bio-fortified eggs as an exemplar in protecting against low vitamin D status in winter.
25-hydroxyvitamin D , Vitamin D , Food analysis , Calcium , Dietary requirements
Hayes, A. 2016. Impact of dietary calcium on vitamin D dietary requirements and bio-fortified food solutions for vitamin D deficiency. PhD Thesis, University College Cork.