Serum 25-hydroxyvitamin D response to vitamin D supplementation using different lipid delivery systems in middle-aged and older adults: a randomised controlled trial.

Food fortification improves vitamin D intakes but is not yet mandated in many countries. Combining vitamin D with different dietary lipids altered vitamin D absorption in in vitro and postprandial studies. This randomised, placebo-controlled trial examined the effect of the lipid composition of a vitamin D-fortified dairy drink on change in 25-hydroxyvitamin D (25(OH)D) concentrations. Sixty-three healthy adults aged 50+ years were randomised to one of the following for 4 weeks: vitamin D-fortified olive oil dairy drink, vitamin D-fortified coconut oil dairy drink, vitamin D supplement or placebo control dairy drink. All vitamin D groups received 20 mu g of vitamin D-3 daily. Serum was collected at baseline and post-intervention to measure 25(OH)D concentrations and biomarkers of metabolic health. Repeated-measures general linear model ANCOVA (RM GLM ANCOVA) compared changes over time. There was a significant time x treatment interaction effect on 25(OH)D concentrations for those classified as vitamin D-insufficient (P < 0.001) and -sufficient at baseline (P = 0.004). 25(OH)D concentrations increased significantly for all insufficient participants receiving vitamin D-3 in any form. However, for vitamin D-sufficient participants at baseline, 25(OH)D concentrations only increased significantly with the coconut oil dairy drink and supplement. There was no effect of vitamin D on biomarkers of metabolic health. Vitamin D fortification of lipid-containing foods may be used in lieu of supplementation when supplement adherence is low or for individuals with dysphagia. These results are important given the recent recommendation to increase vitamin D intakes to 15-20 mu g for older adults in Ireland.

Automated summary

Food fortification of vitamin D improves intake but is not mandatory in many countries. Combining vitamin D with different dietary lipids can affect absorption. This randomized trial investigated the effect of the lipid composition of a vitamin D-fortified dairy drink on 25-hydroxyvitamin D concentrations. The results showed that for individuals classified as vitamin D-insufficient, all forms of vitamin D supplementation increased concentrations significantly. However, for vitamin D-sufficient participants, only the coconut oil dairy drink and supplement had significant increases. There was no effect on metabolic health biomarkers.