Background: Food fortification could be an effective method of increasing vitamin D intakes and preventing deficiency with minimal risk of excessive dosing.
Objective: Secular trends in vitamin D intakes were examined over a 10-y period.
Methods: We compared vitamin D intakes among 18- to 64-y-old adults from the base diet, fortified foods, and supplements in 2 nationally representative dietary surveys in 1999 and 2009 implemented using the same methodology.
Results: There was a slight increase in the median (IQR) intake of vitamin D from 2.9 (3.2) to 3.5 (3.7) mu g/d (mean +/- SD, 4.3 +/- 4.0 to 5.0 +/- 6.4 mu g). The median (IQR) intake from the base diet was 2.3 (1.6) mu g/d in 1999 and 2.1 (1.8) mu g/d in 2009. In vitamin D supplement users, median (IQR) intakes were 7.6 (6.7) and 8.7 (7.2) mu g/d and the prevalence of inadequacy decreased from 67% to 57% in 2009. Although the consumption of vitamin D-containing supplements was similar in the 2 surveys (17% and 16%), the use of calcium-vitamin D supplements increased from 3% to 10% among women aged 50-64 y. The prevalence of fortified food consumption was also similar at 60%, and median (IQR) vitamin D intakes in consumers were 2.9 (2.2) and 3.7 (2.9) mu g/d in 1999 and 2009, respectively. Mathematical modeling of food fortification using modified vitamin D composition data showed that there is potential to increase vitamin D intakes at the lower end of the distribution, without increasing the risk of exceeding the Tolerable Upper Intake Level.
Conclusions: We report small increases in vitamin D intakes among Irish adults over a decade of focus on vitamin D and in the context of a voluntary fortification policy. Strategic management of vitamin D in the food supply is required to yield measurable benefits.