Vitamin D3 content of cows' milk produced in Northern Ireland and its efficacy as a vehicle for vitamin D fortification: a UK model.

Cows' milk is a relatively poor source of vitamin D but figures listed in UK food composition tables may be outdated. Samples of milk were collected for 1-year and vitamin D3 concentrations analysed using HPLC. Milk consumption data were obtained from the National Diet and Nutrition Survey (Years 1-4). A theoretical model applied vitamin D3 fortifications of 1 μg, 1.5 μg and 2 μg/100g to simulate improvements in vitamin D intakes. Mean ± SD vitamin D3 in whole milk was 0.06 ± 0.02 μg/100g. No seasonal differences were apparent. Fortification of cows' milks with 1 μg, 1.5 μg and 2.0 μg/100g, theoretically increased median vitamin D intakes from 2.0 μg/day to 4.2 μg, 5.1 μg and 5.9 μg/day, respectively. Higher vitamin D3 in milk from this study than that currently in food composition tables, suggests further analysis is warranted. This model suggests vitamin D fortification of cows' milk is an effective strategy to help more of the population achieve recently revised RNIs for vitamin D.