Efficacy of fortification of cow's milk as a dietary strategy to increase dietary vitamin D intakes

Abstract

The majority of vitamin D required by humans is derived by ultraviolet (UV) radiation of the 7-dehydrocholesterol in the skin (1) . Vitamin D can also be obtained from the diet, and these sources of vitamin D are of particular importance here in the UK and Ireland as a number of factors, including age, skin pigmentation, clothing and the use of sun protection, and geographical location, negatively influence the skin's ability to synthesise the vitamin (2) . Milk is a source of naturally occurring vitamin D (albeit providing a small contribution); the vitamin D content of whole, semi-skimmed and skimmed milk is currently listed as 0.03 μg, 0.01 μg and trace per 100 g, respectively (1) . Numerous studies have reported the effectiveness of dairy fortification as a strategy to increase dietary vitamin D intakes at the population level (3,4) . The aim of this study was to use population level dietary data to simulate how fortified cow's milk could contribute to total dietary vitamin D intake using a dietary modelling approach.Data from the National Diet and Nutrition Survey (NDNS) rolling programme (2008)(2009)(2010)(2011) were obtained from the UK Data Service (5) . A total of 12,239 recorded diary days (n3,073) were available for analysis. The vitamin D content of whole, semi-skimmed, skimmed and 1% fat milk was then manipulated to apply three incremental levels of fortification (1 μg, 1.5 μg and 2 μg per 100 ml), and the effect on total vitamin D intake was investigated in all milk consumers.A total of 82.5% diary days reported an intake of cow's milk, with intakes of consumption ranging from 2-1,764 ml with a mean intake of 202 (SD 180) ml/d. While semi-skimmed milk proved the most popular type of milk among consumers (51% of diary days), the mean volume of whole milk consumed was higher, compared to that of semi-skimmed milk (249.7(SD 207) vs.187(SD 162.1 ml/d; P < 0.001). As a result, the simulated fortification of whole milk showed the greatest increase in total vitamin D intake.Results show that fortification of UK cow's milk with vitamin D, at concentrations similar to that applied in the US/Canada (approximately 1 μg/100 ml), would significantly increase consumer's vitamin D intake. Such fortification would therefore be an effective strategy to increase vitamin D intakes, and subsequently improve the vitamin D status at the population level. While this study has focused solely on the effect of vitamin D fortification of cow's milk, more research is needed to investigate the impact of such fortification on the vitamin D content of other dairy products and their contributions to consumer's dietary vitamin D intakes.

Dietary strategies for achieving adequate vitamin D and iron intakes in young children in Ireland

“…Both of these strategies would increase mean intakes of vitamin D to >10 lg day À1 at all ages at the same time reducing the prevalence of inadequate intakes to <25% for 1-and 2-year-old children and <40% for 3-and 4-year-old children. Our findings are in agreement with other studies in young children across the world that have shown that fortifying CM, providing vitamin D supplements or replacing CM with GUM would be effective strategies for increasing vitamin D intakes and status and improving the prevalence of inadequate intakes (16,17,(22)(23)(24)38,50) . Similar dietary modelling approaches using data from the National Diet and Nutrition Survey in the UK have shown that fortifying CM (50) and replacing CM with young child formula (38) would be effective strategies for increasing intakes and improve status of vitamin D at a population level.…”

“…Our findings are in agreement with other studies in young children across the world that have shown that fortifying CM, providing vitamin D supplements or replacing CM with GUM would be effective strategies for increasing vitamin D intakes and status and improving the prevalence of inadequate intakes (16,17,(22)(23)(24)38,50) . Similar dietary modelling approaches using data from the National Diet and Nutrition Survey in the UK have shown that fortifying CM (50) and replacing CM with young child formula (38) would be effective strategies for increasing intakes and improve status of vitamin D at a population level. The recent Kimi trial in Germany also found that the daily consumption of vitamin D fortified GUM in children aged 2-6 years prevented the decrease in serum 25(OH)D concentrations typically noted in the winter and could be an effective measure for improving vitamin D status in a young population (16) .…”

“…The effect of fortification of CM was modelled at three levels of vitamin D: (i) 1 μg/100 mL; (ii) 1.5 μg/100 mL; and (iii) 2 μg/100 mL. The levels of CM fortification were based on published scenarios from other studies and also the levels of vitamin D in fortified milks currently available on the Irish and other European Union (EU) markets. Within the database, all commercially available CM and beverages made up with CM (including milkshakes, hot chocolate recipes etc.)…”