The Vitamin D Project

The Institute of Medicine (IOM) recently increased the dietary reference intakes of vitamin D for all of the age groups. In IOM’s 2011 report, the recommended vitamin D nutrient intake tripled for most of the population: from 200 IU up to 600 IU daily, and the Tolerable Upper Level (UL) is 4000 IU daily. Looking at the dietary vitamin D intakes among Canadians between ages 18 and 70 from the 2004 Canadian Community Health Survey Cycle 2.2 (CCHS 2.2); Canadian intakes of vitamin D averaged to 200-300 IU vitamin D per day in foods. It becomes clear that extension of vitamin D fortification to additional foods can be effective and it is an appropriate strategy for improving vitamin D intakes in the general population.

It has already been demonstrated that we can get vitamin D into cheddar cheese and that it is as biologically available as vitamin D delivered in a liquid supplement. This new project aims to optimize the fortification process and deliver all of the vitamin D into cheese, and to measure its bioavailability in cooked meals and related health benefits. The primary aim of this study is to determine whether the bioavailability of vitamin D in cheese is affected by cooking. The secondary aim is to address the question of whether vitamin D fortified food can improve a general measure of health, as measured by the SF-36 questionnaire. In collaboration with George Brown College, study participants will consume individual pizzas prepared using Vitamin D fortified mozzarella cheese. Approximately 120 adults between ages 18-70 will be recruited at George Brown College (GBC). We will present talks on the role of vitamin D in food and nutrition, and invite participation.

We will also invite participants by posting invitations on bulletin boards at approved locations at GBC. Each subject will be randomly assigned to 1 of 2 groups so that subjects and researchers are blinded to the group assignment. Each week, individual pizzas will be prepared using a 30-gram cheese sample that has been numerically coded for each subject. One group will consume the following each week for 8 weeks: 1) 60 subjects receive a pizza meal baked with 30-gram fortified cheese at 200 IU vitamin D 2) 60 subjects receive a pizza meal baked with 30-gram fortified cheese at 28,000 IU vitamin D A conventional t-test, comparing the change in serum 25-hydroxyvitamin D in the group of subjects receiving vitamin D in cheese at baseline to post supplementation (8 weeks). The SF36v2 scores will be generated by the Qualitymetric’s outcome consulting division. The results of this experiment will provide scientific support for commercialization of vitamin D fortified cheese in Canada. It will validate the usefulness of vitamin D fortified cheese in cooked meals in increasing serum 25-hydroxyvitamin D levels and improving the well being scores in adult subjects. This may be of benefit to the public, to the dairy industry, and implement vitamin D fortification practices to cheese.