Vitamin D metabolites in bovine milk and butter

The main goal of this study was to establish the content of vitamin D3, 25-hydroxyvitamin D3 (25OHD3), vitamin D2, and 25-hydroxyvitamin D2 (25OHD2) in dairy products. Composite samples of milk, cream, and butter (1.5–80% fat), and organic milk (3.5% fat) were analyzed. Each composite sample was sampled over 3 months and the sample comprised 12 units (range 8–14). The average content of vitamin D3 and 25OHD3 were 4.6–196 ng/100 g and 4.2–96 ng/100 g, respectively. For vitamin D2 the values, in milk and butter, were 3.4 and 61 ng/100 g, respectively, and for 25OHD2 they were 3.1 and 58 ng/100 g, respectively. Statistically significant effects of food product (p < 0.0001) and season (p < 0.05) on the content of vitamin D3 and 25OHD3 were shown. Vitamin D3 and 25OHD3 were significantly associated with fat (R = 0.88, p < 0.0001 and R = 0.96, p < 0.0001, respectively). Differences were observed between organically and conventionally produced milk. Implementation of these values into Food Databanks has to be done carefully, due in part to a lack of consensus on the relative bioactivity between the vitamin D active compounds, and partly because quantification of dihydroxy vitamin D compounds were not included in this study.