Contribution of Vitamin D 2 and D 3 and Their Respective 25-Hydroxy Metabolites to the Total Vitamin D Content of Beef and Lamb.

Background: Red meat and meat products can contribute meaningfully to the mean daily intake of vitamin D. Beef and lamb can contain vitamin D ₃ and 25-hydroxyvitamin D ₃ [25(OH)D ₃ ] but also potentially vitamin D ₂ and 25-hydroxyvitamin D ₂ [25(OH)D ₂ ], all of which contribute to meat's vitamin D activity.
Objectives: We aimed to measure the vitamin D ₃ , vitamin D ₂ , 25(OH)D ₃ , and 25(OH)D ₂ content of Irish beef and lamb.
Methods: Full striploin steaks (longissimus dorsi) ( n  = 39) from beef cattle slaughtered in winter, spring, summer, and autumn as well as lamb steaks (hind leg) from sheep slaughtered in autumn ( n  = 8) were sourced and homogenized. The contents of all 4 vitamin D-related compounds were analyzed using an LC-tandem MS method in conjunction with the National Institute of Standards and Technology's standard reference material no. 1546a-Meat Homogenate. The total vitamin D activity of meat was defined as: {vitamin D ₃ + [25(OH)D ₃  × 5] + vitamin D ₂ + [25(OH)D ₂  × 5]}.
Results: The median (IQR) total vitamin D activity of striploin beef steak ( n  = 39, irrespective of season) was 0.56 (0.37-0.91) μg/100 g. The content of all 4 vitamin D compounds in beef steak varied significantly ( P  < 0.0001) with season ( n  = 8-11/season group). Median total vitamin D activity of beef steak increased in a stepwise manner ( P  < 0.0001) from winter to the following autumn (increasing from 0.31 to 1.07 μg/100 g). The mean total vitamin D activity of lamb samples ( n  = 8) from autumn was 0.47 μg/100 g.
Conclusions: About one-third of the total vitamin D activity of Irish beef was attributable to its combined vitamin D ₂ and 25(OH)D ₂ content, estimates of which are largely or completely missed in food composition tables. There was significant seasonal variation in all 4 vitamin D compounds as well as in total vitamin D activity, which has implications for vitamin D nutrient claims for beef.
(Copyright © The Author(s) on behalf of the American Society for Nutrition 2020.)