A Review of Vitamin D and Its Precursors in Plants and Their Translation to Active Metabolites in Meat

Vitamin D plays crucial roles in calcium absorption, bone metabolism, and immune, neurological and cardiovascular-related functions. In plants, it plays an important role in the form of D-2 (ergocalciferol). Intake of vitamin D and its precursors by livestock varies with the specific forage crop, season, presence of fungal infestation and geographic location. Oral supplementation with vitamin D-3 is highly effective at raising plasma and tissue levels of vitamin D and its metabolites in livestock. The vitamin D-3 content varies in different cuts of meat, with higher levels typically correlated with increased fat content, although the same does not hold true for 25(OH)D-3. The highest vitamin D-3 content in meat is typically found in pork (mean content of 2.5 mu g/kg) and chicken (mean of 2.4 mu g/kg), followed by beef (mean of 2.2 mu g/kg), with lamb containing the least (mean of 1.1 mu g/kg). Storage and processing generally have minimal impact on the content of vitamin D or its metabolites in meat, aside from an increase on an as-is basis resulting from moisture loss. Due to their widespread availability and consumption, meat products appear to be a significant source of vitamin D and its hydroxylated forms for much of the global population.