There is limited data on the effect of UV light exposure versus orally ingested vitamin D(3) on vitamin D metabolism and health. A 4-week study with 16 pigs (as a model for human physiology) was conducted. The pigs were either supplemented with 20 µg/d vitamin D(3) or exposed to UV light for 19 min/d to standardise plasma 25-hydroxyvitamin D(3) levels. Important differences were higher levels of stored vitamin D(3) in skin and subcutaneous fat, higher plasma concentrations …