... 51–70 years, 10 µg (400 IU)71+ years, 15 µg (600 IU)Natural sourcesNatural sources of vitamin D include ... :Fatty fish species, such as: Catfish, 85 g (3 oz) ... , cooked, 100 g (3.5 oz), provides 15 IU (0.15 IU/g)Fish liver oils, such as cod liver oil, 1 ... Tbs. (15 ml) provides 1360 IU (90.6 IU ...