Stability of vitamin D3 and vitamin D2 in oil, fish and mushrooms after household cooking.

Information on the retention of vitamin D in food following household cooking is scarce. So far the retention of its metabolites vitamin D3, vitamin D2, and 25-hydroxyvitamin D3 has shown that the type of food and the cooking method are the essential determinants, and there is no significant difference between the metabolites. We investigated the retention of vitamin D3 and vitamin D2 in sunflower oil, vitamin D3 in rainbow trout, and vitamin D2 in button mushrooms. The investigated cooking methods were boiling at different pH, steam cooking, microwave cooking, pan-frying, and oven baking. There was no difference between the retention of vitamin D3 and vitamin D2 added to sunflower oil, which ranged from 70 to 99%. In rainbow trout, the retention of vitamin D3 at 85-114% was not significantly different from 100%, except for panfrying at 85%. However, the retention of vitamin D2 in mushrooms at 62-88% was significantly different from 100% (p ≤ 0.05).