Saturday Dec 7, 2013 (foodconsumer.org) -- Cooking can deactivate vitamin D leading to a loss of active vitamin D.  A new study in Food Chemistry reveals cooking vitamin D containing foods like eggs and margarine for 40 minutes at ordinary temperatures in an oven can cause a 60% loss of vitamin D.

J. Jakobsen and P. Knuthsen from Technical University of Denmark in Søborg, Denmark tested how vitamin D3 and 25-hydroxyvitamin D3 in eggs, vitamin D3 in margarine and vitamin D3 and vitamin D2 in bread can survive during a cooking process like boiling, frying in pan and oven and baking.

The study found about 39 to 45% vitamin D compounds in eggs and margarine after cooking in an oven for 40 minutes could be retained.  Interestingly, frying which was conducted at relatively high temperature but for a shorter time could result in a retention of 82 to 84%.  Similarly, 86 to 88% of vitamin D was retained in boiled eggs.  A similar magnitude of retention of vitamin D was found in baked bread, 69% in rye bread and 85% in wheat bread.

Retention of vitamin D2, D3 and 25-hydroxyvitamin D3 in eggs was similar.

Vitamin D is only found in a few foods like eggs, cold water fatty fish like Salmon and mushrooms.   Dietary supplements should be used particularly in Winter. In Summer, sunlight exposure should be the main source of vitamin D.

Vitamin D deficiency has been linked to over 100 health conditions including cancer, heart disease, diabetes mellitus, depression, brain disorders like Alzheimer's disease.

Vitamin D is fairly safe to use.  Up to 10,000 IU per day can be tolerated in adults.  Vitamin D experts believe that adults should use 5000 IU per day to prevent diseases. (David Liu,  PHD)