My dietary staple is currently a soup made from meat, bone, and assorted vegetables pressure cooked for two hours at 15 psi (at the boiling point of about 250° F). I consume it in its entirety, including the bones which become soft and edible. Since this is my primary source of nutrients, I am concerned that the persistent use of pressure cooking may lead to imbalance.
I have found many studies that suggest that certain vitamins (such as vitamin C) are retained very well by pressure cooking, but all these studies use very short cooking times -- minutes, not hours.
I can easily estimate the nutrients going into the pressure cooker, but I'm having a hard time estimating the nutrients coming out. Does anyone have information of the effect of pressure cooking for long times (hours) on the nutrient content of food?