What is the Effect of Pressure Cooking on Nutrition?

We consulted an expert to find out more about the pros and cons of pressure cooking and nutrition. Q: I've long wondered about the effect pressure cooking has on the nutritional value ofthe food. We know that high heat damages some nutrients, such as polyunsaturated fats and certain vitamins, and can cause theformation of unhealthy chemicals as found in grilling and baking. On the other hand, pressure cooking exposes the food to heatfor a shorter length of time. Is there any information on the effect of pressure cooking on nutrition and which foods are mostsensitive? -Steve Billig, Denver, CO
A: To answer your question, we consulted Kantha Shelke, Ph.D; a Chicago-based food scientist andspokesperson for the Institute of Food Technologists. Here's what she told us:

• Pressure cooking can reduce heat-sensitive nutrients (e.g., vitamin C, folate) and bioactive phytonutrients, such as betacarotene, glucosinolates (helpful compounds found in cruciferous vegetables) and omega-3 fatty acids, that are beneficial for human health. But so do other cooking methods-and generally to more or less the same extent.
• With vegetables and fruits, the heat-sensitive nutrients (e.g., vitamin C, folate and bioactive phytonutrients) are generally most susceptible to degradation during pressure cooking. Consuming the cooking water can help restore some of these losses.
• In the case of grains and legumes, although the vitamins and heat-sensitive vitamins and phytonutrients are vulnerable to deterioration, the net result of pressure-cooking is a positive nutritional gain-from the increased digestibility of the macronutrients (protein, fiber and starch) and the increased bioavailability of the essential minerals.
• Pressure-cooked meat-based dishes show a significant reduction in unsaturated fat contents, but it appears that iron is not lost.
• In addition to making foods like grains and legumes more digestible, pressure cooking does not create any of the unhealthy chemicals associated with baking and grilling methods.