Most raw food, like our bodies, is very perishable. When raw foods are exposed to temperatures above 118 degrees, they start to rapidly break down, just as our bodies would if we had a fever that high. One of the constituents of foods which can break down are enzymes. Enzymes help us digest our food. Enzymes are proteins though, and they have a very specific 3-dimensional structure in space. Once they are heated much above 118 degrees, this structure can change.
Once enzymes are exposed to heat, they are no longer able to provide the function for which they were designed. Cooked foods contribute to chronic illness, because their enzyme content is damaged and thus requires us to make our own enzymes to process the food. The digestion of cooked food uses valuable metabolic enzymes in order to help digest your food. Digestion of cooked food demands much more energy than the digestion of raw food. In general, raw food is so much more easily digested that it passes through the digestive tract in 1/2 to 1/3 of the time it takes for cooked food.
Eating enzyme-dead foods places a burden on your pancreas and other organs and overworks them, which eventually exhausts these organs. Many people gradually impair their pancreas and progressively lose the ability to digest their food after a lifetime of ingesting processed foods.
But you certainly can steam and blanch foods if you want your food at least warm. Use a food thermometer and cook them no higher than 118 degrees Fahrenheit. Up to this temperature, you won’t be doing too much damage to the enzymes in food.