Don't believe claims that cooking destroys the nutritional value of your food, or that you must take enzyme pills to replace the enzymes lost in cooking. One popular author says that heating food above 118 degrees destroys 50 percent of the protein in our food, 50 percent of vitamins, and 80 percent of minerals, and all of the enzymes. These statements are nonsense. Protein and minerals are not destroyed by heat. Some vitamins are lost in cooking, but you still get plenty if you have a reasonably varied diet. The enzymes in food that are destroyed by heat are of no use to you anyway; you make your own enzymes for digestion of your food.

In your stomach and intestines, food is separated into carbohydrates, fats and proteins. Then enzymes made by your body break the carbohydrates, fats and proteins into their building blocks, and only these building blocks can be absorbed into your bloodstream. Enzymes in foods have no function in your body because they are treated like any other protein that you eat. Enzymes in foods are broken down into the building blocks of protein called amino acids in your intestines, so it makes no difference whether or not they are broken down by cooking.

The only common enzyme problem is lack of intestinal lactase that breaks down the double sugar in milk, which can cause diarrhea and cramping when you eat dairy products. You do not need to take enzyme pills unless you suffer from chronic diarrhea or severe weight loss, and the enzymes that may be prescribed for these conditions are copies of enzymes that your body makes, not the enzymes that are found in foods.

Many people believe that fresh fruits and vegetables always contain more nutrients than cooked ones, but cooked carrots have higher levels of antioxidants than fresh carrots. Cooking carrots in the presence of a small amount of oil or butter increases the amount of two antioxidants called beta carotene and phenolic acid. Cooking also increases the amount of lycopene you get from tomatoes. Cooking breaks the plant cells open to increase the absorption of these antioxidants and other beneficial plant chemicals. Adding a little oil or butter increases absorption of fat soluble chemicals.

Some vitamins are affected by cooking, but you'll still get plenty. The enzymes in food that are destroyed by heat are of no use to you; your body makes the enzymes you need to digest your food. Most of the nutrients in food (minerals, proteins, fats, carbohydrates) are not destroyed by heat, and many common foods are unpalatable or unsafe if they are not cooked. I recommend eating the widest possible variety of fruits and vegetables, raw or cooked, and fresh, frozen, canned or dried.

Gabe Mirkin, M.D.

Dr. Gabe Mirkin has been a radio talk show host for 25 years and practicing physician for more than 40 years; he is board certified in Sports Medicine and three other specialties.

Dr. Mirkin's daily features on fitness have been heard on CBS Radio News stations since the 1970's. He has written 16 books including The Sportsmedicine Book, the best-selling book on the subject that has been translated into many languages. His latest book is The Healthy Heart Miracle, published by HarperCollins.

Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. A Boston native, Dr. Mirkin did his residency at the Massachusetts General Hospital. He has served as a Teaching Fellow at Johns Hopkins Medical School, Assistant Professor at the University of Maryland, and Associate Clinical Professor in Pediatrics at the Georgetown University School of Medicine. He has run more than forty marathons and is now a serious tandem bicycle rider with his wife, nutritionist Diana Mirkin.