A fresh peach vs. a canned peach. Which is better? For the majority of fruits and vegetables, raw is better. But it's not that simple.
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Finding a happy balance
A diet high in essential nutrients that is both enjoyable and easy to prepare isn't impossible if you  Eat a variety of foods, both raw and cooked.
When cooking foods, use methods that preserve nutrients.
Steaming and stir-frying are two good choices.
Use the shortest possible cooking time.
Save liquids from cooked foods -- water from cooked vegetables, juices from canned fruit -- for other uses. Use vegetable cooking liquids in soups or stews. Or consume cooking liquid or juice from the can along with the food.
-- Mary Miller
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The vitamin content of raw fruits and vegetables is generally higher (although not by a significant amount) than the cooked versions. Vitamin losses after cooking are anywhere between 5 percent and 25 percent, depending on the food and cooking method. Mineral content doesn't change much with cooking, nor does the amount of protein. Fiber decreases a little after fruits are heated and processed.
If you don't like fresh peaches and you love the canned version, then what is better -- a canned peach or no peach at all?
"Consumers shouldn't feel that they are limiting the nutritional value of their diet if they consume cooked foods," says Roberta L. Duyff, a registered dietitian and author of the "American Dietetic Association Complete Food and Nutrition Guide" (John Wiley and Sons, 2002).
"The public needs to be reassured that using food from the pantry and freezer, along with raw food, is a perfectly good way to get needed nutrients."
Raw food purists claim that uncooked food is alive. Their philosophy is based on the fact that raw foods have active enzymes -- the live components -- that allow chemical reactions to take place in the plant. Once the food is cooked, these enzymes are destroyed. This is true, but we usually don't consider raw beef to be alive even though chemical processes are occurring within the protein structure of the meat.
Our bodies have all the enzymes needed in the gastro-intestinal tract to digest food. Scientific research has not shown that humans need enzymes from raw food for digestion.
Most raw food followers believe cooking makes all vitamins and minerals inorganic. There seems to be some confusion over the meaning of inorganic. According to most of us trained in the life sciences, all minerals are naturally inorganic (lacking a carbon atom). Without opening an organic can of worms, let's just say this: Scientific literature doesn't back up the statement that suggesting cooked food is inorganic and thus unusable by the body.
All foods are not more nutritious when raw. "Cooking doesn't add nutrients that weren't there in the raw form, but it can make some nutrients, especially carotenoids, more available," says Duyff.
For instance, cooked carrots have more beta carotene than raw carrots because that nutrient's availability is improved by steaming. This goes for pumpkin and sweet potatoes as well.
Beans, potatoes and legumes usually have more protein and carbohydrates available for digestion after they've been cooked.
Cooked tomatoes have more vitamin C than raw, and tomatoes cooked in a small amount of olive oil have more lycopene, a member of the same family as beta carotene, available for absorption.
"Cooking makes some foods, such as potatoes, more edible and appealing," says Duyff.
Consider broccoli. For most of us, it's easier to eat a bowl of cooked broccoli than the same amount of raw florets.
"It takes a tremendous amount of effort and artistry to have your food look like [Roxanne Klein's]," Duyff reminds the home cook.
A raw foods diet isn't practical for most of us. In order to prepare the recipes being served in raw-food restaurants, expensive equipment, such as dehydrators, slicers, and juicers would be needed.
Shopping for and preparing a total raw foods diet in Pittsburgh could be monotonous and bland during winter months when a wide variety of seasonal fruits and vegetables are not available or are costly.
This type of food preparation is safe at a restaurant level where a local health department is monitoring everything. At home, careful washing, storage and preparation is important. The food must be safe to eat. Many types of bacteria can be on the surface of fruits and vegetables. This is one of Duyff's primary concerns about a raw foods diet.
Heat can destroy pathogens and other toxic substances. "The Centers for Disease Control and Prevention says that sprouts should be cooked before eating," says Duyff. In the past few years, researchers have found that raw sprouted alfalfa contains a substance called canavanine, which in large quantities can cause severe lupus-like symptoms. Cooking destroys this substance so, in this case, cooked is better. Other fruits and vegetables can also contain contaminants or naturally occurring toxins.
Cooking can kill harmful bacteria in meat, poultry and seafood. On the other hand, meat and fish cooked at very high temperatures can cause dangerous, possibly cancer-causing compounds to form. Moderate heat is ideal for meats. Most raw food diets are vegetarian diets, so meat isn't part of the meal plan.
"Some people need to have cooked foods because of chewing problems, usually in young children or the elderly," says Duyff. People need to be reassured that they can eat healthful meals from mostly cooked foods.
Food should taste good. Trying to make tomato sauce from fresh tomatoes in January would probably be disappointing, where using canned would yield a sauce with a good tomato flavor.
A well-balanced raw foods diet is difficult to plan without a background in nutrition. For example, vegans cannot get Vitamin B12 from a raw foods diet. Other nutrients might also be in short supply. It can be difficult to get enough calories from a totally raw diet because of the bulk of the foods.
The solution is to consider a diet that consists mainly of raw foods, if they're tolerated: fresh fruits and vegetables that are high in nutrients and fiber, combined with lean meat and fish and cooked whole grains and legumes. Remember: There is no one perfect food or perfect diet.
So it's a matter of making tradeoffs. Do what works within your budget, lifestyle and food preferences.
Freelancer Mary Miller of Fox Chapel is a registered dietitian.
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