But exactly what qualifies as a whole food, and why are whole foods special?

The idea is simple: Whole foods are foods and ingredients that are as close to their natural state as possible. They are minimally processed and unrefined, and they typically contain no added sugar, salt, fat or synthetic preservatives, flavorings or colorings.

For example, a boiled potato is a whole food; a potato chip is not. A fresh tomato is a whole food; a glass of V-8 juice is not.

Of course, there's no legal definition for "whole food," just as there's no legal definition for "natural." But within the natural foods industry, this view of a whole food is generally accepted and valued.

There are good reasons for all of us to value whole foods.

Whole foods have the nutritional advantage over processed foods of containing the most complete array of nutrients our bodies need. They not only contain vitamins, minerals and dietary fiber, but they are also likely to contain other health-supporting substances -- phytochemicals -- that don't come packaged in a tablet or added back to processed, packaged foods.

Nutrition scientists think these nutrients may work in synergy with each other when they're eaten in the amounts and combinations they're found in naturally in whole foods.

So how whole does a food have to be to have the most benefit? That depends.

Generally, the less processed, the better, though some slightly processed foods can be highly nutritious, too.

Wheat germ is a good example. Wheat germ is the inner portion of a kernel of wheat left after the hull has been removed. It's missing some fiber and is not technically a whole food, but it's still a concentrated source of folate, vitamin E, zinc and other nutrients.

Here are some examples of whole -- or nearly whole -- foods and others that are not:

• Whole: cooked oatmeal, wheat berries, brown rice. Breads and pasta made with 100 percent whole-wheat flour are good enough; those made from refined, white wheat flour are not. Shredded wheat is whole; cornflakes are not.
• Fresh broccoli, apples, cauliflower and snap peas are whole foods. Fruit leather, fruit drink and pickle relish are not. Fresh, frozen counts; canned doesn't. That's not to say that canned peas and carrots don't have nutritional merit. They do, but not as much as vegetables that haven't been cooked and soaked in salt water. Fruit juice isn't a whole food, but freshly squeezed juice has more nutritional value than juice that has been bottled and stored in the refrigerator for two weeks.
• Whole almonds, sunflower seeds, and dried beans that have been soaked and cooked are whole foods. Slivered almonds, nut butters with no added salt, and canned garbanzo beans (rinsed to remove most of the salt) are close enough.

The same general approach is true for combination foods. A piece of celery with freshly pressed peanut butter is a whole food snack; a toaster pastry is not.

The idea is not to get overly concerned about whether or not a food fits the precise definition of whole. The aim is to build as large a proportion of your diet as possible from foods close to their natural state.

It's simple guidance that helps ensure you'll get what you need from the foods you eat.