Looking for a definition of "natural foods" is looking for trouble. Ask 10 people in the supermarket what natural foods are and you get various answers, the most frequent being, "I don't know."

Ask the Food and Drug Administration how to define the term and a spokesman says: "We wouldn't touch that with a 10-foot pole!"

The manager of a health food store gave it a try last week. Craig Sharp of Sun and Earth said natural foods are "foods as they are in nature, untouched by man. They haven't been sprayed, extracted, smashed, altered, frozen." And then he added: "Not everything sold in a health food store fits that description."

Not everything advertised in the supermarket as natural fits that description either.

Sidney Margolius makes a stab and probably comes closest to a definition in his book "Health Foods: Fact and Fake."

"Natural Foods: a vaguely used term, usually taken to mean foods that have a minimum of refining (i.e., whole grain cereals) and no additives or preservatives, but sometimes used to include foods grown without chemical fertilizers, hormones, or pesticides (so-called 'organic' foods)."

Or possibly the person who described natural foods as "the opposite of synthetic" had the right idea.

Sharp said there is also a "broader definition of natural which includes processed foods that contain additives from natural sources." But to him, such foods are "borderline cases."

Beatrice Trum Hunter's description of the recipes in "The Natural Foods Cookbook" might be called the purist's definition. Her recipes stress ". . .the use of whole, natural foods. They call for whole grains rather than re fined flours and cereals; honey and other natural-sweetening agents rather than refined sugar; herbs rather than salt and spices; vegetable oils rather than animal fats. Vitamin-rich yeast and sourdough replace vitamin-destroying leavening agents such as baking powder and baking soda."

One thing is certain: natural and wholesome cannot be equated.

Sharp said there is a whole category of "natural junk food" like potato chips and candy that we sell here. Candy is still candy whether it's sweetened with honey or sugar. It still has a lot of calories."

Whatever natural foods may be, there are plenty of them that claim the distinction and more make their debuts each month. The establishment food industry has hopped on the bandwagon. It isn't necessary to go to a health food store anymore to find products touted as natural.

The first of the supermarket "natural" foods probably was natural cereal. Among the competing brands: "Kellogg's Country Morning, the all nauural cereal with natural sweetening-brown sugar and corn syrup;" "Nature Valley Granola-no additives, no preservatives;" "Quaker 100% Natural - naturally sweetened with brown sugar and honey." But all of these products contain brown sugar which is no more "natural" than refined white sugar. Brown sugar is a refined mass of fine sugar crystals covered with a film of highly refined, colored, molasses-flavored syrup.

Some of the old-time cereals also use the word natural on their packaging. Both Nabisco's Shredded Wheat and Spoon Size Shredded Wheat are "100% Natural Whole Wheat." The cereal is natural but it also comes in direct contact with a synthetic and possibly hazardous additive in the packaging material, BHT, which is used to prevent rancidity.

One of the most commonly used terms in today's processed foods is "natural flavor." Mant people are misled by the term. They equate natural flavor with a natural product. Most ice creams are naturally flavored but ice cream manufacturers are not required to list the ingredients on the label. Even if they were, the source of the "natural flavor" might remain a secret. Because a package of ice cream says "Peach Ice Cream - Natural Flavor," the shopper should not expect to find pieces of peach in the ice cream. Peach flavor may be peach "extractives" or peach "essence," derivatives of peaches made possible by the sophisticated technology of the food laboratory.

It is not at all clear from reading labels what is meant by: "Brownberry Bleu Cheese Croutons with other natural flavors," "Tang-natural orange flavor," or "Country Time-natural lemon flavor." Neither the juice nor rind of the fruits is listed on the label of the drinks and the croutons don't say what the source of the natural flavors is.

Giant Food's Swiss-style yogurts are "naturally flavored" and contain "other natural flavors." They also contain modified food starch and gelatin, which are not natural constituents of yogurt. Recently Giant switched its low-fat yogurts to "all natural." At one time they, too, contained modified food starch.

"Doxsee Natural Clam Juice" is a confusing name since the product contains monosodium glutamate, spices and salt in addition to the clam juice.

It is almost impossible to know what the makers of Lipton Iced Tea Mix mean when they say on the label that the product contains "natural sugar." What is "natural sugar?" Outside of unprocessed sugar cane, no one is quite sure what it is.

And what can one make of these products?

Damian's natural ice cream, which contains "natural stabilzers," guar and carob beans and Irish sea moss (also known as carrageenan).

Shiloh Farm natural ice cream, containing natural stabilizers: "locust beans are seeds from the pod of the carob tree; guar seeds are endosperm of an Indian legume."

These additives get back to Sharp's broader definition of natural": processed foods with "natural additives." Commenting on those products, Sharp said, "That's not the way you make ice cream at home."

Tiger Milk Carob Coated Bars: "goodness from nature - no preservatives, no chocolate. Ingredients include soy protein isolate, sodium caseinate, tricalcium phosphate, natural flavor."

Ever-Crisp Jumbo Size Cake Cups' "all natural ingredients" include natural vegetable food coloring, natural flavor extractives.

New Vegit, "The natural all-vegetable seasoning," contains "hydrolized protein derived from soya beans." Hydrolized means the water has been removed.

Hain Natural Salad Dressing Mixes are "sweetened with natural honey, no preservatives, no chemicals or M.S.G." MSG or monosodium glutamate is a flavor enhancer. The mixes contain dextrose and algin (derived from kelp) so-called natural additives.

Daddy Crips potato chips are "100% natural, no preservatives added, nothing artifical." The potato chips contain MSG and hydrolized cereal solids.

Natural Turbinado sugar is an "all-purpose natural sweetener. This sugar is not 'empty calories' because it retains some of the natural minerals . . . which are entirely removed from refined sugar.

"The most important is iron."

While turbinado sugar may not be as highly refined as white sugar, it is refined. The difference between its mineral content and the mineral content of refined white sugar is according to most authorities inconsequential and the package does not offer the percentage of these minerals so a comparison could be made between the two products.

Natural foods? Maybe the best way to define one is to ask if you could make it yourself in your own kitchen.