Since the time when the kitchen stove was a campfire outside a cave, people have tinkered with ways to preserve and enhance food. Food was fragile, delicate, prone to rot, and easily injured. Bugs infested it, bacteria invaded it, mold infected it, and the air made it rancid.

Something had to be added to protect food and perhaps make it tastier, too. So the ancient Romans used sulfites to disinfect wine containers and help preserve the wine. Europeans in the 13th and 14th centuries embraced Marco Polo because he brought back spices from the Orient to season their bland diet. Travelers to the New World stored meat in salt to preserve it during their long voyages across the Atlantic Ocean. Later, pioneers in America used saltpeter to preserve their meat.

Food additives are so much a part of the American way of eating today that most of us would find it difficult to put together a meal that did not include them.

Take a typical lunch, for example: sandwich, instant soup, gelatin dessert, and a cola drink. The bread has been fortified with vitamins and also contains an additive to keep it fresh. The margarine has been colored pale yellow--or, if you use salad dressing, it has been made with emulsifiers to keep it from "separating." The luncheon meat contains nitrite; the soup, an additive to keep it from becoming rancid; the gelatin, red coloring to make it pretty. Finally, the cola has coloring, flavoring, sweeteners, and carbonation.

An additive is intentionally used in foods for one or more of these four purposes:

1. To maintain or improve nutritional value. Many foods are fortified with vitamins and minerals that might otherwise be lacking in a person's diet or that have been destroyed or lost in processing.

2. To maintain freshness. Foods last as long as they do on the shelf or in the refrigerator because of additives that retard spoilage, preserve natural color and flavor, and keep fats and oils from turning rancid.

3. To make food more appealing. The most widely used additives are those intended to make food look and taste better. These include coloring agents, natural and synthetic flavors, flavor enhancers such as MSG (monosodium glutamate), and sweeteners.

4. To help in processing or preparation. A wide variety of compounds are used to give body and texture to foods, evenly distribute particles of one liquid in another, affect cooking or baking results, control acidity or alkalinity, retain moisture, and prevent caking or lumping.

Additives for Nutritional Purposes
Goiter, rickets, pellagra, beriberi--most Americans have barely heard of these diseases, much less suffered them. Their disappearance in the United States over the past 50 years is in large measure the result of adding essential vitamins and minerals to such everyday foods as milk, flour, cereals, and margarine.

Nutritional fortification began in 1934 when iodine was first added to table salt to prevent goiter, enlargement of the thyroid gland caused by iodine deficiency. Fortification of milk with vitamin D, which began in the 1930s, has helped prevent rickets. Later, it became standard practice to add iron and B vitamins--niacin, thiamine, and riboflavin--to flour, breads, and cereals to prevent iron deficiency, anemia, pellagra, beriberi, and mental retardation. Today, many additional foods are enriched or fortified with vitamins, minerals, and amino acids.

Consumers can tell which foods are fortified, because all products with nutrients added must be labeled. A misconception among some consumers is that addition of vitamins and minerals always makes the food superior to unfortified foods. In fact, adding nutrients already abundant in the diet provides no extra benefit, because the body uses only what it needs. There also can be too much of a good thing. Excessive amounts of some nutrients, such as vitamins A and D, or of trace elements, such as copper, zinc, molybdenum, and selenium, can be toxic.

Is fortifying food tampering with nature? Some critics say it is. They maintain that nutrients synthesized in the laboratory and added during processing are inferior to those present naturally in foods. Actually, each vitamin, mineral, or amino acid has a specific molecular structure that is the same whatever the origin of the compound. The body cannot distinguish between a vitamin that occurs naturally in a plant or animal product and the same compound created in a laboratory.

Additives That Maintain Freshness
Basically, there are two ways that foods can "go bad." The first, and potentially most serious, is spoilage caused by molds, bacteria, fungi, and yeasts. Bacterial contamination of food can cause distressing digestive disorder, as well as deadly botulism.

Over the years, a number of common substances have been used to protect foods from microbial action. The oldest is salt, probably used before recorded history, to preserve meat and fish. Sugar has long been used in jams and jellies and to help preserve canned and frozen fruits. Today, such chemicals as sodium propionate and potassium sorbate are used to extend the shelf life of breads, cheeses, syrups, cakes, beverages, mayonnaise, and margarine.

The second, and less serious, way that food can "go bad" is the undesirable change in color and flavor that occurs with the exposure of foods to oxygen. The resulting oxidation is what causes fresh sliced apples or peaches to turn brown or butter to turn rancid after being exposed to air for varying lengths of time.

Preservatives used by the modern food industry perform either or both of two major functions:

1. As antimicrobial agents, they keep the food from spoiling.
   
2. As antioxidants, they keep foods from becoming rancid or developing off-colors and flavors.

Antioxidants are used in a wide variety of food products--particularly the large number that contain fats and oils--to prevent rancidity. Antioxidants slow the development of off-flavor, off-odors, and color changes caused by chemical reactions that take place when foods are exposed to oxygen, moisture, heat, or certain enzymes present in many natural fats. The time it takes for fats and oils to become rancid varies with the particular fat and storage conditions. Unsaturated fats have less resistance than saturated fats to rancidity. Vegetable oils contain more unsaturated fats, but also small amounts of naturally occurring antioxidants such as tocopherols.

Although animal fats are more saturated, they have fewer naturally occurring antioxidant substances. Therefore, animal fats generally require added or higher levels of antioxidants than do vegetable oils.

Antioxidants retard oxidation by scavenging oxygen on the surface of the food. These preservatives are not necessarily exotic chemicals. Vitamins C and E are among the 27 compounds added to foods as antioxidants. Even the lemon juice squeezed on sliced apples to keep them from turning dark is technically an antioxidant.

Since so many foods contain fats and oils susceptible to oxidative and other reactions that cause rancidity and off-odors, the food industry considers it important to inhibit these reactions so as to extend the shelf life of the food products.

Additives to Make Food Appealing
Some additives are put into foods simply to make them more appealing. Coloring agents, for instance, contribute nothing to nutrition, taste, safety, or ease of processing. And some consumer advocates argue that food is made to look more appetizing at the risk of increasing health hazards.

Today food colors are used in virtually all processed foods. While their use is not restricted, per se, they cannot be used in unnecessary amounts or to cover up unwholesome products. Artificial colors must be listed as ingredients in all foods except butter, ice cream, and cheese. There are 33 colors currently permitted for use in foods. Some 1,700 natural and synthetic substances are used to flavor foods, making flavors the largest single category of food additives.

Additives Used in Preparing and Processing Foods
The functions of these additives are many. Some cause baked goods to rise. Others prevent ice crystals from forming in ice cream and keep peanut butter from separating into oily and dry layers. Because of such additives, shredded coconut stays fresh and moist in the can. There are seven major groups of additives that are considered aids in processing and preparation of foods.

1. Emulsifiers(Mixers)--Some liquids don't mix unless there is an emulsifier around. In salad dressing, for example, oil and vinegar normally separate as soon as mixing stops. When an emulsifier is added, the ingredients stay mixed longer. Many emulsifiers come from natural sources. Lecithin, naturally present in milk, keeps fat and water together. Egg yokes, which also contain lecithin, improve the texture of ice cream and mayonnaise. The mono- and diglycerides come from vegetables or animal tallow and make bread soft, improve the stability of margarine, and prevent the oil and peanuts in peanut butter from separating.

2. Stabilizers and Thickeners--These compounds "improve" the appearance of foods and the way they feel in the mouth by producing a uniform texture. They work by absorbing water. Without stabilizers and thickeners, ice crystals would form in ice cream and other frozen desserts and particles of chocolate would settle out of chocolate milk. Stabilizers also are used to prevent evaporation and deterioration of the volatile flavor oils used in cakes, puddings, and gelatin mixes. Most stabilizers and thickeners are natural carbohydrates. Gelatin, made from animal bones, hooves, and other parts, and pectin, from citrus rind, are used in home and commercial food processing. Extra pectin, for example, is added to thicken jams and jellies.

3. pH Control Agents--These affect the texture, taste, and safety of foods by controlling acidity or alkalinity. Acids, for example, give a tart taste to such foods as soft drinks, sherbets, and cheese spreads. A more important use is to ensure the safety of low-acid canned foods, such as beets. Alkalizers alter the texture and flavor of many foods, including chocolate. After cocoa beans are picked, they are allowed to dry and ferment before they are made into chocolate. During processing, alkalizers are sometimes added to neutralize the acids produced during fermentation and to provide darker, richer color and milder flavor in the finished product.

4. Leavening Agents--Although air and steam help create a light texture in bread and cake, carbon dioxide is the key to making baked goods rise properly. Without leavening agents that produce or stimulate production of carbon dioxide, we would not have light, soft baked goods.

5. Maturing and Bleaching Agents--are used primarily to get flour ready for baking because natural pigments give freshly milled flour a yellowish color. Flour also lacks the qualities necessary to make a stable, elastic dough. When aged for several months, it gradually whitens and matures to become useful in baking.

6. Anti-caking Agents--Compounds such as calcium silicate, iron ammonium citrate, and silicon dioxide are used to keep table salt, baking powder, confectioner's sugar, and other powdered food ingredients free flowing. By absorbing moisture, these chemicals prevent caking, lumping, and clustering that would make powdered or crystalline products inconvenient to use.

7. Humectants--are substances that retain moisture in shredded coconut, marshmallows, soft candies, and other confections. One of the most common is glycerine. The sweetener sorbitol also is used for this purpose.

Protecting the Consumer
Former generations could add just about anything they wanted to food as long as it didn't poison someone. But increasing knowledge about food science and possible long-term harmful effects of food chemicals on health led Congress in 1958 to enact the Food Additive Amendment to the Federal Food, Drug and Cosmetic Act to ensure the safety of the additives. In 1960 the Color Additive Amendments were enacted to make sure colorings used in foods (drugs, medical devices, and cosmetics, as well) were safe.

For purposes of FDA regulations, chemicals added to food--other than pesticides and animal drugs--fall into four categories:

1. food additives,
   
2. generally recognized as safe (GRAS) substances,
   
3. prior-sanctioned substances, and
   
4. color additives.

Food additives--The "toughest" category in terms of regulations and safety testing is the food additive category. This covers substances that have no proven track record of safety; scientists just don't know that much about them.

Additives such as the artificial sweetener aspartame and the emulsifying agent poly-sorbate 60, which is found in salad dressing and other food, were substances that needed to be tested before they could be used because it was not known whether they were safe. Subsequent testing proved them safe.

But what is "safe"? Congress has defined safety as "a reasonable certainty that no harm will result from use of an additive." The FDA evaluations examine whether the additive has any toxic effects, may cause birth defects, interferes with nutrition, or affects individuals with allergies.

When an additive is tested, it is usually fed in large doses over an extended period of time to at least two different animals. These feeding studies, usually done by or for a food company that wants to use or sell the additive, are designed to determine whether the substance causes cancer, birth defects, or other injury to the animals. Cancer is of particular concern. A special provision of the 1958 and 1960 additive amendments, the so-called Delaney clause, states that if an additive is found to cause cancer in humans or animals it may not be added to the food.

The company submits the results of all these tests to the FDA for review. If the FDA review finds that the additive is safe, the agency establishes regulations for how it can be used in food. This commonly includes a 100-fold margin of safety, which means that the substance may be used in food at a level that is no more than 1/100th of the highest level at which it was fed to test animals and did not produce any harmful effects.

GRAS--The second group of substances is known as GRAS, an acronym for substances "generally recognized as safe." This group includes several hundred substances whose use in food is considered safe by experts based either on a history of safe use before 1958 or on published scientific evidence.

Congress established the GRAS category in 1958 because they felt that it was unnecessary to require industry to develop evidence to prove the safety of substances that were already generally regarded as safe by knowledgeable scientists. Included are many spices and herbs, salt, sugar, and vitamins that "logic and common sense," in the words of one expert, tell us are safe to use.

Of the more than two dozen GRAS antimicrobials and antioxidants, FDA has reaffirmed that six may continue to be safely used. These are benzoic acid, methylparaben, propyl gallate, propylparaben, sodium benzoate, and stannous chloride. Of the remainder, FDA has either not finally acted on its published proposals to reaffirm their safety or is still evaluating data before taking final action. The two most widely used antioxidants still being reviewed by the agency are butylated hydroxyanisole (BHA) and its related compound, butylated hydroxytoluene (BHT).

Some of these GRAS substances are:

• Ascorbates and erythorbates--[ascorbic acid (vitamin C), ascorbyl palmitate, calcium ascorbate, erythorbic acid, sodium ascorbate, sodium erythorbate]. Okayed for use. Used in many foods and beverages, concentrated milk products, meat products, baked goods, candies, fats and oils, gravies, breakfast cereals, and processed fruits and vegetables.
  
• Benzoic and sodium benzoate--Okayed for use. Used in many products.
  
• BHA (butylated hydroxyanisole and BHT butylated hydroxytoluene)--are approved antioxidants. Used in breakfast cereals, gum, convenience foods, vegetable oils, shortening, potato flakes, enriched rice, potato chips, and candy.
  
• Parabens--Used in many foods for more than 50 years.
  
• Propionic acid--and its salts. Used for many years in baked goods and cheeses.
  
• Propyl gallate--Widely used antioxidant in foods.
  
• Sorbic acid--and its salts. Used in food for over 30 years.
  
• Stannus chloride--Prevents color changes and offensive odors in foods.
  
• Sulfiting agents--Used by the food ser-vice industry--restaurant salad bars are a major example--to keep lettuce and other vegetables fresh and crisp and to prevent discoloration. Many restaurants no longer use it.
  
• Tocopherols--Contribute vitamin E to the diet.

Inclusion in either of the latter two categories--GRAS and prior-sanctioned--does not guarantee a substance's safety; sometimes new evidence shows that "logic and common sense" erred. If new data suggest that a GRAS or prior-sanctioned substance may be unsafe, then FDA requires the manufacturer to conduct studies to ascertain the ingredient's safety. For example, the artificial sweeteners saccharin and cyclamates are substances that were once included on the GRAS list but came under fire several years ago because of new evidence that they may cause cancer in animals. Based on this evidence they were removed from the GRAS list; in fact, cyclamates were banned from use in food altogether. (Saccharin continues to be used because Congress granted it a special exemption.)

Color Additives--The Color Additive Amendments subject substances in the fourth category--dyes used in foods, drugs, cosmetics, and medical devices--to premarket testing similar to that required for the first category--food additives. Colors in use when the amendments were passed were placed on a provisional approval list pending further investigation to confirm their safety. Nearly 200 colors were on the provisional approval list in 1960. Since the passage of the amendment, several of the colors have been dropped because manufacturers were no longer interested in marketing them or because they were found to be unsafe.

Food additives may also be present in food packages. Known as indirect additives, they can end up in the food so FDA requires that they be evaluated.

Reporting Reactions to Additives
Some bodies just don't like certain foods. And when that happens, the body's reactions can range from headaches or hives to seizures or death. Food additives have not been exempt from blame either. With the introduction of the artificial sweetener aspartame in soft drinks in 1983, complaints blaming food additives for allergic reactions soared. To better monitor the effects of additives and deal with consumer complaints, FDA set up the Adverse Reaction Monitoring System (ARMS) in early 1985.

FDA officials investigate the complaints, which are then classified by the severity of the symptom (headaches, mood changes, nausea, etc.) and the frequency and consistency of the symptom's association with eating or drinking a particular product (whether the symptom occurred more than once, and how soon it occurred after the suspect product was eaten).

If you suspect you have had an allergic reaction to an additive, contact your local physician for treatment. You or your doctor might want to then contact the nearest FDA field office (look in the blue pages of your phone book) to report the reaction.

MSG (Monosodium Glutamate)
The best known flavor enhancer is the amino acid monosodium glutamate (MSG), widely used in restaurants and in prepared foods. Scientists are not sure exactly how it works, but suspect that it increases the nerve impulses responsible for the perception of flavors.

MSG is the controversial chemical best known as the cause of "Chinese restaurant syndrome" (claims are that relatively large amounts of MSG are often used in food served in Chinese-style restaurants), and it contains a major amino acid that the human body makes on its own and that can kill critical brain cells in some people, research scientists have discovered.

But whether eating large quantities of the flavor enhancer can cause any damage other than the brief symptoms of flushing, sweating, dizziness, or headache that many diners feel after a Chinese dinner is a matter of continuing debate. According to Dr. Thomas Kearney, a pharmacologist at the poison control center of the University of California, there is no question that even modest amounts of MSG added to food at home or in a restaurant can cause a variety of unpleasant symptoms in 15% to 25% of those who ingest it. But, he says, contrary to what most people believe, the effect is rarely if ever an allergic reaction. Annoying effects strike within 10 to 20 minutes after eating a meal containing even small amounts of MSG, and they rarely last more than two or three hours, he says.