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Carcinogens and mutagens.

Ever since the American Chemical Society proclaimed that cigarette smoking causes cancer of the lungs and other forms of cancer, there has been suspicion that all forms of food heated to or beyond the smoke point are equally harmful to your health and should be discouraged because of the harmful chemicals produced by the effect of heat on the food. This includes the roasting of coffee, broiling of meats, baking of breads and practically every other food heatprocessed.

A large number of substances that occur naturally in food after cooking have been found to contain carcinogenic (cancer causing) or mutagenic (causing mutations in animals) elements when evaluated by criteria customary used to assess the cancer-causing potential of chemicals, These natural carcinogenics are more numerous, more widespread and often more potent than synthetic chemicals added by food manufacturers. Because of the small amount present, there has been no illness resulting from the natural or synthetic variety of any chemical, nor has there been'any serious evidence that these substances have had a serious impact on cancer incidence in the U.S. Moreover, carcinogenics are present in so many foods that it would be unrealistic to ban them. In every case to date, the amount of hazardous chemical is so small an amount in any food, not eaten to excess, its deleterious effect will not become evident.

Many people find it disturbing that carcinogens and other potent harmful substances may be present in food. Upon learning that food contains hazardous substances, they obtain a list and avoid the implicated ones. Fortunately, this is not necessary or even possible. No human diet can be free from all carcinogens. Actually, it is difficult to find food that does not contain some harmful chemical that occurs naturally or is produced during cooking. And roasting is particularly prolific of these, as even the simplest carbohydrate, when caramelized, produces mutagens and other harmful chemicals.

This was most dramatically dramatized by Dr. Richard Hall, vicepresident of McCormick & Company in his 1977 article published in "Nutrition Today." Dr. Hall analyzed the menu for a first class restaurant lunch, applying U.S. safety criteria. He looked at all evidence on adverse health effects that have previously been encountered in animal testing, as well as human experience, He eliminated from the menu all foods containing ingredients not meeting the criteria for food additives. At the end of the experiment, Dr. Hall was left with a single safe food--Hearts of Palm Salad. He commented that this had survived the test only because so little was known about its composition. Had it been studied in greater detail, potentially toxic ingredients would most likely have been found here, as well.

The foods eliminated from Dr. Hall's menu included carrots, radishes, onions, olives, melons, ham, shrimp, potatoes, butter, parsley, rolls, broccoli, hollandaise sauce (four offending ingredients), watercress, lemon herb salad dressing (nine offending ingredients), four types of cheese, bananas, apples, milk, water, 'wine, and, of course, tea and coffee. Some of these items were eliminated because they contain carcinogens, others held toxic substances of different types.

Roasting, broiling, baking, smoking, and frying of foods produces brown and burned products which contain highly carcinogenic components. One of the most common benzo(a)pyrene from the decomposition of protein is present in coffee aroma but in such minute amounts to as require an estimated consumption of 100 cups per day for several years before exhibiting any effect. Bread crusts, toast, and flied potatoes as well as coffee contain mutagens in addition to the carcinogen but in harmless amounts.

Anti-coffee advocates are already using the information that roasting produces carcinogens and mutagens__ergo we should give up coffee. They argue: many mutagens are carcinogenic. Coffee is highly mutagenic. One cup of coffee has 50 times the mutagenic activity of smoke absorbed from smoking a single cigarette.

A variety of mutagenic constituents have been identified in coffee although many are still unknown. An aromatic component (Diacetyl) is one of the identified mutagens, as is the closely related methyl glyoxal, which is highly mutagenic in bacteria,

A cup of fresh-brewed coffee contains about half a milligram, while instant coffee contains only about a fifth as much. Preliminary evidence indicates that methyl glyoxal is a carcinogen in injection tests in rats. It is also found in bourbon whiskey, wine, apple brandy, sake, toast, soy sauce, tomatoes, boiled potatoes, and roast turkey.

A cup of coffee also contains 150 mg. of chlorogenic acid and, another bacterial mutagen. This substance has not been tested for carcinogenicity. During roasting, coffee develops a small amount of benzo (a) pyrene, a strong mutagen and carcinogen which is released during extraction and brewing. Non-astringent tannins occur in coffee, tea and in many other foods derived from plants. In ingestion studies, tannins cause liver cancer in rats and mice. The caffeine in coffee and tea, while not itself carcinogenic, is claimed to be able to promote the growth of enzymes that increase the rate of development of tumors in laboratory animals. It can cause birth defects in animals tested at high doses--much higher than typical human ingestion levels. As to the toxicity of caffeine, a daily intake of 100 cups of brew is required to cause convulsions in humans and may possibly be fatal if ingested in a single dose.

Roasting of coffee causes production of carcinogens and mutagens in the brew, but in such small amounts as to have negligible effect on human longevity. As a result of the anti-cigarette, antismoking campaign, sentiment is rising against coffee and other roasted products. Researchers will continue to seek evidence that coffee is harmful, which the industry should be prepared to counter.
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Title Annotation:Coffee Break with Dr. Samuel Lee; food compositions
Author:Lee, Samuel
Publication:Tea & Coffee Trade Journal
Article Type:Column
Date:Jan 1, 1993
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