In Sunday Leader

Chemicals In Nature’s Food

By Dr Harold Gunatillake
Health Writer

Our diets are made up of water, macronutrients (carbohydrates, proteins and fats), micronutrients (vitamins and minerals), and thousands and thousands of other naturally occurring chemicals. Some of these chemicals given to laboratory rodents in research projects for long periods seem to cause cancer, or have been shown to be “mutagens” when tested with bacteria. Mutagens generally damage the DNA genetic material in the cells of animals. Hence, such chemicals are referred to as ‘animal carcinogens’. A test called Ames Mutagen is done to assess and predict how likely a chemical can cause cancer in animals.

Way back in 1958, when the United States Congress passed legislation through the Food, Drug, and Cosmetics Act to keep “carcinogens” out of processed foods, it was assumed that natural foods had no cancer producing chemicals, other than what humans add into processed foods in the form of food additives, or inadvertently, in the form of pesticide residues. Also the Act banned using artificial substances that possibly could cause cancer in the lab animals.

Scientists Bruce N. Ames and Lois Swirsky Gold have analysed human exposure to chemicals, both natural and man-made (synthetic), that have been classified as “rodent carcinogens.”

Human dietary intake of nature’s pesticides is about 10,000 times higher than the human intake of synthetic pesticides that are rodent carcinogens. In addition, human diets are full of naturally occurring rodent carcinogens.

Natural chemicals

Many of these naturally occurring rodent carcinogens are pesticides – the plants produce them to repel or kill predators. These chemicals produced by the respective plants defend against bacteria, fungus, insects, and other animal predators.

They are often chemically related to the common industrially produced pesticides, and other environmental pollutants. Examples are the pyrolisidines that are found in comfrey, saffrol which is found in black pepper, sassafras which is a potent carcinogen in mice, aflatoxins which are produced from the aspergillusmould, and many other compounds such as phenols, quinine, and catechols, all of which are capable of generating free radicals and causing damage to our body. Of about 10,000 such natural pesticides, only about 60 have been tested in rodent experiments. These chemicals are found in a wide variety of our edible vegetable plants: Brussels sprouts, cantaloupe, cauliflower, cherries, lentils, chili peppers, cocoa, garlic, grapes, lettuce, and radishes, to name just a few.

Fortunately, most of these chemicals in food are detoxified through the liver, just like our prescription drugs. There are mixed function oxidases (MFO) in the liver to deactivate these naturally occurring chemicals in food.

This system is swiftly brought into action when required to deactivate foreign chemicals in many of our dietary vegetables

Let’s go through the rodent carcinogens prevalent in some of the food we eat daily;

• Cream of Mushroom Soup – hudrazines
• Carrots – aniline, caffeic acid
• Cherry Tomatoes – benaldehyde, caffiec acid, hydrogen peroxide, quercetin glycosides
• Celery – caffiec acid, furan derivatives, psoralens
• Mixed Roasted Nuts – aflatoxin, furfural
• Green Salad – allylisothiocyanate, caffiec acid, estragole, methyl eugenol
• Prime Rib of Beef with Parsley Sauce – benzene, heterocyclic amines, psoralens
• Broccoli – allylisothiocynate
• Baked Potatoes – ethyl alcohol, caffeic acid
• Sweet Potato – ethyl alcohol, furfural
• Red Wine, White Wine – ethyl alcohol, ethyl carbamate
• Coffee – benzo(a)pyrene, benzaldehyde, benzene, benzofuran, caffeic acid
• Catechol – dibenz(a)anthracine, methylcatechol, hydrogen peroxide
• Tea – benzo(a)pyrene, quercetinglycosides

Naturally occurring mutagens and carcinogens found in foods and beverages:

• Acetaldehyde (apples, bread, coffee, tomatoes) – mutagen and potent rodent carcinogen
• Acrylamide (bread, rolls) – rodent and human neurotoxin; rodent carcinogen
• Aflatoxin (nuts)- mutagen and potent rodent carcinogen, also a human carcinogen
• Allylisothiocyanate (arugula, broccoli, mustard) – mutagen and rodent carcinogen
• Aniline (carrots) – rodent carcinogen
• Benzaldehyde (apples, coffee, tomatoes) – rodent carcinogen
• Benzene (butter, coffee, roasted beef) – rodent carcinogen
• Caffeic acid (apples, carrots, celery, cherry tomatoes, coffee, grapes, lettuce, mangos, pears, potatoes) – rodent carcinogen
• Hydrazines (mushrooms) – mutagens and rodent carcinogen
• Hydroquinone (coffee) – rodent carcinogen
• d-limonene (black pepper, mangos) – rodent carcinogen
• 4-methylcatechol (coffee) – rodent carcinogen
• Methyl eugenol (basil, cinnamon and nutmeg in apple and pumpkin pies)- rodent carcinogen
• Psoralens (celery, parsley) – mutagens; rodent and human carcinogens

Present scientific knowledge suggests that residues of synthetic, and natural rodent carcinogens in our diets mentioned above, are unlikely to pose a risk of cancer in the quantities we consume on a daily, monthly, or yearly basis.

The data is inadequate to evaluate human risk at low doses, and the uncertainties are enormous. So readers need not worry about the presence of rodent carcinogens in the natural and synthetic food they eat. Only tiny levels are found in them. The food becomes carcinogenic when given to rodents in large doses over a lifetime.