Get enough vitamin C – reduces levels of nitrosamines
Get Enough Vitamin C
Dietary changes and added vitamin C may inhibit the production of nitrosamines, compounds believed to increase the risk of cancer of the stomach, bladder, esophagus and mouth, according to Helmut Bartsch, Ph.D., chief of the Unit of Environmental Carcinogenesis and Host Factors at the International Agency for Research on Cancer in Lyon, France. Dr. Bartsch said nitrosamines are formed through a series of chemical and microbial reactions, initially in the mouth and then in the gastrointestinal tract. Nitrosamine production is enhanced in people who ingest a high level of nitrate, chew tobacco, have a urinary bladder infection or live in an area where there is a high incidence of stomach and esophageal cancer.
As for individual dietary and geographic risks for nitrosamine production, Dr. Bartsch said naturally occurring nitrates are impossible to avoid, since there are significant amounts in vegetables and drinking water. He added, however, that moderate consumption of these foods should not pose a problem.
Dr. Bartsch cited a number of studies showing that vitamin C inhibits the production of nitrosamines, especially in smokers. In one study, nitrosamine formation in smokers was partially inhibited by the daily addition of one gram of vitamin C to their diets. In other research, Dr. Bartsch and his colleagues studied male volunteers from Bombay, India, who smoked western-type cigarettes and bidis (native cigarettes) or chewed betel quid containing Indian tobacco. The researchers measured the levels of nitrosamine compounds in urine samples during a 24-hour period. They reported that the mean levels of nitrosamine were higher in the habit groups, especially in the cigarette and bidi smokers, than in the non-habit groups.
“Vitamin C at a dose of 100 mg three times a day effectively reduced the levels of urinary [nitrosamines] in smokers and chewers,” Dr. Bartsch said. “There is now good evidence that tobacco specific nitrosamines are major carcinogenic agents, both alone and in combination with other tobacco constituents, in tobacco-associated cancers, in smokers, and, to an even greater degree, users of smokeless tobacco products.”
In a Chinese study of subjects residing in areas of high risk and low risk to nitrosamines, those in high risk areas who supplemented their diets with moderate amounts of vitamin C effectively reduced their urinary levels of nitrosamines to levels found in undosed subjects in low-risk areas.
Nitrite, a compound related to nitrous oxide, can react with another type of nitrogen compound known as an amine to form a nitrosamine. “Nitrite is a relatively unstable compound both in the environment and under physiological conditions,” said Steven R. Tannenbaum, Ph.D., professor of toxicology and food chemistry at the Massachusetts Institute of Technology, Cambridge. “It can react with a variety of organic and inorganic compounds leading to products as harmless as nitrogen gas, or as deadly as more of the nitrosamines. Many of the reactions that nitrite could undergo in the body or in the environment are still unknown. Consider that 30 to 35 percent of the nitrite added to meat or consumed in the diet cannot be accounted for. Some of this must be in compounds of unknown structure and thus of unknown toxicological significance.”
The major types of reactions involving nitrite, however, are reasonably well known and understood, particularly in relation to toxicological risk. In the environment, the risk is simply formation of carcinogenic compounds, that is, the formation of nitrosamines. In the body, however, the situation is more complex and therefore not fully understood in terms of risk.
For generations, Dr. Tannenbaum said, nitrate and nitrite have been used with salt to preserve meat and fish. Although this form of exposure has diminished there are other sources of nitrates and nitrites, such as industrial and agricultural products.
“The richest sources of nitrate in our environment are plant foods such as spinach, lettuce, celery and potatoes,” Dr. Tannenbaum continued. “Nitrate is the form of nitrogen taken up by plants. It is stored in roots, leaves and tubers, thus explaining its occurrence in those plant species.”
In Choose to Live, Joseph D. Weissman, M.D., pointed out that sodium and potassium nitrates are used as preservatives, especially for delicatessen meats, to guard against the growth of clostridium botulinum, a bacterium that produces the toxin responsible for botulism food poisoning. Nitrates and nitrites also lend a bright red color and distinctive flavor to these meats.
“As beneficial as nitrates are, there are considerable risks associated with them.” Dr. Weissman explained. “Bacteria cause nitrates to undergo a chemical conversion into nitrites, which in turn can be converted into nitrosamines in the gastrointestinal tract. Nitrosamines can cause birth defects and are responsible for the formation of stomach and nasopharyngeal cancers.”
Dr. Weissman added that nitrosamines may appear in rubber products, including baby bottle nipples, especially if the nipples are heated along with the bottle contents. And the migration of nitrosamines from paperboard packaging into food has been demonstrated under laboratory conditions, he said.
In Healing Nutrients, Patrick Quillin, Ph. D., R.D., reported that vitamin C (2,000 mg daily) and vitamin E (400 IU daily) reduced nitrosamine formation by up to 95 percent in a study involving 10 college students.
Perhaps vitamin C’s greatest potential relates to is antioxidant properties and its ability to deactivate free radicals, which are dangerous free-roaming chemicals inside the body. This ability is the key to the vitamin’s role in preventing cancer, according to a report in Environmental Nutrition.
In a 20-year-old Swiss study, which is still being analyzed, the most significant finding so far is a strong inverse relationship of vitamins C, A and E to stomach and colon cancers. This study, involving 6,000 men of all ages, has found that people who consume diets low in these nutrients are more likely to develop gastrointestinal cancers.
“The researchers, based at the Geriatric Clinic Kantonspital in Basel, conclude that the effects of vitamin C are enhanced by other antioxidants in people’s diets such as vitamins A and E, beta-carotene selenium and certain enzymes. Apparently, vitamin C alone is insufficient,” the publication reported.
Since we are bombarded with nitrates and nitrites in food, air and water, supplementing the diet with vitamin C and other antioxidants may be a good idea.
REFERENCES: 1. Bartsch, H., et al. “Human Exposure to Endogenous N-Nitrose
Compounds: Mechanisms of Formation and Implications
in Cancer Etiology.” Presented at the Eleventh Annual
Bristol-Myers symposium on Cancer Research, Madison, Wis.,
Oct 5-6, 1988. 2. Tannenbaum, Steven R., Ph.D. “A Policy Perspective on
Safety: Nitrite and Nitrate.” Public Issue Report by Hoffmann-LaRoche
Inc., 1984. 3. Weissman, Joseph D., M.D. Choose to Live New York Grove
Press, 1988. 4. Quillin, Patrick, Ph.,D., R.D., Healing Nutrients. Chicago
Contemporary Books 1987. 5. “Uncovering New Roles for Vitamin C; International with Nutrients
Is Key.” Environmental Nutrition, Vol. 9, No. 12, December
PHOTO : The American Cancer Society and the American Lung Association joined forces for this anti-smoking campaign.
PHOTO : For the sake of your health and your family’s: put out that cigarette. It is the best way to lower deadly nitrosamines and maintain a healthy store of vitamin C.
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