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Life Extension Magazine

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April 2003

Carcinogens Are Everywhere,
But Do You Have To Worry?

Dr. Ames' suggestion for cancer prevention

Dr. Bruce Ames has been a long-time proponent of using DNA- protecting nutrients, like folic acid, to neutralize the effects of natural and synthetic carcinogens. His contention is that since it is impossible to avoid the thousands of carcinogens present in our diet, the best we can do for now is to protect our precious genes against mutation. 21-25

The most impressive study on folic acid showed that women who consumed folic acid supplements for at least 15 years reduced their risk of colon cancer by an astounding 75%. The fact that there were 88,756 women participating in the study makes this finding especially significant. The authors explain that folic acid obtained from supplements showed a stronger protective effect against colon cancer than folic acid consumed in the diet. This study also helps to confirm the work of Dr. Ames, who has authored numerous articles showing that folic acid is extremely effective in preventing the initial DNA mutations that can lead to cancer later in life. This data came from the famous Nurses' Health Study conducted at the Harvard Medical School.26 This study demonstrated that the degree of protection against cancer is correlated with how long a DNA-protecting substance (such as folic acid) is consumed. The women who took more than 400 micrograms of folic acid per day for 15 years experienced the 75% reduction in colon cancer, whereas short-term supplementation produced only marginal protection.


(apples, bread, coffee, tomatoes)
-mutagen and potent rodent carcinogen

(bread, rolls)
-rodent and human neurotoxin;
rodent carcinogen

(nuts)-mutagen and potent rodent carcinogen;
also a human carcinogen

Allyl isothiocyanate
(arugula, broccoli, mustard)
-mutagen and rodent carcinogen

(carrots)-rodent carcinogen

(apples, coffee, tomatoes)-rodent carcinogen

(butter, coffee, roast beef)-rodent carcinogen

(bread, coffee, pumpkin pie, rolls, tea)
-mutagen and rodent carcinogen

(coffee)-rodent carcinogen

Benzyl acetate
(jasmine tea)-rodent carcinogen
1,2,5,6-dibenz(a)anthracene (coffee)-rodent carcinogen

(apples, basil)-rodent carcinogen

Ethyl alcohol
(bread, red wine, rolls)-rodent and human carcinogen

Ethyl acrylate
(pineapple)-rodent carcinogen

Ethyl benzene
(coffee)-rodent carcinogen

Ethyl carbamate
(bread, rolls, red wine)
-mutagen and rodent carcinogen

Furan and furan derivatives
(bread, onions, celery, mushrooms, sweet potatoes, rolls, cranberry sauce, coffee)
-many are mutagens

(bread, coffee, nuts, rolls, sweet potatoes)
-furan derivative and rodent carcinogen

Heterocyclic amines
(roast beef, turkey, overcooked fish)
-mutagens and rodent carcinogens

(mushrooms)-mutagens and rodent carcinogens

Hydrogen peroxide
(coffee, tomatoes)-mutagen and rodent carcinogen

(coffee)-rodent carcinogen

(coffee)-rodent carcinogen

Methyl eugenol
(basil, cinnamon and nutmeg in apple and pumpkin pies)-rodent carcinogen

(celery, parsley)-mutagens; rodent and human carcinogens

(nutmeg in apple and pumpkin pies, black pepper)
-rodent carcinogen

*(References can be found at, or you may just want to browse the entire website.)

Evidence is growing that low levels of folic acid may be a factor in the cause of several cancers. Supplementation with folic acid has been shown to be protective against the development of breast cancer particularly in women who are on estrogen replacement therapy, drink alcohol or use tobacco. A 16-year study of 88,818 women showed that those who drank alcohol reduced their risk of breast cancer by 50% when they took folic acid (600 mcg/day).27 A 12-year Mayo Clinic study of over 40,000 women aged 55 to 69 found that women who drank alcohol were at no greater risk of breast cancer as long as they maintained normal folic acid levels.28

Scientists in the Netherlands have found that folic acid, vitamin C, and the carotenoid, beta-cryptoxanthin are protective against lung cancer. This large prospective study, consisting of 58,279 men of ages 55 to 69 years, found that high folic acid intake reduced the risk of small cell, squamous cell and adeno carcinomas of the lung.29

Researchers at Yale University found that people who consumed nutrients such as folic acid, vitamins C, B6, beta-carotene and fiber had a lower risk of cancers of the esophagus and stomach. A 1988 study showed an association of folic acid deficiencies with abnormalities in esophageal cells in those people at risk for esophageal cancer. There were significantly lower concentrations of folic acid present in the blood of patients with cellular dysplasia or malignancy than in cells of normal patients.30

Studies show that lower levels of folate and antioxidants increases the risk of cervical cancer. In a study at the University of Alabama in Birmingham, women whose cervical cells were loaded with folate were two to five times less likely than women with low folate levels to develop cervical dysplasia, the precursor of cervical cancer. [Cervical cancer is now considered a sexually transmitted disease associated with certain strains of human papilloma virus (HPV), or genital warts. In a group of 324 women with cervical cancer and HPV, statistically lower levels of folic acid were found.]

Pancreatic cancer is almost universally fatal, yet a study of 29,133 healthy male smokers showed that those with the lowest folic acid intake were 48% more likely to contract pancreatic cancer.31

While studies show that as little as 400 mcg per day of folic acid confers a cancer-protection benefit, most Life Extension members take 800 mcg, and sometimes, higher amounts per day.

A prudent course

We now know that our bodies have been inundated by significant amounts of natural and synthetic carcinogens. Two startling new studies show that we are already loaded with synthetic carcinogens that are not readily removed from the body.

Two of the participants in the Mt Sinai School of Medicine study2 were astounded when they were told that they had over 100 different carcinogens in their bodies, even though they regularly ate organic produce, avoided red meat, and kept pesticides out of their homes.*

There are some common sense lifestyle modifications that can reduce the carcinogen burden. For example, acrylamide32 is a newly identified carcinogen found in foods such as potato chips, french fries, certain highly cooked breads and cereals. The media reported widely on the potential risks of acylamide and we carried an article about it in the February 2003 issue of this publication. Since then, some scientists have sought to refute the purported dangers of acrylamide. Whatever the dangers of acrylamide turn out to be, it makes sense to avoid potato chips and French fries because they contain artery-clogging trans fatty acids and obesity-inducing carbohydrates. This fact holds true for most breads and any food that is cooked at extremely high temperature.

It has long been known that heavily cooked foods inflict massive damage to the genes. A group at the University of Minnesota reported that women who ate overcooked hamburgers had a 50% greater risk of breast cancer than women who ate rare or medium hamburgers. The famous Iowa Women's Health Study found that women who consistently eat well-done steak, hamburgers and bacon have a 4.62-fold increased risk of breast cancer.33

Cooking foods at high temperatures causes the formation of gene-mutating heterocyclic amines, which is why deep fried foods are so dangerous to eat. Heterocyclic amines have been linked to prostate, breast, colorectal, esophageal, lung, liver and other cancers. While health conscious people try to avoid foods that are known carcinogens, even grilled salmon contains a potent dose of gene-mutating heterocyclic amines.34

While one can reduce their exposure to cancer-causing heterocylic amines, it may be impossible to keep them from forming within the body. Enzymatic activities that naturally occur in the liver can inadvertently manufacture heterocyclic amines from otherwise harmless organic compounds.35


When laboratory studies are conducted to test if natural or synthetic chemicals cause cancer in rodents, the scientists use very high amounts of the suspected carcinogen.*

Moreover, most chemicals, whether natural or synthetic, are potential toxicants at high doses but may be perfectly safe when consumed in low doses.**

*Ames BN, Gold LS, Shigenaga MK. Cancer prevention, rodent high-dose cancer tests, and risk assessment. Risk Analysis, 1996, 16(5): 613-17.
**Ames BN, Gold LS. Too many rodent carcinogens: mitogenesis increases mutagenesis. Science, August 31, 1990, 249: 970-1.

The carcinogenic dangers of heterocyclic amines have been discussed in previous issues of Life Extension magazine. Heterocyclic amines, however, are not the only dietary culprit involved in gene mutation. Other mutagenic agents found in food include nitrosamine preservatives, aflatoxin molds and pesticide and herbicide residues.

It makes sense to avoid unhealthy foods that also contain known carcinogens, but since even healthy fruits and vegetables contain some carcinogens, one cannot possibly completely avoid them. The bottom line is that we need to eat a certain number of calories and this inevitably exposes us to agents that could cause cancer. A consistent finding in epidemiological studies is that people who consume the most calories have significantly higher incidences of cancer. There are several mechanisms that can explain why overeating causes cancer, but one mechanism is that more gene mutations occur in response to higher food intake.

Since avoiding all dietary carcinogens cannot be done, identifying methods to neutralize their gene mutating effects becomes a critical part of a life extension program.

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