Foods that May Promote Cancer
Numerous foods and their components are suspected of being implicated in the development of cancer. These include naturally occurring substances as well as artificial additives. Food preservation methods and cooking techniques may also influence the food’s potential for promoting cancer. In addition, cancer-causing agents, which are commonly found in pesticides and packaging can sometimes get into our bodies through the food we eat.
As research continues, a number of foods initially denounced as cancer-causing have later been cleared of all charges whereas many new suspects have been added. Despite these constant changes, it is possible to make a few general recommendations of how to minimize the risk of cancer that are likely to stand the test of time:
- Limit fat to 30% or less of your caloric intake and try to eliminate saturated and trans fats from your diet as much as you can. That means to keep most of your fat intake monounsaturated or polyunsaturated.
- Eat processed meats and red meat in moderation, i.e. no more than five ounces (140 grams) per day, while three ounces (90 grams) a day is thought to be a healthy amount.
- Keep salt intake to 6 grams a day or less (this corresponds to the dietary recommendation for sodium of 2.3 grams per day).
- Cook food at low temperatures, particularly when using cooking oil. Steaming or boiling is better than grilling, barbecuing or frying.
- Keep perishable foods refrigerated or frozen and consume them promptly.
- Do not drink more than two alcoholic drinks a day.
Dietary Fat and Cancer Risk
Although the research results on the relationship between dietary fat and cancer are not conclusive, there is no question that population groups with a high intake of fat have a higher cancer rate. Many population studies have found a strong correlation between dietary fat and cancer, particularly the colon, breast, rectum, lining of the uterus and prostate cancers. However, most studies suggest that it is total fat intake, rather than a specific type of fat, such as saturated, trans-unsaturated, monounsaturated or polyunsaturated, that shows a link with cancer.
But despite all the suspicious statistics, there is still not enough evidence to say with certainty that dietary fat directly increases the cancer risk. Several recent studies have failed to find a link between total fat intake and breast cancer whereas studies of patients with colon and prostate cancer have also been unable to show that fat itself plays a major role as a risk factor. Therefore, further research is needed before we can conclude that decreasing the amount of dietary fat can protect us from cancer.
Dietary fat may work in many different ways to promote various types of cancer. For example, high consumption of fat may stimulate the production of estrogen, while high levels of estrogen are known to promote the growth of breast tumors. Studies show that decreasing the amount of fat in the diet leads to reduced levels of estrogen. However, despite population and animal studies linking high fat consumption to increased risk for breast cancer, several large controlled studies of women have failed to confirm such relationship. Another theory has it that bile production may play some role in the promotion of tumor growth in the colon. High consumption of fat leads to increased production of bile acids in the liver and an excess of bile acids may in turn encourage the growth of cancerous tumors in the colon and rectum. Saturated fat in particular is linked to increased incidence of colorectal cancer.
Despite the lack of evidence that dietary fat encourages cancer, there are other good reasons to cut back on fat, especially its tendency to promote heart disease as well as weight gain. And excess weight, as we all know, has been found to be one of the major risk factors for cancer. Possible reasons for the link between total caloric intake and cancer include: taking in excessive calories may make it easier for cells to multiply; fatty tissues are storing carcinogenic chemicals that would have been otherwise expelled from the body; and release of hormones from fatty tissues may accelerate the growth of malignant tumors.
Red Meat and Possible Cancer Link
Many researchers believe that high consumption of red meat carries risks of cancer, particularly colon cancer. Red meat typically contains more fat than poultry or fish and some studies have linked red meat consumption to an elevated risk of colon cancer, but this risk does not seem to be associated with the fat content of the meat. Therefore, some experts suggest that it may not be the meat itself, but the lack of other protective dietary components such as vegetables and fruits, that contributes to increased risk of colorectal cancer. It needs to be mentioned here, though, that there are also studies, which have found little evidence that red meat increases the risk of cancer.
Processed and Barbecued Meat and Cancer
Nitrosamines, commonly found as preservatives in cured meat but also in fish, cheese and beer, are known to be carcinogenic, capable of promoting cancer long time after ingesting them. Now we know more than 300 varieties of nitrosamines that have been shown to promote cancer. Since vitamins C and E inhibit the formation of nitrosamines in the body, food manufacturers are now required to add vitamin C to their products during the curing process.
Just like cured meat, smoked foods have long been implicated in promoting cancer. The smoking process, but also charring during barbecue, deposits polycyclic aromatic hydrocarbons on the surface of the meat and these compounds are known to be carcinogenic. Population studies have showed increased cancer rates among groups who consume large quantities of smoked or barbecued meat, with stomach cancer, in particular, being higher than average.
Yet another group of carcinogenic compounds formed during barbecuing and grilling of meat are heterocyclic amines. They are formed when high heat is applied to creatinine, a compound found in the muscle and blood of all animals. Heterocyclic amines can induce genetic mutations in cells that leave them vulnerable to cancer. These carcinogens are mostly linked to cancers of the gastrointestinal tract, although some laboratory studies have also suggested a connection to other types of tumors.
Alcohol and Cancer Link
Although drinking in moderation may have a beneficial effect on heart health, the same is not true for alcohol and cancer. Numerous studies suggest a higher risk of several types of cancer among those who drink. Again, this is not without controversy, as ethanol (pure alcohol) does not seem to cause cancer in laboratory animals. However, alcohol is metabolized to acetaldehyde and this substance has been found to have carcinogenic effects in laboratory studies.
High alcohol consumption is most often associated with cancer of the liver, esophagus, mouth, pharynx, larynx, breast, digestive tract, bladder, rectum and lungs. In addition, there is a synergistic effect between alcohol consumption and cigarette smoking, i.e. when these two are working together, they have a greater chance of causing cancer than either does alone. This is especially true of cancers of the throat and mouth.
We do not know yet how alcohol works as a cancer-promoting agent. It is suggested that alcohol may promote cancers in several different ways: by suppressing the immune system and thus impairing the body’s ability to eliminate cancerous cells; decreasing levels of vitamins A and E, two antioxidant vitamins believed to play a role in preventing cancer; activating certain enzymes which contribute to malignancy; inhibiting damaged DNA from repairing itself; changing bile metabolism; directly stimulating tumor growth; and dosing the area with cancer-causing nitrosamines present in alcoholic beverages, particularly beer.
Food Additives and Pesticides as a Potential Cancer Risk
There is a long list of reputedly toxic chemicals that have found their way into our food. The average western diet includes hundreds of additives that have been put into food to enhance flavor, improve appearance and retard spoilage. In addition, there are foreign chemicals in food that get there accidentally when farmers feed dietary supplements to their animals or dust crops with pesticides. Despite growing public concerns, many experts believe that the risk of cancer from food additives is minimal.
In fact, even old pesticides, that have been banned for decades, may continue to pose problems. Perhaps the best example is DDT, traces of which still show up in water, soil and produce. The same is true, for example, of polychlorinated biphenyls (PCBs) and dioxins that are considered to be amongst the most potent carcinogens known and are still omnipresent in the environment.
Another potential source of food contamination are packaging materials and their components, such as benzene, that can get into foods and produce adverse effects. Benzene is thought to cause leukemia and tests have shown that it can migrate from packaging into poultry, meat, cheeses and other packaged foods. This chemical also forms naturally in soft drinks. Furthermore, using plastic wraps made of low-density polyethylene for microwaving can release a chemical called diethylhexyl adepate (DEHA) into the food. DEHA is a suspected carcinogen, linked to breast cancer. Another similar compound, di-2-ethylhexyl phthalate (DEHP), is found in plastic wraps and bottles and is also suspected of promoting the growth of cancer cells.
Unfamiliar herbal products are yet another common source of contamination with carcinogenic substances. Take the Chinese herb, Aristolochia fangchi, as an example. This plant has been linked to kidney failure and urothelial cancers, yet it is available as a dietary supplement.