DIETARY FACTORS ASSOCIATED WITH CANCER
Studies undertaken into the causes and origin of cancer have identified certain dietary factors that may influence their occurrence. However, most of these studies have been epidemiological studies based on animals and cannot be directly translated into cause and effect in humans.
The comments below were made by one of our tutors who has years of experience working as a dieticien for a government authority; however, it should be noted:
- These are only general comments; and specific advice should be sought from a health professional.
- Individual needs vary from person to person, and from one cancer to another.
- New research is always on the horizon, sometimes deepening old knowledge, and sometimes enlightening us to new and very different knowledge.
Severe restriction of calorie intake has been associated with the inhibited growth of tumors. This is believed to be due to the restricted amount of energy available for tumor growth. It should be noted that a reduced calorie diet also means that there are less nutrients available and one of these might be responsible for the inhibited tumor growth.
Laboratory results have indicated that when protein intake is at or below the minimum amount required for optimal growth, tumor development is inhibited. Research has also shown that in the case of chemical-induced cancers, tumor growth is accelerated when protein intake is two to three times above the minimum level.
Higher protein intake has also been linked to the increased risk of cancer, especially breast and colon cancer. However, there is not enough evidence available to categorically link excessive meat consumption to higher risk of cancer.
Tumor formation can be effected by both the type and amount of fat intake within a person’s diet. Again, higher incidences of breast and colon cancer have been linked with a higher intake of fat. There are various theories as to why this occurs, one research group believe that it is related to the increased amount of anaerobic bacteria of the intestine and biliary steroid secreted.
Some researchers believe that increased fibre intake can protect against certain cancers such as colon cancer. This has been attributed to the reduction time the food travels through the intestine, affecting bile acid metabolism, benefiting intestinal flora in turn reducing bile acid degradation and diluting potential carcinogens in the bowel.
Increased amounts of Vitamin A can be linked to protective effect against cancer, whereas deficiency in Vitamin A has been shown to be linked to increased susceptibility to chemically-induced cancers.
It has been shown in humans that the consumption of foods high in Vitamin C is associated with a lowered risk of gastric and esophageal cancer.
Research of cancer in mice has shown that injections of high doses of Vitamin C can halve the rate of tumor growth. This was evident in cancers of the brain, ovaries and pancreas. These researchers believe that by increasing ascorbic acid intake, the body generates hydrogen peroxide which acts against cancer cells.
Research undertaken by Oxford University (2009) has linked an increased risk of cancer in men and women who consume alcohol on a regular basis. The report indicated that beer, wine and spirits all led to a higher risk of cancer in both men and women at the same degree. The risk of breast cancer in women was significantly higher in those who drank alcohol. Other cancers thought to be increased by alcohol consumption at a lesser degree were mouth, throat, rectum, esophagus, larynx and liver.
Heavy smokers that also consume large amounts of alcohol are reported to demonstrate a higher incidence of mouth, pharynx, and larynx and esophagus cancer. In the US, excessive beer drinking has been associated with a higher risk of developing colorectal cancer.
Coffee and Tea
Some previous research had made tentative links between the consumption of coffee and pancreatic and kidney cancer. However, most studies do not demonstrate such a link.
Tea was also once believed to be link with various cancers. Over 2000 studies have shown that there is little evidence to suggest that tea consumption increases risk of cancer. Some researchers believe that the main risk of cancer from tea drinking is increasing the chance of esophageal cancer by drinking scalding hot water.
The consumption of Green Tea is believed to have preventative qualities against prostate and ovarian cancer, especially in Asian countries where it is consumed in much larger quantities.
There has been much controversy surrounding the use of artificial sweeteners. These have been linked with various forms of cancer as well as genetic abnormalities and other chronic diseases.
There are different types of artificial sweeteners, which have had various degrees of correlation with their link to certain cancers. However, none have been conclusively linked to cancer when taken at their typical consumption rate.