Greens and their Role in Cancer Prevention
Cancer, the malignant growth or tumour that results from uncontrolled and abnormal cell division, ranks just below cardiovascular disease in the United States as a leading cause of death. Today cancers prognosis is far brighter than it has been in the past and the identification of the risk factors, innovative therapies and new detection techniques offer people encouragement and hope.
According to the American Dietetic Association, a review published Journal refers to the types of fruit or vegetables that largely often appear to be protective against cancer are raw vegetables, followed by green vegetables, cruciferous vegetables, allium vegetables, carrots, and tomatoes.
How leafy green vegetables might prevent cancer
One reason why the debate among scientists about vegetables and cancer risk continues: no means of explaining possible cancer prevention has yet been found. One study showed that people who added more leafy green vegetables to their diet have a lesser amount of risky DNA and when DNA is less risky it has less methylation in certain genes.
The proposed model works in the following way:
More vegetables → Less DNA Methylation → Lower Risk of Lung Cancer
According to studies an opposite model can also be expressed:
Less Vegetables → More DNA Methylation → Higher Risk of Lung Cancer
The significance of methylation
The addition of a simple four atom molecule to a substance is known to be methylation, and in this case it would be a gene in a person’s DNA. Thus a gene changes how it works when it is methylated; therefore an association occurs between “higher” methylation and an increased risk of cancer. It appears that the methylation interferes with the control of normal cell division, hence allowing some cells to grow wildly and the result is cancer.
Potentially reduced lung cancer risk
In a study which used over 1,000 subjects and sputum was coughed up from deep inside their lungs, these samples contained a number of lung tissue cells. In eight key genes the lung cells were analyzed for methylation, specific genes were selected since they were known to have been associated with the risk of cancer. Smokers and ex-smokers were chosen as subjects because they are of higher risk of lung cancer. Researchers specifically looked at the subjects’ diets; they found that those who ate more leafy green vegetables were at a lower risk of developing cancer. It also showed that the risk decrease in subjects who took multivitamins.
Vegetables may be epigenetic
According to experts they believe there are two major causes of cancer. Firstly genetic, which is a change in one or more genes in the DNA; this usually occurs through damage or mutation. Secondly epigenetic, this refers to a factor outside the genes that changes the normal control of a gene or genes, therefore making them function differently.
A well known substance in vegetables, a photochemical, might be epigenetic. Epigenetic changes are gradual, accumulation may occur until there are sufficient changes to overcome the normal control mechanisms of the cells. It might be possible to stop these changes before it reaches the dangerous stage, when caught in time.
The vegetable – cancer controversy
While studies have shown that an association exists between vegetable consumption and less cancer risk, others have not. The famous ATBC study, showed an elevation in lung cancer risk in smokers who consumed supplementation of beta-carotene (a form of vitamin A).
More than 29,000 male smokers participated in this clinical trial; they were randomly assigned to take supplementation of beta carotene, vitamin E, both or the placebo. ATBC researchers reported that after the average follow-up period of six years, the
participants who took the supplements had a 16 percent higher incidence of lung cancer than among those who took a placebo. The death rate from all the causes was 8 percent higher in those participants who received beta-carotene supplementation.
Phytochemicals do prevent against cancer (in this case in non-smokers), but like the ATBC study it clearly shows that individuals who smokes does not really make a big difference in prevention but definitely in progression.
Phytochemicals and cancer prevention
What are phytochemicals (also known as phytonutrients)?
Phytochemicals are found in plants and acts as a chemical defense, protecting plants against bacteria, fungi and viruses. The consumption of large amounts of brightly colour fruits and vegetables (blue, green, orange, purple, red, yellow and white), beans, and whole grains/cereals, containing phytochemicals could reduce the developing of diabetes, certain cancers, heart disease and hypertension. The function of phytochemicals varies by the type and colour of the fruit and vegetables, while they also function as nutrient protectors or antioxidants, preventing the formation of carcinogens (cancer causing agents).
- A phytochemical – indoles-, are found in broccoli, Brussels sprouts, cabbage, cauliflower, mustard greens, etc. (also known as cruciferous vegetables). They contain active agents and sulphur that destroys cancer-causing chemicals. Indoles could stimulate enzymes in women that produce estrogen not that effective and detoxify toxins in food, therefore protecting against the development of breast cancer.
- Lignans are found in fatty fish, flaxseed, walnuts and whole grain products. It is suggested that they also block hormones that can cause the spreading of cancer, such as prostaglandins and estrogen. Parsley contains polyacetylene which destroys a powerful cancer-causer benzopyrene. Rosemary, a well known herb, is graced with quinines, a biological antioxidant that is non-enzymatic and is reported to obstruct carcinogens and co-carcinogens. Sterols are found in the skin of a cucumber and is said to lower cholesterol and in licorice, triterpenoids slows the growth of fast growing cells, such as cancer cells.
- Lutein is found in leafy green vegetables. Cataracts and macular degeneration might be prevented by lutein, as well as breast cancer and reducing the risk of heart disease. Research showed that lutein also helps in the prevention of colon and skin cancer.
A number of 83,234 healthy women participated in a long-term study and evaluated the association between carotenoid intake and breast cancer. The intake of food and supplements containing lutein and zeaxanthin might reduce the risk of breast cancer in premenopausal women, according to researchers. A strong association occurred among women with a higher risk of breast cancer, as established by a family history of the disease, as well as through vegetable consumption (drinking at least one alcoholic beverage per day). Another study of 540 women indicated that an increased risk of breast cancer was found in women with very low intakes of lutein, due to the lack of supplementation or a poor diet.
The most dangerous type of skin cancer is known as malignant melanoma, and there is a rapid increase in its prevalence. Sun exposure and having a fair complexion that burns easily is a crucial risk factor. According to one of the largest case-controlled studies, an association was reported between diet and melanoma and found that a high intake of fruit and vegetables (containing lutein), reduces the risk of melanoma drastically. There is also believed that xanthopyll carotenoid protects the skin against sun damage through the prevention of melanoma. Xanthophylls provides protection on tissue level, rather than plasma level, hence eating lutein-containing foods wont necessarily be protective on the day of sun exposure, but daily consumption of lutein rich foods will be beneficial.
- In artichokes and green tea polyphenob are found, this phytochemical may also offer some protection from cancer. Data from Case Western Reserve University suggests that green tea contains an important chemopreventive effect against all of the stages of carcinogenesis; and it also may be helpful against inflammatory reactions that are associated with exposure to solar radiation and chemical tumour-promoters.
Dark green leafy vegetables are listed under the “Foods that fight cancer” in accordance with The American Institute for cancer research:
Chicory, collard greens, mustard greens, kale, leaf lettuce, romaine lettuce, spinach and Swiss chard are great sources of folate, fibre and carotenoids such as flavonoids and saponins, as well as lutein and zeaxanthin.
According to AICR’s second expert report Food, Nutrition, Physical Activity, and the Prevention of Cancer: carotenoids found in food possibly protects against the risk of cancer of the mouth, larynx and pharynx.
Researchers found that carotenoids found in food seem to prevent cancer by functioning as antioxidants, basically scouring possibly dangerous free radicals from the body before they cause any harmful effects. Laboratory research discovered that carotenoids in dark leafy green vegetables can decrease the growth of certain types of cancer cells, including those in the breast, lung, skin and stomach.
Foods containing folate, according to The Second Expert Report, noted that it lowers the risk of pancreatic cancer and foods rich in dietary fibre most likely decreases the risk of developing colorectal cancer.
Much research has been done on fruits and vegetables (especially leafy green vegetables) containing vitamins, provitamins, dietary minerals, fibre and a variety of phytochemicals, which have been claimed to have antibacterial, antifungal, antiviral, antioxidant and anticarcinogenic properties etc. Research has shown that all of these significant factors play an important role in cancer prevention, decreasing the risk in developing cancer.
By eating many fruits, vegetables, whole grains and legumes and also reducing the intake of saturated and trans fats, people obtain the best possible nutrition at the smallest possible risk. Maintaining a healthy weight through regular physical activity and a healthy diet is also beneficial.
Fix your diet first, then take supplements
AIM offers products such as AIM BarleyLife and LeafGreens that are rich in amino acids, antioxidants, vitamins, chlorophyll, folic acid, live enzymes, containing minimal fibre as well. When your diet does not meet all the daily needs for a healthy functioning body, these products can be considered to achieve whole body health. AIM BarleyLife and LeafGreens could be taken at the same time; these two products are complementary and will ensure that your daily needs are met. Just remember to eat vegetables every day as well.
By Lezaan Vermeulen – AIM Nutritionist