Research published this week showed that two common herbs, parsley and dill, can help to fight cancer. When compounds from the two herbs were combined, scientists from the Moscow Institute of Physics and Technology reported, they prevented tumour growth by interfering with cell division. Many foods are said to be anti-carcinogenic. But which are the ones that are supported by scientific evidence?
A key source of antioxidants, watermelon gets its characteristic colour from lycopene, the same cancer-fighting compound found in tomatoes. And, while the amount of the antioxidant in a watermelon fluctuates according to growing conditions, US government findings reported in the Agricultural Research journal suggested that watermelon may contain more lycopene than raw tomatoes. Watermelon juice is now available in supermarkets and, according to the American Institute for Cancer Research, “in one human study, lycopene from raw watermelon juice was absorbed as well as the lycopene from heat-treated tomato juice”.
As a member of the cruciferous family of vegetables (cabbage, cauliflower, brussels sprouts and kale are siblings), there is much to be said for broccoli in terms of cancer prevention. It contains sulforaphane, a potent compound that helps to boost the body’s protective enzymes and flush out cancer-causing chemicals. Broccoli is also among the vegetables being investigated as part of a new treatment known as “green chemoprevention”, where seed or plant extracts are used to prevent disease. In laboratory trials at the University of Pittsburgh last year, it was revealed how extracts made from broccoli sprouts protected mice against oral cancer.
Tomatoes are renowned for being the best source of lycopene, a powerful antioxidant that not only gives tomatoes their red colour but protects against DNA and cell damage. Indeed, men who consume more than ten portions of tomatoes a week — as fresh tomatoes, tomato juice or even baked beans — could cut their risk of prostate cancer by up to one fifth, according to researchers at Bristol University. Another study, published in Nutrition and Cancer, showed how high intakes of lycopene helped to stop endometrial cancer cell growth.
When researchers at Marshall University in West Virginia gave mice with breast cancer the equivalent of 50g of walnuts a day, they noticed how the growth rate of tumours was less than half that of the mice who ate no walnuts. Meanwhile, the beneficial omega-3 fatty acids in the nuts were shown to cut levels of the hormone IGF-1, which has been implicated in prostate and breast cancer.
The vibrant yellow spice contains an antioxidant called curcumin; in a study last year by researchers at Emory University in Atlanta, this was shown to slow the development of the human papillomavirus (HPV), which causes oral and cervical cancers. Other research has shown that curcumin suppresses the spread of cells that lead to head and neck cancer and helps to reduce levels of damaging inflammatory cytokines — proteins that affect how cells behave, which are also linked to cancer — in saliva.
People who eat kidney beans and other pulses such as lentils and pinto beans at least three times a week can help to reduce their risk of developing polyps — small growths in the lining of the bowel that can become cancerous — by up to one third, according to scientists at Loma Linda University in California. According to the study’s author, Dr Yessenia Tantamango, the fibre content of beans and pulses is the key. “Pulses, dried fruits and brown rice all have a high content of fibre, known to dilute potential carcinogens,” she says. A report in the American Journal of Clinical Nutrition suggested that for every 10g of fibre a woman added to her daily diet, her risk of breast cancer was reduced by 7 per cent.
Food scientists at Texas A&M University found that red-flesh plums have antioxidant levels to rival blueberries — and they may help to reduce the risk of breast cancer. In trials, even the most aggressive form of breast cancer cells died after treatment with plum extract, although normal cells were unaffected. “This is very, very attractive from the point of view of being an alternative to typical chemotherapy, which kills normal cells along with cancerous ones,” says the researcher Dr David Byrne. Previously the Texas team showed how dried plums — or prunes — can lower the risk of colon cancer by helping to promote healthy gut bacteria.
Rich in beneficial plant chemicals, garlic has been shown to prevent the formation of carcinogens that form in the stomach when high levels of nitrates, a common food preservative found in foods such as processed meats, are consumed. It’s one of the reasons why participants in the Iowa Women’s Health Study who ate the most garlic had a 50 per cent lower risk of colon cancers than those who avoided garlic. Eating raw garlic twice a week could halve the risk of developing lung cancer, according to another study in the journal Cancer Prevention Research, and it has been reported to kill brain cancer cells, blocking pathways that lead to the development of tumours.
Resveratrol, a chemical found in the skin of red grapes, is effective at preventing bowel cancer, but interestingly, less is more, according to a study conducted at the University of Leicester last summer. A daily dose of resveratrol equivalent to the amount found in one large (250ml) glass of red wine was twice as effective as a higher dose in stemming tumour growth.
An apple a day could help to keep cancer away, provided that you eat the peel. Compounds called triterpenoids — which inhibit or kill cancer cells — have been identified in apple peel. At Cornell University apples have been found to reduce the number and size of breast tumours in laboratory animals, something food scientists put down to the triterpenoids they contain. In other research, carbohydrates called oligosaccharides that are found in apples were shown to kill up to 46 per cent of human colon cancer cells, outperforming the most commonly used chemotherapy drug.
Although the World Health Organisation has recently warned that very hot drinks may be linked to cancer of the oesophagus, or gullet, scientists at the University of Southern California have reported how coffee consumption — decaf, instant or espresso — decreases the risk of colorectal cancer. “We found that drinking coffee is associated with a lower risk of colorectal cancer, and the more coffee consumed, the lower the risk,” says Stephen Gruber, the senior author of the study.
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