A growing body of evidence suggests that certain foods may cut cancer risk, protect against heart disease and preserve mental faculties. But just how do these "superfoods" improve our health, and should we be including them in our everyday diet?
"Diets rich in fruits and vegetables are generally associated with lower disease risks, in particular cardiovascular disease and some cancers," says the British Nutrition Foundation, which adds, "The search is on for the components of fruits and vegetables that convey these health benefits."
Scientists all over the world are hard at work trying to identify these components. An enormous amount of medical research is underway examining links between diet and disease. There is already a large volume of evidence suggesting that certain foods have significant protective effects against illnesses ranging from cancer to heart disease and Alzheimer's. In this article, we highlight a selection of foods that studies to date suggest may have particular health-giving properties.
Cruciferous and dark green vegetables: can they cut cancer risk?
Cruciferous vegetables - including broccoli, kale, cauliflower, cabbage and sprouts - contain isothiocyanates, which are thought to stimulate the body to break down potential carcinogens, and thus prevent normal cells from becoming cancerous. Several recent studies have produced evidence that cruciferous vegetables may protect some people against prostate and certain other types of cancer.
For example, scientists from the International Agency for Cancer Research in France reported that eating a weekly helping of cruciferous vegetables might reduce the risk of developing lung cancer in individuals with a particular genetic make-up. The researchers found that people with a certain genetic mutation who ate the most broccoli, cabbage and brussels sprouts were around one-third less likely to develop the disease than those with the same mutation who ate these vegetables less often.
In another recent study, published in the British Journal of Cancer, a research team from Georgetown University in the USA showed that a naturally occurring compound in cruciferous vegetables (indole-3-carbinol), when added to cells, significantly boosted the activity of the genes BRCA1 and BRCA2, which play a vital role in detecting damaged DNA and triggering a cell's response to repair it.
In their study of more than 400 Chinese men, meanwhile, Professor Colin Binns and his colleagues at Curtin University of Technology in Australia found that men who regularly consumed spinach - as well as other fruit and veg such as tomatoes, watermelons and citrus fruit - significantly reduced their risk of developing prostate cancer compared with men who did not eat much of these foods. In their report in the International Journal of Cancer, the authors say that eating extra portions of dark green vegetables might cut the risk of developing prostate cancer by up to 50 per cent.
Prof Binns stated, "We recommend eating more yellow, orange, and red vegetables and fruits such as tomatoes, watermelon, citrus and pumpkin, plus dark green vegetables such as spinach, because the risk of prostate cancer declines with increased consumption of the lycopene and other carotenoids found in these fruits and vegetables."