Why are we asking this question now?
The term superfoods entered the language in the 1990s to denote foods packed with nutrients that supposedly have health-giving properties. Some are exotic, such as alfa alfa, spirulina and wheatgrass, and some prosaic such as broccoli, beans and beetroot.
The latest addition to the pantheon - watercress - was announced by scientists yesterday. Researchers at the University of Ulster, who fed large quantities of the peppery salad leaf to 60 men and women daily for eight weeks, showed it increased antioxidants in their blood and decreased DNA damage to their white blood cells. They concluded, in the American Journal of Clinical Nutrition: "The results support the theory that consumption of watercress can be linked to a reduced risk of cancer."
Are the watercress claims credible?
Not really. The research was funded by British watercress suppliers. Karol Sikora, professor of cancer medicine at Imperial College, delivered a delicious putdown yesterday.
He said: "The real problem is that it's not watercress specific - there's nothing magic there. The press release, from what is essentially a marketing association, is grossly overstated. We know that fruits and vegetables all do affect DNA damage, hence the five-a-day strategy to prevent cancer. There is absolutely nothing special about watercress."
What does the term superfood mean?
There is no definition of a superfood - and no definitive list. New candidates are regularly put forward, usually backed by a large dollop of marketing hype. Among the best known are oily fish (salmon, mackerel, tuna, etc) for omega 3 fatty acids, blueberries for vitamin C, brazil nuts for selenium, carrots for beta-carotene, tomatoes for lycopene, olive oil for the anti-inflammatory compound oleocanthal, red wine for resveratrol and garlic.
Health claims range from improving IQ to preventing cancer and heart disease, increasing sporting ability and enhancing appearance. Although their benefits are often overstated there is little doubt that they are a worthwhile addition to any diet.
Why not take vitamin pills and nutritional supplements instead?
Because eating is a pleasure - swallowing pills is not. Research on vitamins has also yielded confusing results with claims showing they protect against heart disease or cancer soon contradicted by new studies showing the opposite.
The argument for superfoods, which contain the vitamins in their raw unprocessed state, is that they are natural food sources, safe and easily absorbed. Calcium, for example, sold as calcium carbonate - chalk - is difficult to digest. In a glass of (low-fat) milk it is easily absorbed.
Does designating something as a superfood have an effect?
Yes. Sales of blueberries soared a couple of years ago after claims the fruit could help protect the body from a range of illnesses. Nutritionists say blueberries are bursting with vitamin C and offer one of the best sources of the antioxidant anthocyanin, believed to help keep the heart healthy and maintain youthful skin. In summer 2004, the US Department of Agriculture researchers revealed blueberries contained pterostilbene, which could be as effective as prescription drugs in helping lower cholesterol. Blackcurrant growers in the UK hit back with a campaign to promote the benefits of their "forgotten fruit", saying the berries contained more antioxidants than their foreign-grown rivals.
Source - Independent