Watercress is packed with 15 essential vitamins and minerals. Weight for weight, it contains more vitamin C than oranges, more calcium than milk, more iron than spinach, more folic acid than bananas and has secretly enjoyed superfood status for centuries. Now, research from the University of Southampton has found new evidence that regularly eating the plant could prevent against cancer.
The benefits of watercress were first recognised in ancient Greece when Hippocrates, the father of medicine, is said to have deliberately located his first hospital beside a stream so that he could grow a plentiful supply of watercress with which to treat his patients. Greek soldiers ate it to increase their strength; Anglo Saxons took it to prevent baldness; Roman emperors believed it enabled them to make bold decisions; American Indians used it to dissolve kidney stones; and philosopher Francis Bacon claimed it could ‘restore a youthful bloom’.
Watercress sandwiches became a national institution during both World Wars when Britain had to rely on local produce, and experiments during the 1930s found it to be a powerhouse of nutrients. But through the latter half of the 20th century the popularity of watercress fell, mainly due to increased competition from imported and exotic produce.
In 2003 however, watercress farmers joined forces to revive the profile of this great British plant, forming the Watercress Alliance. The group is made up of the three largest producers in the UK, Bakkavor, Vitacress and The Watercress Company, who farm and distribute from 100 acres across Hampshire and Dorset.
The new research from the University of Southampton, led by Professor Graham Packham and funded by the Watercress Alliance, has found that volunteers who ate a bowlful of watercress a day, had elevated levels of cancer-fighting molecules in their blood within hours of eating it.
The research revealed that the plant compound in the leaves of watercress that causes its peppery taste, phenylethyl isothiocyanate (PEITC), is able to block the function of a protein called Hypoxia Inducible Factor (HIF), which plays a key role in cancer development. As tumours develop, they outgrow their existing blood supply. To get past this barrier, cancer cells send out signals that cause the surrounding normal tissues to grow new blood vessels and supply the growing cancers with oxygen and nutrients.
HIF is necessary for this process to work. However, PEITC, which is abundant in watercress, blocks the function of HIF and thereby inhibits the growth of cancer, while also helping recovering patients avoid a recurrence of the disease.
Watercress Alliance member Dr Steve Rothwell says: ‘We are very excited by the outcome of Professor Packham’s work, which builds on the body of research that supports the idea that watercress may have an important role to play in limiting cancer development.’
The study follows a dietary trial by the University of Ulster, which found that DNA damage to white blood cells was considerably reduced in 60 healthy volunteers, including 30 smokers, who were asked to eat an 85 gram bag of fresh watercress every day for eight weeks.
The beneficial changes were greatest among the smokers, who had significantly lower levels of antixoidant compounds at the start of the study. Earlier research from Princeton University in New Jersey, found that watercress protected smokers from a key tobacco carcinogen implicated in lung cancer.
Other trials at Ulster found that eating watercress protects against eye diseases such as cataracts, and the raised levels of antioxidants also protect cells from the effects of free radicals, which are responsible for heart disease.
Claire MacEvilly, a nutritionist at MRC Human Nutrition Research in Cambridgeshire, says: “What is interesting to us, is that the scientists have been able to quantify the actual amount of watercress needed to reduce the risk of developing cancer and that the recommended amount is achievable in a typical day.”
Molecular biologists at Purdue University in Indiana discovered in 2005, that watercress could actually correct its genetic code if inheriting from flawed parents, to grow normally again like its grandparents. The results, described by researchers as ‘spectacular,’ defy the scientific law of inheritance and present the notion that the plant, unlike any other species, can effectively heal itself and maintain its pure ancestral blueprint.
Whether this means that watercress is genetically geared as a ‘healing’ entity is a matter for further scientific research. History tells us that our ancestors believed in its revitalising powers, but wider studies into its medicinal properties have yet to be undertaken before bodies such as Cancer Research UK would be able to officially endorse it.
For now, scientists have awarded the aquatic plant natural superfood status and can back its supplementary health benefits. The encouraging findings from the University of Southampton however, are the first step to proving that one of Britain’s oldest salad vegetables might really be the key ingredient in the fight against one of the world’s oldest diseases.