Reduce your cancer risk: eat watercress!

We know that eating more fruits and vegetables can help reduce your risk of cancer. In particular, cruciferous vegetables such as cauliflower, Brussels sprouts, watercress, and mustard greens, have been linked with a reduced risk of cancer. These vegetables contain a higher amount of a substance known as glucosinolates, which are known to be anti-carcinogenic. Watercress has the highest concentration of these substances, as well as high amounts of beta-carotene.

Given these links, researchers in the United Kingdom designed a study (Am J Clin Nutr 2007;85(2):504-10) to see if watercress intake could be directly linked to blood markers of cancer risk, which include low blood levels of antioxidants (such as beta-carotene), and DNA damage to cells. They recruited 60 otherwise healthy men and women between the ages of 19 and 55 years to participate in the study. Half of each group of men and women smoked between 15 and 25 cigarettes per day. The 60 subjects were divided into two groups that contained equal numbers of men and women and equal numbers of smokers and nonsmokers.

The study is what is known as a crossover study: for eight weeks, one group consumbed 85 grams of watercress every day in addition to their regular diet. At the same time the other group continued with their regular diet as the control group. There then followed a 7-week "washout" phase, during which both groups followed their regular diet. Finally, a third phase switched the watercress group and the control group: the former watercress group followed its regular diet, while the former control group consumed 85 grams of watercress each day.

Each subject's blood was tested at the beginning and ending of each phase of the study to test for DNA damage, blood levels of carotenoids, and other markers of cellular damage that can lead to cancer. They found that the watercress supplementation led to decreases in DNA damage by up to 23.9%, and that levels of beta-carotene were increased by one-third. Interestingly, the effects of watercress consumption were stronger in those who smoked.

What this means for you

All the more reason to eat watercress in your salads. Don't like watercress? Try Lemon Butter Brussels Sprouts, Pan Grilled Broccoli, Collard Greens, or Napa Cabbage Salad.

First posted: February 13, 2007