Healthy men consuming the green leafy vegetable had less damage to DNA and lower levels of markers of oxidative stress, a result attributed to the high antioxidant content of watercress, report researchers from Edinburgh Napier University in Scotland and the University of Ulster in Northern Ireland.
“The lipid-soluble antioxidants alpha-tocopherol, gamma-tocopherol and xanthophyll were all elevated following supplementation with watercress, and, in doing so, indicates the potential for watercress to act as a source of blood-rich antioxidants,” wrote the researchers in the British Journal of Nutrition.
“The increased concentration of xanthophyll following the acute dose of watercress may therefore have played a contributory role in the increased protection of lymphocyte DNA in this supplemented group.”
Exercise and oxidative stress
Oxygen-breathing organisms naturally produce reactive oxygen species (ROS), which play an important role in a range of functions, including cell signaling. However, over production of these ROS from smoking, pollution, sunlight, high intensity exercise, or simply aging, may overwhelm the body’s antioxidant defenses and lead to oxidative stress.
“As it has been shown that an overconsumption of oral antioxidants may lead to a pro-oxidant state, causing a disturbance in redox biochemistry, it is therefore imperative that food sources naturally high in antioxidant vitamins are considered, due to their capacity to provide increased systemic and cellular protection without excessively elevating in vivo antioxidant vitamin concentrations,” explained the researchers.
In order to test the efficacy of watercress with respect to exhaustive exercise, the researchers recruited 10 healthy men with an average age of 23 to participate in their eight week study.
Participants were given 85 grams of watercress to consume every day for eight weeks. They also participated in an eight week study with no watercress consumption to act as controls.
Results from the exercise tests showed that exercise during the no-watercress period led to an increase in DNA damage, as well as increases in lipid peroxidation, a marker of oxidative stress.
However, such increases were not observed during the watercress period, said the researchers.
Additionally, blood samples revealed increased levels of fat-soluble antioxidants alpha-tocopherol, gamma-tocopherol and xanthophylls.
“In the present investigation, serum [levels of the pro-oxidant compound hydrogen peroxide] H2O2 decreased following exhaustive exercise under both supplemented conditions but increased in the control groups,” wrote the researchers, led by the University of Ulster’s Gareth Davison.
“These data would lend support to the suggestion that watercress may provide effective in vivo protection against H2O2 production as a function of exercise. It is also plausible that the elevated lipid-soluble antioxidants (under both supplemented protocols) are directly scavenging superoxide and therefore result in a net decrease in H2O2 production.
“The observed increase in lipid-soluble antioxidants, as that demonstrated following exercise, may also play a key role in the protection against cell membrane lipid peroxidation.”
“The study demonstrates that exhaustive aerobic exercise may cause DNA damage and lipid peroxidation; however, these perturbations are attenuated by either short- or long-term watercress supplementation, possibility due to the higher concentration of lipid-soluble antioxidants following watercress ingestion.”
Source: British Journal of Nutrition
Published online ahead of print, FirstView Articles, doi: 10.1017/S0007114512000992
“Acute and chronic watercress supplementation attenuates exercise-induced peripheral mononuclear cell DNA damage and lipid peroxidation”
Authors: M.C. Fogarty, C.M. Hughes, G. Burke, J.C. Brown, G.W. Davison