It is not normally thought of as an energy food. But watercress could give you the boost you need before going to the gym.
Nutrients in the peppery leaves reduce exercise-related damage to DNA, research shows.
While exercise has many benefits, it also leads to higher-than-usual production of free radicals – dangerous oxygen molecules said to have a hand in everything from ageing to diabetes and cancer.
Watercress, it seems, is particularly rich in antioxidant chemicals that mop up these free radicals. Eaten ahead of exercise, it keeps DNA damage at bay.
Sports scientists from Edinburgh Napier University took blood samples from ten healthy young men and asked them to eat a small bag of watercress a day for eight weeks.
They then put them through their paces on a treadmill, by making them run fairly quickly while gradually increasing the gradient.
Sports scientist Mark Fogarty said: ‘It was like running up a hill that was gradually getting steeper.’
Finally, the men had their blood tested again.
A few weeks later, the process was repeated without the watercress.
The results showed a clear increase in DNA damage after exercise – unless the men had eaten watercress.
Dr Fogarty said: ‘Although we are all aware of how good exercise can be for our bodies, pounding the treadmill, lifting weights, or doing high-levels of training can take its toll.
‘The increased demand on the body for energy can create a build-up of free radicals which can damage our DNA.
‘What we’ve found is that consuming a relatively small amount of watercress each day can help raise the levels of important antioxidant vitamins which may help protect our bodies, and allow us to enjoy the rewards of keeping fit.
‘It’s an interesting step forward in sports nutrition development and research.’
The good news for keep-fit fans who were not fond of watercress is that there may be no need to eat it every day.
The experiments, published in the British Journal of Nutrition, also showed that eating an 85g bag of the salad leaves two hours ahead of exercise had a similar effect.
Dr Fogarty said that while watercress is a member of the same family as cauliflower, cabbage and broccoli, weight for weight, it contains ten times as many helpful chemicals as any other fruit or vegetable.
The watercress for the study was supplied by a salad-growing firm, but the watercress industry did not have any other involvement in the research.
An earlier study, from 2007, concluded that eating watercress could help protect against cancer.
Experts then commented that the recommendation of a bag a day might turn people green.