As part of the trial, forty people with MS will consume a hot chocolate drink every day over six weeks.
Half will get a drink rich in flavonoids while the others will be given a drink with low levels of flavonoids.
Flavonoids are thought to help reduce inflammation and are found in many types of food, including dark chocolate with cocoa levels over 70 per cent.
Dr Shelly Coe, who is running the trial, said: “Dark chocolate is generally seen as a food that’s bad for you but it has good things in it - including flavonoids.
“We’ve run the idea of this trial past a lot of people such as those at MS support groups and medics, and they’ve really liked it.
“We’ll be looking at the impact of cocoa flavonoids on inflammation and the role that plays in fatigue. There’s no cure for fatigue in people with MS, although the majority of those with the condition experience this symptom at some point.”
The trial is being funded by UK’s MS Society.