Image copyright David Davies/PA Image caption Lewis Moody helped England win the World Cup in 2003

Former England captain Lewis Moody was given the nickname 'Mad Dog' during his rugby-playing days, such was his fearless commitment to club and country.

Yet, at the same time, unbeknown to his team-mates, friends and coaches, the England flanker was committed to fighting another very different foe.

Moody was diagnosed with an inflammatory bowel disease called ulcerative colitis in 2005, but kept his condition secret while continuing to play top-level rugby.

Now retired, he wants to raise awareness of the Crohn's and Colitis UK charity which helps around 260,000 people in the UK with this type of disease.

I lost 10kg of weight in about 10 days. I was losing blood, I felt awful Lewis Moody

He admits that his battle against colitis has been extremely difficult.

"In 2008 I had a really bad flare-up. I lost 10kg [22lb] of weight in about 10 days. I was losing blood, I felt awful and I just wanted to sleep the whole time.

"I couldn't leave the house. Getting out of the front door was a challenge in itself. The disease was making life really difficult."

By that stage, he had got used to rushing to the nearest toilet several times on the way to training and found himself regularly walking out of the tunnel at the start of a match, only to run back down it again to find the facilities.

What is colitis and Crohn's? Ulcerative colitis and Crohn's disease are the main conditions described as inflammatory bowel disease.

Ulcerative colitis is caused by inflammation and ulceration in the colon and rectum which can produce symptoms of diarrohea, pain, fatigue and anaemia.

is caused by inflammation and ulceration in the colon and rectum which can produce symptoms of diarrohea, pain, fatigue and anaemia. Crohn's disease is characterised by inflammation of the gastrointestinal tract and produces similar symptoms. Crohn's and Colitis UK

Moody even moved house to be closer to the training ground because of his feelings of urgency, which are common to sufferers of both ulcerative colitis and Crohn's disease.

Other symptoms can include diarrhoea, pain, anaemia, fatigue and sometimes inflammation of the joints, skin, liver and eyes.

When he did eventually talk to players and coaches about his condition, they already knew something was wrong, and he felt relieved to be able to talk about it.

Using medication, Moody had been able to keep his colitis under control but after years of taking painkillers and anti-inflammatories for rugby injuries he felt "like a walking medicine cabinet" - and stopped taking everything.

He decided to strip his diet right back to alleviate his symptoms, and then reintroduce different foods a week at a time to work out what his body could tolerate.

Eating oily fish and boiled chicken and carrots for an extended period wasn't pleasant, he says, but he did learn that cutting out red meat, dairy, spicy foods and caffeine meant he did not have to start taking medication again.

Image copyright Matthew Peters Image caption Lewis Moody and Darren Fletcher have both suffered with ulcerative colitis

Since retiring from rugby in 2011, he has reintroduced some dairy produce into his diet without any problems.

"I'm lucky I managed to find a way to control it, but everyone has got their own way and their own regime," he says.

Manchester United footballer Darren Fletcher, who joined Moody to launch United for Colitis in aid of the charity Crohn's and Colitis UK, recently returned to playing for the club after a year out following surgery to help control his ulcerative colitis.

Everybody has a different form of inflammatory bowel disease, says Sarah Rogers from Crohn's and Colitis UK, and that is why it is so awkward to treat.

If you're unlucky, you may need to take a form of anti-inflammatory for the rest of your life or have an operation Sarah Rogers, Crohn's and Colitis UK

"If you're lucky, you can manage it on a diet alone - by avoiding foods that cause a flare-up. But if unlucky, you may need to take a form of anti-inflammatory for the rest of your life or have an operation. Even surgery is no guarantee of a cure."

Many people with the disease end up severely ill and housebound because they are petrified of having an accident. It can also have a significant impact on their work and social life.

Around 260,000 people are affected by Crohn's and colitis in the UK and there are up to 18,000 new cases a year. It is particularly common in developed countries.

New research is focusing on what could trigger the disease in individuals and on the role of bacteria in the gut.

At present, scientists think that both Crohn's and colitis are caused by a combination of factors including the genes we are born with, how our digestive systems react to bacteria in the intestine and a set of unknown triggers which could include viruses, stress and diet.

Moody is proud that, despite his debilitating illness, he never missed a game and still wanted to train.

"I've dealt with lots of injuries before and needed a determined mindset to get through them. With this, it was the same. I didn't want to let it beat me."

"I didn't want to be defined by it. It was just another hurdle to overcome," he says.

England's 'Mad Dog' knows no other way.