Dave Reavely has dedicated his life's work to unravelling the mysteries of the food we put on our tables every day. He is a kind of food detective.

As a nutritional therapist, the Sunderland-born 54-year-old advises people on which foods could cause problems in their diets.

It's a career with very personal roots in Dave's own childhood – at just nine years old, he began to experience the first signs of arthritis.

Dave, who grew up in Nookside, said: "I was quite sporty and my left knee began to swell up after a game of football. I saw a doctor in Sunderland and he put my leg in plaster for six weeks and after that it was fine so I thought no more about it.

"But then the arthritis came back in my other joints when I was in my teens, and by then I was old enough to realise the implications."

Both his parents had been diagnosed with the debilitating condition, but instead of resigning himself to fate, the teenage Dave began to search for answers and a possible cure.

He said: "Both my parents had arthritis so I knew it could be genetic.
There's a tendency for people to believe that nothing can be done about genetic problems so I set out to prove otherwise.

"I spent a lot of my free time playing football, weight lifting, swimming and running and the arthritis was stopping me from doing that."

Dave switched from a typical "western" diet to eating more fruit and vegetables and cutting out processed foods, and was delighted with the results.

He said: "I went to the City Library where I was drawn towards the books on nutrition. It was a revelation to realise that diet could be influential to my health.

"When I changed my diet I was able to continue with all these sports."

Dave's third book on the subject, called The Big Fat Mystery, has just been published, and it follows on from The Natural Athlete and The Cool Kid's Guide to Healthy Eating.

It is a practical guide to food intolerances and how they can stand between dieters and their quest to shed pounds.

Packed with recipes, advice and snippets of Dave's own experiences, the book is a welcome bite of common sense in a sea of faddy diets.

Dave left Sunderland when he was 22 to train as a PE teacher at the Northumberland College of Education in Ponteland.

He said: "Being my main subject, sport inspired my first book, The Natural Athlete, which was all about healthy eating for sports people."

Helping athletes reach their peak through nutrition is still part of Dave's work, and he is nutritional advisor to Jamie Johnson, one of the UK's first female professional boxers, and world title contender in the USA.

He now lives in Croydon with his partner Jenny, and works as a nutritional practitioner, and food intolerance tester.

His work has won him the support and friendship of Jan De Vries, one of the UK's leading practitioners of alternative health, and a regular guest on Richard and Judy and Gloria' Hunniford's Open House.

Dave said: "I met Jan when I was working in Scotland. I knew he lived nearby so I sent him the manuscript of one of my books and he invited me around.

"I was picked up in a white Mercedes and taken to his mansion. He is a lovely chap and I feel like I've known him all my life.

"He said he liked the book and offered to write the foreword and he's also written an endorsement for The Big Fat Mystery."

The inspiration for The Big Fat Mystery came from Dave's work with business partner Viv Farrant, offering food intolerance testing.

Dave said: "We've dealt with an incredible number of people who are affected by food intolerances.

"People know if they have a food allergy because their body will react within minutes. If they are allergic to say, kiwi fruit, their lips may swell up and they can make the connection straight away.

"But most people with food intolerances can be affected hours or days later."

Food intolerances can cause a range of problems – poor digestion, bloating, acid reflux, and indigestion – which can lead to long term problems with Irritable Bowel Syndrome and constipation.

Dave said: "By missing out the offending foods the body has a chance to recover. Food intolerances don't just cause digestive problems, they can cause skin complaints, migraines, and we've even treated one person with depression. With the food intolerance testing we observed a lot of people who were finding it difficult to regulate their weight. Some were training five or six times a week and eating sensibly but were still hitting a plateau.

"We would find that they were intolerant to wheat and that would make the difference – this inspired me to write the book.

"I helped a marathon runner last year who was overweight, but fit. He had a wheat intolerance and by cutting it out of his diet he lost two stone in 12 weeks.

"When a body is intolerant to something it sees it as a toxin and retails fluid to dilute it."

Dave practises what he preaches with zeal.

He said: "Now I am a vegetarian because I find it suits me better. My diet is based around good, organic fruit and veg and I avoid grains because I have an intolerance to them.

"My health is pretty good. I go the gym five times a week, I play five-a-side and I swim.

"I often think about what would have happened if I hadn't changed my diet and I honestly think I would have ended up in a wheelchair by now."

"There's a lot of stuff about 'super' foods in the media and I think it's very confusing for people.

"In my experience, a lot of people react badly to wheat and refined carbohydrates like white bread and white flour and refined sugar.

"If people want to see an improvement in their health then small overall changes can have a big impact.

"If the problem is quite serious then I would recommend seeing a nutritional therapist."

* Dave Reavely is a member of the British Association of Nutritional Therapists, and holds a diploma in Nutritional Medicine. For more information visit: www.fooddetective.co.uk

The Big Fat Mystery is published by John Blake Publishing, and is available to buy on amazon.co.uk from May 5.

Dave's top tips

1. Go organic. Organic fruit and vegetables are more expensive, but better for your body and peace of mind in the long run.

2. Avoid "super" foods touted by the media and try to eat everything in moderation.

3. If you believe you have an allergy or an intolerance, seek help from a qualified nutritional advisor.

4. Eating the right food is a brilliant start to good health, but make sure you are doing enough exercise each week.

5. Don't panic if you slip up. The odd chocolate bar does not mean you've failed, and is an essential part of a well-rounded approach to your diet.

For recipes from Dave's book make sure you get a copy of today's Echo.