Caroline White was 16 when she began reading Harry Potter stories to her younger sister. She wished she was like Hermione Granger, the clever, bookish one who always passed her potions test. The trouble was that Caroline felt neither clever nor bookish. Unusual names such as Hermione made her stumble: “It was terrible I just couldn’t say it aloud. Hermy-owny, Her-my-one. My sister was in hysterics but I could barely get past the first chapter.”

What was even more humiliating was hearing the ten-year-old saying, “Mummy, I’m a better reader than Caroline because I can read Hermione.”

Six years later, Caroline is a self-assured student teacher. She believes she alleviated the problem with good old cod liver oil. It is called fish oil now that it’s made from sardines and pilchards and the makers have disguised the taste that disgusted a generation of postwar children but the proposition remains: fish is good for the brain.

It wasn’t until Caroline was in her early twenties that she was diagnosed with dyslexia, a difficulty with reading, writing and sequencing that is thought to affect 5 per cent of the population. Add to that related conditions such as dyspraxia (a developmental disorder that causes difficulty in activities requiring co-ordination and movement) and attention deficit disorder, and the figure rises to some 20 per cent.

Like Caroline, many people go undiagnosed for years. She masked her problems by asking friends to help and worked very, very hard. While she managed to gain reasonable grades in her GCSEs, A-levels were a different matter. “My grades were poor. I was hysterical when I saw my results. I lost my conditional place to do speech therapy at Cardiff and I was heartbroken.” She hastily accepted a psychology course through clearing but dropped out after a year.

Returning to the part-time job tutoring autistic children that she’d had since she was 16 confirmed to her that teaching was what she most wanted to do. But last year, when she began a four-year teaching course at King Alfred’s College in Winchester, her problems resurfaced.

“My assignments were being returned with low marks for spelling and grammar. I knew my spelling was poor but I’d never realised my grammar was so bad.”

She was referred to an educational psychologist. “She did lots of tests, said my IQ was above average then asked me to read a simple piece of text, without stopping and going back over words. I could hardly read it. When she asked me questions, I could only answer two — the first one and the last. I remembered nothing in the middle. She assessed me as mildly dyslexic.”

Far from being dismayed by such a diagnosis, Caroline was delighted. “It was a great weight off my shoulders. When I failed my A-levels and people around me were getting really good grades I thought I must be stupid.”

The diagnosis also allowed Caroline to get help. At college she has a weekly session with the dyslexia tutor, who helps to structure her assignments, teaches techniques for revision and for understanding essay questions. “I now know I have to read things over and over again to understand them.”

But Caroline had her breakthrough when she attended a conference in Edinburgh, in which Dr Alexandra Richardson, a senior research Fellow at Mansfield College, Oxford, presented a paper on the use of fish oil supplements.

Dr Richardson’s research is based on the premise that people with dyslexia and related conditions may be deficient in essential fatty acids, which are important for proper brain function, possibly because of a dependence on heavily processed foods or a failure in some people to metabolise them properly.

Intriguingly, Dr Richardson reported promising results from trials among schoolchildren suffering from dyslexia and attention deficit hyperactivity disorder (ADHD), who had taken nutritional fish oil supplements.

Caroline was immediately impressed: “There was nothing anecdotal about it, it was pure science. Her research sold it to me.”

She immediately began taking fish oil supplements. “After three weeks I found reading much easier and after three months was able to type much quicker. The proof came when I left an assignment to the last minute and was able to type 800 words in an hour. It was a miracle.”

However, when the college year ended and the summer vacation began, Caroline slipped out of the routine of taking the supplements. “When I returned to college in the autumn I looked at my computer screen and the words were moving. It was really shocking. I’d heard dyslexics talking about words dancing on the screen. Now I was seeing them.”

She resumed taking the fish oil and again her reading improved. “I decided to have one last stab at Harry Potter and to my delight I was able to read it almost straight through in two days. I very quickly moved on to the next one in the series. I still have problems with my written work, but can read any book to a class now without having to rehearse it at home. I also think dyslexia has made me a better teacher. I will never assume a child is lazy or not trying; like me, they could be covering something up. Dyslexia has given me an empathy with children. I know what it’s like to have that barrier; to feel you are different.”

WHAT ARE THEY?

FISH OILS are nutritional supplements that supply omega-3 and omega-6 fatty acids from marine fish and botanical oils. They are essential for normal brain function and occur naturally in oily fish, such as sardines and mackerel, and green leafy vegetables and some nuts. Capsule or liquid formulations provide a concentrated dose for those who may be deficient in these fatty acids. Once adequate levels have been reached, these can be reduced to a maintenance dose.

SUITABLE FOR adults and children suffering from dyslexia, dyspraxia and attention deficit disorder, for good eye and brain function.

COST Eye Q £7.99 for 60 capsules (dose: 12 capsules a day) from www.equazen.com. MorEPA £12.99 for 60 capsules (two capsules daily) from www.healthyandessential.co.uk. Seven Seas Cod Liver Oil capsules, £4.49 for 60 daily doses at Sainsbury’s

CONTACT Food and Behaviour Research at www.fabresearch.org