FRED RITTER was sure that his breakfast bran would keep him healthy. After all, most health education messages were stressing the importance of dietary fibre in the prevention of bowel cancer and other diseases.
So each day, the 53-year-old businessman ate a portion of bran. Then, eight months or so into his new health regime, he became ill with abdominal pains and chronic sickness.
When puzzled surgeons operated they found that his bowel had effectively seized up, with solid bran blocking the small and large bowels. So firm was this mass of fibre that it had to be cut away. But some of it had also got into the body tissue where it sparked off toxic reactions. He has now had four operations, with a fifth likely.
"I started taking bran after I was told it was good for the bowel, but my life has been completely devastated by it," he says. "The effects on me of taking something which was meant to be healthy have been unbelievable, and I was only taking half the recommended amount a day.
"After the last operation, my body went into shock and all the involuntary muscle system in the gut totally stopped. I couldn't keep anything down and I dropped from 12 or 13 stones to nine. I have now been told this week that I will need a fifth operation."
Bran is one of a huge range of health foods, supplements and vitamins whose consumption has rocketed in the last two decades. But while some can be beneficial, it is being increasingly recognised that many are toxic in large and even moderate amounts, however natural and innocuous they appear. In very high concentrations, even carrot juice can kill.
"A patient who consumed quite phenomenal quantities of concentrated carrot juice and who was also taking vitamin pills containing A and B, gradually increased the amounts and eventually started to turn orange. His GP diagnosed jaundice, which may have in part been true because there was indeed liver damage, and he died," says Dr Mike Clifford, leader of the food safety research group at the University of Surrey.
Vitamin C, one of the most popular of vitamin supplements, which is taken for a diverse range of motives, from the prevention of cancers and colds to stopping cataracts forming, has also now been shown to be toxic.
Research by a team of specialists at the University of Leicester established that taking more than 500mg of vitamin C daily, not uncommonly recommended amounts, increased the levels of particular chemicals in the blood which indicate that DNA is being damaged. Over the long term, that kind of DNA damage is associated with cancer, rheumatoid arthritis, and heart disease.
"Some companies say that a gram a day is the amount of vitamin C to be taken, while supermarket shelves suggest 500mg a day. But extrapolating our figures, that would do damage. Unless you're very severely deficient in vitamin C, you don't need to take those sizes of doses. Yet some people do so for years," says Professor Joseph Lunec of the university's chemical pathology department.
Over-indulgence in beta-carotine, the main source of vitamin A, has also been linked to an elevated risk of cancer, while high doses of vitamin B6, a substance often used by women to relieve pre-menstrual tension, can cause neurological symptoms like tingling and numbness.
Nuts and dried fruit, which have increasingly become part of health-food diets, can be a source of illness too. Mould growth as a consequence of poor storing can produce toxins like aflatoxin and ochratoxin which have been linked to liver damage, nervous system problems and cancer.
Consumption of dried fruit, rich sources of vitamin C and fibre, has also shot up, but can also cause rare problems. In the current issue of the British Medical Journal, surgeons in Portsmouth report the case of a woman who underwent an emergency operation seven days after she had swallowed a dried apricot. The fruit had reconstituted itself, swollen in size and blocked her intestine.
Some Chinese supplements and alternative medicines have been associated with a range of toxic side-effects. Doctors have, for example, been alerted to the potential dangers of products containing a herb called gwai-kou, which has been reported as causing damage to the central nervous system, paralysis, nerve damage, comas and convulsions among users in Hong Kong.
Fred Ritter wants to see clearer warnings about the potential hazards of health food, a view echoed by his surgeon, consultant Mr Ken Shute, of the Royal Gwent Hospital.
"You would not expect a relatively innocuous substance like bran to cause this kind of problem, but it has, and people need to be aware that anything that has an effect must have a side-effect," he says.
"He presented with abdominal pain, vomiting, and classic small bowel obstruction symptoms. When we operated we found this mass of solid bran that was totally obstructing the bowel. Tiny bits of bran had also got into the tissue and caused the most astounding inflammatory tissue reaction. His main problem was obstruction but that led to this tissue reaction leading to fibrosis and recurrent intestinal obstruction.
"There is no doubt that western populations don't take enough fibre, and as a result we end up with bowel disorders. But the problem is that if we try to put it all right in one go, we can do ourselves a lot of harm. When we give advice to people that a high-fibre diet is good for you, we really have to also give warnings not to overdo it. I think there is a public perception that there is no limit to the amount of goodness something like bran will do.
"Good nutrition is a mixed diet, everything in moderation, avoid excesses, and don't go on fads where you have ridiculously low levels as part of a diet or ridiculously high levels as supplements," he says.
He agrees that there is common misconception that there is no limit to the amount of benefit to be had from health foods and supplements, and no dangers in having larger amounts.
"If we are hearing one loud message that says that if we don't have vitamins we run the risk of disease, and a much quieter message that too much is not a good thing, there is an imbalance in the message and people will get the wrong idea. But of course there are plenty of companies which make money by selling a lot of supplements and health foods and they don't make so much money by warning people not to consume too much."
The health food and supplement industry is big business, with business worth, according to one estimate, more than $250bn a year in the USA and Europe. Vitamins make up a substantial share of the business but, as Dr Robert Youngson, author of Medical Curiosities, says, few of us really need the high levels we take: "Any reasonable mixed diet, especially one featuring breakfast cereals, will contain far more than the minimum requirements."
In fact, as he points out, vitamins and supplements are so widely available in an average diet, we would all be hard pressed not to get the vitamins we need in the everyday food we eat.