Margaret Moss reports and comments on the Allergy Research Foundation/Allergy Academy conference: Food intolerance – whose problem is it?
Dr Michael Radcliffe, an allergist, said that adverse reactions to foods can be divided into allergy mediated by IgE antibodies, allergy not mediated by IgE antibodies, and non-allergic food sensitivity. He said that elimination diets can result in considerable reductions in days in hospital, outpatient appointments, repeat prescriptions and GP consultations. The reliability of tests is limited. They may fail to pick up problem foods, or they may pick up foods that are not a problem.
Professor Simon Murch, a paediatric gastroenterologist, said that hay fever was first reported in the early nineteenth century. By the end of that century it was common, probably because of particulates in the air. In the middle of that century, asthmatics and people with eczema were noted to have digestive problems.
Unfortunately today many doctors tend not to connect symptoms in different parts of the body. As infectious disease has reduced, allergy has increased. Eosinophilic oesophagitis is driven by immune system cells called T cells, not by IgE antibodies. Babies learn not to mount an immune system attack against foods. This acceptance of foods by the immune system is called tolerance. Allergy may be caused by a failure to establish tolerance towards certain foods in the first place, or by a loss of tolerance later on. The right gut microorganisms establish tolerance to foods. Toothpaste and braces both contribute to allergy.
Dr Nikhil Thapar, a paediatric gastroenterologist, said that most allergic children have gastrointestinal problems. The immune system in the gut, and the nervous system controlling the passage of food through the intestines, send messages to each other. Mast cells, and other cells called eosinophils, in the gut produce many chemicals that can damage it.
The dietician, Dr Rosan Meyer, advocates eliminating food additives, and reducing salicylates and amines, at different times. Yet Dr. Rapp has pointed out that, if you have a lot of nails in your shoe, removing one has little effect. An elimination diet that does not remove enough may fail to produce any result. Moreover, salicylates are only one type of phenol that causes reactions in susceptible people.
Dr. Meyer uses milk pre-treated with the enzyme lactase, to break down the double sugar in milk, called lactose, into glucose and galactose. That worries me, as drinking ready made galactose may be more damaging for the arteries than digesting lactose gradually. She would give a multivitamin if the diet were short of fruit and vegetables, but would not give vitamin therapy that addressed the cause of the intolerances. What about vitamin D, in order to help the T Regulatory cells calm down the immune system?
The vet, Dr Karin Allenspach, sees dogs with chronic gut problems. More than half have food responsive diarrhoea. Antibiotics work in a minority of cases. Testing IgE and IgG antibodies is not helpful, but there are other useful antibody tests. Eating an elemental diet, in which all food is pre-digested, is useful in over half of cases. She said that giving probiotics does not help in this illness, but does in others. Raw diets are advocated by some, but they can lead to campylobacter infections.
Dr Kamran Rostami, a gastroenterologist, told us that an average of 10 to 20 grams of gluten are consumed per day by Europeans, but sometimes some people may have as much as 50 grams in a day.
Coeliac disease is an autoimmune condition related to eating wheat, rye and barley. In the 1950s, only the most serious cases were diagnosed. The villi of the small intestine are finger like structures which increase the surface area, allowing more food to be digested. In coeliac disease these are destroyed, leading to a reduced surface area for absorption, and so to poor absorption of food, especially fats and fat soluble vitamins. Now coeliac disease is diagnosed in far more people than in the past.
Wheat protein allergy is a different disease from coeliac disease. It is diagnosed by skin prick tests and IgE antibody tests, but positive tests may be due to pollen allergy, not wheat allergy. So the tests are not reliable. Wheat protein allergy may affect the gut, skin, and respiratory system. It can cause exercise induced anaphylaxis, baker’s asthma, and rhinitis, and skin contact can cause a nettle-like rash.
Non coeliac gluten sensitivity is diagnosed when gluten causes reactions that are not due to coeliac disease or wheat protein allergy. I asked what Dr. Rostami thought about research suggesting that sourdough bread is better tolerated than ordinary bread. He did not know if it was better, but he thought it was plausible.
Dr Marios Hadjivassiliou, a neurologist, said that, for every 7 patients with coeliac disease arriving at a gastroenterology clinic, two arrive at a neurology clinic with dysfunction in the part of the brain called the cerebellum. Coeliac disease can cause a lack of coordination and balance, damage to the peripheral nervous system and jerking. Nearly half of coeliacs have headaches similar to migraine. Over half of coeliacs have neurological disease that shows up on MRI scans.
Professor Anthony Campbell, a scientist, said he thought that Charles Darwin was intolerant to milk. About two thirds of the world’s population loses most of the lactase enzyme, that breaks down milk sugar to glucose and galactose, by adulthood. So they only tolerate a small amount of milk.
Many people with irritable bowel syndrome and inflammatory bowel disease have limited tolerance of lactose, the sugar in milk. This can cause gut pain, diarrhoea, constipation, muscle and joint pain, palpitations and frequent passing of urine. Milk sugar that is not broken down is not absorbed, and feeds microbes in the gut, which produce various chemicals, which can inactivate hormones and neurotransmitters. Poor absorption of other sugars, including glucose, galactose and fructose, also causes symptoms. He criticised the official advice not to test for lactose intolerance in irritable bowel syndrome.
Professor Glenn Gibson, a microbiologist, told us that microorganisms in our intestines influence the immune system. These gut organisms may be different in fat people from thin people. Bacteria that change sulphate into sulphide use sugars as fuel, and produce hydrogen sulphide, which is harmful. Other bacteria produce different gases. The bifido bacteria often sold in probiotic capsules do not produce gas. Probiotic bifido, acidophilus and lactococci bacteria reduce flatulence, diarrhoea and bloating.
He works on prebiotics, foods that we cannot digest, that feed beneficial bacteria. Transgalactooligosaccharides, or TOS for short, are chains of galactose that increase some bacteria in the gut, and increase SIgA, a beneficial antibody, while reducing other bacteria, and chemicals that are involved in inflammation. Some similar chains of sugars, like fructooligosaccharides (FOS) can produce flatulence, but TOS does not. He said we cannot assume that, when such chains of sugars are put into processed foods, they still act as probiotics. This must be tested.
It was an interesting day. I should have liked a little on food toxicity. Foods are mixtures of nutrients and toxins, natural and added, and I find it beneficial to reduce the toxins in the diets of people with symptoms arising from food. Certainly matters have progressed since the days when you were told that, if your biopsy for coeliac disease was normal, and you could digest lactose, then your problems must be heavily psychological.
However, it seemed to be assumed at this meeting that you can easily eliminate any sort of biochemical problem, and having done so turn to immunology. This does seem simplistic. Sometimes biochemical problems are due to total inactivity of a protein. There is a fair chance that that may be detected early by a paediatric clinic. However, often a gene causes a protein to be made a bit wrongly, so that it works up to a point, but inefficiently. This may well not be detected in childhood, and we have only a very few units for adult metabolic disease in this country. There are many genetic differences between people, which are called polymorphisms. Some of these affect our processing of foods. I myself have at least four of those. We have medical as well as scientific immunologists, although not enough of them. Until we have either scientific biochemists who see patients, or medical biochemists, the chemical causes of food sensitivity will be neglected.
Another point that could have been made is that, in allergy, even very small amounts of food matter. In food sensitivity, the amount of food consumed matters. Someone with lactose intolerance may tolerate milk in a cup of tea, but not a whole glass of milk. A person’s ability to absorb the fruit sugar fructose may be normal, but a diet of smoothies and fruit juice may involve too much fructose to absorb, and the remaining fructose may feed gut microorganisms, producing a painful amount of gas. Another person may be able to absorb and process a certain amount of fructose, but may be unable to carry out the chemical processing of all the fructose, in a diet high in smoothies and fruit juice.
It was an interesting day, and it was good to see a hall full of professionals wanting to learn about food allergy and intolerance. It was good that the limitations on testing were mentioned. I remember the late immunologist, Dr. David Freed, saying that, just because nothing has shown up on testing, it is wrong to assume that there is nothing wrong.