The human body's immune system is designed to recognise any foreign material in the body and start up a complicated series of events to remove the foreign material. Normally this system recognises foreign material like viruses, bacteria or a thorn in the skin. The defence mechanisms then destroy these and protect us from further infection.
This defence mechanism also monitors the uptake of digested food in the small intestine. Starches, sugars and fats are simple molecules and present no problem to this system. The more complex proteins may be recognised as foreign and stimulate the immune system, particularly if the lining of the small intestine has suffered slight damage and the protein is being absorbed in an undigested state.
Gluten is a mixture of complex protein found in the grain of wheat. Similar proteins are found in barley, rye and, to a smaller extent, in oats. It is also found in the wild relatives of these grains such as spelt.
Gluten is recognised as a foreign substance by the lining of the small intestine in some people. This results in an immune response: inflammation with swelling and soreness. Over a period of time the lining of the small intestine breaks down and loses the tiny villi that absorb the food. This is the coeliac condition.
Once this has happened the only cure is to avoid all food that contains gluten. The immune system remembers all past foreign material and will respond rapidly to a recurrence of the invasion.
Symptoms of the immune response to gluten can range from a feeling of heaviness after a meal to persistent diarrhoea and abdominal swelling and pain. The damage to the small intestine can then result in weight loss and many other symptoms linked to the poor absorption of food such as anaemia. Because the symptoms are so variable and similar to other diseases the diagnosis of the Coeliac condition should always be made by a doctor.
Symptoms can appear at any age. They may first appear when a baby is weaned onto foods containing gluten, or in a few cases they may appear first in old age. Some doctors now think that weaning babies onto foods containing gluten may increase the chance of the coeliac condition arising in later life. Bread and biscuits containing wheat flour should not be introduced into the young child's diet until at least seven months old. If there is any family history of adverse reactions to food then the baby's diet should be free of gluten until one year old.
When a person suffering from the coeliac condition first starts a gluten free diet the response may be dramatic but usually a slow but steady improvement over several weeks or months can be expected. This is because of the time it takes for the lining of the digestive system to regrow.
A coeliac on a gluten free diet should remain on this diet for life.
The immune system will remember gluten and although the response to an isolated inadvertent intake of gluten may be slight, a repeated stimulation to the immune system can cause prolonged damage. This can occur with few apparent symptoms.