Background
Over the years there have been a number of different approaches to diet in UC. Even now advice may vary from one treatment centre to another. Understandably, many people are confused as to which diet they should be following.

Advice will vary depending on the site of the disease and past and current treatments. However, it is generally agreed that in most cases of UC, the normal guidelines for a healthy balanced diet should be followed.

What is a balanced diet?
The basic dietary principles for UC are no different to those for the general population. Starchy foods (potato, rice, bread, pasta, breakfast cereals) should form the basis of all meals. Fruit and vegetables should also form a large part of the diet, unless otherwise indicated, with at least five portions per day. Dairy foods, which provide calcium and protein, should be taken three times a day. Protein foods, (meat, fish, eggs, pulses, nuts, etc.) are essential for growth and repair and also provide iron - these should be taken twice daily. Other foods ( spreads, oils, fatty and sugary foods, alcohol, etc.) provide few nutrients other than energy but add variety to the diet – these should be enjoyed in moderation only. The diagram shows in which proportions these foods should be eaten to maintain a healthy balance.

Diagram required

However, having an illness of the digestive tract will have an effect on the way in which your body handles food. For some people this may mean they have difficulty in eating such a wide variety of foods or that they have increased requirements for certain foods.

How does inflammation affect dietary requirements?
When the gut becomes inflamed pain, discomfort or nausea may experience. These can cause appetite to be poor, which after a while, will lead to weight loss.

An inflamed large intestine may not be able to reabsorb sufficient water or salt from the bowel and this can result in the passing a large volume of diarrhoea or semi-solid stool. Protein loss can occur from leakage of the damaged intestinal lining. If this lining bleeds there is a risk of becoming deficient in iron which can lead to anaemia.

When medical treatment is used to reduce the symptoms of a relapse, appetite should then return. A nutritious diet, high in calories and protein, is then needed to replace lost energy and nutrients.

If appetite remains poor for a while, small, frequent meals and snacks may be more manageable than a few large ones. Extra energy can be obtained from simple carbohydrates or sugars such as sweet drinks, biscuits and sugary desserts, but try to have these in addition to other foods rather than instead of them, as they supply little if any extra vitamins or minerals. Special high energy and nutritious drinks can be obtained on prescription from your doctor. Medical advice should be sought if you are losing weight or struggling to regain it.

Fluids need to be replaced during bouts of diarrhoea and vomiting to prevent dehydration. Usually this can be achieved by drinking more liquid but in severe cases, a solution of salt and glucose in water may be prescribed to improve absorption. In hospital, fluid losses are sometimes replaced by giving fluids into a vein.

Should the inflamed gut be rested?
When the gut becomes inflamed, eating frequently provokes pain because the lining of the intestine is irritated by food passing through. However, it is unwise to stop eating and drinking altogether, as this will make the body very weak.

In certain circumstances, for example if the gut has become completely obstructed, it may be necessary to stop eating and receive nutrition via a vein into the blood. This is known as Total Parenteral Nutrition (TPN). There is no evidence to suggest that resting the gut in this way reduces inflammation in ulcerative colitis. Medical treatment and/or surgery will be needed and once the gut can be used again, the diet can be built back up to normal. This is different to Crohn's disease where TPN 'dampens' down inflammation in most cases and is sometimes used as a treatment or as preparation for surgery. Special artificial diets known as 'enteral diets' are also effective in Crohn's disease to reduce inflammation, but they are not helpful in ulcerative colitis.

Are there any foods that should be avoided?
The answer to this depends to some extent on whether you have Crohn's disease or ulcerative colitis. Some people with Crohn's disease demonstrate intolerances to certain foods and they are therefore advised to avoid these. However, this should only be done with medical and dietetic supervision. People with ulcerative colitis do not normally demonstrate food intolerance but may find that certain foods aggravate their symptoms.

The guidelines for a healthy normal diet should be followed, restricting or avoiding those foods that aggravate symptoms. Some common irritant foods are discussed below:

High Fibre Foods
The amount of fibre in the diet needs to be tailored to the individual. During a relapse, high fibre foods such as wholemeal bread, high fibre breakfast cereals, dried fruit and pulses, beans, lentils, peas and sprouts, may make diarrhoea worse. Reducing fibre may help reduce bowel movements. When symptoms improve, fibre can be gradually reintroduced back into the diet to the level that is tolerated.

Those who suffer from constipation or who are troubled by passing hard stools need to maintain an adequate level of fibre in the diet. Bulking agents, stool softeners or osmotic laxatives may be helpful and should be discussed with a doctor or nurse.

High Fat Foods
When the small intestine is inflamed in Crohn's disease the capacity to absorb fat is impaired and even a moderate amount of fat in the diet may cause wind and diarrhoea. Restricting high fat foods may help. However, it is important to replace these foods with carbohydrate- and protein-rich foods to prevent weight loss.

Lactose (milk sugar)
Lactose is the sugar found in milk and some dairy products. A small number of people may find they are not able to absorb lactose very efficiently. Unabsorbed lactose reaches the large intestine and can cause wind and diarrhoea. This may happen only during a flare-up of the disease.

Usually small amounts of milk, for example in tea or coffee, do not cause any problems. Dairy products such as butter, cheese and yoghurt are also well tolerated. If milk is excluded, it should be replaced with low lactose milk or with soya milk. This should be discussed with a dietitian to ensure nutritional balance is maintained.

Other possible irritant foods
Some foods may irritate the lining of the intestine even in people without IBD, but when inflammation is present this may make the intestine more sensitive. Some people find beer or other alcoholic drinks; excess fruit or fruit juice, onions and spicy foods aggravate symptoms.

If there is a narrowing of the intestine, some foods that are not well digested may cause colicky pain. This happens when the intestinal muscles contract strongly to try to push the food through the narrowed area. Fibrous vegetables, gristle, dried fruit, skins, pith, seeds and nuts may cause such problems and should be avoided if this is the case.

Wind is caused by bacterial fermentation of food residues in the colon. If fat or lactose are not absorbed properly these may be fermented in the colon and give rise to excess wind. High fibre foods that are not digested completely may also have this effect.

Does surgery affect dietary requirements?
Resection of part of the large intestine in either Crohn's disease or ulcerative colitis does not usually require a special diet. After the operation, the diet will be built up gradually from liquids to a light diet and then back to a normal diet. If the whole of the large intestine is removed, an ileostomy or pouch will be formed. The small intestine needs some time to adapt to some of the functions of the large intestine and, at first, plenty of fluids and salt are required. It is advisable not to take too much fibre initially to reduce output from the stoma, but this can be gradually increased to suit the individual. Absorption of nutrients is usually normal, (unless, in the case of Crohn's disease, some of the terminal ileum has also been removed) and therefore patients should keep to a normal varied diet. Patients with ileostomies may prefer to avoid foods, which cause an unacceptable odour such as onions, lentils, pulses and sprouts.

Are vitamin and mineral supplements necessary?
Absorption of minerals and vitamins is usually normal in ulcerative colitis, even in the presence of diarrhoea, as the main site of absorption, (i.e. the small intestine), is not affected. However, extra iron may be required if there has been extensive bleeding and anaemia is diagnosed. If the diet is very restricted, for example fruit and vegetables are poorly tolerated, this may result in a reduced intake of certain vitamins and minerals. A multivitamin and mineral supplement may be helpful. Very large doses of individual vitamins and minerals are rarely required. Those who find they need to restrict lactose should discuss their diet with the dietitian and may require a calcium supplement.

However, if you do not have specific vitamin or mineral deficiencies, there is no evidence to suggest that extra vitamins and minerals in the form of a supplement are necessary or helpful in ulcerative colitis.