Situated beneath the diaphragm in the upper right part of the abdomen, the liver is the largest organ in the body (weighing 1-1.5kg in adults). All of the blood that leaves the stomach and intestines must pass through the liver before reaching the rest of the body. The liver is thus strategically placed to process nutrients and drugs absorbed from the digestive tract into forms that are easier for the rest of the body to use. In essence, the liver can be conceived of as the body's refinery.

Furthermore, your liver plays a principal role in removing toxins from the blood whether they were ingested or internally produced. The liver converts them to substances that can be easily eliminated from the body.

Many drugs taken to treat diseases are also chemically modified by the liver. These changes govern the drug's activity in the body.

The liver also makes bile, a green-yellow fluid which contains detergent-like substances essential for digestion. Bile is stored in the gall bladder which contracts are eating, and discharges bile into the intestine.

HOW ARE NUTRITION AND THE LIVER INTERRELATED?

Nutrition and the liver are interrelated in many ways. Some ways are well understood; others are not. Your liver plays a key role in converting food into the chemicals essential for life. The liver serves several important metabolic tasks in handling nutrients.

Carbohydrates (sugars), absorbed through the lining of the intestine, are transported through blood vessels to the liver and then converted into glycogen and stored. The liver breaks down this stored glycogen between meals, releasing sugar into the blood for quick energy to prevent low blood sugar levers (hypoglycaemia). This enables us to keep an even level of energy throughout the day. Without this balance we would need to eat constantly to keep up our energy.

The liver is vital in maintaining the body's protein and nitrogen metabolism. Proteins in foods can be broken down into amino acids in the intestine and delivered to the liver for use in making body proteins. Excess amino acids are either released by the liver and sent to the muscles for use or are converted to urea for excretion in the urine. Certain proteins are converted into ammonia, a toxic metabolic product, by bacteria in the intestine or during the breakdown of body protein. The ammonia must be detoxified by the liver and made into urea which is then excreted by the kidneys.

Through the production of bile, the liver makes it possible for dietary fat to be absorbed. In addition, vitamins A, D, E and K, which are fat soluble, are dependent on bile from the liver for absorption.

HOW DOES THE LIVER AFFECT NUTRITION?

Many chronic liver diseases are associated with malnutrition. Patients with cirrhosis are often malnourished, with wasting of the muscle mass and an emaciated appearance. An inadequate diet alone does not contribute to the development of the liver disease. People who are well nourished, but drink alcohol, are also susceptible to alcoholic liver disease. It is know that a dramatic loss of weight (35-50%) can be associated with liver disease of any type. Such severe weight loss is encountered in starving populations or in obese patients who have had their intestines surgically shortened as a means of reducing weight.

WHY SHOULD PEOPLE WITH LIVER DISEASE MAINTAIN A WELL-BALANCED DIET?

It is vitally important that patients with liver disease maintain a balanced diet, one which ensures adequate calories, carbohydrates, fats and proteins. such a diet will aid the liver in the regeneration of liver cells. Nutrition that supports this regeneration is a means of treatment of some liver disorders.

Patients with cirrhosis, for example, who are malnourished, require a diet rich in protein and providing 2000-3000 calories per day to help the liver re-build itself. However, some cirrhotic patients have protein intolerance. Too much protein will result in an increased amount of ammonia in the blood, while too little protein can reduce healing of the liver. Doctors must carefully prescribe a specific amount of protein that will not elevate the blood ammonia. Lactulose and neomycin are two drugs that help keep the ammonia down.

It is believed that the risk of gall bladder disorders can be reduced by avoiding high fat and cholesterol foods and preventing obesity. The gall bladder is a storage sac for the bile produced by the liver. During digestion, the gall bladder releases bile into the small intestine through the common bile duct. Most gall bladder problems are caused by gallstones and 80-90% of all gallstones are produced from excessive cholesterol which crystallises into small stones. By maintaining a well-balanced diet and avoiding high cholesterol intake, the incidence of gallstone formation may be lowered.

WHEN ARE SPECIFIC DIET RESTRICTIONS REQUIRED?

Beyond the maintenance of a good, well-balanced diet, several liver conditions require specific dietary management.

HEPATIC ENCEPHALOPATHY

Hepatic encephalopathy is a condition of impaired mental functions due to altered liver function. It is often seen when scar tissue formation (cirrhosis) in the liver prevents the normal flow of blood through the liver. The blood which contains toxins is "shunted", or redirected, back to the central circulation and into the brain without first going through the liver for detoxification. Cirrhosis with portal hypertension (an elevation of the portal pressure due to the obstruction of blood flow through the liver) may be treated surgically by shunting some of the blood around the liver, connecting the portal system with the systematic circulation. This "shunted" blood contains high concentrations of amino acids and ammonia and probably, other, as yet unidentified, toxic substances they may cause altered mental function is some patients.

The treatment for hepatic encephalopathy is aimed at reducing toxins that cause this disorder. Just as patients with cirrhosis who have protein intolerance must restrict protein intake, so most patients with hepatic encephalopathy reduce the amount of protein in their diet. Severe protein restriction (to 20 grams a day or less) is impractical for long term therapy. Most physicians will encourage their patients to take approximately 40 grams of protein a day and will prescribe lactulose and neomycin to decrease the production of ammonia in the intestines. Certain specific amino acids (hepatmine) may be less likely to cause hepatic encephalopathy and have even been suggested as therapy. Certain foods (vegetables, milk) contain protein rich in these amino acids and are preferred to meat as a source of protein in affected patients. A dietary supplement rich in these amino acids (hepatic-aid) is available and is in use in many liver centres.

ASCITES AND OEDEMA

Ascites is the accumulation of fluid in the abdominal cavity. Oedema is fluid built up in the tissues, usually the feets, legs or back. Both conditions result from abnormal accumulation of sodium associated with portal hypertension and liver disease. Most affected patients will not require strict fluid restriction. Sodium intake is often restricted for patients with cirrhosis to avoid retention of fluids in the body. Such a diet would allow only 2-4 grams of sodium and would exclude canned soups and vegetables, cold cut meats, condiments such as mayonnaise and tomato sauce, dairy products, cheese and ice cream. Most fresh foods are low in sodium. The best salt substitute is lemon juice (which is salt free).

CHOLESTASIS

Cholestasis is an inability of the liver to excrete bile. This may result in steatorrhoea (fat malabsorption due to inadequate amounts of bile which dissolve fat in the intestines). Steatorrhoea may go unnoticed by the patient or can be associated with weight loss due to lost calories. Stools may be foul smelling and float. Fat supplements are available; the most commonly used being medium chain triglycerides (MCT oil) and safflower oil which are absorbable with less dependence upon bile. They may be used as a caloric supplement. MCT oil is used like any other cooking oil, in salad dressings or in cooking. Patients with steatorrhoea may also have difficulty absorbing fat soluble vitamins. However, water soluble vitamins are absorbed normally. Supplementing the diet with fat soluble vitamins is possible, though it should only be carried out under the guidance of a physician.

WILSONS DISEASE

In Wilson disease there is a defect in copper metabolism. Patients affected by this disorder have an abnormal build-up of copper in the body due to the inability of the liver to excrete it. This inability allows the copper to accumulate in several organs: first the liver and then, usually the brain and the cornea of the eye. Treatment involves the use of a de-coppering agent, penicillamie, which removes the excess copper from the body. Dietary therapy for this disease includes the avoidance of copper-containing foods like chocolate, nuts, shellfish and mushrooms.

HAEMOCHROMATOSIS

Haemochromatosis is a disease in which there is an inappropriate absorption of iron from the intestine. The excessive iron then accumulates in the liver, pancreas, and other organs in the body. Patients with this disease should not be given iron supplements. Aside from this precaution, those with haemochromatosis may follow a normal diet. Treatment is achieved by frequent removal of blood from a large vein.

FATTY LIVER

Fatty liver is related to alcohol, obesity, starvation, some drugs and other factors. It is not caused by eating fat and it should be treated with a well-balanced diet or the removal of the responsible chemical substance or drug.

Finally, patients with liver disease should be wary of supplements to the diet, particularly fad foods or packaged "nutritional" aids. Such foods can contain a lot of salt, potassium or inappropriate protein mixtures. Those that are safe should be taken only under a physician's guidance.

This brochure is for information only. In each individual case professional medical advice should be obtained.
The information contained in this fact sheet is reprinted with the permission of the Canadian Liver Foundation.

Children's Liver Alliance