Consultant Dietician, Great Ormond Street Hospital, London. *
|The human liver is one of the most important organs involved in the metabolism and storage of nutrients.
The liver plays a major role in carbohydrate metabolism. Galactose and fructose - products of carbohydrate digestion, are converted into glucose in the hepatocyte. Liver stores glucose as glycogen and then returns it to the blood when glucose levels become low.
Proteins are converted to substrates that are utilized in energy and glucose production. Liver detoxifies ammonia by converting it to urea, 75% of which is excreted by the kidneys. Synthesis of vital protiens of the blood takes place in the liver.
Fatty acids from the diet are converted in the liver to produce energy.
Vitamins and minerals
The liver stores all of the fat - soluble vitamins in addition to zinc, iron, copper, magnesium and vitamin B12.
The objectives of dietary treatment in hepatitis are to aid in the regeneration of liver tissue and to prevent further liver damage. A high caloric diet daily is needed to promote weight gain and to ensure maximum protein utilization. In general 25 to 35 Kcal/kg estimated weight is prescribed.
An intake of 4-6 gm/kg carbohydrate ensures adequate glycogen reserves needed for the maintenance of liver function for protection against further injury to the liver and for its protein sparing action.
An intake of 1 ½ to 2 grams protein per kg of body weight is recommended.
Diets restricted in fats are not necessary in the majority of patients with hepatitis. In fact, restricting fats all together may retard recovery if calories are thereby limited. Fats from dairy products, cooking fats are easily utilized and add palatability to the diet without large amounts of bulk. If there is anorexia (loss of appetite), fats may cause nausea and should be limited to amounts tolerated by the patient.
Foods of liquid of soft consistency may be preferable if there is anorexia in the initial stages of illness, progressing to wider selection of foods with recovery. The patient must be convinced of the importance of the diet in promoting recovery and preventing relapses. Anorexia is frequently a problem; hence every effort must be made to encourage the patient to eat. Foods must be well prepared and attractively served with consideration given to the individual food preferences. Judicious use of spices and condiments may help to stimulate the appetite. Small to moderate portion at mealtime with high protein between meal supplements are frequently more acceptable than larger meals. Some individuals need assistance in feeding themselves and should be allowed adequate time to eat a leisurely pace.
CIRRHOSIS (PERMANENT LIVER DAMAGE)
Regeneration of liver cells occurs if appropriate diet therapy is initiated before the disease is well advanced. In early cirrhosis, the high protein, high carbohydrate diet outlined for infectious hepatitis is satisfactory. In advanced cirrhosis, however, further modification is needed. Energy requirements are increased to compensate for the extreme weight loss, which often occurs in cirrhosis.
Metabolically, stable cirrhotic patients behave similarly to normal individuals under prolonged starvation.
Fasting low blood sugar can occur because of the decreased availability of glucose from glycogen. Therefor, carbohydrate should provide most of the non-protein calories.
Cirrhotic patients do appear to have an increase protein requirement due to increased degradation in order to supply energy. In uncomplicated cirrhosis, protein requirements range from 0.8 to 1 gm / kg dry weight per day to achieve nitrogen balance. Unnecessary protein restriction may only worsen body protein losses and therefore, must be avoided.
Cirrhosis is marked by impaired fat metabolism. Dietary fats are incompletely metabolized in liver failure. Therefore overfeeding regardless of energy source should be avoided because excess calories can contribute to fat synthesis and accumulation in the liver. A range of 10 to 15 % of calories as fat is generally recommended. Replacement of some of the dietary fat with medium chain triglycerides (found in coconut oil) may be useful.
Vitamin and minerals
Deficiencies of fat-soluble vitamins have been found in all types of liver failure. Therefore, supplementation is necessary.
Fluids and electrolytes
Cirrhosis is characterized by excess sodium and fluid retention with increased urinary potassium losses. In patients with ascites (water accumulation in the abdomen), sodium is commonly restricted to 2 g / day. More severe limitation may be imposed, however caution is warranted because of limited palatability. Fluid intake is usually restricted to 1 liter per day, depending upon the severity of the edema, ascites, and low sodium.
HEPATIC ENCEPHALOPATHY (HEPATIC COMA)
In coma due to liver problem, dietary treatment is geared towards reducing ammonia production. The fundamental principle in the dietary management of hepatic coma is to reduce the protein intake to a minimum thus decreasing the amount of ammonia produced. 0.6 to 0.8 gm/kg/day of protein can be given safely. Vegetable protein and casein based diets have shown promise in reducing encephalopathy. The high fiber content of vegetable protein diet also plays a role in excretion of nitrogenous compounds. As the patient improves, the protein intake is gradually increased by increment of 0.2 g/kg/day to tolerable levels. These patients pose problem in feeding because of anorexia, drowsiness and confusion to irritability. The sugar fat emulsions, glucose in beverages or fruit juices may be used initially through oral or tube feeding.