Minimum protein requirements in liver cirrhosis determined by nitrogen balance measurements at three levels of protein intake

Effect of long-term refeeding on protein metabolism in patients with cirrhosis of the liver

Patients with cirrhosis of the liver require an increased amount of protein to achieve N balance. However, the utilization of protein with increased protein intake, i.e. the slope from regression analysis of N balance v. intake, is highly efficient (Nielsen et al. 1995). In the present study, protein requirement and protein utilization were investigated further by measuring protein synthesis and degradation. In two separate studies, five or six patients with cirrhosis of the liver were refed on a balanced diet for an average of 2 or 4 weeks. Protein and energy intakes were doubled in both studies. Initial and final whole-body protein metabolism was measured in the fed state by primed continuous [15N]glycine infusion. Refeeding caused a statistically significant increase of about 30% in protein synthesis in both studies while protein degradation was only slightly affected. The increase in protein synthesis was associated with significant increases in plasma concentrations of total amino acids (25%), leucine (58%), isoleucine (82%), valine (72%), proline (48%) and triiodothyronine (27%) while insulin, growth hormone, insulin-like growth factor (IGF)-I and IGF-binding protein-3 were not changed significantly. The results indicate that the efficient protein utilization is due to increased protein synthesis, rather than decreased protein degradation, and suggest that increases in plasma amino acids may be responsible for the increased protein synthesis. A comparison of the patients who had a normal protein requirement with the patients who had an increased protein requirement suggests that the increased protein requirement is due to a primary increase in protein degradation. It is speculated that this is due to low levels of IGF-I secondary to impaired liver function, since initial plasma concentration of IGF-I was about 25% of control values and remained low during refeeding.

Dietary long-chain polyunsaturated fatty acids influence the recovery of thioacetamide-induced liver cirrhosis in rats

BACKGROUND

The aim of this study was to evaluate the dietary supplementation with omega-3 and omega-6 long-chain polyunsaturated fatty acids on the fatty acid composition of plasma and red blood cell membranes in rats with thioacetamide-induced liver cirrhosis.

METHODS

Thirty-eight female Wistar rats were given 300 mg thioacetamide/L in drinking water for 4 months to induce the experimental liver cirrhosis. Sixteen rats were used as controls. After treatment with thioacetamide, nine rats of each group were killed. Then, thioacetamide-treated rats were divided into three new groups, each receiving a different diet for 2 weeks: a semipurified diet (n = 9), the same diet supplemented with omega-3 long-chain polyunsaturated fatty acids (n = 10), or the same semipurified diet supplemented with omega-3 and omega-6 long-chain polyunsaturated fatty acids simultaneously (n = 10). The remaining control rats were fed the semipurified diet. Liver histology and plasma and erythrocyte fatty acid composition were assessed.

RESULTS

An apparent improvement of the histological damage took place in the rats fed the omega-3+ omega-6-supplemented diet. The diet supplemented with polyunsaturated fatty acids of the omega-3 series induced increases in the omega-3 long-chain polyunsaturated fatty acid levels in total plasma lipids, plasma lipid fractions and in erythrocyte phospholipids, and decreases in omega-6 long-chain polyunsaturated fatty acids in erythrocyte phospholipids during the recovery of rats with thioacetamide-induced liver cirrhosis. The administration of the diet supplemented with both omega-3 and omega-6 long-chain polyunsaturated fatty acids contributed to increase the levels of total plasma saturated, monounsaturated, and omega-6 long-chain polyunsaturated fatty acids from cirrhotic rats.

CONCLUSION

We conclude that the simultaneous supply of long-chain fatty acids of the omega-3 and the omega-6 series can be beneficial to improve the fatty acid status of this experimental model of liver cirrhosis.

Long-term oral refeeding of patients with cirrhosis of the liver

A previous study has shown that malnourished, clinically stable patients with liver cirrhosis are in protein and energy balance at their spontaneous dietary intake and that an improvement in nutritional status cannot be anticipated at this intake (Nielsen et al. 1993). In the present study we examined to what extent oral intake could be increased by nutritional support, and to what extent dietary protein would be retained with increased intake. The techniques used for balance studies were also validated since this information is not available for patients with liver cirrhosis. Fifteen malnourished patients with alcoholic liver cirrhosis were given increasing amounts of a balanced ordinary diet for 38 (SE 3) d. Intakes of protein and energy were recorded by weighing servings and leftovers on food trays. Protein intake was calculated from food tables. Total N disposal was calculated after measurement of urinary N excretion, and protein balance was calculated from the N balance. A validation study of protein balance in a subgroup of patients (analysis of N in food by the duplicate portion technique, correction for incomplete recovery of urine by measurement of urinary para-aminobenzoic acid (PABA) after administration of PABA tablets, and measurement of faecal N) did not change protein balance values. Protein intake increased from 1.0 (SE 0.1) g/kg per d to 1.8 (SE 0.1) g/kg per d. With increasing protein intake, 84 (SE 8)% of the increase in intake was retained. The rate of protein retention was not saturated at the intakes obtained in this study. Protein intolerance was only encountered in one patient. Available evidence indicates that the requirement for achieving N balance is increased in these patients but protein retention is highly efficient with increased intake. Protein retention is dependent on energy balance. Energy intake was calculated from food tables and total energy expenditure was calculated by the factorial method. A validation study was performed in a subgroup of patients. The energy contents of food sampled by the duplicate portion technique, and of urine and faeces were measured by bomb calorimetry. Resting energy expenditure (REE) was measured by indirect calorimetry before and at the end of the study, and O2 uptake during bicycle exercise was measured before and at the end of the study. The measured intake of metabolizable energy was on average 13% lower than the value given in food tables. Calculated energy expenditure was not changed by the validation study.(ABSTRACT TRUNCATED AT 250 WORDS)

Vegetable versus animal protein diet in cirrhotic patients with chronic encephalopathy. A randomized cross-over comparison

In a randomized cross-over comparison, the effects of a mainly vegetable protein diet were compared with an animal protein diet in eight patients with cirrhosis and chronic permanent encephalopathy, under optimum lactulose therapy. After a run-in period, patients were fed two equi-caloric, equi-nitrogenous diets for 7 days (71 g total proteins), containing either 50 g protein of animal origin or 50 g vegetable proteins. In the last 3 days of each period, nitrogen balance was significantly better during the vegetable protein diet (+0.2 (SD 1.4) g vs. -1.7 (2.4); P < 0.01), the difference being entirely due to a reduced urinary nitrogen excretion. Average daytime integrated blood glucose was slightly higher during vegetable proteins, whereas insulin, plasma amino acids and ammonia were lower. The clinical grading of encephalopathy improved slightly on vegetable proteins, and psychometric tests improved significantly, but remained grossly abnormal. Compliance to dietary manipulation was good. The data prove that a mainly vegetable protein diet is worthwhile in cirrhotic patients with chronic encephalopathy under optimum lactulose therapy. Improved nitrogen balance may be related to more effective nitrogen use for protein synthesis, probably due to blunted hormonal response, and largely outweighs the effects on encephalopathy.

Nutritional assessment and adequacy of dietary intake in hospitalized patients with alcoholic liver cirrhosis

Nutritional assessment and adequacy of spontaneous dietary intake was evaluated in thirty-seven clinically stable hospitalized patients with alcoholic liver cirrhosis. About two-thirds of the patients had ascites or oedema, or both, and, therefore, body weight could not be used for assessment of nutritional status. Lean body mass (LBM; measured by three consecutive 24 h creatinine excretions) was 62 (range 40-95)% of reference values, mid-arm-muscle area (MAMA) was 70 (range 43-115)% and triceps skinfold (TSF) was 45 (range 20-113)% of reference values (all median values). In patients without ascites or oedema, or both, there was a rectilinear correlation between body weight and LBM and between body weight and MAMA (r 0.93 and 0.85 respectively). In patients with ascites or oedema, or both, the correlation between body weight and LBM was poor as could be expected. We suggest that LBM is a useful measure of nutritional status when body weight is unreliable because of ascites or oedema, or both. Energy balance for the group was calculated from energy intake recorded by a 24 h dietary recall and energy expenditure calculated by the factorial method. Median intake was 102 (range 34-176)% of expenditure. N loss was calculated from the average of three 24 h urea excretions. Protein intake was calculated from the 24 h dietary recall. The N balance was positive in the patients as a group (median intake was 120 (range 26-183)% of output). The most malnourished patients tended to have the most positive N balance which was due to a significantly lower N excretion. The protein requirement for N balance was 0.83 (SE 0.05) g/kg per d and only at an intake above 1.20 g/kg per d were all patients in positive N balance. The median intakes of thiamin, folacin, vitamin D, vitamin E, Mg, and Zn were judged to be insufficient. It is concluded that impaired nutritional status is common among patients with liver cirrhosis, even in a stable clinical condition. It is suggested that nutritional status in these patients is evaluated by dietary recalls, in combination with measurement of body weight in patients without ascites or oedema, or both, or in combination with determination of LBM by three 24 h creatinine excretions in patients with ascites or oedema, or both. Criteria for selection of patients that might benefit from nutritional therapy are discussed.

Nocturnal oral glucose supplementation. The effects on protein metabolism in cirrhotic patients and in healthy controls

Nocturnal glucose administration might prevent gluconeogenesis and concomitant protein loss due to hepatic glycogen depletion. In this study the effects of nocturnal oral glucose supplements on nitrogen metabolism were investigated in 8 cirrhotic patients and in 8 healthy controls. During the night, either polymeric glucose was given or water as placebo. In the patients with cirrhosis on placebo, nitrogen balance was not different from controls: -63 +/- 8 vs. -55 +/- 4 mg N/kg b.wt./9 h (mean +/- SEM). Cirrhotic patients had increased nocturnal protein turnover rates (measured with 15N-glycine) and increased early morning levels of free fatty acids (FFA), lactate, insulin, glucagon and growth hormone. After glucose, nitrogen balance improved by 36% in the cirrhotic group, with a decrease in protein turnover rates and a decrease in plasma levels of beta-hydroxybutyrate, urea and glucagon. In the controls, glucose had no effects on nitrogen balance, on protein turnover or on the hormone levels, except for reduced FFA and ketone body levels. These data show that nocturnal calorie supplements improve nitrogen balance during the night in cirrhotic patients but not in healthy controls. Long interprandial intervals should be avoided in cirrhotic patients.

Short-term oral zinc supplementation does not improve chronic hepatic encephalopathy. Results of a double-blind crossover trial

The effect of short-term oral zinc supplementation (zinc sulfate 600 mg/day) on hepatic encephalopathy, was assessed in a double-blind, crossover trial. Fifteen cirrhotic patients with stable, chronic hepatic encephalopathy were randomized to receive either oral zinc or a placebo for 10 days. Following a two-week washout period, these were crossed over to the alternate treatment. Conn's index, which comprises the evaluation of the mental state, asterixis, number connection test, EEG record, and plasma ammonia, was used to score the degree of hepatic encephalopathy, both at the beginning and end of each treatment period. Serum zinc was significantly raised after oral zinc administration and reached the levels observed in cirrhotics without hepatic encephalopathy. Despite this, however, no modification in the parameters included in Conn's index were observed. In conclusion, this study failed to confirm that short-term oral zinc supplementation improves chronic hepatic encephalopathy.

Pathophysiology and clinical basis of prevention and treatment of complications of chronic liver disease

Chronic liver failure is characterized by the appearance of jaundice, ascites, encephalopathy and/or gastrointestinal bleeding. Acute episodes of hepatic decompensation are frequently precipitated by additional events, e.g. septicaemia, diuretic therapy or excessive protein intake. Identification, correction and treatment of these precipitating factors are first steps in the management of chronic liver failure. Nutritional support is important in the treatment of cirrhotic patients, because malnutrition is one of the major determinants of patient outcome. Management of encephalopathy reduces the appearance of gut-derived nitrogenous toxins and corrects imbalances in amino acid metabolism. Treatment of ascites is salt restriction supported by gentle and incremental administration of diuretics. Ursodesoxycholic acid has become a new and promising modality in the management of cholestatic liver diseases. If conservative therapy fails to recompensate liver function, liver transplantation may be indicated.

Effects of the glucosidase inhibitor acarbose in patients with liver cirrhosis

In this preliminary study, we examined the effects of acarbose and placebo together with a standardized breakfast on blood glucose levels, on breath hydrogen excretion and on plasma insulin and glucagon levels; in addition, the effects on fasting blood levels of metabolites were studied following an evening meal with acarbose or placebo. Acarbose significantly reduced blood glucose levels in 10 patients with alcoholic cirrhosis following a meal containing 100 g of carbohydrate. There were no significant changes in plasma insulin after breakfast but glucagon levels were increased at 1 h after the meal. Breath hydrogen excretion did not change significantly. Acarbose given with a late evening snack reduced fasting beta-hydroxybutyrate levels the next morning in these cirrhotic patients.