Vitamin A absorption in cystic fibrosis: risk of hypervitaminosis A.

Vitamin A status was examined in nine adult cystic fibrosis patients and six adult control subjects, together with an assessment of their ability to absorb 10,000 IU of retinyl palmitate from a test meal, taken with appropriate pancreatic enzyme supplements. Median baseline values for plasma retinol and carotene, as well as median serum retinol binding protein concentrations, were significantly lower in cystic fibrosis patients than in control subjects. One cystic fibrosis patient had a raised fasting plasma retinyl ester concentration suggestive of chronic hypervitaminosis A, but no symptoms of toxicity. Measures of vitamin A absorption were also significantly lower in cystic fibrosis patients, although there was considerable overlap with control values. No correlation was observed between measures of baseline status and vitamin A absorption. Measurement of plasma retinyl esters may be an appropriate investigation in those patients considered to be at risk of chronic hypervitaminosis A.

Increased susceptibility to peroxide-induced haemolysis with normal vitamin E concentrations in cystic fibrosis.

Vitamin E status was assessed in 22 patients with cystic fibrosis and 9 controls by measuring concentrations of the vitamin, vitamin E:lipid ratios and peroxide-induced haemolysis in plasma and erythrocytes. For a given concentration of plasma or erythrocyte alpha-tocopherol, erythrocytes of patients with cystic fibrosis were more susceptible to peroxide-induced haemolysis than controls. This susceptibility should be countered by supplementation with vitamin E to maintain higher than normal concentrations of circulating alpha-tocopherol-greater than 4.8 mmol alpha-tocopherol/mol cholesterol.

Paradoxical effects of essential fatty acid supplementation on lipid profiles and sweat electrolytes in cystic fibrosis.

Supplements of evening primrose oil (Oenothera biennis), which contains at least 72% linoleic (18:2n-6) and 7% gamma-linolenic (18:3 n-6) acids (expressed as % fatty acid methyl esters) were given to sixteen cystic fibrosis patients for a period of 12 months. Clinical observations showed no significant changes in patients' weights or respiratory function throughout. Linoleic acid levels in plasma and erythrocyte membranes increased significantly during the first 6 months but this increase was not sustained at its initial level. After supplementation was discontinued reversion to baseline (low) levels occurred within 4 months. Levels of plasma prostaglandins (PG) and urinary PG metabolites varied among individuals over a wide range, and urinary PGF2 alpha metabolites fell during the supplementation. There was a significant fall in sweat sodium concentrations after 6 weeks of supplementation, but sweat chloride was unchanged. It is not known whether the effect of essential fatty acids on sweat Na+ reflects changes in cell membrane conformation or if there is a direct effect on Na+ pump activity.

Nutritional management of cystic fibrosis.

Cystic fibrosis patients have an increased requirement for calories and probably for all the major nutrients. The newer, enteric-coated granular preparations of pancreatic enzyme are more effective than preceding preparations and should permit a normal fat intake. Recent work has emphasized the interdependence of respiratory disease and nutrition.

Comparative trial of pancrex V forte and nutrizym in treatment of malabsorption in cystic fibrosis.

A cross-over trial of pancreatic enzyme replacement therapy has been conducted on 12 children with cystic fibrosis using Pancrex V forte and Nutrizym tablets in equivalent dosage. No differences were found in the effectiveness of these products as measured by stool volume, number of bowel actions, faecal fat excretion, and urine urea excretion. Neither product eliminated the steatorrhoea. Though there was no laboratory evidence to support their choice nine patients expressed a preference for Nutrizym at the conclusion of the trial. This preference was based partly on the smaller number of tablets which are required.