Prolonged low-medium intensity exercise is associated with increased oxidative stress in humans. We hypothesized that competitive equine endurance racing would induce changes in circulatory antioxidants and produce systemic oxidative stress. Forty horses competing in a 140-km endurance race in warm conditions [shade temperature 15–19°C; 62–88% relative humidity (%RH)] were sampled before (Pre), immediately after exercise (End) and at approximately 16 h into recovery ( 16 h). Plasma ascorbic acid concentration was not different between Pre [11.1 (median); 4.6–20.3 mol/L (range)] and End [9.7; 3.0–38.9 (range) mol/L] but was significantly decreased at 16 h (5.5; 2.8–15.5 mol/L; P 0.05). Total red cell hemolysate glutathione (TGSH) concentration was significantly reduced by exercise (Pre 1261; 883–1532 mol/L; End 1065; 757–1334 mol/L; P 0.05) and at 16 h recovery (1032; 752–1362 mol/L; P 0.05). Glutathione redox ratio was unchanged by exercise but was significantly decreased at 16 h compared with that at both Pre and End (P 0.05). The concentration of total barbituric acid reactive substances (TBARS) in plasma was increased compared with that at Pre (309; 66–1048 nmol/L), both at End (408; 170–1196 nmol/L; P 0.05) and 16 h (380; 99–1161 nmol/L; P 0.05). -Tocopherol was unchanged by exercise or recovery. Mean race speed was 16.5 1.6 km/h and ranged from 13.9 to 19.7 km/h. Mean speed during competition in horses that completed the full 140 km (n 28) was significantly correlated with end of exercise ascorbic acid (r 0.622; P 0.0004). Although there were increases in creatine phosphokinase (CK), aspartate aminotransferase (AST) and TBARS and a loss of TGSH, this study failed to demonstrate evidence of classical oxidative stress. J. Nutr. 132: 1622S–1627S, 2002.

Patients with cystic fibrosis (CF) often exhibit malabsorption despite the use of supplemental pancreatic enzymes. Unabsorbed carbohydrates and amino acids can serve as substrates for large intestine anaerobic fermentation, thus increasing excretion of short-chain fatty acids (SCFA) in the feces. Nine patients with CF on regular pancreatic enzyme supplementations in the age range of 5-11 years and one older patient were studied. Three-day stool samples were collected, as were 72-h food records. Stools were analyzed for gross energy, total nitrogen, fat content, and SCFA concentration. A significant difference was found between CF and normal controls in total caloric excretion due to fat malabsorption. No significant difference was found between CF and normal controls in protein or SCFA excretion. Fat excretion as percentage of fat intake was significantly increased in CF patients: 35.3 +/- 10.2% versus 8.0 +/- 3.0%, respectively. These data suggest that carbohydrate supplementation could be more widely used to increase caloric intake in CF patients without causing secondary osmotic diarrhea.

The effect of high dietary vitamin A or tocopherol, or both, on lipid absorption and secretion in the gastrointestinal tract and on serum and hepatic lipids was determined in the chick. High dietary vitamin A increased secretion of cholesterol, bile acids, phospholipids and fatty acids to the duodenum, and tocopherol enhanced cholesterol and bile acid secretion to the duodenum. No differences in over-all absorption were observed. Serum cholesterol was depressed by vitamin A and hepatic lipids were enhanced, except phosphatidyl choline which was depressed. Tocopherol increased hepatic triglycerides and cholesterol. In vitro fatty acid synthesis from lactate by liver homogenates was enhanced by vitamin E and cholesterogenesis enhanced by both vitamin A and tocopherol. delta 9 Desaturation was also enhanced by vitamin E. It is concluded that both vitamin A and tocopherol affect the hepatic synthesis and catabolism of cholesterol and that vitamin E also influences fatty acid metabolism.

1. A fluorescent high-molecular weight lipid–protein aggregate was isolated from the cytosol of chick intestinal mucosa or liver by gel filtration on columns of Sepharose 4B or 6B. 2. This aggregate exhibited carotene-cleavage activity. 3. On incubation of this aggregate, dissociation occurred and low-molecular weight fractions containing Cu and Zn and exhibiting carotene-cleavage activity were found. This fraction appeared on sodium dodecyl sulphate polyacrylamide electrophoresis to have a molecular weight of 7000–11000 and resembled the previously described Cu chelatins in amino acid composition. 4. Carotene cleavage may be effected by a copper–zinc metalloprotein of low-molecular weight, associated in intestinal cytosol with a lipid–protein aggregate.