The present study aimed to determine if the type of dietary fat or oil affects erythrocyte morphology and/or filterability in normal healthy rats. A feeding trial was carried out, in which nine groups of nine rats were fed on diets containing one of the following treatments (test fats or oils): anhydrous milk fat, anhydrous milk fat after passage through a column of active carbon, palm oil, MaxEPA fish oil, hydrogenated coconut oil, anhydrous tallow shortening, margarine hardstock, olive oil and soyabean oil. The test fats or oils supplemented with 10 g safflower-seed oil/kg were incorporated into otherwise nutritionally adequate diets so that the test fat or oil plus safflower- oil contributed 35% of the gross energy of the diet. The rats were fed for 10 weeks. Diet had a significant effect on five of the six classes of erythrocytes identified, and the proportion of cells in each class was shown to be dependent on diet. However, the attribute causing the dependence was not clear. There was no significant effect of diet on erythrocyte filterability index. There was no statistical correlation between erythrocyte filterability index and morphology. Although it has been observed that diet, particularly fish oil, can improve the filterability of erythrocytes once filterability is impaired, the effect of diet on erythrocyte filterability in normal healthy animals including humans is unclear. The importance of the differences in erythrocyte morphology due to diet is also unclear. Both areas deserve further investigation.

The aim of the present study was to investigate whether oat saponins (avenacosides A and B) have any effect on the permeability of the rat intestine to actively and passively transported markers in vitro and in vivo. Intestinal segments were mounted in modified Ussing chambers, and thepassage of the different marker compounds from the mucosal to the serosal side was measured for 120 min. Avenacosides (1 mg/ml) gave a significantly higher passage of the macromolecule ovalbumin and there was a tendency to increased passage of [14C]D-mannitol and [15Cr]EDTA. On the other hand, the saponins did not affect the active transport of [3H]methyl glucose. When rats were given saponins (40 mg/kg body weight)together with markers by gastric intubation, the passage of [51Cr]EDTA into blood and urine was somewhat reduced. For the macromolecule bovine serum albumin, no evident effect on the passage was observed in the presence ofsaponins. Thus, in contrast to the in vitro results, the in vivo marker passage seemed to be unaffected or even reduced in the presence of avenacosides. The study shows that saponinscan affect the permeability of the rat intestine. However, this effect needs further investigation in vivo, especially regarding proteins.

The ability of dietary supplementation with carotenoids to protect chick tissues against oxidative stress in vitro was examined. Male Leghorn chicks were fed on diets supplemented (100 mg supplement/kg diet) with either β-carotene, zeaxanthin (β,β-carotene-3,3'-diol), canthaxanthin (β,β-carotene-4,4'-dione) or α-tocopherol, or on a control diet, from 1 d old until 37 d of age. Tissues (liver, heart, skeletal muscle and plasma) were removed and assayed for total carotenoids and α-tocopherol content and portions subjected to oxidative stress by incubation of homogenates with cumene hydroperoxide and FeSO4. Animals receiving zeaxanthin and canthaxanthin had significantly greater carotenoid concentrations in liver, heart, muscle and plasma compared with untreated controls (P < 0·05); animals fed on diets supplemented with β-carotene or α-tocopherol did not have significantly different tissue carotenoid contents compared with untreated controls. α-Tocopherol supplementation elevated α-tocopherol levels in all tissues examined (P < 0·05). Supplementation with caroteuoids did not affect tissue α-tocopherol levels, but β-carotene lowered plasma α-tocopherol levels by 50% (P < 0·05). Incubation of plasma or tissue homogenates with oxidant stressors induced lipid peroxidation (production of thiobarbituric-acid reactive substances) in all tissues. Animals given α-tocopherol, β-carotene or zeaxanthin had a reduced susceptibility to oxidant stress in liver compared with unsupplemented controls (P < 0·05), and α-tocopherol-supplemented animals had reduced susceptibility in skeletal muscle compared with unsupplemented controls (P < 0·05). Canthaxanthin supplementation did not influence the susceptibility to oxidant stress in any tissue examined. These results suggest that zeaxanthin, a carotenoid present in animal and human diets, may have significant activity as an antioxidant against oxidative stress in tissues.