Partial normalization by dietary cod-liver oil of increased microvascular albumin leakage in patients with insulin-dependent diabetes and albuminuria.

In a double-blind crossover study, we compared the effects of eight weeks of dietary supplementation with cod-liver oil with the effects of supplementation with olive oil on endothelial permeability, blood pressure, and plasma lipid levels in 18 patients with insulin-dependent diabetes mellitus and albuminuria. When the patients received the cod-liver-oil supplement, the mean (+/- SEM) transcapillary escape rate of albumin (as compared with the base-line rate) decreased from 8.7 +/- 0.5 to 6.9 +/- 0.6 percent per hour (P less than 0.01), and the blood pressure decreased from 146 +/- 4/90 +/- 2 mm Hg to 139 +/- 4/85 +/- 2 mm Hg (P less than 0.05). There was no correlation, however, between cod-liver oil's effect on the transcapillary escape rate of albumin and its effect on blood pressure. There was no change from base line after the patients received the olive-oil supplement. During dietary supplementation with cod-liver oil, the plasma concentration of high-density lipoprotein cholesterol increased and the concentrations of very-low-density lipoprotein cholesterol and triglycerides decreased (P less than 0.05 for all comparisons), but the level of low-density lipoprotein cholesterol did not change. In contrast, during supplementation with olive oil, the concentration of low-density lipoprotein cholesterol decreased and the levels of very-low-density lipoprotein cholesterol and triglyceride increased (P less than 0.05 for all comparisons), but there was no change in the level of high-density lipoprotein. No changes were observed in the glomerular filtration rate, degree of albuminuria, insulin requirement, glycosylated hemoglobin level, or blood glucose level during supplementation with either oil. We conclude that dietary supplementation with cod-liver oil lowers the elevated transcapillary escape rate of albumin characteristic of patients with insulin-dependent diabetes and albuminuria, independently of its effect on blood pressure--perhaps by decreasing vascular permeability. We did not find any effect of cod-liver oil on urinary albumin excretion.