Expression of occludin and junctional adhesion molecule A (JAM-A), transmembrane proteins of tight junctions (TJs), was analysed to characterize endothelial paracellular permeability in the heart of rats subjected to a bolus of bacterial lipopolysaccharide (LPS) at a dose of 1 mg/kg. Potential protective effects of natural carotenoids (10 mg/kg/day) produced by yeast biomass Rhodosporidium kratochvilovae on expression of occludin and JAM-A also examined in LPS-injected rats (n = 6 per group). LPS decreased expression of occludin by 40% (P < 0.01), JAM-A by 36% (P < 0.001) and increased plasma levels of malondialdehyde (MDA) and lysosomal N-acetyl-b-D-glucosaminidase (NAGA) compared to controls. Ten-day diet rich in yeast biomass containing carotenoids (torularhodin, torulene, β-carotene) attenuated LPS-induced changes in expression of TJ proteins as observed by increased expression of occludin by 30% (P < 0.05) and JAM-A by 61% (P < 0.001) to the control values. Carotenoids also reduced oxidative stress and cellular injury indicated by decreased levels of MDA and NAGA. The results show that diet rich in yeast biomass containing natural carotenoids could protect mechanisms regulating paracellular endothelial barrier function from LPS-induced damage in the heart.