The effect of olive leaf supplementation on the constituents of blood and oxidative stability of red blood cells

• Olive leaf supplementation decreased plasmatic TAGs, fat storage and body weight.
• Doses usually used by humans did not show deleterious effects on blood constituents.
• Higher doses resulted in a significant red blood cell membrane destabilization.
• Olive leaf may be used in the control of body weight and as cardioprotective.

Olive leaf (OL) supplements are marketed as promoting health and supporting the body in preventing free radical damage. This study examined the effect of different concentrations of OL supplement on the haematological and lipid profile and on the oxidative stability of red blood cells (RBCs). A cohort of healthy pigs was used as a model in a single-centre, randomized, prospective pilot comparison. Twenty four pigs were assigned to three experimental diets: a control group fed the conventional diet and two groups fed the conventional diet supplemented at 50 and at 100 g/kg with OL, during 8 weeks. Blood was collected for haematological, biochemical, and haemostatic studies. OL supplementation resulted in a significant decrease in plasmatic triacylglycerols (TAGs) concentration, aligned with a lower body mass and fat storage but no significant reductions were found for low-density lipoprotein cholesterol (LDLc) and oxLDL levels. The use of the highest dose resulted in significant RBC membrane destabilization.