Haemato-protective influence of dietary fenugreek (Trigonella foenum-graecum L.) seeds is potentiated by onion (Allium cepa L.) in streptozotocin-induced diabetic rats

•We report protective effect of dietary fenugreek & onion on RBCs in diabetic rats.•These spices modulated reduced haematological indices & showed antisickling potency.•Altered lipid profile in RBC membrane in diabetic hyperlipidemia was corrected.•Lipid peroxidation, NO production & reduced ATPase activity were countered .•Osmotic fragility, reduced membrane fluidity, deformability were ameliorated.•The beneficial protective effect on RBCs was higher with fenugreek + onion. We have recently reported the beneficial modulation of metabolic abnormalities and oxidative stress in diabetic rats by dietary fenugreek seeds and onion. This investigation evaluated the protective influence of dietary fenugreek seeds (100 g kg−1) and onion (30 g kg−1) on erythrocytes of streptozotocin-induced diabetic rats, through modulation of reduced haematological indices and antisickling potency. This study also evaluated the altered erythrocyte membrane lipid profile and beneficial countering of increased lipid peroxidation, osmotic fragility, along with reduced membrane fluidity and deformability, nitric oxide production and echinocyte formation. Dietary fenugreek seeds and onion appeared to counter the deformity and fragility of erythrocytes partially in diabetic rats by their antioxidant potential and hypocholesterolemic property. The antisickling potency of these spices was accomplished by a substantial decrease in echinocyte population and AGEs in diabetic rats. Further insight into the factors that might have reduced the fluidity of erythrocytes in diabetic rats revealed changes in the cholesterol: phospholipid ratio, fatty acid profile, and activities of membrane-bound enzymes. Dietary fenugreek seeds and onion offered a beneficial protective effect to the red blood cells, the effect being higher with fenugreek + onion. This is the first report on the hemato-protective influence of a nutraceutical food component in diabetic situation.