The present invention herein discloses potent synergistic compositions of vasoactive mediators enhancers for improving vascular endothelial function. Particularly, the invention relates to synergistic nutritional composition comprising exogenous blend of N1-methyl nicotinamide chloride and standardized red spinach extract enriched with nitrate content along with pharmaceutically acceptable excipients, wherein N1-methyl nicotinamide salt and standardized red spinach extract enriched with nitrate content are present in the ratio of 1:0.5 to 1:8； and N1-methyl nicotinamide chloride and nitrate of standardized red spinach extract, are present in the ratio of 1:0.1 to 1:1. The present synergistic composition is useful for treating endothelial dysfunction such as hypertension, atherosclerosis, thrombosis, myocardial infarction, heart injury.
