Hypertension is a key risk factor for heart, brain, and kidney disease development. Fruit consumption has been associated with a decrease in blood pressure. Lemon juice, which contains antihypertensive compounds, may exert antihypertensive effects. However, no research has verified the antihypertensive effects of citric acid, the most abundant ingredient in lemon juice. In the present study, we demonstrated the antihypertensive effects of citric acid and lemon juice by performing single oral administration tests and the aortic ring assay using spontaneously hypertensive rats (SHRs). Single oral doses of both agents markedly reduced the systolic and diastolic blood pressures in the SHRs. In addition, both these agents relaxed the thoracic aorta from the SHRs; however, these effects were notably attenuated by the removal of the aortic endothelium. Orally administered citric acid was rapidly absorbed and metabolized in vivo. Among the functional compounds in lemon juice, citric acid was identified as the primary antihypertensive component. Although more detailed studies are required to validate our findings, the novel functional attributes of citric acid can achieve the normalization of blood pressure when it is consumed via diet.
Keywords: citric acid; diet; flavonoid; hypertension; lemon; nutraceutical; vasorelaxant.