Antioxidants in the treatment of hypertension

Abstract

Hypertension is a major health problem worldwide. Individuals with hypertension are at an increased risk for stroke, heart disease, and kidney failure. Although the etiology of essential hypertension has a genetic component, lifestyle factors such as diet play an important role. Insulin resistance and glucose intolerance are common features of hypertension in humans and in animal models. Altered glucose metabolism leads to an increased production of the reactive aldehyde, methylglyoxal. Methylglyoxal binds sulfhydryl and amino groups of proteins forming conjugates/advanced glycation end products (AGEs). This alters protein structure and function and can affect vascular calcium channels, enzymes, and tissue proteins leading to increased oxidative stress. These alterations impair endothelial function leading to an increase in intracellular free calcium, peripheral vascular resistance, and hypertension. Supplementation with antioxidants, including vitamin C, E, or B6, thiols such as lipoic acid and cysteine, and the quinone enzyme Q10, have been shown to lower blood pressure in animal models and humans with essential hypertension. The Dietary Approaches to Stop Hypertension (DASH) studies demonstrated that a well-balanced diet, rich in these nutrients, was effective in lowering blood pressure. These antioxidants may achieve their antihypertensive effects by reducing aldehyde conjugate/AGE formation and oxidative stress, by improving insulin resistance and endothelial function, or by normalizing calcium channels and peripheral vascular resistance. In essential hypertension, deficiencies of antioxidants may exist or a higher than normal amount may be required to correct metabolic abnormalities. Dietary supplementation with antioxidants may be a beneficial, inexpensive, first-line alternate treatment modality for hypertension.