In vitro Effects of Beet Root Juice on Stimulated and Unstimulated Peripheral Blood Mononuclear Cells

Intake of fruits and vegetables rich in antioxidants is suggested to reduce the incidence of cancer and coronary heart disease in humans. Exceptional antioxidant activity of beet root extracts has been reported. Likewise in animal models, e.g., extracts of red beetroot Beta vulgaris var. rubra revealed significant tumor inhibitory effects. Red beetroot concentrate is universally permitted as a food ingredient. In this study, effects of a commercially available beetroot juice on freshly isolated human peripheral blood mononuclear cells stimulated with the mitogens phytohaemagglutinin and concanavalin A were investigated in vitro. Tryptophan degradation and neopterin formation were monitored in culture supernatants to determine effects of test substances on immunobiochemical pathways which both are induced by the pro-inflammatory cytokine interferon-γ. Compared to unstimulated cells, the mitogens induced significant formation of neopterin and degradation of tryptophan which is reflected by increasing concentrations of kynurenine together with diminished tryptophan levels in supernatants. Addition of beetroot extracts significantly suppressed these mitogen-induced changes, e.g. the rate of neopterin production as well as tryptophan degradation was dose-dependently suppressed. Our data show that beetroot extract is able to counteract pro-inflammatory cascades in peripheral blood mononuclear cells. Because inflammation is strongly involved in the development and progression of several clinical conditions including coronary heart disease and cancer, beneficial effect of beetroot extract may relate to this anti-inflammatory capacity.