Addition of Milk Does Not Alter the Antioxidant Activity of Black Tea

Abstract

Tea is a polyphenol-rich beverage like wine and catechins are its chief polyphenols. Catechins have cardio-protective effects as they can scavenge free radicals and inhibit lipid peroxidation. Epidemiological studies indicate an inverse relation between tea consumption and the risk of cardiovascular and other chronic diseases. Addition of milk to black tea has been reported to adversely affect its beneficial effects, but the data are not unequivocal. Therefore, we assessed the effect of the addition of milk to black tea on its ability to modulate oxidative stress and antioxidant status in adult male human volunteers. Although the area under the curve of plasma catechins was lower on the consumption of tea with milk compared to black tea, it did not affect the beneficial effects of black tea on total plasma antioxidant activity, plasma resistance to oxidation induced ex vivo, and decreased plasma and urinary thiobarbituric acid reactive substance levels. The results suggest that addition of milk may not obviate the ability of black tea to modulate the antioxidant status of subjects and that consumption of black tea with/without milk prevents oxidative damage in vivo.

Addition of milk prevents vascular protective effects of tea

“…28 However, it should be noted that other studies failed to establish an effect of milk on antioxidant properties of tea. 29,30 The reasons for these discrepant findings are largely unknown but may be attributed to different physiological/experimental endpoints (e.g. in vitro and in vivo, and assays for measurements of antioxidant activities).…”

Investigating the effects of food matrix and food components on bioaccessibility of pomegranate (Punica granatum) phenolics and anthocyanins using an in-vitro gastrointestinal digestion model

“…Alternatively some studies have shown that the addition of milk to tea inhibits its antioxidant activity whereas other workers have reported that the addition of milk does not alter the antioxidant activity of polyphenols in tea, coffee, or cocoa beverages (Richelle, Tavazzi, & Offord, 2001;Serafini, Ghiselli, & Ferro-Luzzi, 1996). Lower levels of plasma catechins have also been reported after drinking tea with milk compared to black tea (Reddy, Vidya Sagar, Sreeramulu, Venu, & Raghunath, 2005). In contrast, other workers have reported that milk had no effect on plasma levels of catechins (Van het Hof, Kivits, Weststrate, & Tijburg, 1998).…”

A Review of the Antioxidant Mechanisms of Polyphenol Compounds Related to Iron Binding

“…Since plasma concentrations of polyphenols in humans commonly reach 1-10 lM [25][26][27][28][29], these compounds might be expected to have a protective effect on red blood cells. Grinberg, et al have reported such protective effects for polyphenols in green and black tea against red blood cell lipid peroxidation, noting a concentration-dependent inhibitory effect on • OH production, and cytoprotection of red blood cells in vitro from primaquine-induced oxidative stress due to O 2…”

“…1), which constitute up to 30% of the plant's dry leaf weight [24]. Within just 2 h after consumption of one cup of green or black tea (350-600 ml) [25][26][27][28], catechins have been found in concentrations of 0.3-1 lM in human plasma and may even approach 10 lM with higher doses [29]. Flavonols ( Fig.…”