The influence of beverage composition on delivery of phenolic compounds from coffee and tea

Abstract

Epidemiological data suggest that consumption of coffee and tea is associated with a reduced risk of several chronic and degenerative diseases including cardiovascular disorders, diabetes, obesity and neurodegenerative disorders. Both coffee and tea are a rich source of phenolic compounds including chlorogenic acids in coffee; and flavan-3-ols as well as complex theaflavins and thearubigens in tea. Coffee and tea are two of the most commonly consumed beverages in the world and thus represent a significant opportunity to positively affect disease risk and outcomes globally. Central to this opportunity is a need to better understand factors that may affect the bioavailability of specific phenolic components from coffee and tea based beverages. An overview of the phenolic composition of coffee and tea is discussed in the context of how processing and composition might influence phenolic profiles and bioavailability of individual phenolic components. Specifically, the impact of beverage formulation, the extent and type of processing and the influence of digestion on stability, bioavailability and metabolism of bioactive phenolics from tea and coffee are discussed. The impact of co-formulation with ascorbic acid and other phytochemicals are discussed as strategies to improve absorption of these health promoting phytochemicals. A better understanding of how the beverage composition impacts phenolic profiles and their bioavailability is critical to development of beverage products designed to deliver specific health benefits.

Introduction

Beverages prepared from the roast and ground seeds of the coffee plant (Caffea canefora and arabica) and dried leaves of the tea shrub (Camiella sinensis) are two of the most commonly consumed beverages in the world. While primarily prized for their flavor and aroma, more recent epidemiological and biological data support a potential role for both coffee and tea in the prevention of several chronic and degenerative diseases including cancer [1], [2], [3], cardiovascular disorders [4], obesity and diabetes [5], [6], [7], [8] as well as neurodegenerative disorders [9], [10]. These findings have intensified interest in characterization of specific bioactive constituents present in coffee and tea that may serve as physiologically active agents.

Both coffee and tea are rich sources of bioactive phytochemicals including methylxanthines, amino acids, phenolic acids and polyphenols (Fig. 1). While caffeine, the primary methylxantine in both beverages, is well known for its stimulatory and metabolic effects [11], [12], [13] the phenolic and polyphenolic constituents of coffee and tea have drawn recent attention due, in part, to their natural abundance and reported biological activities including: antioxidant activities [14], [15], [16], stimulation of NO production and vasodilation [17], regulation of xenobiotic-metabolizing enzymes [18], [19], increased fatty acid oxidation and insulin sensitivity [20], [21], and modulation of glucose absorption and utilization [22], [23], [24].

While a direct relationship between specific coffee and tea phenolics and a physiological effect have not been clearly demonstrated, the combination of epidemiological and preliminary biological evidence, along with the abundance of phenolic compounds in coffee and tea, have stimulated interest in the absorption, distribution and metabolism of these compounds in humans. Bioavailability data on tea polyphenols, and to a more limited extent coffee phenolics, varies widely [25]. While inter-individual variation is a factor, assessment of phenolic absorption from coffee and tea beverages is additionally complicated by the fact that these beverages are commonly consumed along with secondary ingredients such as food additives (stabilizers and antioxidants), sweeteners (sucrose, corn syrups, and non-caloric sweeteners), creamers (milk and non-dairy creamer) added by consumers or formulated by food processors. The extent to which processing or formulation may modify the phenolic profile of coffee and tea or influence their bioavailability is critical to understanding ultimate physiological effects elicited by these beverages. Therefore, while the abundance of physiologically active phenolic and polyphenolic compounds in coffee and tea offers a significant opportunity to positively affect disease risk and outcomes globally, this potential remains linked to the need to better understand factors that may affect the bioavailability of specific phenolic components from coffee and tea beverages.

The purpose of this paper is to provide an overview of key research describing the phenolic profile of coffee and tea associated with health promoting activities including the impact of processing on coffee and tea phenolics composition; the bioavailability of coffee and tea phenolics including the impact of gastric and intestinal digestion, small intestinal uptake and metabolism on physiological phenolic profiles; and finally, the impact of beverage formulation factors on bioavailability of tea and coffee phenolics will be discussed.