Tea and coffee are popular drinks the World over. In fact, tea in particular is second in popularity as a beverage behind only water. Tea and coffee have both been shown to produce beneficial health effects when consumed frequently, and this relates in large part to the high concentrations of antioxidant nutrients within the coffee bean and tea leaf. Coffee contains a number of antioxidant phytochemicals that are bioactive in humans including caffeic acid and chlorogenic acid. The antioxidant phytochemicals in tea comprise mainly of the catechin group of flavonoids in green tea, and tannins in black tea. However, while some of the phytochemicals in tea and coffee are bioactive and have beneficial antioxidant effects in humans, both tea and coffee are good sources of minerals that may contribute to their beneficial health effects. Researchers have therefore analysed the mineral content of tea and coffee in order to assess the relative importance of their contribution to daily minerals intakes.
For example in one study1, 24-hour dietary recall was used to assess the coffee and tea consumption in a large group of New Zealanders. Chemical analysis was then performed on tea and coffee in order to assess their possible contributions to mineral intakes. The results showed that men drank significantly more tea and coffee than women. Tea was a good source of manganese and had high levels of potassium. Coffee contained more potassium than tea and also had high levels of magnesium. However the manganese content of coffee was more variable than tea but in some cases was significant. Other minerals were not present in nutritionally important concentrations. Of course, some of the minerals present in tea and coffee were present in the water in which the tea and coffee are brewed. It is therefore important to separate the water minerals from the minerals in the tea and coffee when performing analysis. The water was a significant source of a number of minerals and contributed significantly to intakes.
Dr Robert Barrington’s Nutritional Recommendation: Tea and coffee therefore contribute significantly to the mineral intakes of New Zealanders. While the brewing water undoubtedly contributes to the minerals supplied by drinking tea and coffee, both tea leaves and coffee beans do contain significant amounts of minerals. Tea and coffee may therefore be important sources of minerals in the human diet.
RdB
