Tea and coffee as sources of some minerals in the New Zealand diet

Abstract

Daily intakes of tea and coffee of a representative sample of adult New Zealanders (865 men and 1100 women) were calculated from 24-h dietary recalls. The mineral concentrations in tea and coffee samples were determined by atomic absorption spectrometry and used to estimate daily mineral intakes from these beverages. More than 80% consumed tea and about 60% consumed coffee on the day of the recall. The men drank significantly more tea than the women (p less than 0.001), but coffee intakes were similar. The results indicate that for New Zealand adults tea is a very good source of manganese and it also contains appreciable amounts of potassium. Coffee is a better source of potassium than tea, has appreciable amounts of magnesium, and may contribute significantly to manganese intakes in some instances. The amounts of copper, zinc, sodium, calcium, and iron extracted from tea leaves and coffee beans in the brewing processes are too low to be of any nutritional significance but minerals in the water used in their preparation may make a significant contribution to dietary intakes.

Influence of brewing pots on mineral content of black tea infusions

“…Drinking tea contributes to dietary mineral intake [12,21,26]. Depending on the quantity of tea daily consumed and the hardness of tea the mineral contents show alterations in individuals [2].…”

“…Tea is known as a good source for K and Mn, in addition to the flavonoids in its composition or other beneficial components [7,20,26].…”

Influence of tea drinking on manganese intake, manganese status and leucocyte expression of MnSOD and cytosolic aminopeptidase P

“…For moderate to heavy tea drinkers, defined in this study as those consuming at least 1 l (four mugs) black tea infusion per day, the values were significantly higher and dependent upon the concentration used for the Mn content of tea infusions. Previously, figures around 0.5 mg/100 g have been reported for the Mn content of black tea infusions although those as low as 0.1 mg/100 g have also been suggested (Gillies and Birkbeck, 1983;Matsushima et al, 1993). Clearly the type of tea, including its geographical origin, degree of fermentation prior to drying and leaf size, as well as type and temperature of water, length of brewing time and strength of tea brew will all impact upon the concentration of Mn and other nutrients present in the infusion.…”

“…Tea drinking is a potentially major source of dietary manganese (Mn) as 1 l (four standard mugs) of black tea is estimated to contain 1.8-5.2 mg Mn (Gillies and Birkbeck, 1983;Fraile and Flynn, 1991;Matsushima et al, 1993;Powell et al, 1998;Matsuura et al, 2001).…”

Evaluation of arsenic and selenium in Brazilian soluble coffee by inductively coupled plasma atomic emission spectrometry with hydride generation

“…The determination of macronutrients, micronutrients and toxic elements in soluble coffee is of great general interest, particularly because of the importance of coffee in nutrition to millions of people around the world (Krivan et al, 1982). Previous work on the composition of coffee and its products is mainly concerned with the mineral contents and studies on toxic elements are scarcely reported (Clarke et al, 1974;Gillies et al, 1983;Horwitz et al, 1974;Kuennen et al, 1982;Kapur et al, 1974;Koch et al, 1989;Lara et al, 1975/76). No information exists on the content of arsenic and selenium in this product although a number of publications (Goulden et al, 1981;Nakahara et al, 1985;Nakahara, 1981;Nygaard et al, 1982;Oliveira et al, 1983;Pahlavanpour et al, 1980;Ybanez et al, 1992) demonstrated that hydride generation, followed by introduction of gaseous hydrides into an ICP was a suitable method for the determination of several trace elements, including arsenic and selenium, for which detection limits were inadequate for foods and related matrices when conventional pneumatic nebulization was used.…”