Aluminium in tea—concentrations, speciation and bioavailability

Analytical Problems with the Evaluation of Human Exposure to Fluorides from Tea Products

“…polyphenols, in the examined sample can influence the amount of aluminium involved in the formation of the complexes with fluoride ions. According to literature data substantial (10-90 %) amounts of aluminium can be bound by organic tea components (Flaten 2002;Kralj et al 2005).…”

Aluminum Contents in Dry Leaves and Infusions of Commercial Black and Green Tea Leaves: Effects of Sucrose and Ascorbic Acid Added to Infusions

“…Aluminum concentrations in tea products and its dissolution during the preparation of infusions has been investigated by Flaten [16], Fung et al [12], Moghaddam et al [17], and Wong et al [8,18]. So far, the effects of sucrose and/or lemon juice, as ascorbic acid, on the leaching out of aluminum from the dry tea leaves to water during infusion have not been assessed.…”

Selective Determination of Aluminum Bound with Tannin in Tea Infusion

“…The discovery of a possible correlation between the Al concentration in drinking water and the incidence of Alzheimer's disease has led to a renewed interest in the co-ordination chemistry of Al. [1][2][3][4][5][6] The bioavailability of Al is strictly linked to the distribution of the element among different chemical species. 3,7 The studies on speciation of Al in food samples are very limited, although there are many studies on the Al species in water samples.…”

“…12 It has been assumed that the polyphenols, which account for about 40% of the dry residue of tea infusions, are the most important ligands of Al complexes in tea because they have phenolic hydroxyl groups (such as flavonoid, phenolic acids, coumarin, tannin and lignan) and provide a large number of potential sites for complex formation. 6,13 Polymeric phenols can be divided into two groups; tannin and lignin. Tannins comprise a heterogeneous group of plant polyphenols, all of which are able to combine with skin proteins.…”

“…[1][2][3] If these polyphenols are decomposed in the gut, Al bound with tannin could become more bioavailable. 6 Studies on Al species under stomach conditions before and after gastrointestinal digestion were published. 10 Ultrafiltration studies showed that as much as 86% of the 0.45 µm filterable Al in tea infusions was retained by a 20000 Da molecular-mass cut-off filter and 96% was retained by 10000 and 500 Da molecular-mass cut-off filters.…”