Cadmium and cobalt in tea and coffee and their relationship to cardiovascular disease

Abstract

Both cadmium and cobalt are known to cause hypertension and cardiac pathology. Coffee drinking, but not tea drinking, has recently been implicated in the latter. Various brands of teas and coffees were analysed for cadmium and cobalt in order to discover whether these elements might be responsible for the deleterious effects of coffee. Coffee infusions made from finely-ground coffee beans, coffee made from instant powders, one of pure coffee and 2 of coffee and chicory blends, and tea infusions, were analysed by atomic absorption spectrophotometry. The cadmium content of 5 teas, averaged, was found to be 0,0298 μg/g tea. That of 7 coffees was 0,03  μg/g coffee, the average of 3 different methods, each of which averaged 0,027, 0,018 and 0,045 μg/g coffee. Pure instant coffee powder had the highest cadmium content and bush tea the lowest. The cobalt content of coffee was found to be considerably higher than that of tea. The content of 5 teas, averaged, was 0,20 μg/g tea and that of 7 coffees was 0,93 μg/g coffee, the average of 3 different methods, each of which averaged 0,75, 0,89 and 1,14 μ/g coffee. The cobalt content of pure instant coffee powder was the highest and that of bush tea and one other commercial brand of tea, the lowest. In view of the fact that quantities of these elements ingested by even heavy coffee drinkers, form only a very small proportion of the total daily intake, no firm conclusions can be drawn about their toxicity from this source.

S. Afr. Med. J., 48. 230 (1974).