Sumber : independent.co.uk, Jabed Ahmed. 27 februari 2025

Scientists have found that brewing tea naturally absorbs heavy metals like lead and cadmium, effectively filtering dangerous contaminants out of water. Heavy metals are absorbed on the surface of the tea leaves, where they stay trapped, researchers at Northwestern University in the US found.

The scientists estimated that tea preparation can reduce about 15 per cent of lead from drinking water. This applies to a typical cup of tea, with the tea bag brewed for three to five minutes. However, steeping for longer than five minutes, for example, can absorb more lead, according to the researchers.

The scientists also tested the differences between loose-leaf and the typical tea bags bought at the supermarket. Finely ground tea leaves, particularly black tea leaves, removed slightly more metal ions than whole leaves. The researchers attributed this to the ground leaves having a greater surface area.

The researchers also found cotton and nylon bags only absorbed small amounts of the contaminants, while cellulose bags absorbed much more. However, the researchers said they are not suggesting people start using tea leaves as a water filter.