Tea’s potential longevity and health benefits depend on the way one consumes the beverage, a major new review of studies suggests.
Drinking tea has been shown to help prevent diabetes, obesity, heart disease, and some types of cancer due to its anti-inflammatory properties.
Tea, typically made from the leaves of Camellia sinensis, also has potential protective effects for the brain and the ability to reduce muscle loss in the elderly, previous studies have revealed.
Green tea, in particular, has been highlighted for its heart-protective effects, reducing blood pressure and improving cholesterol levels.
However, despite extensive studies, there is also not enough data to assess whether Chinese oolong tea, white tea, dark tea, or yellow tea is more or less effective than green tea, researchers say.
Scientists now claim that the way one drinks tea matters due to potential health concerns, particularly with bottled and bubble teas that may contain harmful additives like artificial sweeteners and preservatives.
Pesticide residues, heavy metals, and microplastics in tea may also pose health risks, warns the new study published in the journal Beverage Plant Research.
While contaminants may not pose significant health risks in typical consumption, they remain a concern for long-term heavy tea drinkers, researchers say. They caution that even when the health benefits of tea are clear, its consumption in processed forms like bottled tea and bubble tea should be moderated.
“The presence of sugar, artificial sweeteners, or refined starch, as well as flavouring agents and preservatives, in bottled or bubble tea beverages may cause health concerns in reducing or overshadowing the beneficial health effects of tea,” scientists write in the new study.
While green tea extracts have become a popular dietary supplement for weight reduction, there have also been many case reports of liver toxicity of such extract-based supplements, the study warns.
The toxicity is due to the chemical epigallocatechin, or EGCG, found in green tea, researchers say.
“This overdose toxicity is consistent with laboratory experiments; for example, daily administration of 500-750 mg of EGCG/kg (body weight) by intragastric infusion caused dose-dependent liver toxicity,” scientists wrote.
“Nevertheless, toxicity due to the consumption of tea as a beverage has not been reported in humans, even though gastrointestinal irritation due to drinking tea, especially green tea, is known to occur,” they wrote.
The research review also notes that a plastic teabag steeped in boiling water could release as many as over 109 microplastic particles, which may pose potential health risks.
Overall, the latest research review concludes that a moderate consumption of traditional, freshly brewed tea can be beneficial, especially for preventing heart diseases, diabetes, and cancer.
“Additional research would further elucidate the health benefits and assess some of the health concerns of tea consumption,” scientists wrote.