Tea under the microscope
Tea is one of the most popular drinks in the world, but what does science say about … INTEREST BREWING: Tea consumption is linked to a number of health benefits. … at the intersection of the Leichhardt Hwy and Fairy Meadow Rd,. News …
TEA is one of the most popular drinks in the world. Tea is personal – everyone has opinions about making the perfect cup. But what does science say about getting the most out of your brew?
It’s not the only reason to drink it, but tea consumption is linked to a number of health benefits. It’s thought to improve mood and cognition and reduce the risk of heart disease and diabetes.
Tea is a source of micronutrients, including fluoride, magnesium and zinc.
However, the health benefits are mostly linked to three main bioactive compounds: catechins, caffeine and L-theanine. Bioactive compounds are non-essential nutrients that may impact health.
Laboratory and animal studies have suggested these compounds may have multiple health effects, but the results in human studies are much less clear.
Catechins are a type of polyphenol, a group of chemicals with antioxidant properties.
Antioxidants are molecules that prevent cell damage. Caffeine makes you feel alert and the amino acid L-theanine is believed to be responsible for tea’s relaxing properties.
These compounds also contribute to your brew’s taste and mouthfeel.
Which tea is healthiest?
Black, oolong, white and green teas all come from the same plant, Camellia sinensis.
The differences come from the harvest timing and processing, particularly the level of oxidation, a reaction that occurs when processed leaves are exposed to high oxygen levels.
Black tea is fully oxidised, oolong is partially oxidised, while green and white teas are unoxidised. White teas are from early harvests, green from later.
Processing has little impact on L-theanine, with similar levels found in all teas.
Caffeine levels vary widely, however, and black tea typically has the most.
Catechins are altered by oxidisation, so levels are highest in green and white teas.
More antioxidants and less caffeine means green tea is typically considered the healthier option, so green tea has been the focus of most studies regarding health benefits. However, all teas are a good source of L-theanine, caffeine and catechins.
But be warned. Having “tea” on the label doesn’t guarantee bioactive content or health benefits. Pre-packaged iced teas and instant teas may have limited bioactives and can be high in sugar. Herbal and fruit teas don’t contain any actual tea leaf and so properties vary.
Excessive consumption of tea can also be harmful, leading to overconsumption of caffeine.
Tannins, which is another group of polyphenols in tea, can also bind to iron and reduce iron absorption if consumed with or soon after a meal.
Brew science
Getting the maximum health benefit from your cuppa is more about the brewing than the tea you choose.
Patience is important. If you are jiggling the tea bag in the cup for 15-30 seconds, you are probably only getting a fraction of the bioactives you would by following the maker’s instructions.
Brewing with freshly boiled water for two to three minutes, as per the instructions, extracts about 60% of the catechins, 75% of the caffeine and 80% of the L-theanine.
The longer you brew, the more bioactives you get, but also the stronger the taste. Research has found that brewing for 20-30 minutes at 80C extracts the maximum level of bioactives, but that’s not really practical for daily life, and probably isn’t very tasty.
Interestingly, the pH of water also impacts the extraction process. Low pH (acidic) water extracts bioactives better than high pH (basic) water.
The pH of tap water is about seven, which is neutral, so there might be a benefit to adding lemon with your tea, rather than after its brewed.
Milking it
Some studies have suggested milk alters the antioxidant activity and health benefits of tea.
