Daily Bulletin


Daily Bulletin

The Conversation

  • Written by Emma Beckett, Postdoctoral Fellow (Human Molecular Nutrition), School of Medicine and Public Health, University of Newcastle

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 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 oxidized, oolong is partially oxidized, while green and white teas are unoxidized. 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 black tea typically has the most. Catechins are altered by oxidisation, so levels are highest in green and white teas.

image Green tea is usually thought to be healthiest. www.joannabeckettdesign.com, Author provided

More antioxidants and less caffeine means green tea is typically considered the healthier option. So green tea has been the focus of most studies of the 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 over consumption of caffeine. Tannins, which are 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 around 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 80°C 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.

Tea in the microwave?

The idea of making tea in the microwave is horrifying for purists. It’s argued microwaves are inferior to kettles for heating water, as there is less control over the temperature. But the microwave could actually be a useful tool for extracting more bioactives.

Microwaves can actually increase the levels of bioactives in your cup. Adding freshly boiled water to the teabag, steeping for 30 seconds, followed by a minute in the microwave (medium power) extracts more bioactives than a standard three minute steep.

Does milk change the health benefits of tea?

Some studies have suggested milk alters the antioxidant activity and health benefits of tea.

But others have shown the same level of antioxidants reach the blood after consuming tea with and without milk. There’s no real science behind the age old question of when the milk should be added. The Royal Society of Chemistry suggests adding it first prevents denaturation, or clumping, of milk proteins, which might give the milk a stale taste.

image Milk probably doesn’t affect how healthy the tea is. www.joannabeckettdesign.com

Loose leaf vs teabags

Loose leaf may contain more bioactives because they use higher quality leaves. But leaves in teabags are cut smaller, and this is thought to enhance the extraction process.

Lower quality teas may also include more stems, which are higher in L-theanine than the leaves. So while fancy loose leaf might taste better, you probably get more bang for buck from a humble tea bag.

Health benefits might not be the only reason we choose to drink tea, but if you want to get the most out of your cup, patience is the key. Whichever type of tea you choose, the longer you brew, the more goodness in each cup.

Authors: Emma Beckett, Postdoctoral Fellow (Human Molecular Nutrition), School of Medicine and Public Health, University of Newcastle

Read more http://theconversation.com/what-science-says-about-getting-the-most-out-of-your-tea-75767

Writers Wanted

The missing question from New Zealand's cannabis debate: what about personal freedom and individual rights?

arrow_forward

NBN upgrades explained: how will they make internet speeds faster? And will the regions miss out?

arrow_forward

The Conversation
INTERWEBS DIGITAL AGENCY

Politics

Did BLM Really Change the US Police Work?

The Black Lives Matter (BLM) movement has proven that the power of the state rests in the hands of the people it governs. Following the death of 46-year-old black American George Floyd in a case of ...

a Guest Writer - avatar a Guest Writer

Scott Morrison: the right man at the right time

Australia is not at war with another nation or ideology in August 2020 but the nation is in conflict. There are serious threats from China and there are many challenges flowing from the pandemic tha...

Greg Rogers - avatar Greg Rogers

Prime Minister National Cabinet Statement

The National Cabinet met today to discuss Australia’s COVID-19 response, the Victoria outbreak, easing restrictions, helping Australians prepare to go back to work in a COVID-safe environment an...

Scott Morrison - avatar Scott Morrison

Business News

What happens to all those pallets?

Pallets — they're not something everyday people often give much thought to. But they're an integral part of any business which receives or distributes large quantities of goods. But once the goo...

News Company - avatar News Company

Ten tips for landing a freelance transcription job

Transcription jobs are known to be popular in the field of freelancing. They offer fantastic job opportunities to a lot of people, but there are some scammers who wait to cheat the freelancers. ...

News Company - avatar News Company

How To Remove Rubbish More Effectively

It can be a big task to remove household rubbish. The hardest part is finding the best way to get rid of your junk. It can be very overwhelming to know exactly where to start with so many option...

News Company - avatar News Company



News Company Media Core

Content & Technology Connecting Global Audiences

More Information - Less Opinion