BLACK tea helps in mental alertness and ability to focus, while green tea catechins may play a part in reducing fat deposits around vital organs, the Lipton Tea Institute revealed recently.
In a Tea Science Symposium 2008 organised by the tea purveyor last week, experts unveiled new evidence of the benefits of black tea and green tea.
Jane Rycroft, beverages global nutrition manager for Unilever, said that studies have shown that black tea consumption has a positive effect on your levels of alertness during the day.
The key ingredient is said to be an amino acid called L-theanine, a natural component found almost exclusively in tea. Each cup of black tea naturally contains five mg to 23 mg of L-theanine, depending on the blend and brewing method.
About 10 years ago, Japanese researchers discovered that 200 mg of L-theanine increases alpha brain waves, which are associated with a relaxed yet alert mental state during rest.
To further investigate this, Unilever commissioned Oxford University to conduct a series of EEG (electroencephalography: measurement of electrical activity produced by the brain as recorded from electrodes placed on the scalp) studies with L-theanine in healthy volunteers.
The studies confirmed that 50 mg L-theanine (found in a few cups of tea, such as Lipton's Yellow Label tea, as the company pointed out) increases alpha brain activity gradually over time, with apparent effect after 80 minutes of drinking the theanine and still apparent 105 minutes later.
Emerging research also suggests that L-theanine may play a role in the ability to focus attention. Recent research has shown that there is a very specific pattern of alpha activity when humans focus their attention on information coming from a variety of sensory stimuli. This is known as the alpha attention effect.
The study showed that 250 mg L-theanine improves attention-related alpha activity, which may enable individuals to focus attention more effectively. Given this evidence, scientists from the Lipton Institute of Tea have shown that two to three cups of tea can help you focus and they believe this is due to theanine combined with the other benefits of tea.
As for green tea, catechins have been the recent focus as evidence points towards their effects on body composition and fat distribution. Catechins are a large group of very active flavonoids found in high quantities in green tea.
According to Niels Boon, a research scientist at Unilever Food and Health Research Institute who also spoke at the symposium, recent studies have shown that consumption of catechin-enriched green tea has repeatedly shown it to be an effective treatment in reducing visceral obesity (excessive deposition of fat around the organs) in Asians.
The combined effects of catechins and caffeine in green tea could trigger increased energy expenditure in the body. Studies have shown that visceral obesity is linked to increased risks in diabetes and cardiovascular diseases.
In a clinical trial conducted by Unilever in Shanghai, volunteers were asked to consume daily either a placebo, one serving of catechin-enriched green tea (ie, 470 mg/day) or two servings of the beverage (total catechins: 940 mg/day) for eight weeks. The results showed that one serving of the catechin-enriched green tea had helped to reduce body weight by almost one kg and waist circumference by 1.8 cm in eight weeks.
If taken longer, 90 days for instance, the more green tea taken, the greater the effect. Those who took two servings of a 440 catechin beverage a day for 90 days saw body weight reduced by 1.2 kg, waist circumference reduced by two cm, and the amount of visceral fat reduced by almost 6 per cent.
This indicates that there is a correlation between dosage and result over a longer period of consumption. So far, research suggests that long-term consumption of catechin-rich green tea has stronger effects on body composition and fat distribution than body weight in Asian populations.
Emphasising the value of drinking tea, Aart Jan Van Triest, vice-president of brand development beverages-Asia, Unilever, said: 'The life we lead today is much more busy and stressful than those of our parents. It becomes harder to make time to lead healthier lives. For many of us, drinking tea is already a daily habit - knowing that you are already on to a good thing may encourage you to include other healthy habits as part of your daily life.'
This story was first published in The Business Times on July 12, 2008.
