Nutrition Spotlight: Caffeine and L-theanine in Tea

2 Jan

According to a Unilever study recently reported in a Food Navigator-USA article, there is evidence to support the notion that compounds in tea, primarily caffeine and L-theanine, can be beneficial for one’s mood and mental focus.

Despite the European Food Safety Authority’s recent rejections of two Unilever health claims petitions (13.1 and 13.5) which linked black tea consumption to improved mental focus, the company is continuing its extensive research on the many benefits of tea consumption. Suzanne Einother and Vanessa Martens, employed at Unilever Research and Development, Vlaardingen (the Netherlands), are responsible for a recent review in the American Journal of Clinical Nutrition which, concerning a number of studies of tea consumption, notes “particularly consistent evidence for improved attention” throughout. They added that tea “consistently improved self-reported alertness and arousal” among subjects.

“These studies,” they said, “showed the validity of laboratory findings by supporting the idea that tea consumption has acute benefits on both mood and performance in real-life situations.”

The review was first formally presented on September 19th, 2012, at the Fifth International Scientific Symposium on Tea and Human Health in Washington, D.C.

Scientific research of tea has long focused on green tea, the benefits of which are well-documented and include improving oral and cardiovascular health, aiding in weight-management and reducing the risks of Alzheimer’s disease and some forms of cancer.

Black tea is simply green tea which is oxidized by fermentation, and contains between 3% and 10% of water-extractable polyphenols; original green tea, by comparison, contains between 30% and 40%. Fresh tea leaves contain four primary extractable polyphenols: epicatechin, epicatechin gallate, epigallocatechin and epigallocatechin gallate.

Unilever’s research, however, has focused more on L-theanine, an amino acid extracted from tea leaves, and caffeine. L-theanine is believed to help reduce stress while improving one’s quality of sleep. Since it is found in very low concentrations (less than 2%) in tea leaves, drinking tea cannot deliver effective dosage levels of 100 to 200 milligrams per day.

In the past, L-theanine has been linked to other various health effects, including improved attention, relaxation and certain “neuro-protective” effects. For example, it has been suggested that the amino acid is responsible for increased alpha activity during rest (as shown in EEG models), which can improve relaxation.

In the new review, Einother and Martens used data from randomized control trials focusing on tea’s effects on attention and mood.

“From the totality of research on tea summarized,” they wrote, “[…] it can be concluded that consumption of black tea may improve attention and self-reported alertness. These conclusions are further supported by studies on caffeine and on theanine and caffeine in combination.”

They are quite clear, however, about the pockets of uncertainty which remain for the time being: “Research on the benefits of tea is promising for attention and alertness, although questions remain regarding the scope and magnitude of impact as well as the sensitivity of different individuals. Whereas the bioavailability of both caffeine and theanine has been established, as well as the [suggested] mechanisms of action in the brain, they extent to which they actually cross the blood-brain barrier in humans and how much this is associated with [individual] changes in subsequent performance and mood measures are as yet unknown.”

http://www.foodnavigator-usa.com/Trends/Health-Wellness/Unilever-on-tea-Available-evidence-supports-tea-and-tea-ingredients-for-mood-and-performance-benefits

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