L-theanine comes into focus
The substance from tea finds its way, sans the caffeine, into drinks and supplements marketed as concentration helpers. Does it work?
By Shari Roan
May 04, 2009
Loaded with caffeine and taurine to stimulate the central nervous system, energy drinks have become the go-to solution when you need a quick, energizing pick-me-up.
But sometimes energy isn't what you need. Concentration and attention can start to fade in the face of those midafternoon doldrums and a host of distractions. Something to perk up the mind and enhance focus would do the trick.
Some beverage manufacturers say they have just the solution. They're touting a new kind of drink that emphasizes focus over ferocity. The key substance is the amino acid L-theanine, which preliminary research suggests might calm the brain to enhance concentration and mental stamina.
Certain formulations of SoBe Lifewater and Vitamin Water now contain L-theanine, as does a new beverage called ViB. And Gatorade recently introduced a drink with the amino acid as well. That product -- Tiger -- was named for and marketed by (who else?) golfer Tiger Woods, the king of concentration in the sports world.
"Focus and concentration is the next generation of the energy drink," says Scott Smith, vice president of Taiyo International, a major producer of L-theanine in a patented tea extract called Suntheanine. "This will put you in an alert state -- in a zone -- but it's not going to keep you up at night."
L-theanine is not a new discovery. The substance comes from the Camellia sinensis plant species, otherwise known as tea.
Despite its caffeine content, tea is cherished for its soothing effects.
"It's one of the reasons people drink tea," says Dr. Jack F. Bukowski, a scientist with the Nutritional Science research Institute, an industry-based nonprofit organization that studies nutritional supplements. "The combination of the caffeine and the L-theanine gives people the same amount of energy as caffeine alone but less of a jittery-ness."
That may be true for a cup of tea. But much less is known about the benefits of L-theanine when it's extracted from tea and packed into pills or blended into beverages at quadruple the dose.
"We've gotten that wrong before," says Lenore Arab, a professor of medicine at the David Geffen School of Medicine at UCLA. "We've learned so often that we make a mistake if we pull a substance out and take it in a supplement. But L-theanine is an interesting substance."
The studies done on L-theanine thus far have been small, funded largely by companies with an interest in the product. That's not surprising. Early research on a potential supplement is often done by companies that believe there's a profit to be made. What remains to be seen is whether large-scale studies will back up early findings.
What intrigues researchers thus far is evidence that L-theanine is readily absorbed in large quantities, crosses the blood-brain barrier and gets into the brain fast.
Several studies suggest that the substance stimulates alpha waves in the brain, which are associated with alertness. The brain generates a range of electrical activity that reflects various mental states, such as sleep, daydreaming, agitation or concentration. The alpha waves represent the alert state.
* In one study, the alpha rhythms of 13 people were monitored with electroencephalography, more commonly called EEG, which records electrical activity in the brain. Participants performed a demanding visual-spatial attention task after being given either 250 milligrams of L-theanine or a placebo.
The study, published last year in the journal Brain Topography, showed L-theanine enhanced the processes responsible for sustaining attention, says John J. Foxe, a neuroscientist at the Nathan Kline Institute for Psychiatric Research in New York who conducted the study.
"In all the studies, theanine had an effect on the alpha rhythm and a small but measurable effect on people's performance," says Foxe, who receives some funding for the L-theanine studies from Unilever, which makes Lipton tea.
* Another study examined the effects of as little as 50 milligrams of L-theanine -- what researchers called a more realistic dietary dose -- in 16 healthy people.
The participants underwent EEG while relaxing with their eyes closed. They showed increased alpha-wave activity indicating "a relaxed but alert mental state" compared with 19 other participants who did not receive L-theanine. The study, also funded with a grant from Unilever, was published last year in the Asia Pacific Journal of Clinical Nutrition.
* L-theanine may also protect the brain from some types of damage and help people who already have cognitive dysfunction.
A recent analysis of nine studies on stroke and tea consumption found that the more tea people consumed, the greater the reduction in stroke risk. The study, conducted by UCLA's Arab, was published online in February in Stroke: Journal of the American Heart Assn.
"The problem with stroke is so much damage can happen so quickly," she says. "It's possible that something in tea is protecting the brain from the damage of stroke."
That's not to say L-theanine is the protective factor, but it has a chemical structure similar to that of glutamate, a cell-damaging substance released during a stroke. Thus, one hypothesis is that L-theanine's presence may block glutamate receptors during a stroke, limiting brain damage.
* Researchers are also exploring whether the substance could benefit people with mood and neurocognitive disorders.
A study of 60 people with schizophrenia found those taking L-theanine along with antipsychotic medications had fewer emotional and cognitive symptoms compared with patients taking a placebo and antipsychotic medications. The study, by Dr. Michael S. Ritsner of Technion-Israel Institute of Technology, is undergoing review for publication.
Sorting it out
Of course, it's possible that L-theanine may not have the same positive health effects if separated from the other chemicals found in tea, which is also rich in antioxidants.
"Based on what we know now, I'd stick with drinking tea," Arab says when asked about the possible benefits of the L-theanine supplements or drinks with L-theanine.
There is some evidence that L-theanine works better in conjunction with caffeine.
The dose also matters. The L-theanine contained in a cup of tea ranges from 2 milligrams to 100 milligrams, Bukowski says. In L-theanine studies, the dosages range from 50 milligrams to 400 milligrams. There is no known toxic dose of L-theanine or any reports of harm from the substance.
The dose found in energy drinks ranges from 50 milligrams to 200 milligrams, says Taiyo's Smith. Studies show that the effects increase with the dosage. L-theanine tends to stay in the brain for about six hours, Foxe says.
But, he cautions: "These are laboratory tests of attention. What this means for people driving a car, we don't know. It's not going to turn you into Tiger Woods. I don't know that it will take even two strokes off your game. My personal opinion is there is a lot of science to be done. The science is good, but very little has been done."
The effects are clearly subtle, adds Bukowski, who has performed consulting work for Taiyo.
"For someone who has to really concentrate, for example, in golf where you have to really concentrate while putting the ball and striking the ball, it could help keep your game plan in check without being jittery and emotional," he says.
"It would be less useful for running in a marathon or something purely aerobic. It's not ever going to be as big as caffeine because you don't get that jolt you get with caffeine."