With life in today?s society being so stressful, many people are looking for natural ways to achieve mental tranquility and sleep improvement without becoming lethargic in the process. Now you can offer your customers a safe, fast-acting and effective alternative to kava kava (Piper methysticum), St. John?s wort (Hypericum perforatum) and valerian (Valeriana officinalis).
From Japan comes L-theanine, a neurologically active nonprotein amino acid, originally derived from the leaves of the tea plant Camellia sinensis. This amino acid quells anxiety and stress without negative side effects1 and promotes a sense of relaxation and well-being without causing drowsiness.2,3 While not a sedative, L-theanine?s calming properties can improve sleep quality and satisfaction without increasing sleep duration or causing wake-up grogginess.4 Basically, L-theanine?s ability to help your customers decompress and relax encourages a restful night?s sleep, allowing them to awaken more refreshed and energized.
First discovered in green tea leaves by Japanese scientists in 1949,5 L-theanine later was found in black and oolong teas.6,7,8 Its only other known natural occurrence is in the edible wild mushroom Xerocomus badius.9 In 1964, the Japanese Ministry of Health and Welfare approved L-theanine as a food additive in all foods except infant food.10,11 Since then, its popularity has spread from Japan to Europe, with more than 50 food products containing L-theanine available in those two places. In 2000, L-theanine was introduced as a dietary supplement in the United States.12
L-theanine is noted for imparting green tea?s sweet, brothy ?umami? flavor (the Japanese ?fifth taste?) and relaxing effect;13 however, L-theanine constitutes only 1 to 2 percent of the dry weight of tea.8,11,12,14 Thus, large-scale production of L-theanine historically has been an expensive process.11 But in 1990, the Taiyo Kagaku Co. in Japan developed a method of obtaining isomerically pure L-theanine (free of D-theanine),1,11 which it trademarked as Suntheanine.12 Its patented enzymatic process produces ultra-high-purity L-theanine 1,10,12,13,14 using a soil-derived microorganism and the ?starter? ingredients ethylamine and glutamic acid (two naturally occurring constituents of tea and the breakdown products of theanine),13 which make possible standardized mass production and global marketing.11
The Dietary Supplement Health and Education Act of 1994 sets safety standards, in addition to providing guidelines for definitions, health claims and labeling of dietary supplements and ingredients. It also grants the U.S. Food and Drug Administration the authority to establish good manufacturing practice regulations. The implementation of quality control systems ensures that national and international L-theanine supplement makers routinely meet GMP specifications.10
When extracted from tea leaves, theanine is predominantly in the L-form, as opposed to the enantiomeric racemic combination of L- and D-theanine found in many synthesized supplements labeled as L-theanine. A recent analysis of six commercially available L-theanine supplements found that the enzymatically synthesized Suntheanine brand was the only sample demonstrating L-isomer purity. The other five samples tested contained a 50-50 (racemic) mix of D- and L-theanine.14 This is significant since nearly all of the human studies conducted with L-theanine have used the Suntheanine brand. It is also important to note because the safety and efficacy of D-theanine or racemic mixtures are wholly unknown.
How L-theanine works
Animal and test-tube studies have revealed the fate of L-theanine after it is orally ingested. It is absorbed into the blood through the small intestinal tract?s brush-border membrane within 30 minutes of contact.15,16 It is then easily transported into the brain through the blood-brain barrier?s leucine-preferring amino acid transporter system.17,18 Brain concentrations of L-theanine significantly increase one hour after intake and peak at five hours. L-theanine does not appear to accumulate, being metabolized in the blood, liver and brain, then completely eliminated in the urine within 24 hours.17 Whether these pharmacological profiles operate in humans remains to be evaluated.
L-theanine influences the release and concentration of several neurotransmitters. It increases dopamine,18 can either increase18 or decrease19,20 serotonin, and raises gamma-amino-butyric acid levels in the brain.6 Each of these neurotransmitters may play a role in mediating the effects of L-theanine?s ability to modulate mood (by creating a sense of relaxation and thereby promoting a sense of well-being), as well as its ability to perform a number of other actions demonstrated in animal studies?including enhancing memory and learning ability1,11 and regulating blood pressure.1,18,20,21
By promoting a sense of relaxation and well-being without interfering with cognitive abilities, L-theanine allows for increased focus and concentration, especially in those with high stress levels. This improves the ability to remember and learn.1,11 By increasing dopamine and GABA, and influencing brain concentrations of serotonin, L-theanine can also help lower blood pressure18,20,21 and inhibit the stimulating effects of caffeine.6,22,23
Relaxation without sedation
Human brain-wave studies confirm L-theanine produces a state of alert relaxation.2,3 In one study using female university students 18 to 22 years old, 50 volunteers were classified into five groups according to anxiety levels, from high to low. Four women from the high-anxiety group and four from the low-anxiety group were selected for the brain wave measurement tests.2 These eight women took an oral solution once a week at a fixed time of day, and brain waves were measured and analyzed for 60 minutes after intake. They were given 100 ml plain water (as the control) the first and fourth week, 50 mg L-theanine (Suntheanine) in 100 ml water the second and fifth week, and 200 mg L-theanine (Suntheanine) in 100 ml water the third and sixth week. L-theanine?s slightly sweet umami taste may have ?unblinded? the subjects if they compared it with the water placebo.
An electroencephalograph was used to record four sets of brain waves: alpha (awake and relaxed), beta (awake and excited), delta (deep sound sleep), and theta (drowsy, dozing, light sleep). Results showed no alpha waves observed with the water solution. However, both groups experienced significant increases in their alpha waves 30 minutes after administration of both L-theanine solutions, which peaked after 40 minutes, indicating they were in a relaxed state of mind. The intensity of the alpha brain wave emissions appeared to increase in a dose-dependent manner, in that the 200 mg L-theanine solution produced more alpha waves than the 50 mg solution, especially in the high-anxiety group. Moreover, the levels of theta waves in both groups remained unchanged during the observation period for all the test solutions, indicating that L-theanine did not induce drowsiness.2
An equivalent brain-wave study using 20 healthy men 18 to 30 years old found similar results for L-theanine?s effect on relaxation and concentration.3 In this study, the placebo and L-theanine (200 mg Suntheanine) were in the form of tablets instead of oral solutions (thus minimizing the chance of ?unblinding?). Despite the different delivery form, the outcome confirmed the previous study?s conclusion that L-theanine promoted the production of alpha waves, with the greatest impact on those with high anxiety.3
To evaluate L-theanine?s effect on fatigue perception, another study tested 20 healthy volunteers 30 to 55 years old who experienced constant tiredness for more than one month without any known underlying disease as the cause. Subjects were given either a placebo or test solution containing 200 mg Suntheanine for seven consecutive days. They were then crossed over to the opposite treatment for another week. An EEG was used to measure brain waves for one hour after each administration, and a fatigue-sensitivity-scale questionnaire was given before and after each seven-day test period. Among those with high anxiety, significant increases in alpha waves and decreases in fatigue scores after a week of taking the L-theanine solution, but not with placebo, were noted. This suggests L-theanine was effective at promoting mental relaxation and alleviating the sense of fatigue.24
Improved sleep quality
Since L-theanine does not appear to produce theta brain waves,2 it does not induce drowsiness or directly promote sleep through sedation. However, it has been shown to improve sleep quality, postsleep fatigue recovery and sleep soundness, and dream state without increasing sleep time or causing grogginess upon awakening.4 In a double-blind sleep study with 26 healthy men (13 daytime workers 25 to 36 years old and 13 students 20 to 33 years old), participants felt more refreshed and satisfied with the L-theanine treatment than with the placebo.4 Four participants dropped out of the study.
The study encompassed two six-night treatment periods, with an initial three-night adaptation period and a one-day washout between crossovers. Participants were given 200 mg L-theanine (four 50 mg Suntheanine tablets) or four placebo tablets one hour before bedtime. Every morning during the sleep-analysis phase they answered questionnaires about mood, sleep onset and sleep states (sleepiness, sleep quality, dream quality, exhaustion recovery and refreshed awakening). Their sleep/wake pattern was analyzed using a wrist activity monitor during the day and polysomnogram at night for each treatment period.
No significant difference in feelings of daytime sleepiness between the L-theanine and placebo treatments was observed, confirming that L-theanine does not cause drowsiness. However, compared with the placebo, the L-theanine treatment did improve sleep quality, dream quality and sleep onset, with a noticeable reduction in nighttime awakenings and nightmares. Even though sleep time was the same for both treatments, subjects taking L-theanine reported a feeling of prolonged sleep and a significant decrease in fatigue upon rising. They awoke feeling refreshed, good-spirited and more self-confident.4
Guidelines for use
Stress can interfere with your customers? quality of life as well as quality of sleep, leaving them feeling anxious. Poor sleep, in particular, can result in feelings of tiredness, with difficulty concentrating or trouble coping with daily activities and annoyances. Relaxing and enhancing both their waking and sleep experiences can help reduce their fatigue and improve their ability to deal with tension and anxiety.
Based upon the studies cited above, to promote alert relaxation and mood enhancement, a person should take 50 mg to 200 mg L-theanine, with the strongest effect associated with the highest dose. Calming effects are felt 30 to 40 minutes after intake and last for several hours. For sleep enhancement, take 200 mg one hour before going to sleep. While L-theanine has no known adverse reactions and can be ingested with or without food, pregnant and nursing women should check with their health care provider before using this supplement. Unlike anti-anxiety herbs such as kava kava and St. John?s wort, or sedative herbs like valerian that cause sleepiness, L-theanine does not cause drowsiness nor impair mental or physical functioning. It is thus a safe and effective way to overcome stress.
Monique N. Gilbert is a natural health advocate, free-lance writer and author of Virtues of Soy: A Practical Health Guide and Cookbook (Universal Publishers, 2001). She can be reached at [email protected]
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