Natural Foods Merchandiser

Tea Leaves Promise Well-Being

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]

Additional Benefits of L-theanine

L-theanine is an analog of glutamic acid,25 which is an excitatory neurotransmitter in the central nervous system and an integral component in the synthesis of GABA (an inhibitory neurotransmitter).26 Because L-theanine is structurally similar to glutamate (a form of glutamic acid most abundant in bodily fluids), it can protect the brain from toxic levels of this neurochemical by serving as a competitive antagonist on glutamate receptors, thereby shielding brain cells from glutamate-induced toxicity.25,27,28 Although glutamate is essential to brain chemistry, too much can destroy brain cells or cause degenerative brain disease. If the brain doesn?t get adequate blood flow, as in the case of ischemic stroke, glutamate concentrations surge, resulting in increases in calcium ions and free radicals, which can damage brain cells.25,28 By binding to glutamate receptors, L-theanine helps guard against neuronal death and damage,27,28 as well as vascular dementia.28 These observations are based upon in vitro and animal studies.

Immune system booster
Recent studies suggest tea containing L-theanine enhances the immune system and the body?s ability to fight infection.29,30 Eleven nontea drinkers and 10 nontea, noncoffee drinkers were asked to drink five to six cups of freshly brewed black tea or instant coffee a day, respectively, for two to four weeks (both beverages contained varying amounts of caffeine).29 Chemical analysis of the tea revealed a daily total theanine intake of approximately 226 mg. However, the percentage of the L-isomer of theanine was not determined, as tea leaves have differing amounts of theanine, with up to 10 percent D-theanine.8 Subjects were assessed for both numbers and function of gamma-delta T cells. These specialized lymphocytes appear to play a prominent role in resistance to various infections.

The experiments showed that 50 percent or more of the tea drinkers displayed strong gdT cell responses (increased gamma-interferon production) within two weeks of tea consumption, which seemed to persist through the fourth week. No notable responses were seen among the coffee drinkers.29

Interestingly, the gdT cell function was stimulated by the addition of heat-killed bacteria or ethylamine and isobutylamine, two naturally occuring alkylamines found in wine, apples and other plant products. Significantly, EA also occurs in tea and is produced in the body after tea ingestion, likely from the breakdown of L-theanine in the gut or after it is absorbed.15,30 Indeed, some in vitro work suggests that L-theanine does not itself elicit any gdT response, and only theanine that has been exposed to acid, thus yielding EA (and glutamate), does.30 Collectively, this work indicates that foods and beverages, especially tea brewed from Camellia species, may keep the gdT cells in a ready and primed state, and therefore be more capable of mounting a swift and robust response to infectious invaders.29

Tumor development inhibitor
L-theanine has been found to reduce tumor growth and proliferation of the AH109A hepatoma (liver cancer) cell line in animals.31,32 It suppresses angiogenesis by intercepting the supply of nutrients and oxygen to tumors,31 and inhibits the invasion and spread of cancer cells.32

Chemotherapeutic drug enhancement
In animal studies, L-theanine also improves the anti-tumor action of cancer-fighting drugs like doxorubicin,33,34,35,36 adriamycin,37,38 idarubicin39 and pirarubicin.40 When combined with these drugs, L-theanine increases their concentrations in cancer cells but inhibits their outflow from tumor cells to normal cells.33 This reduces adverse side effects from chemotherapy and enhances its anti-tumor activity, especially in cases of drug-sensitive, drug-resistant and metastatic tumors. 33,35,36,39

Weight-loss promotion
L-theanine has been shown to work in conjunction with green tea catechins and caffeine to reduce body weight, fatty accumulation, triglycerides and nonesterified fatty acids in animals.41 L-theanine?s anti-obesity effects in reducing food intake41 were most likely caused by the increase of dopamine release18 and decrease of serotonin concentrations19,20 in the brain. Animal research has suggested that these neurotransmitters may help regulate appetite and food intake.42 An L-theanine and caffeine combination seemed to be responsible for suppressing body weight increase and fat accumulation. Caffeine also appeared to work synergistically with green tea catechins in increasing thermogenesis and fat metabolism. Additionally, catechins and theanine were suggested to lower blood lipid levels.41


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Natural Foods Merchandiser volume XXV/number 11/p. 46, 48

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