[Lotus]

Well, how do you like this, green tea raises growth hormone (theanine in tea raises GABA), even at resting.

Determination and comparison of γ-aminobutyric acid (GABA) content in pu-erh and other types of Chinese tea.
Zhao M, et al. J Agric Food Chem. 2011.
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Abstract
Two previous studies have reported that pu-erh tea contains a high level of γ-aminobutyric acid (GABA), which is the major inhibitory neurotransmitter in the central nervous system and has several physiological functions. However, two other researchers have demonstrated that the GABA content of several pu-erh teas was low. Due to the high value and health benefits of GABA, analysis of mass-produced pu-erh tea is necessary to determine whether it is actually enriched with GABA. A high-performance liquid chromatography (HPLC) method was developed for the determination of GABA in tea, the results of which were verified by amino acid analysis using an Amino Acid Analyzer (AAA). A total of 114 samples of various types of Chinese tea, including 62 pu-erh teas, 13 green teas, 8 oolong teas, 8 black teas, 3 white teas, 4 GABA teas, and 16 process samples from two industrial fermentations of pu-erh tea (including the raw material and the first to seventh turnings), were analyzed using HPLC. Statistical analysis demonstrated that the GABA content in pu-erh tea was significantly lower than that in other types of tea (p < 0.05) and that the GABA content decreased during industrial fermentation of pu-erh tea (p < 0.05). This mass analysis and comparison suggested GABA was not a major bioactive constituent and resolved the disagreement GABA content in pu-erh tea. In addition, the GABA content in white tea was found to be significantly higher than that in the other types of tea (p < 0.05), leading to the possibility of producing GABA-enriched white tea.
PMID 21395338 [PubMed - indexed for MEDLINE]


Determination of theanine, GABA, and other amino acids in green, oolong, black, and Pu-erh teas with dabsylation and high-performance liquid chromatography.
Syu KY, et al. J Agric Food Chem. 2008.
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Abstract
Dabsyl chloride (dimethylaminoazobenzene sulfonyl chloride), a useful chromophoric labeling reagent for amino acids and amines, was developed in this laboratory in 1975. Although several methods have been developed to determine various types of amino acids, a quick and easy method of determining theanine, GABA, and other amino acids has not been developed in one HPLC system. In this paper are analyzed the free amino acid contents of theanine and GABA in different teas (green tea, black tea, oolong tea, Pu-erh tea, and GABA tea) with a dabsylation and reverse phase high-performance liquid chromatography (HPLC) system coupled with a detector at 425 nm absorbance. Two reverse phase columns, Hypersil GOLD and Zorbax ODS, were used and gave different resolutions of dabsyl amino acids in the gradient elution program. The data suggest that the tea source or the steps of tea-making may contribute to the theanine contents variations. High theanine contents of high-mountain tea were observed in both green tea and oolong tea. Furthermore, the raw (natural fermented) Pu-erh tea contained more theanine than ripe (wet fermented) Pu-erh tea, and the GABA contents in normal teas were generally lower than that in GABA tea.
PMID 18652476 [PubMed - indexed for MEDLINE]




Growth hormone isoform responses to GABA ingestion at rest and after exercise.
Randomized controlled trial
Powers ME, et al. Med Sci Sports Exerc. 2008.
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Abstract
Oral administration of the amino acid/inhibitory neurotransmitter gamma aminobutyric acid (GABA) reportedly elevates resting serum growth hormone (GH) concentrations.
PURPOSE: To test the hypothesis that GABA ingestion stimulates immunoreactive GH (irGH) and immunofunctional GH (ifGH) release at rest and that GABA augments the resistance exercise-induced irGH/ifGH responses.
METHODS: Eleven resistance-trained men (18-30 yr) participated in this randomized, double-blind, placebo-controlled, crossover study. During each experimental bout, participants ingested either 3 g of GABA or sucrose placebo (P), followed either by resting or resistance exercise sessions. Fasting venous blood samples were acquired immediately before and at 15, 30, 45, 60, 75, and 90 min after GABA or P ingestion and were assayed for irGH and ifGH.
RESULTS: At rest, GABA ingestion elevated both irGH and ifGH compared with placebo. Specifically, peak concentrations of both hormones were elevated by about 400%, and the area under the curve (AUC) was elevated by about 375% (P < 0.05). Resistance exercise (EX-P) elevated time-point (15-60 min) irGH and ifGH concentrations compared with rest (P < 0.05). The combination of GABA and resistance exercise (EX-GABA) also elevated the peak, AUC, and the 15- to 60-min time-point irGH and ifGH responses compared with resting conditions (P < 0.05). Additionally, 200% greater irGH (P < 0.01) and 175% greater ifGH (P < 0.05) concentrations were observed in the EX-GABA than in the EX-P condition, 30 min after ingestion. GABA ingestion did not alter the irGH to ifGH ratio, and, under all conditions, ifGH represented approximately 50% of irGH.
CONCLUSIONS: Our data indicate that ingested GABA elevates resting and postexercise irGH and ifGH concentrations. The extent to which irGH/ifGH secretion contributes to skeletal muscle hypertrophy is unknown, although augmenting the postexercise irGH/ifGH response may improve resistance training-induced muscular adaptations.
PMID 18091016 [PubMed - indexed for MEDLINE]