Antidepressant Effect of Shaded White Leaf Tea Containing High Levels of Caffeine and Amino Acids

Abstract

The young leaves of green tea become lighter in color than usual when protected from sunlight by a shading net for about two weeks while growing. These leaves are called “shaded white leaf tea” or SWLT. In the eluate of SWLT, the amount of amino acids (361 mg/L) was significantly higher than that in regular tea (53.5 mg/L). Since theanine and arginine, the first and second most abundant amino acids in SWLT, have significant antistress effects, we examined the antistress effect of SWLT on humans. SWLT or placebo green tea (3 g) was eluted with room-temperature water (500 mL). Participants consumed the tea for one week prior to pharmacy practice and continued for 10 days in the practice period. The state-trait anxiety inventory, an anxiety questionnaire, tended to be scored lower in the SWLT group than the placebo, but other stress markers showed no differences. The effect of the difference in SWLT components examined with mice showed that aspartic acid and asparagine, which are abundant in SWLT, counteracted the antistress effects of theanine and arginine. Large amounts of caffeine also interfered with SWLT’s antistress effect. Thus, SWLT, which is high in caffeine and amino acids, suppressed depressant behavior in mice.

Green and white teas as health-promoting foods

“…Many investigations claim healthy effects of tea and its bioactive compounds on mental health, 85 memory and learning, 29,86 stress, 17,23,25,87 anxiety, 17,23,25,85,87 depression, 85,88 and neurodegenerative diseases. 29,86,[89][90][91][92][93][94] Depression is one of the most common psychiatric disorders, whereas stress is a major risk factor for depression. Tea consumption reduce the risk of depression.…”

“…29 EGCG had some of the neuroprotective effects against neural injury and Huntington's disease, amyotrophic lateral sclerosis and more prevalent neurodegenerative diseases. 89 Catechins in green tea extract have neuroprotective and memory-enhancing effects in an animal model of Parkinson's disease. It also suppressed the formation of amyloid plaques and halted immunohistochemical alteration and oxidative damage.…”

Tea as a Source of Biologically Active Compounds in the Human Diet

“…Epidemiological studies have demonstrated a correlation between the consumption of phenolic compounds and a reduced incidence of certain types of neoplasms and other chronic diseases, e.g., cardiovascular, neurodegenerative diseases, and type II diabetes [6,9,[13][14][15][16][17][18]. The biological effects of phenolic compounds also include the antiosteoporotic, antiatherosclerotic, antiallergic, anti-obesity, antifibrotic, hypolipidemic, hypocholesterolemic, antidiabetic, antiviral, antimutagenic, antimicrobial, and even antidepressant effects [19][20][21][22][23]. Ullah et al [12] believe that due to the wide range of health-promoting effects of polyphenols, their conjugates in combination with important drugs may enhance the potency of these compounds and possibly even extend their therapeutic effects.…”

Green Tea Suppresses Brain Aging

“…In SWLT, the theanine level is increased around 5-fold, and the arginine around 13-fold, compared to normal Sencha ( Table 3 ); its CE/TA ratio is 1.12, thus suggesting a stress-reducing effect. However, no significant stress-reducing effect of this variety was observed in a clinical study [ 110 ].…”

“…In SWLT, complete shading for two weeks causes the decomposition of soluble proteins, and its free amino acid composition is significantly different from that of general Sencha [ 110 ]. Although theanine levels are increased in this variety, the proportion of theanine in its total amino acid level is lower compared to Sencha, while the proportions of arginine, glutamine, asparagine, aspartic acid, etc., were higher.…”