International Tea Day

  Tea catechins are responsible for the astringent taste of green tea. Catechins of green tea leaves are account for about 10 % of dry w eight, including （-）- epigallocatechin gallate（ EGCg）50 %,（-）- epigallocatechin（ EGC）30 %,（-）- epicatechin gallate （ECg）10 % and（-）- epicatechin（EC）10 %. Crystals of catechins are sampled in the photographs on the right. A variety of biological activities are attributed to anti-oxidative, radioprotective, ant-mutagenic, antitumor, anti-hyperglycemic, anti-hypercholesterolemic, fat reducing, anti-ulcer, anti-bacterial, bowel modulating, anti-viral, anti-carious, anti-hypertensive actions and the inhibitory activity of some enzymes. ■  Cancer Chemoprevention : Recently, some review articles have reported the relationship between the tea consumption and the human cancer risk. A general overview of the pertinent epidemiological studies on tea consumption and cancer prevention in different organs such as bladder and urinary tract, breast, colon a...

  Caffeine , 1,3,7-trimethylxanthine , is widely distributed in natural products, i.e, tea, coffee, cocoa and as an additive in many soft drinks. During preparation of coffee and tea, the strength of brew influences the caffeine content of the beverage . Standard average caffeine contents per cup of these beverages are listed right. As normally ingested from food sources, caffeine shows a variety of biological effects those have attracted the interest of pharmacologist and clinicians.  Caffeine is regard as follows; ･ Diuretic ･ Cardiac muscle stimulant ･ Central nervous system stimulant ■ Effect on Sleep:  Much interest also has been concerned in the possible role of caffeine intake to central nervous system. In adults, the most sensitive function modified by caffeine is going to sleep. In one experiment, caffeine or placebo was taken blindly 0.5 hr before retiring, and the time of going to sleep was assessed by questionnaires next morning. Sleep postponement in adults h...

 Japanese green tea contains γ-glutamylethylamide , named theanine, at the level from 1 to 2 % in dried leafy materials. While most amino acids are found at lower level, theanine accounts for＞50 % of total free amino acids in tea. Theanine is the source of Japanese green tea’s characteristic delicious taste  (known as“umami”). There is a scientific interest about the biological effect of theanine on central nervous system. ■ Relaxation Effect: The relaxation feeling after drinking Japanese green tea may be linked with the presence of theanine. Studies on animals and human volunteers showed that oral administration of theanine generated α- waves in the brain, suggesting that theanine could bring about a relaxation feeling, because brain α- waves are generated under relaxing condition.   ■  Effect on Blood Pressure:  When theanine was orally administered to spontaneously hypertensive rats (SHR), their blood pressure was decreased in a dose dependent manner. Howev...