Beneficial Effects of Green Tea—A Review

Abstract

Tea is the most consumed drink in the world after water. Green tea is a ‘non-fermented’ tea, and contains more catechins, than black tea or oolong tea. Catechins are in vitro and in vivo strong antioxidants. In addition, its content of certain minerals and vitamins increases the antioxidant potential of this type of tea. Since ancient times, green tea has been considered by the traditional Chinese medicine as a healthful beverage. Recent human studies suggest that green tea may contribute to a reduction in the risk of cardiovascular disease and some forms of cancer, as well as to the promotion of oral health and other physiological functions such as anti-hypertensive effect, body weight control, antibacterial and antivirasic activity, solar ultraviolet protection, bone mineral density increase, anti-fibrotic properties, and neuroprotective power. Increasing interest in its health benefits has led to the inclusion of green tea in the group of beverages with functional properties. However, although all the evidence from research on green tea is very promising, future studies are necessary to fully understand its contributions to human health, and advise its regular consumption in Western diets, in which green tea consumption is nowadays limited and sporadic.

• green tea
• polyphenols
• catechins
• antioxidant activity
• human health

• CI = confidence interval
• DNA = deoxyribonucleic acid
• DPPH = 2,2-diphenyl-l-picrylhydrazyl assay
• DMPD = N,N-dimethyl-p-phenylendiamine assay
• EC = (−)-epicatechin
• ECG = (−)-epicatechin-3-gallate
• EGC = (−)-epigallocatechin
• EGCG = (−)-epigallocatechin-3-gallate
• FRAP = ferric reducing ability of plasma assay
• GA = gallic acid
• GTP = green tea polyphenols
• HDL = high density lipoproteins
• HR = hazard ratio
• LDL = low density lipoproteins
• OR = odd ratio
• ORAC = oxygen radical absorbance capacity assay
• PCL = photochemiluminescence assay
• RR = relative risk
• TEAC = Trolox equivalent antioxidant capacity assay
• TRAP = total radical-trapping antioxidant parameter assay
• UV = ultraviolet

Key teaching points:

• Green tea contains numerous components with antioxidant activity: polyphenols (especially catechins), minerals, vitamins.

• Green tea contains more catechins than black or oolong teas.

• The strong antioxidant potential of catechins, and especially EGCG, are widely demonstrated in vitro and in animal studies. In addition, catechins possess antimutagenic, antidiabetic, anti-inflammatory, antibacterial and antiviral properties.

• Recent human studies suggest that green tea may contribute to reduce the risk of cardiovascular disease and cancer, and has another beneficial effect on health.

• Although research of green tea is very promising, future studies considering dietetic, environmental and life style factors, are necessary to fully understand its contribution to human health.

Key teaching points:

• Green tea contains numerous components with antioxidant activity: polyphenols (especially catechins), minerals, vitamins.

• Green tea contains more catechins than black or oolong teas.

• The strong antioxidant potential of catechins, and especially EGCG, are widely demonstrated in vitro and in animal studies. In addition, catechins possess antimutagenic, antidiabetic, anti-inflammatory, antibacterial and antiviral properties.

• Recent human studies suggest that green tea may contribute to reduce the risk of cardiovascular disease and cancer, and has another beneficial effect on health.

• Although research of green tea is very promising, future studies considering dietetic, environmental and life style factors, are necessary to fully understand its contribution to human health.

We thank M.J. Martinez-Vique for revising the English grammar of the original manuscript. We thank Antiguo Tostadero (specialized tea shop) for its cooperation and interest in this research.