title: Using natural dietary sources of antioxidants to protect against ultraviolet and visible radiation-induced DNA damage: an investigation of human green tea ingestion.
abstract: Oral ingestion of green tea is a potent dietary source of antioxidant polyphenols. These compounds are of interest as they may be able to provide additional protection to the body to help prevent the deleterious effects of ultraviolet A and visible radiation (UVA/VIS) produced indirectly via reactive oxygen species (ROS) in sunlight exposed skin. A small clinical study was conducted in ten healthy adult volunteers. Samples of whole blood were obtained from each before and 30, 60 and 90 min following ingestion of three breakfast cups of green tea (540 ml in total) prepared in a standardised manner. Peripheral leucocytes were isolated from each blood sample and exposed to increasing periods of UVA/VIS irradiation in the laboratory (0, 9, 12 or 18 min). Alkaline single cell gel electrophoresis (the comet assay) was then conducted to determine the level of DNA damage in each sample from each individual. The findings support those of our previous pilot study and indicate that drinking green tea did significantly reduce the genotoxic effects observed in peripheral blood cells 60 min following ingestion when artificially exposed to 12 min of UVA/VIS irradiation in the laboratory. It is postulated that this protection is afforded by the polyphenol compounds (known to be contained within green tea) via scavenging or quenching of the damaging ROS induced by this form of light exposure. Further investigation should consider whether this dietary-induced protection could be extended to cells of the skin.
authors.affiliation: Clinical Photobiology, Peninsula Medical School, University of Exeter, Knowledge Spa, Royal Cornwall Hospital, Truro, Cornwall TR1 3HD, UK.
authors.forename: Helena
authors.initials: H
authors.lastname: Malhomme de la Roche
authors.forename: Susan
authors.initials: S
authors.lastname: Seagrove
authors.forename: Anisha
authors.initials: A
authors.lastname: Mehta
authors.forename: Preshita
authors.initials: P
authors.lastname: Divekar
authors.forename: Sandra
authors.initials: S
authors.lastname: Campbell
authors.forename: Alison
authors.initials: A
authors.lastname: Curnow
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000494:pharmacology*; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects*; D005260:Female; D006801:Humans; D008027:Light / Q000009:adverse effects*; D008297:Male; D017382:Reactive Oxygen Species / Q000378:metabolism; D013662:Tea / Q000737:chemistry; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D013662:Tea