Green but not black tea may lower the risk of coronary artery disease (CAD), the limited evidence suggests. The researchers performed a meta-analysis of 18 observational studies identified from a search of PubMed and EMBASE databases from 1966 through November 2009. Thirteen studies were on black tea and five on green. 'The authors do recognise several limitations to this analysis such as a small number of included studies, observational study designs prone to confounding and differing methods for measuring tea consumption. They therefore conclude that additional studies are needed before firm conclusions can be drawn. So no need to switch teas just yet then. '