Dietary supplements with green tea marketed in Portugal: information on website, labels and antioxidant activity

The use of plants and their health benefits have been recognized over the years. Its use and consumption of herbal dietary supplements has increased in the last years in United States and Europe. Internet is one of the most required options to buy dietary supplements (DS). Several studies suggest that information on most sites is incomplete, poorly referenced, and may contain illegal claims. Thus, a conscious and informed decision is essential for consumers. Camellia s inensis , also known as green tea, is one of the most consumed plants worldwide and has been recognized by its antioxidant potential over the years. This activity can protect several diseases with an oxidative stress origin. For these reasons, a study was performed to evaluate the quality of information on websites selling dietary supplements with green tea. A modified DISCERN tool was used to evaluate websites from pharmacies/parapharmacies, websites from food health stores, and websites without physical space. Websites scored 1 or 2 at evaluation rating (Low – serious or extensive outcomes). These results reveal the importance of developing a checklist for the online marketing of herbal products, based on DISCERN instrument, or other. These instruments can guide health professionals, who have a very important role in directing patients to high-quality sources of information.Legal framework for dietary supplements varies among countries, and in Portugal, DS are regulated by the Direção Geral de Alimentação e Veterinária (DGAV). Although there are directives published by European Commission, in Portugal, decree-law are incomplete and DS safety is placed on the substance’s manufacturer or marketer. In addition, clinical trials are not required for DS in Portugal, which allows adulteration, falsification, contamination and incorrect labels. In Portugal, DS can be sold in pharmacies, parapharmacies, supermarkets, dietetic stores and online, and consumers should be able to make informed and appropriate health care choices. Also, consumers use DS labels (information provided on the packaging) and leaflets to further their understanding about some DS ingredients, relevant indication(s), directions for use, side effects, contraindications and drug-supplements interactions. For these reasons, another study was performed using an adapted form to evaluate legal and scientific information of twenty green tea DS sold in pharmacies, parapharmacies and health food stores in Portugal. From the legal and scientific points of view none of the websites fulfilled all the analyzed criteria. Seven DS (35.0%) had indications of use similar to those mentioned in the literature. Adverse reactions and drug interactions information were rarely provided by two and three DS, respectively. Green tea is a complex mixture of several constituents, which include phenolic compounds like catechins, flavonoids, and phenolic acids. This chemical composition is associated with antioxidant activity. Antioxidant products demand has been increasing over the last years. They are referenced as having a protective role in many diseases, like cancer, neurodegenerative and cardiovascular disorders. Considering the lack of legislation, in Portugal, that controls DS prior to its introduction in the market, the last aim of this thesis was to evaluate antioxidant activity of six green tea supplements (three isolated and three mixture of substances/plant extracts). This evaluation was performed by common assays, namely, DPPH, superoxide and Fe2+ chelating assays. Results showed that antioxidant activity depends on composition and concentration of each substance present in green tea’s DS. In addition, green tea DS studied showed different antioxidant results at different assays performed. These thesis results may contribute to understand the importance of quality information provided by websites selling DS, and also the importance of regulation regarding its manufacturing and selling