Des études scientifiques existent pour la majorité des plantes médicinales commercialisées, mais elles sont souvent incomplètes.
Sur les 1000 plantes incluses dans la review (parmi celles commercialisées en occident), seulement 15,7 % on fait l'objet d'études cliniques complètes, 50,9 % seulement de tests in vitro ou sur des animaux, 20,8 % d'analyses chimiques concernant les composés actifs mais pas la plante utilisée en entier, et 12,1 % d'aucun test scientifique. Quelques unes des plantes commercialisées sont mêmes dangereuses pour la santé.
Cette review confirme que la phytotérapie peut être efficace, mais que les plantes sont très hétérogènes et surtout que la commercialisation d'une espèce n'est absolument pas une garantie qu'elle ait des effets positifs sur la santé.
L'article contient des tableaux très détaillés avec les tests cliniques réalisés concernant 9 plantes parmi les plus utilisées (Althaea officinalis, Calendula officinalis, Centella asiatica, Echinacea purpurea, Passiflora incarnata, Punica granatum, Vaccinium macrocarpon, Vaccinium myrtillus, Valeriana officinalis)
Figure 1 : types d'études réalisées sur les principaux extraits de plantes commercialisés en occident.
Figure 2 : même chose, mais focalisé sur les plantes aux supposées propriétés anti-inflammatoires.
Violet : tests in vitro _ ou _in vivo (sur des animaux)
Bleu : tests cliniques complets
Vert : recherches phytochimiques (sur les molécules actives mais pas sur la plante dans son ensemble)
Orange : aucune étude réalisée
Rouge (Fig. 1) : plantes dangereuses pour la santé
Objective: The aim of this review is to evaluate and summarize the available scientific information on the commonest plant extracts marketed in Western countries. In view of the intense, ongoing search for new plant extracts with powerful anti-inflammatory activity, we paid particular attention to this topic. The aim is to provide broad coverage of as many potentially useful plants as possible and then to focus on those with the greatest therapeutic potential.
Methods: Our bibliographic sources were the SciFinder databases: CAPLUS, MEDLINE, REGISTRY, CASREACT, CHEMLIST, CHEMCATS (update to October 2007). In order to assess the value of clinical trials, we focused a specific search on clinical investigations concerning nine plants with the most trial data, viz., Althaea officinalis, Calendula officinalis, Centella asiatica, Echinacea purpurea, Passiflora incarnata, Punica granatum, Vaccinium macrocarpon, Vaccinium myrtillus, Valeriana officinalis. This was carried out in several databases (update to June 2008): ISI Web of KnowledgeSM (ISI WoK), SciFinder (CAPLUS, MEDLINE, REGISTRY, CASREACT, CHEMLIST, CHEMCATS) and PubMed (indexed for MEDLINE).
Results: Our survey covers roughly a 1000 plants, although clinical trials have been published only for 156 plants supporting specific pharmacological activities and therapeutic applications. However, for about half of the plants, in vitro and in vivo studies provide some support for therapeutic use. For one-fifth of the plants included in our search, only phytochemical studies were found. Their properties and indications were often attributed to the presence of certain compounds, but no evidence concerning the activities of the whole extracts was presented. We found that for about 12% of the plants, currently available on the Western market, no substantial studies on their properties had been published, while there was strong evidence that 1 in 200 were toxic or allergenic, so that their use ought to be discouraged or forbidden. Nine plants had considerable evidence of therapeutic effect, viz., A. officinalis, Calendula officinalis, Centella asiatica, E. purpurea, Passiflora incarnata, Punica granatum, Vaccinium macrocarpon, Vaccinium myrtillus, Valeriana officinalis.
Conclusion: The present review provides a baseline on the level of evidence available on many herbal preparations and should be of help to those intending to research further on these topics.
