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Table 3 Systematic reviews of clinical trials of herbal medicines (at least 2 reviews per herb)

From: Systematic reviews of complementary therapies – an annotated bibliography. Part 2: Herbal medicine

      Features   
Author Indication Intervention Comparisons Studies 1/2/3/ Results Author's Conclusion
Year      4/5   
Echinacea ( Echinacea purpurea, angustifolia and pallida )
Barrett upper resp. echinacea placebo 13RCT y/p/y/ Overall quality modest. All 4 Echinacea may be beneficial for
99 [40] infections (incl.    y/n prevention studies show only early treatment of acute upper
   combinations)     minor trends, 8 of 9 treatment respiratory infections; little evidence
       studies with generally positive to support the prolonged use for
       results prevention
Melchart common echinacea placebo, no 16 RCT y/y/y/ Minor effects in prevention and Echinacea extract can be efficacious
99 [41] cold (incl. treatment   y/p treatment, promising effects in for the common cold, but evidence
   combinations)     early treatment. Heterogen. insufficient for recommendations
       preparations  
Melchart immuno- echinacea placebo, no 18 RCT, 8 y/y/y/ Most studies low quality. Most Echinacea extracts can be
94 stimulation (incl. treatment CCT y/n studies show immunostimulating efficacious immunostimulators, but
[42, 43]   combinations)     effects evidence insufficient for
        recommendations
Cranberries ( Vaccinium macrocarpon )
Jepson urinary cranberries placebo 4 RCT y/y/y/ In 3 of 4 trials cranberries effective Insufficient evidence, further research
98 [44] tract inf.     y/n for at least one of the outcomes of needed
  (prevent)      interest  
Jepson urinary cranberries   O RCT y/y/-/ No trials meeting the inclusion No evidence available
98 [45] tract inf.     -/- criteria  
  (treatm.)       
Mistletoe ( Viscum album )
Kleijnen cancer mistletoe placebo, no 11 y/y/y/ Most studies low quality. Most Insufficient evidence to recommend
94 [46]    treatment RCT/CCT n/n studies show longer survival with mistletoe outside of clinical trials
       mistletoe but not the best trial  
Kiene 89 cancer mistletoe no treatment, 2 RCT, 33 y/n/n/ Most studies low quality. 9 of 12 Available evidence supports positive
[47, 48]    none CCT, 11 y/n interpretable studies suggest effects of mistletoe
     other   positive effects on survival  
     studies    
Peppermint ( Mentha piperita )
Jailwala irritable 1. peppermint placebo 1. 3 RCT p/y/y/ Chinese herbal therapy trial rated In both cases efficacy not clearly
2000* bowel oil   2. 1 RCT n/n as positive, one of three established
[49] syndr. 2. Chinese     peppermint oil trials rated as  
   herbal     positive  
   therapy      
Pittler 98 irritable peppermint placebo, 8 RCT y/y/y/ Global improvement rates The role of peppermint oil for IBS
[50] bowel oil other   y/y significantly higher compared to has not been established beyond
  syndr.   treatment    placebo. Quality of trials doubtful reasonable doubt
Saw palmetto ( Serenoa repens )
Boyle ben. Permixon® placebo, 11 RCTs, ?/n/n/ peak urine flow 2.20 (95% Cl 1.20– Despite some limitations strong
2000 [51] prostate (saw other 2 UCS y/y 3.20) ml/s increase over placebo; evidence that the extract tested has
  hyperplasia palmetto) treatment    significant decrease nocturia beneficial effects
Wilt 2000 ben. saw palmetto placebo, 14 RCT y/y/y/ Saw palmetto superior to placebo Evidence suggests that saw
&98 prostate   other (plac), y/y for nocturia, self rating, peak urine palmetto improves urological
[52, 53] hyperplasia   treatment 5 RCT   flow; similar effects as finasteride symptoms and flow measures.
     (other)    Further studies needed
  1. legend see table 1