Reduction of influenza-like infections by a phytoextract-vitamin-combination: a randomized, double-blind, placebo-controlled study

Recurrent infections are signs of a weakened immune system, and can be traced to a lack of vitamins and minerals. The objective of this study was to investigate the effect of a nutriological combination of vitamins, trace elements and phytochemicals on the incidence and duration of influenza-like infections. Healthy subjects at risk of increased infection exposure took part in a randomized, double-blind, placebo controlled study, each involving a supplementation period of 12 weeks. The occurrence and severity of influenza-like infections and resort to study medication was documented by diary entries. SF-36 questionnaires to measure the health-related quality of life were completed at the start and end of the study. At final examination compliance was examined with respect to returned study medication, diaries and a questionnaire administered to evaluate the effect, safety, and tolerability of the test substance. Of 100 randomized participants, 80 (38 test treatment and 42 placebo) completed the study according to the protocol. In the test treatment group there were 60 influenza-like infections (1.6 infections/12 weeks), significantly fewer (p = 0.0003) compared with the placebo group with 113 episodes (2.7 infections/12 weeks). Further, the average number of days that the infection lasted was shorter in the test treatment group at 10.0 +/- 6.7 days, which was significantly shorter (p = 0.0003) than the placebo group at 28.5 +/- 13.6 days. The influenza-like symptom score and the mean duration of sick leave did not differ statistically between groups. Participants in the test treatment group assessed the global effectiveness of the test substance significantly better (p < 0.0001) than the participants of the placebo group. At the beginning of the study there was no difference between groups with respect to SF-36 results. However, at the completion of the study 6 of the 8 scales of SF-36 in the test treatment group were significantly better compared with the placebo group. In summary, consumption of the complex nutriological test preparation was associated with a significant reduction in the incidence of influenza-like infections, as well as their duration, and it was associated with significantly improved vitality, social functioning, and psychological well-being.