One of the most exciting things about working with herbs today is that their age-long uses are gradually being verified by modern research into their mode of action. To say that we now know all about any particular herb would, however, be nonsense – complexity is written into the action of any living organism. Issues such as the synergistic effect of the individual constituents of any herb must be taken into account, when the pharmaceutical research model is very much focused upon single components.
In addition, holistic medicine accords great importance to the specifics of each case, acknowledging that remedies do not necessarily have a blanket effect on anyone who takes them, but have subtler actions dependent on the balance of health of the individual concerned.
In a fascinating study undertaken at the University of St Andrews, the ability of the herbal remedy Echinacea to affect people differently, depending on their state of health, was elucidated for the first time.
The study objective
The efficacy of Echinacea purpurea to prevent and treat colds and flu-like infections is based on modulatory effects on the immune system.  It is largely unknown how this modulation manifests in vivo, and how the effects develop in subjects with a higher susceptibility to colds or low immune response. The goal of this study was to monitor several immune mediators during Echinacea treatment using an ex vivo stimulation model. 
The study design
A total of 30 healthy subjects who reported having two or more common colds a year were included in the study. Individual stress levels were assessed using the perceived stress score-10 questionnaire (PSS-10). During the study the subjects were to record common cold symptoms in a diary if they occurred. There was a run in phase of two days when the subjects took no remedy, and then they began to take a standardised alcohol extract of fresh herb (95%) and roots (5%) of the traditional medicinal plant Echinacea purpurea. During the run in and the following 10-day study phase, blood samples were taken from the subjects every day and any side effects were noted.
The blood samples were treated with standardised immune stimulants (such as lipopolysaccharide, variant 055:B5 from E. coli) and then tested for a raft of immune mediators. The results were analysed in relation to the stress levels and immune response of the subjects in the run in phase.
The immune mediators
The immune response involves the production of inflammatory chemicals such as TNF-a and IL-1b. Overproduction of these chemicals means a surge in the most unpleasant symptoms associated with colds and flu – high temperature, sweating, headaches, aching joints, etc. Keeping the production of TNF-a and IL-1b to a moderate level is therefore desirable. In this study, levels went down by as much as 24%.
A healthy immune response involves the sustained release of substances such as IL-10, IL-8, MCP-1 and IFN-g, which help to fight viruses and other infections.
IL-10 is the antagonist to TNF-a and is produced by monocytes and mast cells. It went up by as much 13% over the study period.
IL-8 and MCP-1 are produced by monocytes and vascular endothelial cells to recruit lymphocytes to the site of infection. These mediators activate neutrophils and natural killer cells (NK), which are important in viral infections. After Echinacea treatment, their production had risen by around 25% each.
IFN-g inhibits viral replication and is produced by TH1 Cells, It activates macrophages and is recognised as an immune-stimulatory mediator. It rose by up to 25% during the study.
- Echinacea steadily reduced pro-inflammatory mediators such as TNF-α and IL-1β, whilst amplifying anti-inflammatory IL-10
- Echinacea up-regulated MCP-1 and IL-8, which recruit lymphocytes to the site of infection
- Those subjects whose mediator production was low initially, experienced a strong amplification of antiviral IFN-g, of anti-inflammatory IL-10, and of IL-8 and MCP-1. Those whose production was high initially did not experience this amplification, but their production of inflammatory TNF-α and IL-1β was reduced.
- In all groups involved in this trial, no cold episodes occurred during the whole investigation period
This study therefore shows for the first time that Echinacea reduces inflammatory processes and increases lymphocyte recruitment in the face of pathogenic stimulation. Echinacea has a balancing or modulating effect on the immune system.
The study also shows that the activation of antiviral defences by Echinacea appears prominently in subjects with higher stress levels and/or susceptibility to colds. General support of immune reactions was observed in subjects with a weak immune performance and initially low production of immune mediators. Echinacea’s immune modulation is therefore adaptive, depending on the state of health of the subject. Stressed or vulnerable subjects will benefit particularly from its effects, whilst the stronger subject need have no concerns about overly stimulating their immune system.
And generally speaking, it’s good to know that Echinacea is still doing the job of preventing colds!