From the Guidelines
Echinacea has no significant effect on white blood cells (leukocytes) in terms of prevention and treatment of common colds, as most products are not effective and potential effects are of questionable clinical relevance. The use of Echinacea for immune system support is based on its purported ability to stimulate the activity and production of white blood cells, but recent evidence suggests this may not be the case. According to a 2020 European position paper on rhinosinusitis and nasal polyps 1, a 2014 Cochrane systematic review by Karsch-Völk concluded that most Echinacea products are not effective in preventing and treating common colds. Some key points to consider when evaluating the effect of Echinacea on white blood cells include:
- The lack of strong evidence supporting the use of Echinacea for immune system support
- The potential for some Echinacea products to have weak benefits, but these effects are of questionable clinical relevance
- The need for caution when using Echinacea, particularly for individuals with autoimmune disorders, due to its potential immune-stimulating properties. Given the current evidence, it is essential to approach the use of Echinacea with caution and consider alternative, evidence-based treatments for supporting immune function and preventing illnesses.
From the Research
Effect of Echinacea on White Blood Cells
- Echinacea has been shown to increase circulating total white cell counts, with significant increases observed during the first 2 weeks of administration 2.
- The herb has also been found to alter differential counts, with mononuclear cells significantly increased and granulocytes decreased 2.
- Studies have demonstrated that Echinacea can stimulate cellular immunity and anti-bacterial defense, with increases in granulocytes and lymphocytes observed in mice fed Echinacea purpurea extract 3.
- Echinacea has been found to enhance systemic immune response during a common cold, with significant and sustained increases in circulating total white blood cells, monocytes, neutrophils, and NK cells observed in volunteers taking an Echinacea preparation 4.
Specific Effects on Immune Cell Populations
- Echinacea extracts have been shown to increase percentages of CD49+ and CD19+ lymphocytes in spleen and natural killer cell cytotoxicity in mice 5.
- The herb has also been found to induce similar, but differential, changes in the percentage of immune cell populations and their biological functions, including increased antibody response to sheep red blood cells and concanavalin A-stimulated splenocytes 5.
- Echinacea purpurea aqueous extracts have been found to induce the production of interleukin (IL)-6 and tumor necrosis factor (TNF)-α in human primary monocyte-derived macrophages, with a minimal effect on IL-1β and prostaglandin E2 (PGE2) 6.
Mechanisms of Action
- Echinacea has been found to modulate both innate and adaptive immune responses, with the herb's immunomodulatory effects attributed to its ability to enhance non-specific immune response and elicit free radical scavenging properties 4, 5.
- The herb's extracts have been shown to trigger the phosphorylation of the extracellular signal-regulated kinase (ERK) 1/2 and p38 signaling pathways and upregulate the cyclooxygenase (COX)-2 expression in human primary monocyte-derived macrophages 6.