With the onset of the colder months, the number of respiratory infections increases. Colds with a scratchy throat, cough, and stuffy nose are recurring symptoms for many people during the autumn and winter months. Infections that occur frequently or last for several days, noticeably impacting daily life, are particularly burdensome.
This raises a fundamental question: What mechanisms determine how our body reacts to pathogens? And what role can natural plant substances play in this?
One of the best-known plants in this context is Echinacea, also known as purple coneflower. It has been used in traditional herbal medicine for centuries. Today, modern science is studying its constituents and investigating, among other things, its connection to the immune system and colds.
Our immune system: A collaboration of specialized cells
Our immune system is a complex network of specialized cells, tissues, and signaling molecules. It consists of two closely interconnected areas: the innate and the adaptive immune system.
The innate immune system forms the first line of defense. Macrophages engulf and break down pathogens. Natural killer cells, also known as NK cells, recognize and eliminate, among other things, virus-infected body cells. These defense mechanisms react quickly and largely non-specifically.
The acquired immune system complements these processes with specialized T and B lymphocytes. It reacts specifically to certain pathogens and develops immunological memory so that the body can react more quickly upon renewed contact.
To enable both areas to work together, the immune cells communicate via messenger substances called cytokines.
The crucial factor is the balance between activation and regulation. The immune system must react quickly and effectively without allowing inflammatory processes to spiral out of control.
These complex signaling pathways are also the focus of part of Echinacea research.
Echinacea: A medicinal plant with a long tradition
Echinacea originates from the North American prairies. Various indigenous communities traditionally used the plant for sore throats, colds, and external wound care.
Later, Echinacea found its place in European herbal medicine and remains one of the best-known medicinal plants there to this day.
It owes its name to its striking flower head. The Greek word echinos It means hedgehog and refers to the characteristic, spiky flower cone.
Of the various Echinacea species, three are particularly important:
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Echinacea purpurea, the purple coneflower
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Echinacea angustifolia, the narrow-leaved coneflower
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Echinacea pallida, the pale coneflower
Although these species are closely related, they differ in their composition. Even within a single plant, roots, leaves, and flowers have different compositional profiles.
Characteristic plant substances include alkamides, caffeic acid derivatives and polysaccharides.
The alkamides are of particular interest.These fat-soluble compounds can interact with the cannabinoid receptor CB2, which is found on immune cells, among other things, and is involved in the regulation of cellular signaling pathways.
Experimental studies therefore focus on how echinacea ingredients can influence the activity of immune cells and the release of certain messenger substances.
But what about clinical trials in humans?
Echinacea and colds: What human studies show
A randomized, double-blind, placebo-controlled human study from 2012 investigated the use of an Echinacea purpurea preparation in 755 healthy adults over a period of four months.1
The specimen under investigation was predominantly made from above-ground plant parts.
During the study period, 149 cold episodes were documented in the echinacea group, compared to 188 in the placebo group.1
A difference was also observed in the total number of cold days: 672 cold days were recorded in the echinacea group, compared to 850 in the placebo group. This corresponds to approximately 21% fewer documented cold days.¹
Furthermore, the researchers observed differences in recurring cold episodes and certain virus-confirmed respiratory infections.
The study thus provides interesting clinical data on a specific echinacea preparation and its use during the cold season.
What a large review study on Echinacea found
In addition to individual human studies, there are also scientific reviews that consider several studies together.
A 2014 Cochrane review evaluated 24 randomized, double-blind trials with a total of 4,631 participants.²
The study investigated whether different echinacea preparations can prevent colds or influence their course.
An exploratory joint analysis of prevention studies suggested a possible relative reduction in the risk of catching a cold by about 10 to 20%.²
However, the individual comparisons did not reach statistical significance.
An important point of this review concerns the differences between the preparations examined. Because not all echinacea is the same.
Depending on the plant species, plant part used, manufacturing process and dosage, the ingredient profiles can differ significantly.
These differences are particularly relevant for the interpretation of scientific studies. Results obtained with one specific extract cannot automatically be applied to every other echinacea preparation.
Echinacea angustifolia: What makes the root special
While Echinacea purpurea has been studied in many clinical trials, Echinacea angustifolia also has a long tradition in herbal medicine.
The narrow-leaved coneflower is particularly distinguished by its root, which contains various characteristic secondary plant compounds.
These include alkamides and caffeic acid derivatives such as echinacoside.
Alkamides are the focus of experimental studies because certain representatives can interact with the cannabinoid receptor CB2.
This receptor is found on immune cells, among other places, and is involved in the regulation of various cellular signaling pathways.
Echinacoside is another interesting constituent of the root. This phenolic compound is being studied particularly for its antioxidant properties.
Together, these groups of substances shape the characteristic ingredient profile of Echinacea angustifolia.
It is important to distinguish between the different Echinacea species. Clinical results from studies with Echinacea purpurea do not automatically describe the properties of a root extract from Echinacea angustifolia.
Why plant species, plant part and extraction are crucial
With plant extracts, the name of the plant alone is not the deciding factor.
The part of the plant used can also make a significant difference. Roots, leaves, and flowers contain sometimes different concentrations of certain secondary plant compounds.
In addition, there are the growing conditions and the processing.
While simple plant powder contains the dried and ground starting material, extraction involves the targeted removal and concentration of specific ingredients.
Depending on the extraction method, different compositions can result.
Therefore, for the evaluation of an Echinacea extract, a clearly defined botanical origin, the plant part used and a verifiable standardization to selected ingredients are important quality characteristics.
This distinction plays a central role, especially in the interpretation of scientific studies.
Echinacea between tradition and modern immunology research
Echinacea combines centuries of use in traditional herbal medicine with current scientific questions.
The focus is on both the characteristic ingredients of the different echinacea species and their possible interactions with immunological signaling pathways.
Furthermore, clinical studies have investigated the correlations between certain echinacea preparations and the frequency or duration of colds.
What is particularly interesting is how much the individual types and preparations can differ from one another.
Although Echinacea purpurea, Echinacea angustifolia, and Echinacea pallida belong to the same plant genus, they have different constituent profiles. The choice between roots and above-ground parts of the plant also influences the composition.
Echinacea thus demonstrates particularly clearly why in modern plant research not only the plant itself, but also its precise botanical origin and processing are important.
Sources
¹ Jawad M, Schoop R, Suter A, Klein P, Eccles R. Safety and Efficacy Profile of Echinacea purpurea to Prevent Common Cold Episodes: A Randomized, Double-Blind, Placebo-Controlled Trial. Evidence-Based Complementary and Alternative Medicine. 2012;2012:841315. https://doi.org/10.1155/2012/841315
² Karsch-Völk M, Barrett B, Kiefer D, Bauer R, Ardjomand-Woelkart K, Linde K. Echinacea for preventing and treating the common cold. Cochrane Database of Systematic Reviews. 2014;CD000530. https://doi.org/10.1002/14651858.CD000530.pub3