What is Echinacea?
Echinacea is a group of plant species. There are 9 species belonging to the echinacea subfamily. Extracts from these species have largely been used in traditional medicine to treat blood poisoning, bacterial infections, and the common cold .
Natural Sources of Echinacea
Three species of echinacea are generally used for human consumption:
- Echinacea purpurea
- Echinacea angustifolia
- Echinacea pallida
The roots of the 3 species are used, either fresh or dried. Typically, the flowers, leaves, and stems of E. purpurea are used too .
Commercially available products can be found in different formulations:
- Dried roots
- Dried leaves
- Tinctures (extract in alcohol)
- Water-based extracts
- Freshly pressed into a juice
They might include the whole plant, only roots or the flowers, leaves, and stems.
Depending on the extraction conditions and part of the plant used, the active chemicals can vary amongst different echinacea formulations .
Components of Echinacea
Although they belong to the same subfamily, each species of echinacea has a particular set of molecules with biological activity. Different growing conditions, time of harvest, drying, and storage conditions also change the quantity of the active compounds in each plant [2, 4].
In general, the active molecules are:
- Alkamides (alkylamides)
- Glycoproteins and polysaccharides
- Caffeic acid derivatives (phenylpropanoids)
- Volatile oils
- Others: Alkaloids, flavonoids (quercetin, kaempferol, isorhamnetin, patuletin-3-rutinoside), anthocyanins, phenolic acids (p-coumaric, p-hydroxybenzoic, and protocatechuic acids) .
Mechanism of Action
Echinacea has various effects on the immune system. The mechanism of action in humans is not completely understood.
Echinacea can Activate Dendritic Cells
Antigen presenting cells are white blood cells that contribute to the immune system by recognizing foreign molecules. Dendritic cells are one type of them and require activation to function. After they are activated, they can produce pro and anti-inflammatory molecules called cytokines.
- Increase activation of dendritic cells
- Increase release of immune molecules (IL-8, IL-1beta and IL-18)
- Echinacea may also increase production (TNF-alpha and IL-6)
- Increases antioxidants
- Increases proteins that support cell structure
Root extracts may be more effective in activating dendritic cells than leaf extracts .
Echinacea Can Affect Macrophages
Macrophages are a type of white blood cell. They “eat” (phagocyte) foreign substances and dead cells in our blood. When activated in response to inflammatory signals or bacteria, they release inflammatory molecules called cytokines .
Some inflammatory molecules released by macrophages can activate natural killer cells (NK cells). Natural killer cells can then clear the infection from the body or recruit other white blood cells that assist in eliminating infections.
- Echinacea may increase the production of specific molecules (IL-2 and IFN-gamma) that activate macrophages and natural killer cells.
- During bacterial infection, echinacea may reduce inflammation (TNF-alpha and IL-1beta).
- This reduces the symptoms and irritation caused by inflammation but does not treat the cause infection.
The ability to increase macrophage activity during health and decrease macrophages during infection gives echinacea two different benefits:
- Preventing illness when healthy
- Reducing inflammation when sick
The active components of echinacea, alkamides, and polysaccharides, may have specific effects on macrophages.
- Alkamides may improve the activity of macrophages in healthy lungs.
- This is mediated by their activity at the macrophage cannabinoid receptors (CB2), resulting in the production of inflammatory molecules (TNF-alpha and NO).
- When exposed to bacteria, alkamides may deactivate macrophages.
- This reduces inflammation, but some studies have shown increases in inflammatory molecules (TNF-alpha and NO).
- Polysaccharides can increase the activation of natural killer cells.
- This may be caused by their ability to increase the production of inflammatory molecules (IL-1, TNF-alpha, and IL-6).
- They also increase the production of reactive oxygen species (ROS) by macrophages. This aids in the destruction of bacteria.
- Polysaccharides may reduce inflammation during viral (influenza) infection (IL-10 and IFN-gamma).
Echinacea Has Antimicrobial Activity
Echinacea extracts disrupt the fungal cell wall. This effect is mediated by alkamide molecules found in echinacea .
Echinacea has antiviral activity against viruses that have cell membranes. These include:
- Herpes simplex
- Influenza A and B
- Respiratory syncytial virus
Other Mechanisms of Echinacea
Echinacea inhibits the enzyme hyaluronidase. Hyaluronidase is responsible for breaking down hyaluronic acid in the skin, which is an important component of skin cells. When broken down, the tissue loosens up and causes inflammation. Inhibiting the breakdown of hyaluronic acid reduces inflammation and promotes skin healing [22, 23].
Health Benefits of Echinacea
1) Echinacea May Reduce Symptoms of the Common Cold
In a study with 282 patients (DB-RCT), echinacea taken at the first symptom of a cold reduced the severity of the symptoms .
One analysis found that echinacea extracts help prevent colds and shorten their duration (1.4 days) .
When studying the effects of rhinovirus colds in humans, which is the most common virus responsible for colds, echinacea helped prevent the symptoms of the common cold .
A different meta-analysis found some extracts have no clinically relevant effect in the prevention of colds .
The positive effects of echinacea extracts on cold symptoms likely derive from its anti-inflammatory activity on the airway .
2) Echinacea Improves the Immune Response
In a study of 6 adults treated for 3 days, echinacea extract reduced inflammation and increased production of molecules (IFN-alpha) that fight infection .
Echinacea inhibited inflammatory molecules (IL- 6, IL-8) after viral infection in lung cells. In a model of the human airway, treatment with echinacea reduced mucus in the lungs (reduction in mucopolysaccharide and mucin) [32, 33].
In mouse white blood cells, echinacea affected antibody (immunoglobulin) production in contradictory ways. Although some studies indicated that antibodies are increased, others have reported that echinacea has no effect or can even decrease antibodies [34, 35, 36].
3) Echinacea Improves Skin Problems
In cells, echinacea inhibited collagen breakdown by free radicals. It also aided in wound healing (cicatrizing) after topical application in rats. This is attributed to its antioxidant activity and ability to reduce skin irritation (inhibition of hyaluronidase) [37, 38].
Echinacea can aid in the treatment of acne by inhibiting the growth of the bacteria P. acnes and limiting inflammation .
In 49 patients, treatment with echinacea for 3 months (DB-RCT) helped improve the symptoms of atopic dermatitis (redness and swelling) .
4) Echinacea May Reduce Inflammation
Echinacea extract decreased airway inflammation and expanded air passages in guinea pigs, having an effect similar to salbutamol .
Echinacea decreases inflammation through the inhibition of pro-inflammatory molecules and by binding to the cannabinoid receptor (see Mechanism for more details). This does not necessarily help fight infections but can help reduce the symptoms of infection.
These effects might also result from the ability of echinacea to inhibit cyclooxygenase, an enzyme that helps in the formation of inflammatory molecules (prostaglandins, thromboxane, and levuloglandins). Cyclooxygenase is the target of many non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen .
5) Echinacea Fights Infection
Echinacea Has Antiviral Activity
In multiple cell studies, echinacea had antiviral activity against herpes simplex, rhinoviruses, human, avian, and swine influenza viruses. Echinacea is not effective against viruses once they have entered the cell [18, 33].
In dog kidney cells, echinacea extract also prevented the influenza A virus from binding to cells, preventing the virus from entering .
Echinacea extract decreased the severity of influenza infection in mice .
Echinacea displayed its effects mainly in viruses with membranes (such as herpes simplex, influenza, and coronaviruses), probably through its ability to interact with membranes and block hemagglutinin and neuraminidase receptors.
Echinacea Fights Fungus
In mice, echinacea treatment protected against lethal infections with different species (C. albicans and Listeria monocytogenes) .
This effect might be derived from the ability of echinacea to damage the fungal cell wall .
Echinacea Kills Bacteria and Parasites
Echinacea has anti-bacterial activity against S. pyogenes, H. influenzae, L. pneumophila, C. difficile, and P. acne .
In human cells, echinacea also kills parasites L. donovani, L. major, and T. brucei .
6) Echinacea May Help Cancer Treatment
Echinacea also prevented the death of normal cells that were treated with chemotherapy, resulting in the death of only cancerous cells .
7) Echinacea May Improve Insulin Resistance in Diabetes
Echinacea extracts increased the activity of insulin in mouse fat cells, resulting in increased glucose uptake. This is caused by the activation of PPAR-gamma. Therefore, echinacea might be useful for the treatment of insulin resistance related to obesity or type 2 diabetes [49, 50].
8) Echinacea Is an Antioxidant
In mice injected with echinacea for 3 weeks, the antioxidant activity (SOD) of blood was increased .
9) Echinacea May Reduce Anxiety
Echinacea also reduced mild anxiety in 32 healthy adults taking echinacea for 7 days .
In rats, echinacea reduced anxiety-like behaviors .
10) Echinacea May Reduce Pain
Echinacea extract inhibits the TRPV1 receptor, a receptor that influences our perception of pain and reduces inflammation. It also inhibits cyclooxygenase enzymes, which are the target of many non-steroidal anti-inflammatory drugs (NSAIDs) that relieve pain [56, 6].
11) Echinacea May Help with Depression
According to data from clinical trials, side effects from echinacea consumption are rare. The common adverse reactions seen include rash and mild stomach problems such as nausea and stomach aches [2, 27].
Due to the effects of echinacea on immune function, people with autoimmune or systemic diseases like tuberculosis, multiple sclerosis, or AIDS should not use echinacea. This also applies to patients taking immunosuppressants .
Echinacea Is Safe During Pregnancy
Echinacea Is Safe for Children
Limitations and Caveats
Despite the multiple biological activities of echinacea, many of the benefits have not yet been proven in humans.
The overall effects of echinacea on humans are difficult to establish since the clinical trials conducted have used different kinds of echinacea extracts. Some clinical trials have found no effects of echinacea on immune function and or the treatment of colds .
The concentration of biologically active compounds in echinacea varies between species and even between individual plants .
Alkamides from echinacea extracts are biologically available, meaning that they enter the bloodstream and can act internally. Other chemical compounds found in echinacea (caffeic acid derivatives, polysaccharides) have not been studied for their biological availability and it is not known if they reach the blood after oral uptake .
Modern echinacea supplements are composed of multiple echinacea species. The composition of these supplements can vary depending on which species were used and which parts of the plant were included (stem, flower, extracts). Therefore, echinacea supplements purchased from different sources can have varying health outcomes for the body.
Drug Interactions and Genetic Variations that May Influence Your Response to Echinacea
Echinacea affects the activity of enzymes responsible for breaking down drugs and potentially toxic compounds. These include:
This could induce toxic blood concentrations of certain drugs such as (S)-warfarin and theophylline. It could also increase the availability of drugs that are broken down by the enzyme CYP3A4 such as verapamil, cyclosporine, and tacrolimus .
Most users report that echinacea is effective for the relief and prevention of cold symptoms, especially if taken during the winter season.
One long-term user reports that it helps them with cold sores, fever blisters, and stress.
One user reported having an allergic reaction and severe vomiting. Another said echinacea use caused headaches.
One user claims that echinacea gave them oral thrush and a bad taste in the mouth, in addition to a loss of appetite.