The advent of antibiotic resistance directs the scientific world towards the search for natural remedies that can fight infections. Evidence obtained from in vitro and in vivo studies demonstrates the antimicrobial potential of some natural resources.
Before going into the merits of natural antibiotics and therefore of the resources that nature makes available to deal with infectious diseases, it is necessary to take a step back and consider some crucial aspects.
Wanting to start with a basic definition, by antibiotic we mean a chemical substance capable of destroying bacteria and other microorganisms, or inhibiting their growth. Although traces of pharmacological treatments aimed at eradicating infections date back to more ancient times, we begin to refer to the aforementioned term starting from 1928, when the scientist Sir Alexander Fleming discovered an antibiotic substance, commonly known as Penicillin, starting from the fungus Penicillium notatum.
To date, antibiotics are effectively used in the treatment of various infectious processes, proving essential for everyone’s health. However, the massive and reckless use of these agents has led to the inexorable advent of bacterial strains resistant to them, undermining the original efficacy of the products available in the clinical setting. This problem has pushed the healthcare world to shift attention to resources present in nature, so that they can be a winning weapon in fighting infections.
Natural antibiotics: what they are and how they work in the body
By now overwhelmed by the mad rush towards scientific and technological progress, modern society seemed to have put aside the primordial mechanisms that regulate life on the planet. And yet, biology has continued to apply its own rules, expressing itself in the complexity of living forms. It is in this broader context that the enormous potential of the botanical world lies, with properties that are often underestimated.
Regarding the fight against infectious diseases, however, there is a newfound awareness, which sees technological progress being applied to the study of ancient natural remedies.
Although it is not possible, to date, to indicate with certainty the best natural antibiotic, the main medicinal herbs to which antibiotic properties have been scientifically attributed will be examined.
Before resorting to the use of natural antibiotics, although these are natural remedies, it is, in any case, important to submit to the doctor any pharmacological therapies in place in order to avoid risky interactions. It is also essential to pay particular attention in the case of pregnancy and breastfeeding, as well as pathological predispositions.
1. Garlic: a plant rich in resources
Emerging in the botanical world for its popularity, the nickname “garlic”, or Allium sativum, identifies a plant commonly used in the culinary field to flavor dishes, by virtue of its intense organoleptic characteristics.
Beyond the very affirmed role mentioned above, garlic is notoriously a medicinal plant with versatile properties, due to the large amount of chemical substances – more than 200 – present in it. More specifically, antibacterial, antifungal and antiparasitic properties have been attributed to garlic, as well as anticancer and hepatoprotective properties. Finally, it seems that garlic can have a positive effect on blood glucose and cholesterol values.
As far as bactericidal power is concerned, garlic boasts a broad-spectrum impact capacity, proving effective on gram-negative bacteria, such as Helicobacter pylori and Escherichia coli, and gram-positive bacteria, such as components of the genus Staphylococcus. Studies concerning the potential natural bactericidal effect of garlic also involved opportunistic pathogens, notoriously antibiotic-resistant, such as Pseudomonas aeruginosa and Klebsiella pneumoniae.
The antibiotic properties of this medicinal plant are attributable to various substances contained in it, such as allicin, allyl sulphide, bioflavonoids quercetin and cyanidin, and allistatins.
Commonly used to treat urinary and intestinal infections, garlic can be consumed as it is and raw, although this approach requires larger quantities: a decidedly not feasible choice due to the marked organolepticity mentioned above. An alternative to direct consumption consists in making herbal teas starting from garlic as it is, although the heat partially deactivates its chemical components, generating a less effective remedy.
In addition, there are various supplements in capsules obtained from garlic extracts and products based on the relative essential oil on the market, although medical supervision is desirable for the use of the latter.
2. Eucalyptus: for the well-being of the respiratory tract
Several species of medicinal plants belong to the genus Eucalyptus which owe their origin to the southern geographical area, although they are currently cultivated in different climatic areas.
Widely studied for its phytotherapeutic properties, Eucalyptus globulus is a species particularly known for its essential oils, which have been attributed antimicrobial, antifungal, and antioxidant properties. More specifically, several studies conducted on samples taken from individuals suffering from pharyngitis and other respiratory diseases, have shown the effectiveness of eucalyptus essential oil in counteracting various bacterial agents, such as Staphylococcus aureus, Streptococcus pneumoniae, and Haemophylus influenzae. The pharmacological activity of eucalyptus is to be attributed to its main chemical component, namely eucalyptol or 1-8 cineole, which enriches the related essential oil.
Generally, the use of eucalyptus is indicated for infectious processes affecting the respiratory and urogenital tracts. In addition to the essential oil, the intake of which should be supervised by a health professional, eucalyptus is commercially available in the form of capsule supplements. Alternatively, you can resort to the consumption of herbal teas, obtained from eucalyptus leaves.
3. Cinnamon: a spice against infections
Known throughout the world and used for centuries for culinary and medicinal purposes, cinnamon is a spice obtained from the inner bark of trees of the Cinnamomum genus, to which evergreen plants of mostly tropical origin belong.
Cinnamon obtained from the Cinnamomum zeylanicus variety, also defined as “true cinnamon”, has been attributed various medicinal properties of an anti- inflammatory and antimicrobial type, as well as a potential beneficial activity at the cognitive and cardiovascular level.
More specifically, as regards the natural antibiotic property, several in vitro studies have demonstrated a potential antimicrobial effect on a broad spectrum of pathogenic bacteria, including Bacillus cereus and subtilis, Helicobacter pylori, Listeria monocytogenes and Clostridium perfringens, as well as on some fungal species belonging to the genera Aspergillus and Candida. Further in vivo studies provided evidence for cinnamon’s antimicrobial activity, with particular reference to enteric bacteria.
Particularly indicated in case of urogenital infections, cinnamon can be taken by ingesting a few drops of diluted essential oil, whose main components, obtained from the bark of the plant, are cinnamaldehyde, linalool and eugenol. As for essential oils in general, it is advisable that the use of cinnamon essential oil is subjected to the supervision of a doctor, in order to avoid contraindications related, as regards internal use, to the health of the mucous membranes.
As an alternative to essential oil, it is also possible to use herbal teas made from cinnamon powder, or cinnamon supplements in capsules.
4. Sage: so much versatility in a single aromatic herb
In addition to its common decorative and culinary use, sage lends itself to numerous phytotherapeutic applications. Sage derivatives are in fact useful in case of digestive difficulties, amenorrhea and intestinal spasms.
Several scientific studies have attributed to sage essential oils an antimicrobial power against different species of microorganisms, be they bacteria or fungi. These include the pathogenic bacteria Bacillus subtilis, Staphylococcus aureus and dermatophyte fungal species.
The antimicrobial power of sage (in particular of the essential oil) is attributable to its main chemical components, including 1-8 cineole, although the actual relevance of the minor components cannot be excluded, suggesting a probable synergistic effect.
Particularly known for treating infections of the oral cavity and upper respiratory tract, dried sage leaves can be used for the production of infusions to be used in gargling. As for essential oils, they too can be used in the same way, as long as they are diluted and dosed in the right quantity. Suffumigi carried out starting from a few drops of essential oil can also assist the antiseptic effect by adding an expectorant and balsamic action.
For the same antimicrobial applications, it is finally possible to resort to derivatives of Salvia sclarea, a botanical variant with a lower concentration of thujone, which is a potentially neurotoxic chemical component if taken in excess.
5. Oregano: a natural antibiotic with an intense aroma
Widely widespread in the culinary field due to its intense aroma, Origanum vulgare is a herbaceous plant of Mediterranean origin, whose role in traditional medicine is definitely known and applied to various pathological diseases of the rheumatic, digestive and respiratory type.
Some in vitro studies have attributed antimicrobial activity to oregano. In particular, the bactericidal activity of the relevant essential oil appears to be broad-spectrum, orienting towards gram-positive bacteria, including Staphylococcus aureus, and gram-negative bacteria, such as Escherichia coli.
In addition to its bactericidal and bacteriostatic power, fungicidal properties have also been attributed to oregano, in particular as regards Candida albicans infections. Finally, there is no lack of potential antiparasitic properties, documented for the parasite Blastocystis hominis.
The antimicrobial activity of essential oils of oregano has been attributed to its components carvacrol and thymol, which have also been associated with antioxidant properties.
Derivatives of oregano are suitable for the treatment of urinary and intestinal tract infections. The active ingredients of its dried leaves can be taken by seasoning dishes, or by making herbal teas. A few drops of the aforementioned essential oil can instead be applied to internal use, as long as there is knowledge of the methods and correct doses of use.
6. Peppermint: from cooking to phytotherapeutic power
Peppermint derives from the Mentha genus, which includes the well-known herbaceous plants widespread in the Mediterranean area and commonly used as a spice and decoration in the culinary field. In addition to its role in cooking, peppermint is known in traditional medicine for its antimicrobial, antispasmodic and regularizing potential of the menstrual cycle.
As regards the antimicrobial power, some studies conducted on essential oils of peppermint show a bactericidal efficacy on the Escherichia coli and Staphylococcus aureus species, as well as a relevant fungicidal activity, evident on some dermatophyte fungal species and on Candida albicans.
Peppermint boasts a rather broad chemical composition, although the antimicrobial power has been attributed to its main component, namely menthol. However, the medicinal properties mentioned above vary according to various factors, such as climate, geographical distribution and growing conditions.
Herbal teas and peppermint infusions are suitable for the treatment of infections affecting the oral cavity, upper respiratory tract and urinary tract. Suffumigi made with a few drops of its essential oil add decongestant activities to the antiseptic power, useful in case of cough and cold.
7. Propolis: a very popular remedy
Propolis is a resinous material closely linked to the activities with which bees strengthen their hive. Beyond this aspect, propolis has long been known for its multiple medicinal activities of an anesthetic, anti-inflammatory, antioxidant and immunostimulating type. Last but not least, the antimicrobial activity of propolis arouses particular scientific and commercial interest, especially as regards infectious diseases affecting the upper airways.
In vitro studies conducted on the essential oils of propolis, have shown a broad spectrum efficacy, with particular reference to the bacterial species Moraxella catarrhalis and Haemophilus influenzae. Furthermore, there is no lack of evidence of efficacy in relation to fungal species of the genus Candida.
The antibiotic power of propolis has been attributed to the synergistic action of its chemical components, among which various phenols and flavonoids stand out. It is possible to take the aforementioned active ingredients by consuming honey with propolis, particularly indicated in case of infections of the oral mucosa.
The treatment of oropharyngeal infections can also be carried out using propolis-based nebulizers, which can be used several times a day. Propolis is also marketed in the form of supplements in capsules or tablets, to be used in the treatment of intestinal or urinary diseases. Finally, a few drops of propolis tincture, diluted in water, can be used to gargle and treat infections affecting the oral mucosa.
8. Echinacea: a natural antibiotic with a complex action
Another medicinal herb, somewhat known for its multiple properties, is represented by Echinacea purpurea, a perennial herbaceous species, native to North America and cultivated in different geographical areas.
Regarding its antimicrobial potential, Echinacea purpurea has shown viricidal activity against some viral agents responsible for acute respiratory infections, such as influenza viruses and rhinoviruses.
Several studies have demonstrated bactericidal activity against some pathogens involved, also in this case, in respiratory diseases. These pathogens include Haemophilus influenzae, Streptococcus pyogenes and Legionella pneumophila, although the bactericidal mechanism is specific to individual agents. More generally, echinacea seems to exert a positive effect on respiratory infections by associating an anti-inflammatory action with the aforementioned antimicrobial effect.
In addition to respiratory diseases, echinacea also seems to have a beneficial effect on dermatological diseases caused by the Herpes simplex and Acne vulgaris viruses. Among the chemical components involved in the antimicrobial action of echinacea are various phenols and alkamides.
As mentioned above, echinacea is commonly used for the treatment of infections affecting the respiratory tract and oral cavity. In this regard, it is possible to resort to herbal teas and infusions obtained from the dried plant, or to diluted mother tincture, in order to gargle.
9. Aloe vera: between fame and debates
Known and debated since very ancient times, Aloe vera is a herbaceous species, of the perennial type, cultivated all over the world and with a varied chemical composition. As for the phytotherapeutic aspect, the usefulness of the Aloe genus is widely related to the treatment of various pathological conditions, such as immune deficiencies, constipation and other gastrointestinal diseases. Specifically, the Aloe vera species are attributed antimicrobial, antioxidant, antidiabetic and antitumor properties.
With regard to the natural antibiotic power of Aloe vera extracts, in vitro studies have shown a broad spectrum bactericidal efficacy, with particular reference to the species Klebsiella pneumonia, Escherichia coli and Staphylococcus aureus. A fungicidal action on components of the genera Candida and Aspergillus has also been documented.
Known in various commercial fields and potentially indicated for the treatment of urinary infections, the active ingredients of Aloe vera can be taken through various phytotherapeutic products, in the form of capsules or herbal teas. Particularly known in the world of natural remedies, is also the Aloe vera juice, to be consumed in the doses indicated by the producers. “Artisan” preparations are strongly discouraged, in order not to incur excessive intake of aloin, a chemical component present in abundance in the outer layer of the plant and highly laxative.
10. Berries: natural antibacterials among commonly used foods
Whether consumed as they are or as edible derivatives of different types, berries are a colorful and rich source of bioactive compounds, such as vitamins, anthocyanins and tannins. By virtue of the aforementioned chemical composition, the consumption of berries is associated with anti-inflammatory, antioxidant and anticancer properties.
Among the medicinal properties attributed to berries, there is also a marked antimicrobial activity, documented by in vitro and in vivo studies, against bacteria of the genera Staphylococcus, Bacillus, Helicobacter and Salmonella. In addition to exerting a bactericidal power, the bioactive components appear to be effective in inhibiting the growth of other bacterial species, such as those belonging to the genera Clostridium and Escherichia.
Berries can be consumed as they are or with pulp and juice concentrates. Phytotherapeutic products based on cranberry are well known, available on the market both as infusions and as supplements in capsules, potentially useful in case of urinary tract infection.
Below is a summary table with the main natural antibiotics and their documented effectiveness:
| Natural antibiotic: | Effective against: |
| Garlic | Helicobacter pylori Escherichia coli Components of the genus Staphylococcus Pseudomonas aeruginosa Klebsiella pneumoniae |
| Eucalyptus | Staphylococcus aureus Streptococcus pneumoniae Haemophylus influenzae |
| Cinnamon | Bacillus cereus and subtilis Helicobacter pylori Listeria monocytogenes and Clostridium perfringens Fungal species belonging to the genera Aspergillus and Candidaz |
| Sage | Bacillus subtilis Staphylococcus aureus Dermatophyte fungal species |
| Origan | Staphylococcus aureus Escherichia coli Candida albicans Blastocystis hominis |
| Peppermint | Escherichia coli Staphylococcus aureus Dermatophyte fungal species Candida albicans |
| Propolis | Moraxella catarrhalis Haemophilus influenzae Fungal species of the genus Candida |
| Echinacea | Influenza Viruses and Rhinoviruses Herpes simplex Acne vulgaris Haemophilus influenzae bacteria Streptococcus pyogenes Legionella pneumophila |
| Aloe vera | Klebsiella pneumonia Escherichia coli Staphylococcus aureus Candida and Aspergillus |
| Berries | Genera Staphylococcus, Bacillus, Helicobacter and Salmonella Bacterial species belonging to the genera Clostridium and Escherichia |
