Herbal Medicine: Garlic as an antimicrobial herb

garlic herbal medicine byron bay herbalist herbalism naturopath blastocytis giardia gut health digestive health

Many plants display antimicrobial properties and are used to treat different forms of infections found throughout the body. One area of research that definitely needs more attention is the effect that these antimicrobial herbs play on our resident microbiome. 

It is not uncommon for a herbal antimicrobial treatment to run for 2-3 months, depending on the specific infection being treated. Many protocols for protozoan parasites like Blastocystis hominis and Giardia lamblia have extended periods of treatment due to their lifecycle and recalcitrant nature.

While certain antimicrobial herbs can wreak havoc on our microbiome (grapefruit seed extract comes to mind) other offer an alternative to the single molecule approach of many biomedical interventions. The complexity of many herbal antimicrobials can confound infectious microbes and inhibit their ability to mutate resistance. Allium sativum is given as a classic example of innate complexity with over twenty active constituents working synergistically to combat microbes (3).

Allium sativum As A Herbal Medicine

Known as garlic, this herb has been used as medicine since antiquity (4) with the clove being used as medicine (5). The key constituents are the organosulfur compounds, particularly alliin, which degrades into allicin (6). It is indicated in digestive tract and respiratory infections including bronchitis, colds and the flu (7) and there are no known contraindications or cautions (8). In many ways garlic stands alone and is commonly recommended by many naturopaths and herbalists for a range of different conditions.

Recently I have been delving into the work of Dr. Jason Hawrelak a naturopath who completed his PhD on the subjects of probiotics, prebiotics and the microbiome. He has done a ton of research into the treatment of dysbiosis, parasite infections (including Blastocystis hominis and Giardia lambliaand in a lecture recommended garlic as an antimicrobial herb, particularly the fresh clove. While much of the research that has been done on the effects of garlic on different microbes is still only in preliminary invitro stages (10), it has shown, according to Hawrelak’s research to selectively target the pathogenic microbes displaying what is referred to as selectivity of action. A good thing for our microbiome!

In-vitro Studies for Garlic

Again we can’t draw any serious conclusions from in-vitro or even animal studies. They only point out the strong need for more research into the effects of the herbs. We can take into account the long history of use of herbal medicines and even the preliminary research lends it’s weight to the usefulness of garlic as a safe antimicrobial herb.

One review paper cited a number of different studies, predominantly invitro looking into the antimicrobial effects of garlic. The studies found garlic to be effective (on agar) against a range of different microbes including

  • Salmonella
  • Escherichia coli
  • Pseudomonas
  • Proteus
  • Staphylococcus aureus
  • Klebsiella
  • Micrococcus
  • Bacillus subtulis
  • Clostridium
  • Mycobacterium
  • Helicobacter
  • Candida
  • Torulopsis
  • Trichophyton
  • Cryptococcus
  • Aspergillus
  • Rhodotorula
  • Entamoeba histolytica

The same paper cites a very interesting clinical trial that I can’t get my hands on yet assessing garlic’s anti-protozoan properties in patients with Giardia infection.  Application of the garlic extract removed symptoms from patients with Giardia infection within 24 hours and after 3 days of treatment stool samples came back clean and clear of the infection.

They include a powerful statement that echoes the same conclusion that Dr. Hawrelak came to about garlic, saying

“It has been documented that garlic exerts a differential inhibition between beneficial intestinal microflora and potentially harmful enterobacteria” 

Have you had any experiences with the healing power of garlic? Share your thoughts below

References and Resources

  1. Blastocystis hominis – A Protozoan Gut Parasite
  2. Giardia Infections – Prevalence, Symptoms and Cause
  3. Herbal Antibiotics Natural Alternatives for Treating Drug-resistant Bacteria
  4.  Plants of Life, Plants of Death
  5. The encyclopedia of medicinal plants
  6. The handbook of clinically tested herbal remedies
  7. Medical herbalism : The science and practice of herbal medicine
  8. The Essential Guide to Herbal Safety
  9. Dr. Jason Hawrelak – Goulds Profile
  10. Efficacy of crude extracts of garlic (Allium sativum Linn.) against nosocomial Escherichia coli, Staphylococcus aureus, Streptococcus pneumoniea and Pseudomonas aeruginosa
  11. Garlic: a review of potential therapeutic effects

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