The Effect of Garlic 

on Good and Bad Bacteria

We love garlic as an antimicrobial for the gut.  It covers so many possible pathogens.  These include Escherichia, Salmonella, Staphylococcus, Klebsiella, Proteus, Bacillus, Clostridium, Neisseria, Proteus, Pseudomonas, Shigella, Mycobacterium and Helicobacter Pylori— all potential poster bacteria for life threatening diseases.  (Ankri and Mirelman, 1999; Belguith et al., 2010; Deresse, 2010; Gupta and Ravishanka, 2005; Uchida et al., 1975; Cellinin et al., 1996; Sivam, 2001 respectively).

The antimicrobial power of garlic doesn’t stop here, for it has also proven to be a very effective antifungal (i.e. inhibiting and killing Candida albicans), antiprotozoal (think of Giardia and Cryptosporidium, both dangerous infections prevented and stopped by garlic) and antiviral properties - garlic kills viruses upon direct contact, including those responsible for viral meningitis, viral pneumonia, as well as herpes infections.  (Ankri and Mirelman, 1999; Harris et al., 2001)

So there is substantial evidence to support the claim for pathogens, but what is the effect of garlic on the good gut bacteria, the probiotic organisms such as Lactobacillus and Bifidobacterium?

Booyens and Thantsha (2013) investigated the antimicrobial effects of different garlic preparations on five strains of Bifidobacteria and one strain of Lactobacillus.

What Booyens and Thantsha discovered was that certain strains of Bifido where more susceptible to garlic’s antimicrobial effects than others, with B. lactis being the least effected, following by some B. longum strains (but not others) and then Bifidum being the most sensitive, whilst the L. acidophilus was not affected at all.

The conclusions we take from this research is that Lactobacillus Acidophilus maintains its status as resistant to garlic and therefore is a probiotic that can be taken with garlic at the same time, whereas, regarding the Bifido species selection as the authors of the research state, “Caution is therefore advised when using probiotic Bifidobacteria and garlic simultaneously.”

In another study, Lactobacillus Casei a probiotic found in the majority of commercial yogurt and sour cream products, showed a degree of resistance to garlic, indicating that its consumption may favour the growth of these beneficial bacterial species in the gut. Garlic intake has the potential to temporarily modulate the gut microbiota.

References:

Booyens and Thantsha, 2013, Antibacterial effect of hydrosoluble extracts of garlic (Allium sativum) against Bifidobacterium spp. andLactobacillus acidophilus, African Journal of Microbiology Research, 7(8), pp. 669-677.  (See the full research)

Effect of garlic powder on the growth of commensal bacteria from the gastrointestinal tract. http://www.ncbi.nlm.nih.gov/pubmed/22480662

Garlic Effect on Probiotics http://bioimmersion.com/blog/garlics-effect-on-probiotics/

Ankri S, Mirelman D (1999). Antimicrobial properties of allicin from garlic. Microbes Infect. 2:125-129.

Belguith HF, Kthiri A, Chati A, Abu Sofah J, Ben H, Ladoulsi A (2010). Inhibitory effect of aqueous garlic extract (Allium sativum).  Food Sci. Technol. 37:263-268.

Deresse D (2010). Antibacterial effect of garlic (allium sativum) on Staphylococcu aureus:  An in vitro study.  Asian J. Med. Sci. 2:62-65.

Gupta S, Ravishankar S (2005).  A comparison of the antimicrobial activity of garlic, ginger, carrot, and turmeric pastes againstEscherichia coli 0157:H7 in laboratory buffer and ground beef. Foodborne Pathog. Dis. 2:330-340.

Uchida Y, Takahashi T, Sato N (1975).  The characteristics of the antibacterial activity of garlic.  Jpn. J. Antibiot. 28:638-646.

Cellini L, Campli D, Masulli E, Bartolomeo DS, Allocati N (1996). Inhibition of Helicobacter pylori by garlic extract (Allium sativum). FEMS Immuno. Med. Microbiol. 13:273-277.

Sivam GP (2001). Protection against Helicobacter pylori and other bacterial infections by garlic. J. Nutr. 131:1106S-1108S.

Harris JC, Cottreli SL, Plummer S, Lloyd D (2001).  Antimicrobial properties of Allium sativum (garlic).  Appl. Microbiol. Biotechnol. 57:282-286.