Garlic as a Natural Antimicrobial: What Science Actually Says
Garlic (Allium sativum) has been used as food and medicine for thousands of years. Many modern social media posts claim that “garlic kills 14 types of bacteria and 13 types of infections”. While garlic does have interesting antimicrobial activity, these very specific numbers are not supported by scientific literature and appear to be internet myths that have been circulating for over a decade.
The real active compound: Allicin
When a fresh garlic clove is crushed or chopped, the enzyme alliinase converts alliin into allicin — the main compound responsible for garlic’s characteristic smell and most of its biological activity.
Allicin (and several other sulfur-containing compounds that form afterward) shows antimicrobial effects in laboratory studies (in vitro).
What bacteria does garlic actually affect in lab studies?
Research has demonstrated that allicin and garlic extracts can inhibit the growth of many different bacterial species, including (but not limited to):
• Staphylococcus aureus (including some MRSA strains)
• Escherichia coli
• Salmonella enterica
• Helicobacter pylori
• Streptococcus pneumoniae
• Bacillus subtilis
• Klebsiella pneumoniae
• Proteus mirabilis
• Pseudomonas aeruginosa (usually weaker effect)
• Listeria monocytogenes
• Shigella species
• Some oral pathogens (Porphyromonas gingivalis, Prevotella intermedia…)
• Some Mycobacterium strains
So yes — garlic shows activity against many different types of bacteria in test-tube studies, sometimes more than 14. But the exact number “14” is arbitrary and not coming from any major review.
Does this mean garlic cures 13 types of infections in humans?
No.
There is a huge difference between:
• bacteria dying in a Petri dish when you add concentrated garlic extract
• and the same effect happening inside the human body after eating garlic
Very few high-quality human clinical trials exist showing that eating garlic (or even taking garlic supplements) can reliably treat or prevent specific bacterial infections.
The strongest evidence exists for:
• Modest help against the common cold (meta-analyses show a small reduction in occurrence and duration)
• Some supportive effect against Helicobacter pylori when used together with conventional antibiotics
• Possible mild blood pressure and cholesterol benefits
But garlic is not a substitute for antibiotics in serious bacterial infections (pneumonia, urinary tract infections, skin infections, sepsis…).
Bottom line (January 2026)
Garlic has real, scientifically documented antibacterial properties especially in fresh, crushed form
It can be a useful part of a healthy diet and may give mild immune support
Specific claims like “kills exactly 14 bacteria and 13 infections” are not evidence-based and are marketing-style exaggerations
Garlic is not a reliable treatment for established bacterial infections — see a doctor when you need antibiotics
Enjoy your garlic — preferably fresh and crushed — but keep realistic expectations about what it can and cannot do.