Garlic

Synonym(s): ajoene, allicin, alliin

Nutrient group: plant extracts & active ingredients

Sources and physiological effects

Dietary sources
Garlic is used worldwide an ingredient in food preperation. Pressed garlic cloves are used as a spice in the Mediterranean, Middle East and Asia. In Spain, garlic sprouts that look like beans and have a milder taste are popular. The plant belongs to the Alliaceae family and has similar characteristics to onion, leek and chives. Early writings from Egypt, Greece, Rome, China and India report on the use of garlic to combat infections, protect against toxins and increase physical performance.
Physiological effects
Antimicrobial	Inhibition of bacterial growth by bacteriostatic properties (growth inhibition of Helicobacter pylori)
Immune system	Stimulation of infection resistance

Detailed information

Antimicrobial properties of garlic

The sulfide components of garlic are efficient bacteriostatics. The main active ingredient, alliin (S-allyl-L-cysteine sulphate), inhibits the growth of gram-positive and gram-negative bacteria (e.g. staphylococci, streptococci) as well as fungi and yeasts. The antifungal effect is probably due to ajoene, a derivative of allicin (1). This and the immune stimulating and cell-protecting properties of the garlic components can increase the effectiveness of antifungals (e.g. amphotericin B) (2). Garlic is also able to inhibit the growth of Helicobacter pylori and has a regulating and normalising effect on the intestinal flora (3)(4).

Indications

Antimicrobial properties of garlic

The sulfide components of garlic are efficient bacteriostatics. The main active ingredient alliin (S-allyl-L-cysteine sulphate) inhibits the growth of gram-positive and gram-negative bacteria (e.g. staphylococci, streptococci) as well as fungi and yeasts. The antifungal effect is probably due to ajoen, a derivative of allicin (1). This and the immunostimulating and cell-protecting properties of the garlic components can increase the effectiveness of antifungals (e.g. amphotericin B) (2). Garlic is also able to inhibit the growth of Helicobacter pylori and has a regulating and normalising effect on the intestinal flora (3)(4).

Administration

General mode of administration
When	Garlic should be taken between meals.
Side effects
No side effects are known to date.
Contraindications
No contraindications are known to date.

Interactions

Drug interactions
Anticoagulants (e.g. ASS, clopidogrel)	Controlled concomitant use may reduce the dose of anticoagulants and their side effects.
Nutrient interactions
None	No relevant interactions are known to date.

References

1) Watzl, B., Leitzmann, C. 1999. Bioaktive Substanzen in Lebensmitteln.
2) Davis, S. R. 2005. An overview of the antifungal properties of allicin and its breakdown products--the possibility of a safe and effective antifungal prophylactic. Mycoses. 48(2):95-100.
3) Canizares, P. et al. 2004. Allyl-thiosulfinates, the bacteriostatic compound of garlic against Helicobacter pylori. Biotechnol Prog. 20(1):397-401.
4) Shmuely, H. et al. 2016. Non-pharmacological treatment of Helicobacter pylori. World Journal of Gastrointestinal Pharmacology and Therapeutics WJGPT. 7(2):171.

References Interactions
Stargrove, M. B. et al. Herb, Nutrient and Drug Interactions: Clinical Implications and Therapeutic Strategies, 1. Auflage. St. Louis, Missouri: Elsevier Health Sciences, 2008.
Gröber, U. Mikronährstoffe: Metabolic Tuning –Prävention –Therapie, 3. Auflage. Stuttgart: WVG Wissenschaftliche Verlagsgesellschaft Stuttgart, 2011.
Gröber, U. Arzneimittel und Mikronährstoffe: Medikationsorientierte Supplementierung, 3. aktualisierte und erweiterte Auflage. Stuttgart: WVG Wissenschaftliche Verlagsgesellschaft Stuttgart, 2014.