Aged garlic extract decreased IL-12 production in peripheral blood monocytes, which in turn could decrease pro-inflammatory cytokines such as IFN-y and IL-2.

Santa Clara University

Garlic contains bioactive sulphur-containing compounds, such as sulphoxide and polyphenols, which can strengthen the immune system. 

The impact of garlic on the immune system 

In the innate immune response to SARS-CoV-2 infection, the host cells' pattern recognition receptors (PRR) recognise evolutionarily conserved molecular structures on the virus, called pathogen associated molecular patterns (PAMPS). When PAMPs bind to PRRs, the inflammatory response begins. PRRs activate several transcription factors to regulate the expression of genes responsible for inflammatory cytokine, interferon, chemokine, and adhesion molecule production.

Onset of Inflammatory Response in COVID-19

Yang, F., Zhang, Y., Tariq, A., Jiang, X., Ahmed, Z., Zhihao, Z., Idrees, M., Azizullah, A., Adnan, M., & Bussmann, R. W. (2020). Food as medicine: A possible preventive measure against coronavirus disease (COVID-19). Phytotherapy research : PTR, 10.1002/ptr.6770. Advance online publication. https://doi.org/10.1002/ptr.6770

Food as medicine: A possible preventive measure against coronavirus disease (COVID-19)

Mice treated with diallyl sulphide, a compound found in garlic, experienced an increased number of white blood cells and number of cells producing antibodies compared to mice not treated with diallyl sulphide. 

The effect of diallyl sulphide from garlic on the immune systems of mice 

In a study by Lui et al., it was found that low concentrations of garlic oil-led  the majority of T-helper cells to respond toward the Th1 type. At high concentrations of garlic oil, T-helper cells were more oriented toward the Th2 type. 
However, a study from Zamani et. Al demonstrated that in rats, garlic oil oriented T-helper cells more toward the Th2 type by increasing IL-4 production in the spleen blood cells.

How garlic oil affects T-helper cells 

Aged garlic extract increased IL-10 In peripheral blood monocytes by inhibiting TNF-a and IL-6, which are inflammatory cytokines that play a key role in the pathogenesis of SARS-CoV-2. 

Aged garlic extract effects on  IL-10 and the pathogenesis of SARS-CoV-2  

The effects of aged garlic extract on IL-12 and the pathogenesis of SARS-CoV-2 

Following SARS-CoV-2 infection of the lungs, host cells release pro-inflammatory cytokines and chemokines, as illustrated in the diagram below. Of the chemicals listed, the three notable cytokines are: 
- IL-1
- TNF- α
- IL-6


The relationship between coronaviruses and chemokines has been extensively studied in other coronaviruses including the SARS-CoV and MERS-CoV epidemics. Current data on SARS-CoV-2 also illustrates a very similar relationship. 

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