• Licorice
• Garlic
• Tea
• Ethanolic leaves extracts of the common fig
• Hexane leaves extract of mango

Yang F. et al. state that pomegranate, black pepper, papaya, soybeans, long pepper, black caraway, barberry, European plum, Chinese box thorn and white mulberry also have immunomodulatory properties that may help prevent COVID-19. Considering their cheap price compared to other measures, consumption of these functional food plants may be a cost-effective strategy to prevent cases of COVID-19.