The target of the foods is Helicobacter pylori, a bacterium which earlier this decade was discovered to be the cause of the majority of stomach ulcers - because it burrows into the stomach lining, causes inflammation which becomes chronic, eventually causing an ulcer. Some research has also linked the bug to gastric cancer.
Now a Dutch team has found that garlic, especially when taken in conjunction with chemicals that reduce stomach acidity, inhibits the growth of H. pylori. "The concentrations of garlic required were rather low," according to Dr Edward Stobberingh of the department of medical microbiology at University Hospital, Maastricht.
At the same time, tea is also useful for fighting infection by the bug, which is found in the stomachs of about 40 per cent of people. Dr Yoshimasa Yamamoto, of Showa University school of medicine, says green tea contains chemicals called catechins that "show strong antibacterial activity" against H.pylori. "The level required for such activity ... is easily reached in the stomach after drinking a cup of green tea," he told the American Society of Microbiology's conference on antimicrobial agents at the weekend.
The application of old remedies could be useful. Though doctors were only recently persuaded that H. pylori really does cause most stomach ulcers, they have been quick to start using antibiotics to kill off the infection.
But that has led to the rise of antibiotic-resistant strains of bacteria, which means that, as Dr Stobberingh noted, "the antibacterial activities of other substances is interesting".