Inhibitory effect of polyunsaturated fatty acids on the growth of Helicobacter pylori: a possible explanation of the effect of diet on peptic ulceration.

Diets high in polyunsaturated fatty acids may protect against duodenal ulcer, possibly through inhibiting the growth of Helicobacter pylori. This hypothesis was tested in vitro by incubating H pylori microaerophilically with a range of polyunsaturated fatty acids. omega-3 Linolenic acid significantly, but reversibly, inhibited growth at 1.8, 2.5, and 5 x 10(-4) M (p < 0.01), while concentrations of 10(-3) M killed virtually all organisms, with cell lysis observed by electron microscopy. Similar inhibitory effects were seen with other polyunsaturated fatty acids, at concentrations of 2.5 x 10(-4) M the relative inhibitory potencies were oleic (C18:1) < linoleic (C18:2) < arachidonic (C20:4) < omega-3 linolenic (C18:3) = omega-6 linolenic (C18:3) = eicosapentanoic (C20:5) acid. Cell fractionation studies with 14C labelled linolenic acid showed that the linolenic acid was associated with the membrane fraction. Commonly ingested dietary polyunsaturated fatty acids inhibit the growth of H pylori in vitro, an effect which deserves further in vivo study.