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Food, Health, and Eco-news
Extra Virgin Olive Oil Undermines Bug Behind Ulcers and Stomach Cancer

Antioxidant polyphenols in extra virgin grade oil prove more potent than their counterparts in tea and fruits

by Craig Weatherby

Many millions of people suffer from gastritis and peptic ulcers... and some develop stomach cancer as a result.

Prior studies have shown that green tea, cranberry juice and certain other polyphenol-rich plant foods inhibit the growth of H. pylori: the bacteria known to cause peptic ulcers and gastritis, and the only one that can survive in the acidic environment of the stomach.

In Western countries, the rate of H. pylori infections roughly matches people's age (e.g., 20 percent are infected at age 20, 50 percent at age 50, 80 percent at age 80).

A minority of infections leads to an ulcer, while many more cause discomfort, abdominal pain or gastritis (inflammation of the mucosal gastric lining).

Chronic H. pylori infection raises the risk of gastric adenocarcinomas and lymphomas, so it's smart to eat foods that help keep the bug in check.

Polyphenols pummel intestinal pathogens, and some friendly bugs

Last June, Spanish researchers reported that in test tubes, key phenolic compounds in extra virgin olive oilits unique, highly potent tyrosol-type antioxidantsinhibited growth of harmful intestinal bacteria such as Clostridium and E. coli (Medina E et al 2006).

And most of the food-born pathogens testedincluding key villains Listeria, Staphylococcus, Salmonella, Yersinia, and Shigelladid not survive more than one hour of contact with extra virgin olive oil (EVOO).

We should note that the phenolic compounds in EVOO also killed the beneficial “probiotic” microorganisms L. acidophilus and B. bifidum. Neither is normally present in significant amounts -- unless ingested via probiotic-enriched yogurt or supplements. Given the excellent health of Mediterranean peoples who consume loads of EVOO, this effect is clearly not a problem.

Cancer- and ulcer-causing bacteria added to EV olive oil's hit list

Exciting new findings published earlier this month show that extra virgin olive oil may be a significantly more powerful preventive and therapeutic ally against this gut-searing, cancer-promoting microbe.

After conducting a test designed to simulate the conditions in the human gut, Spanish researchers found that an extract of naturally polyphenol-rich EVOO exerted strong anti-bacterial effects against eight strains of H. pylorithree of which are regarded as antibiotic-resistant.

As lead author Concepcion Romero wrote in his team's Journal of Agricultural and Food Chemistry paper, “These results open the possibility of considering extra virgin olive oil a chemoprotective agent for peptic ulcer or gastric cancer ….” Of course, as Dr. Romero elaborated, “…this bioactivity must be confirmed… [in animal trials] in the future” (Romero C et al 2007).

There were two striking aspects of the results:

  • The olive oil extract's anti-bacterial effects were dose-dependent, and it was showed benefit at very low concentrations.
  • More than half of the polyphenols in the EVOO diffused into the watery fraction of the gastric juices—the best place to attack H. pylori—and these specific polyphenols (secoiridoid aglycons) inhibited the bug most strongly.
  • The most active phenols in EVOO inhibited H. pylori bacteria in doses much lower than seen with the phenolic compounds in tea, wine, and plant extracts.

As the Spanish group concluded, “In view of the low concentration required to exert bactericidal action against H. pylori … it is promising to carry out studies in vivo with extra virgin olive oil to prevent and control peptic ulcers and gastric cancer caused by this bacteria.”

The results of the study provide another reason to favor extra virgin olive oil, as they follow those of other studies linking its unique polyphenols to enhanced cardiovascular disease health, reduced cancer-causing DNA damage in cells, and lower risks of colon and breast cancers.


  • Romero C, Medina E, Vargas J, Brenes M, Castro AD. In Vitro Activity of Olive Oil Polyphenols against Helicobacter pylori. J Agric Food Chem. 2007 Feb 7;55(3):680-6.
  • Medina E, de Castro A, Romero C, Brenes M. Comparison of the concentrations of phenolic compounds in olive oils and other plant oils: correlation with antimicrobial activity. J Agric Food Chem. 2006 Jul 12;54(14):4954-61.