Study from Germany shows olive oil curbs cancer-causing DNA damage; Spanish trial finds that olive oil’s featured fat lowers blood pressure
by Craig Weatherby
Twin studies from Europe offer more reasons to use olive oil in place of standard cooking oils like corn, canola, safflower, and soy.
Let’s take a closer look.
- Olive oil's "mono" fatty acids appear to protect DNA from cancer-inducing damage by free radicals.
- Olive oil was found to reduce systolic blood pressure modestly in men unused to consuming it.
Olive oil protects DNA from cancer-promoting damage
Scientists have wondered why rates of several cancers are higher in Northern Europe than Mediterranean countries where olive oil corners the culinary scene.
Researchers from Denmark and Germany joined forces to conduct a clinical trial designed to test the idea that olive oil makes a difference (Machowetz A et al 2007).
They recruited 182 healthy men from Northern, Central and Southern regions of Europe for a rigorous (double-blind, randomized, controlled crossover) clinical trial in which the researchers tested the ability of olive oil to protect DNA and RNA from damage by free radicals.
Damage to DNA and RNA can lead to cancer because it results in mutations in cells.
Every day for two weeks, they gave the men 25 milliliters—a little under one ounce—of olive oil.
The German-Danish team then measured the proportions of damaged DNA and RNA in the participants at the beginning and end of the brief trial. This was done by testing their urine for the chemicals produced when free radicals oxidize DNA and RNA.
The men’s urine was tested at the beginning of the study, and as expected, the results indicated that the men from Southern regions had the lowest levels of damaged DNA and RNA.
After two weeks of ingesting the prescribed olive oils, levels of damaged RNA remained unchanged, but the levels of damaged DNA in all of the men had dropped by 13 percent.
As the researchers said, “These findings support the idea that ingestion of olive oil is beneficial and can reduce the rate of oxidation of DNA” (Machowetz A et al 2007).
The outcome suggests that the monounsaturated fatty acid (oleic acid) that predominates in olive oil and macadamia nut oil protects DNA from damage.
In this study, the benefits of olive oil seemed unconnected to its polyphenol antioxidant content. But only extra virgin olive oil—which is the kind highest in polyphenols, by far—provides critical arterial benefits related directly to its antioxidant content (see “Extra Virgin Olive Oil Confirmed as Best Cardiac Prevention Choice”).
Spaniards say olive oil lowers systolic blood pressure
Researchers led by Isabel Bondia-Pons of the University of Barcelona enrolled 110 healthy men from Germany, Finland and Denmark and 45 men from Spain and Italy (Bondia-Pons I et al 2007).
The men were assigned, randomly, to consume just under one ounce (25 milliliters) of one of three similar olive oils daily for three weeks. After a two-week “washout” period, the men switched olive oils for another three weeks and then repeated that regimen, thereby taking olive oil for a total of nine weeks.
Unsurprisingly, blood levels of oleic acid—the monounsaturated fatty acid abundant in olive oil—increased by two to three per cent in the men from the non-Mediterranean countries.
In contrast, probably because their regular diets were high in olive oil, blood levels of oleic acid did not rise in the men from Spain and Italy.
By the end of the trial, the systolic blood pressure in the men from Germany, Finland and Denmark had dropped by three percent, which is considered a significant reduction.
As the Barcelona team concluded, “The results of this study suggest that a moderate consumption of olive oil may be used as an effective tool to reduce SBP of healthy men who do not typically consume a Mediterranean diet” (Bondia-Pons I et al 2007).
- Machowetz A, Poulsen HE, Gruendel S, Weimann A, Fito M, Marrugat J, de la Torre R, Salonen JT, Nyyssonen K, Mursu J, Nascetti S, Gaddi A, Kiesewetter H, Baumler H, Selmi H, Kaikkonen J, Zunft HJ, Covas MI, Koebnick C. Effect of olive oils on biomarkers of oxidative DNA stress in Northern and Southern Europeans. FASEB J. 2007 Jan;21(1):45-52. Epub 2006 Nov 16.
- Bondia-Pons I, Schroder H, Covas MI, Castellote AI, Kaikkonen J, Poulsen HE, Gaddi AV, Machowetz A, Kiesewetter H, Lopez-Sabater MC. Moderate consumption of olive oil by healthy European men reduces systolic blood pressure in non-Mediterranean participants. J Nutr. 2007 Jan;137(1):84-7.