Olive Oil Lowers Oxidative Stress Marker

The ability of olive oil to lower a marker for oxidative damage of DNA in cells suggests that olive oil might lower the risk of cancer.

If you want to avoid developing cancer, then you might want to add eating more olive oil to your list of New Year's resolutions. In a study to be published in the January 2007 issue of The FASEB Journal, scientists from five European countries describe how the anti-cancer effects of olive oil may account for the significant difference in cancer rates among Northern and Southern Europeans. The authors drew this conclusion based on the outcomes of volunteers from Denmark, Finland, Germany, Italy, and Spain, who consumed 25 milliliters (a little less than a quarter cup) of olive oil every day for three weeks. During this time, the researchers examined urine samples of the subjects for specific compounds known to be waste by-products of oxidative damage to cells, a precursor to cancer. At the beginning of the trial, the presence of these waste by-products was much higher in Northern European subjects than their Southern European counterparts. By the end of three weeks, however, the presence of this compound in Northern European subjects was substantially reduced. "Determining the health benefits of any particular food is challenging because of it involves relatively large numbers of people over significant periods of time," said lead investigator Henrik E. Poulsen, M.D. of Rigshospitalet, Denmark. "In our study, we overcame these challenges by measuring how olive oil affected the oxidation of our genes, which is closely linked to development of disease. This approach allows us to determine if olive oil or any other food makes a difference. Our findings must be confirmed, but every piece of evidence so far points to olive oil being a healthy food. By the way, it also tastes great."

I'd like to see more dietary studies using oxidative stress markers as a quicker way to guess at the likely long term effects of various food choices.

The polyphenols in olive oil surprisingly do not look like the cause of the lowered oxidative stress marker.

Another interesting finding in the study suggests that researchers are just beginning to unlock the mysteries of this ancient "health food." Specifically, the researchers found evidence that the phenols in olive oil are not the only compounds that reduced oxidative damage. Phenols are known antioxidant compounds that are present in a wide range of everyday foods, such as dark chocolate, red wine, tea, fruits, and vegetables. Despite reducing the level of phenols in the olive oil, the study's subjects still showed that they were receiving the same level of health benefits.

I'd like to see studies done using different high phenol foods that are low in fat to see if any of the foods can lower oxidative stress using the same marker (8oxodG - sounds like an oxidized form of the nucleic acid guanine) that these researchers used.

The researchers measured the compound 8oxodG in the urine as an indicator of oxidative stress and damage and found olive oil lowered 8oxodG.

Oxidative damage is a process whereby the metabolic balance of a cell is disrupted by exposure to substances that result in the accumulation of free-radicals, which can then damage the cell. The men were found to have around 13% less 8oxodG compared with their levels at the beginning of the study. At the beginning of the study, men from northern Europe had higher levels of 8oxodG than those from southern Europe, supporting the idea that olive oil had a reductive effect.

I've started eating more olives and olive oil. The olive oil is displacing canola oil. But we need a comparative study of the effects of olive oil and canola oil on urine 8oxodG. Ditto for fish oils.

The bigger story on olive oil has been the suspected heart benefit. A September 2006 paper published in the Annals of Internal Medicine found olive oil boosts heart healthy HDL cholesterol while lowering triglycerides and lowering oxidized LDL cholesterol.

Results: A linear increase in high-density lipoprotein (HDL) cholesterol levels was observed for low-, medium-, and high-polyphenol olive oil: mean change, 0.025 mmol/L (95% CI, 0.003 to 0.05 mmol/L), 0.032 mmol/L (CI, 0.005 to 0.05 mmol/L), and 0.045 mmol/L (CI, 0.02 to 0.06 mmol/L), respectively. Total cholesterolHDL cholesterol ratio decreased linearly with the phenolic content of the olive oil. Triglyceride levels decreased by an average of 0.05 mmol/L for all olive oils. Oxidative stress markers decreased linearly with increasing phenolic content.

When you can lower heart disease and cancer risk with the same dietary practice that sounds like a winner to me.