. . . cooking recipes, cookery, food, cooking vacations  


Back to A Passion for Olive Oil

A recent paper* published by Dr. Chopra's research group at the Northern Ireland Center for Diet and Health, University of Ulster, had some interesting conclusions.

Health benefits from lycopene in tomato products have been suggested to be related to its antioxidant activity. Dietary fat may influence the absorption and hence the antioxidant activity of lycopene. The study compared the effect of consumption of tomato products with extra-virgin olive oil versus sunflower oil. The different oils did not affect the absorption of the lycopene into the body, but the tomato/olive oil combination generated increased plasma antioxidant activity by around 20%. Therefore one conclusion drawn from the research was that it would seem that consumption of tomato products with olive oil, but not with sunflower oil, improves the antioxidant activity of the plasma.

Researchers are faced with the question of whether the combination of tomato and olive oil does something synergistically, or whether the beneficial antioxidant effects are caused by olive oil alone. Extra virgin olive oil is particularly rich in the phenolic antioxidants as well as squalene and oleic acid, and high consumption of the foregoing in the diet provides considerable protection against colon, breast and skin cancer, coronary heart disease and aging by inhibiting oxidative stress. Research has shown that scavenging of the hydroxyl radical was significantly higher among extracts of olive oil. This effect was only minimal in seed oils. In addition to their direct antioxidant capacity, extracts of olive oil are also potent inhibitors of xanthine oxidase activity. A constant high olive oil intake in the diet, especially extra virgin olive oil, provides a constant supply of antioxidants. This may reduce oxidative stress through inhibition of lipid peroxidation, a factor that is currently linked to a host of diseases such as cancer and heart disease.

There is a low incidence of skin cancer among Mediterranean populations, and olive oil consumption could be a contributing factor to this low cancer rate. Olive oil contains significantly higher amounts of squalene than seed oils, and squalene is to a large extent transferred to the skin. German researchers believe that this transfer mechanism is probably accomplished by scavenging singlet oxygen generated by ultraviolet light. Japanese scientists also claim that virgin olive oil applied to the skin after sunbathing could protect against skin cancer by slowing tumor growth.

Researchers at the University Hospital "Germans Trias Pujol" in Barcelona, Spain, compared the benefits of olive oil with safflower and fish oil on rats to determine if the type, and not just the amount, of fat in the diet had an impact on cancer tumor growth. They found that the research subjects on the olive oil diet had less precancerous tissue and fewer tumors than the animals fed the other oils.

The researchers believe constituents of olive oil, such as flavonoids, squalene and polyphenols, may help to protect against cancer. Flavonoids and polyphenols are antioxidants, which help prevent cell damage from oxygen-containing chemicals called free radicals.

Another study by researchers at the University of Oxford adds to the growing body of evidence that shows olive oil is as effective as fresh fruit and vegetables in keeping colon cancer at bay.

Dr Michael Goldacre and a team of researchers at the Institute of Health Sciences compared cancer rates, diets and olive oil consumption in 28 countries including European countries, the United States, Brazil, Colombia, Canada and China. Countries with a diet high in meat and low in vegetables had the highest rates of the disease and olive oil was associated with a decreased risk.

The researchers suspect olive oil protects against bowel cancer by influencing the metabolism of the gut. They think it cuts the amount of a substance called deoxycyclic acid and regulates the enzyme diamine oxidase which may be linked to cell division in the bowel.

A study in the March 27, 2000 issue of Archives of Internal Medicine, which was produced by Dr. Ferrara's research team, shows that a diet high in MUFA from olive oil can also help reduce blood pressure levels.

Ferrara and his colleagues found that while consuming the extra-virgin olive oil diet, research subjects reduced the amount of antihypertensive medication necessary to control blood pressure levels by 48%, versus only a 4% reduction on the sunflower oil diet. In addition, eight subjects on the extra-virgin olive oil diet required no antihypertensive medications; all subjects on the sunflower oil diet required antihypertensive medication. The authors conclude that a diet lower in total fat and saturated fat and a diet that contains higher amounts of MUFA can lower blood pressure levels and reduce or eliminate the need for medications in people with hypertension.

So why does olive oil lower blood pressure? One possible reason is its polyphenol content. Polyphenols are potent antioxidants which help arteries dilate, thereby reducing blood pressure. Ten grams of extra-virgin olive oil contains five mg of polyphenols; sunflower oil has no polyphenols.

*Lee, A.; Thurnham, D.I.; Chopra, C. Consumption of Tomato Products with Olive Oil but not Sunflower Oil increases the Antioxidant Activity of Plasma. Free Radical Biology & Medicine, 29:1051-1055; 2000 [Nov. 15th, 2000 issue]

Constantine Alexander
The Olive Tree World

This article came from Constantine Alexander better known as Papa Constantine. Papa Constantine is a Certified Olive Oil Consultant based in Connecticut, USA. His website is no longer available.

© Constantine Alexander, 2001
All rights reserved

Email Hub-UK : info@hub-uk.com