Olive Oil: More Potential Health Benefits Revealed
Olives at the "Heart" of a Heart-Healthy Diet
A wealth of studies on the Mediterranean-style diet suggests that it has great potential to fight against many chronic diseases of aging. People in the Mediterranean region who eat this traditional diet have a low incidence of cardiovascular disease and high life-expectancy rates. Olive oil is a key component of this diet, and researchers are delving into the chemical make-up of this oil to unravel just how it may contribute to a long and healthy life.
The fatty acids found in olive oil - called mono-unsaturated fats - are thought to be responsible for much of its heart benefits. Olive oil is abundant in beneficial oleic acid, and low in less healthy saturated fats. But researchers are finding that it's not just the fatty acid composition of this oil that's healthful. Other components may be just as important. And not just for the heart, but for colon and bone protection too.
Olive Polyphenols: Heart Health & Beyond
Along with its less artery-clogging fatty acids, olive oil contains antioxidants such as vitamin E and poly-phenols - plant compounds with potent antioxidant properties. These compounds are produced in the fruit and leaves of the olive tree, where they afford protection against environmental stresses. Some of the polyphenols unique to olive oil such as oleuropein are being intensely investigated. Early findings suggest that oleuropein and other phenols may work synergistically with the fats in olive oil to protect arteries, bones and colon cells.
Researchers have found that olive oil polyphenols promote the antioxidant capacity of blood and help the inner lining of small blood vessels in volunteers be more responsive to sudden changes in blood flow (1,2). Poor vessel responsiveness is considered an early warning sign of cardiovascular disease. High doses of olive leaf extract with oleuropein are reported to protect against ischemia in animals and lower blood pressure in humans (3,4) - effects that might help explain olive oil's apparent heart benefits.
Colon Cell Protection
Though limited, some population-health studies have pointed to olive oil as protective against colon cancer. As with heart disease, the possible anti-cancer effects of olive oil have been attributed to its high levels of monounsaturated fats. However, newer research is focusing on the role that the polyphenols may play.
For instance, researchers in Ireland report that olive oil polyphenols added to cultured colon cancer cells protected the cells from DNA damage(6). This lab study, which must be confirmed in animals and humans, also found that the polyphenols quieted the invasive activity of the cancer cells.
Anti-inflammatory Effects May Benefit Bones
Inspired by studies suggesting that people eating a traditional Mediterranean diet are less likely to have osteoporosis, French investigators have begun to explore the effects of olive oil polyphenols on bone. In one study, high levels of isolated oleuropein stopped bone loss in an animal model that mimics menopausal osteoporosis(7). Inflammation plays a role in bone loss, and oleuropein has anti-inflammatory as well as antioxidant action. This is exciting and promising work.
Go For the "Extra Virgin"
We know now that olive oil is more than just oleic acid. But to reap its potential benefits, choose extra virgin olive oil. Refined olive oils loose much of their poly-phenol content during processing, while cold pressed virgin oils retain these health-promoting compounds.
- Weinbrenner T, et al. Olive oils high in phenolic compound modulate oxidative/antioxidative status in men. J Nutr 134:2314-21, 2004.
- Ruano J, et al. Phenolic Content of Virgin Olive Oil Improves Ischemic Reactive Hyperemia in Hypercholesterolemic Patients. J Am Coll Cardiology 461864-68, 2005.
- Andreadou I, et al. The olive constituent oleuropein exhibits anti-ischemic, antioxidative and hypolipidemic effects in rabbits. J Nutr 136:2213-19, 2006.
- Dose dependent effect of olive leaf extract standardized to oleuropein on blood pressure of twins. Presented at Phytotherapy Congress in Berlin, October, 2005.
- Hashim Y, et al. Components of olive oil and chemoprevention of colorectal cancer. Nutr Rev 63:374-86, 2005.
- Gill C, et al. Potential anti-cancer effects of virgin olive oil phenols on colorectal carcinogenesis models in vitro. Int J Cancer 117:1-7, 2005.
- Puel C, et al. Dose-response study of effect of oluropein, an olive oil polyphenol, in an ovariectomy/inflammation experimental model of bone loss in the rat. Clin Nutr, Epub May, 2006.