By Russell H. Greenfield, MD Clinical Assistant Professor of Medicine UNC Chapel Hill School of Medicine
The Mediterranean diet is favored by people around the world, and not only for the rich flavors and textures associated with this traditional cuisine. A wide range of health benefits have been ascribed to the Mediterranean pattern of eating, including protection against heart disease, depression, cancer, high cholesterol and dementia.
Brightly colored vegetables and fruit are typically found on the menu, as are cold-water fish, whole grains and healthy fats, especially extra virgin olive oil. Any of these foods eaten regularly, alone or in combination, might be responsible for improvements in health.
Scientists and health-care providers have increasingly been turning their attention to the fruit of the olive tree and its oil, and in some cases to olive leaves, all with good reason.
Heart Health Benefits
The Mediterranean diet developed in an area of the world where the olive (Olea europaea) has long been cultivated. In turn, olives and olive oil hold a place of prominence on the dinner table, so much so it is estimated that nearly half of all the fat ingested in the region comes from olives.
This is noteworthy because olives are known to be an excellent source of monounsaturated fat (oleic acid), to which many of olive oil’s health benefits have been ascribed, especially its capacity to help prevent heart disease. Both olives and high-quality olive oil have been studied for their potential beneficial effects on blood pressure and cholesterol levels, their antioxidant and anti-inflammatory effects, and their mild blood-thinning effects that may help prevent inappropriate blood clot formation.
Olives and olive oil contain a variety of additional compounds that may also offer health benefits. Antioxidant phenols such as hydroxytyrosol possess antimicrobial activity, “thin” the blood, and may help ensure the proper flow of nutrients throughout the body by dilating blood vessels.
A recently discovered phenol present in extra virgin olive oil called oleocanthal has garnered a great deal of interest due to its natural anti-inflammatory activity that compares well with the actions of non-steroidal anti-inflammatory drugs, such as ibuprofen. High-quality extra virgin olive oil that contains oleocanthal confers a slightly bitter, yet enjoyable, peppery taste that is typically experienced at the back of the throat.
Some olive oil constituents also appear to possess anti-cancer activity. The monounsaturated fat, oleic acid, may inhibit a gene, Her-2/neu or Her-2, also known as human epidermal growth factor receptor 2, that can be overactive in a significant number of cases of aggressive breast cancer. In fact, early laboratory data suggest that high-quality olive oil may one day prove to be a useful adjunct in the treatment of Her-2 positive breast cancer.
Hydroxytyrosol, a phenol found in high concentrations in Kalamata olives, may help prevent DNA damage and abnormal cell growth. Other olive oil phenols may play a role in helping to prevent colon cancer, either by impacting the production of irritant bile acids in the gut or by a direct protective effect on the lining of the large intestine. In addition, a compound found in the skin of olives, called maslinic acid, may promote the programmed death of colon cancer cells.
Olive Oil Quality
In simple terms, olive oil is extracted through the physical crushing of olives and the subsequent pressing of the pulpy mass that remains. Oil obtained from the earliest presses (extra virgin) contains the highest concentration of health-promoting phenols and is the least acidic. Ensuing presses, together with other processes, allow for the collection of additional quantities of oil (virgin and ordinary olive oils), but they are typically deemed to be of both lower culinary quality and therapeutic potential.
Supermarkets carry a number of different varieties of olives. Most people are familiar with green and black olives; the main differences between the two are the added ripeness or oxidation of black olives, and the ways they are cured to remove a potentially health-promoting, but very bitter-tasting, compound called oleuropein (green olives are often treated with lye while black olives are cured in brine). Kalamata olives come from the Kalamata region of Greece and are typically cured in water. Generally speaking, studies suggest that black olives are higher in health-promoting phenols and antioxidant activity than green varieties.
Olive Leaf Extract
An extract taken from olive leaves that contains the antioxidant compound oleuropein, which is typically removed from olives through curing, has also been studied for its potential therapeutic benefits. Very preliminary data suggest the extract provides a blood pressure lowering effect that may approximate that seen with the use of low-dose prescription blood pressure medication. An additional benefit of olive leaf extract may be mild lowering of LDL cholesterol levels.
It is still too early to recommend the use of olive leaf extract for the treatment of high blood pressure and high cholesterol, but some people choose to take it under a physician’s supervision, often starting with a conservative dose of 400-500 mg a day.
A traditional Mediterranean-style diet calls for eating about 8-10 olives or ingesting 2-3 tablespoons of olive oil, either by dipping bread in it or preparing meals at low heat with the oil, each day.
Extra virgin olive oil is the least processed, least acidic, best tasting, and likely most healthy choice when it comes to olive oil, but it can be pricey. Look for varieties that are cold pressed and organic, and specifically seek out those that are certified by the International Olive Oil Association or the California Olive Oil Council. High-quality extra virgin olive oil possesses a pleasant aroma, a deep green hue, and a delicious taste, often with a hint of peppery bitterness.
Olives provide added proof that good things come in small packages. Realistically, you don’t have to or may not be able to eat 8-10 olives each day or take a swig of olive oil to be healthy. However, occasionally snacking on olives and making high-quality extra virgin olive oil the primary oil in your kitchen can help support the dietary component of an overall healthy lifestyle.