With all the talk about the supposed benefits of the ‘Mediterranean’ diet we’ve had over the last decade or so, there’s inevitably been some focus on the healthy properties of olive oil. In particular, olive oil is rich in so-called ‘monounsaturated’ fat that is believed to have benefits for the heart and circulation. The presence of olive oil in the Mediterranean diet is generally believed to help explain why those in the Mediterranean region (e.g. Southern Italians) enjoy relatively low rates of cardiovascular disease.
However, there’s more to olive oil than monounsaturated fat. In recent years, there’s been more focus on less plentiful components of olive oil. Such substances, sometimes referred to as olive oil’s ‘minor components’, may only be present in small amounts, but that does mean they do not offer anything in the way of nutritional punch.
One particular type of substance found in olive oil are known as a ‘phenols’ (also known as ‘polyphenols’). One potential effect of phenols is to inhibit blood clotting. This is important because tiny blood clots called ‘thrombi’ (pronounced “throm-bye”) can plug narrowed arteries and precipitate heart attacks and strokes. In other words, the ability to phenols to ‘thin’ the blood may help to prevent the occurrence of such events.
In a study published recently in the American Journal of Clinical Nutrition, the effect of the phenols derived from olive oil were assessed in a group of individuals suffering from high cholesterol [1]. The individuals in this study were fed two olive oils on separate occasions. One of these oils was rich in phenols (400 parts per million) while the other was not (80 ppm).
Before the olive oil was consumed, individuals had blood drawn so that it could be analysed for, among other things, substances known to encourage clotting such as ‘activated factor VII’ and ‘plasminogen activator inhibitor-1’. Compared to the low-phenol olive oil, consumption of the high-phenol oil led to lower levels of both activated factor VII and plasminogen activator inhibitor-1. One would expect these changes to translate into less tendency to form thrombi, and therefore, reduced risk of heart attacks and strokes.
Phenols don’t seem to just reduce the risk of clotting, but are also known to have what is known as ‘antioxidant’ activity ” something that would be expected to reduce the risk of chronic disease including cancer. I’ve added below an article dating from 2005 in which I mention some research linking the consumption of olive oil with a reduced risk of cancer.
The health benefits of olive oil – posted on 30 January 2005
The last decade or two has olive oil has received considerable attention from the nutritional community on account of its heart-healthy properties. The benefits this oil has for us have generally been ascribed to its high content of monounsaturated fat, which studies suggest effects changes in blood fat levels that reduce the risk of cardiovascular complications such as heart attack and stroke. However, another boost was given to olive’s oil image recently when a study published in the Annals of Oncology showed that its most plentiful monounsaturated fat – oleic acid – has the ability to mute the effect of a common breast cancer gene. The promise here is that olive oil, in addition to being good for the heart and circulation, is a bosom buddy too.
While this recent research linking olive oil’s chief constituent with protection from breast cancer is promising, it is actually only part of a body of evidence which suggests this foodstuff may help ward off the big C. Specifically, laboratory studies have identified that olive oil contains a range of compounds known as polyphenols that have what is known as ‘antioxidant’ activity. Through their ability to quench potentially damaging molecules known as ‘free radicals’ in the body, antioxidants are thought to offer some protection against chronic diseases such as cancer.
While the recent Annals of Oncology study does help our understanding of the beneficial effects the constituents of olive oil may have in the body, it is not the first piece of research to link olive oil consumption with a reduced risk of breast cancer. The results of several studies appear to show that relatively high consumers of olive oil have about a 25 per cent reduction in risk of breast cancer compared to low consumers. Other research has linked higher olive oil consumption with a reduced risk of cancers of ovary and womb too. The cancer-quelling properties of olive oil seem to extend to men too; with studies linking its consumption to some protection from cancers of the colon, pancreas and lung. All this research has led some scientists to suggest that a decent intake of olive oil may help to explain the relatively low incidence of certain cancers in the Mediterranean region.
Those looking to get good doses of polyphenols from their olive oil are best advised to opt for extra virgin varieties as lab analysis reveals that it is these oils (from the first pressing of olives) that offer the highest polyphenol content. It will perhaps come as no surprise that it is not just olive oil, but the fruit from which it is derived, that offers a rich stash of these health-enhancing nutrients. However, it appears that olives differ in more than appearance and flavour; tests show that black olives generally contain higher levels of polyphenols compared to green varieties. The preferred chemical constitution of black olives is reflected in enhanced antioxidant activity too. The evidence suggests that olives and olive oil have the potential to protect against both heart disease and cancer. Including these foodstuffs in the diet is likely to bear considerable fruit from a health perspective.
References:
1. Ruano J, et al. Intake of phenol-rich virgin olive oil improves the postprandial prothrombotic profile in hypercholesterolemic patients. Am J Clin Nutr 2007 Aug;86(2):341-6.
