Berna Harmse explains why you should always reach for olive oil when doing your grocery shopping.
Olive oil is one of the heroes of the Mediterranean diet (high consumption of vegetables and olive oil; moderate consumption of protein).
Evidence shows that Mediterranean populations have a reduced risk for certain chronic diseases and extended life expectancy compared with other populations in the world. This is despite their high dietary fat intake, which is usually more than 30% of their total energy intake.
A famous study, carried out in the 1950s, highlighted differences in diseases that occurred between Mediterranean populations and those living in northern Europe and North America, and compared their diets.
Over 30 years, it was found that the Mediterranean diet was associated with low rates of cardiovascular disease (CVD) and certain cancers (breast, colon, lung, ovarian and skin cancer), as well as increased life expectancy.
Compounds specific to olive oil, known as phenolics, seem to possess free radical scavenging properties and so may be able to reduce oxidative damage to DNA.
To know what antioxidants are all about, you need to know about free radicals. Free radicals are all around us, a natural product of our living. However, some factors (smoking, drinking, high-fat diets, too much sun) cause our bodies to produce more radicals than needed. And when produced in excess, these free radicals can start to damage our cells and tissues.
The good news is that antioxidants offer some means of protection for our bodies. Antioxidants can ‘mop up’ the aggressive molecules before they cause the damage.
Types of olive oil – what should you buy?
Olive oil is produced by the pressing or crushing of olive fruit. It comes in different grades, depending on the amount of processing involved. The less the oil is refined by heat and chemical treatments, the higher the quality of the oil.
Virgin varieties of olive oil are believed to offer the greatest health benefits as they retain most of the nutrients from the olive fruit.
Extra virgin olive oil is considered the premium grade of olive oil. It is made from the first pressing of olives. The oil is extracted by the traditional cold-pressing method, where no chemicals and only a small amount of heat are applied.
Virgin olive oil is produced from the second pressing of olives, or from the second-best grade of olives by cold-pressing, without use of chemicals and use of little heat.
Olive oil is also marketed as ‘pure’ olive oil. This type of oil is non-virgin, commercial-grade olive oil. It is ‘pure’ olive oil to the extent that it consists only of olive oil. This grade of olive oil consists of the inferior oil that is a result of subsequent pressings after the virgin oil has been extracted from lower-quality olives. It then undergoes a refining process involving heat, chemical solvents, high pressure and filtration treatments. Lastly, it’s mixed with a small quantity of virgin olive oil to restore colour and flavour.
Good to know
- Locally produced olive oil is better than imported, due to local oil being kept in storage for a shorter time than imported oil. Prolonged storage may result in the breaking down of some of the olive oil’s nutrients
- Use olive oil in place of saturated fat, such as butter, dip bread in it, use it in cakes, sauté, even fry vegetables and meat. But beware, the smoking point is not very high so (deep) frying at high temperatures will cause your food to brown quickly.
Smoking point of oils
When it comes to cooking, not all oils are created equal; some oils can handle the heat and some can’t. An oil’s smoking point is the temperature at which it will start to smoke and break down.
If cooking oil starts to smoke, it should be discarded. It’s likely lost some of its nutritional value and it could impart a bitter, unpleasant taste to your food.
MEET OUR EXPERT – Berna Harmse
Berna Harmse is a private practicing dietitian. She holds a MSc in Dietetics, and has a special interest in oncology nutrition. She is also an external lecturer at Stellenbosch University Division of Human Nutrition.