Why some say olive oil is the world's healthiest ingredient

Olive oil, the "holy oil" has been used to bless babies, consecrate kings and anoint athletes. Used as moisturiser, perfume, food and medicine, it has also been called the "healthiest ingredient in the world".

A new study has found that a compound in olive oil may also help to prevent the growth of brain tumours.

Go on, lather yourself.Credit: Stocksy

Oleic acid, the main ingredient of olive oil, is the most abundant and widely distributed fatty acid in nature, explained the researchers from the University of Edinburgh's school of biological sciences.

It is also believed to stimulate the production of a molecule that can prevent the growth of cancer-causing proteins.

"While we cannot yet say that olive oil in the diet helps prevent brain cancer, our findings do suggest that oleic acid can support the production of tumour-suppressing molecules in cells grown in the lab," said researcher Dr Gracjan Michlewski of their findings published in the Journal of Molecular Biology. "Further studies could help determine the role that olive oil might have in brain health."

It is not just its potential role in brain health that has researchers in a lather. Mary Flynn says her interest in olive oil began in the '80s, at the height of the anti-fat movement.

"I read that diets high in fat from olive oil were related to much lower rates of [heart disease] compared to diets high in fat in the US, which was likely fat from red meat and/ or vegetable seed oils," Flynn, an associate professor of medicine recalls.

"I was just starting in research and the US was just beginning to recommend low-fat diets. I thought this did not make sense based on the health benefits seen with diets high in olive oil fat. This made me start to think it was the nutrient 'fat' [or] it was the food source so I started to become interested in discussing food versus nutrients."

For the past 30 years she has researched and reviewed literature on the role of olive oil in reducing the risk of everything from heart disease to type 2 diabetes to lipid disorders, cancer, osteoporosis and Alzheimer's disease ("as well as other cognitive function issues").

Flynn has called it the world's healthiest ingredient. A big call?

"Definitely the healthiest food known," Flynn responded when I asked. "There is no other food with such a vast and varied literature for benefits. And for most studies, the more you use, the better!
And no study has ever shown a negative effect. I am confident in saying there is no other food as healthy as extra virgin olive oil."

Dietitian Melanie McGrice agrees – sort of.

"I'd agree that extra virgin olive oil is one of the healthiest foods available, but personally, I wouldn't go so far to call it the healthiest," McGrice said.

Dr Joanna McMillan agrees. "I don't think we can say any food is THE healthiest," McMillan said. "No food gives you all you need. It's really dietary patterns that are ultimately important. That said extra virgin olive oil is certainly one food that has an abundance of evidence supporting its inclusion in your diet and the fat/oil with the most evidence of benefit."

McGrice added: "And, I'd have to disagree that people can consume as much as they like. I recently had a client in my weight management clinic who consumed 40 litres per year – and he has a significant weight problem."

Quantity is important, but so is quality. Not all olive oils are made equal and that impacts everything from its nutrients and health-giving properties to the ability to cook with it.

"There is a misconception that you can not cook with olive oil," Flynn said. "Phenols are what make extra virgin olive oil healthy and they are harmed by light, heat, and oxygen, with oxygen seeming to cause the greatest loss. So do not leave olive oil exposed in a pan; add the food as soon as you add the olive oil.

She added: "A study from Spain published last year showed that cooking vegetables in olive oil made the vegetables healthier as the olive oil phenols were absorbed. Deep fat frying had more phenols versus just sautéing. Cooking vegetables in water meant that the phenols in the vegetables went into the water."

The key term that Flynn refers to is extra virgin olive oil (EVOO). Virgin olive oil (VOO) is made with less fresh olives (EVOO uses the freshest olives), so the acidity in the fruit is higher and therefore there is less stability when heated. "Light" olive oil or plain olive oil are chemically refined versions that do not contain the health benefits or the stability during cooking.

So enjoy EVOO, aka the "holy" oil, aka maybe the "world's healthiest ingredient", lather yourself in it and pour it on your veg for a health and taste boost. Just maybe, stop shy of consuming 40 litres of the stuff.

Olive oil grades

Experts from Australia's Cobram Estate, which last week was awarded the world's 'healthiest' EVOO in Malaga and which won gold at the 2017 New York International Olive Oil Competition for its Light and Premiere ranges, explain the difference between various olive oils on the market:

Extra virgin olive oil is the natural juice, cold pressed (or squeezed) from fresh olives. It is 100 per cent natural and the highest grade of olive oil you can buy. Freshness is a key component of EVOO, the fresher the oil the higher the health benefits. EVOO has the highest range of therapeutic properties which are beneficial for weight control, anti-aging, inflammation and cardiovascular health.

Refined olive oils are oils of inferior quality due to the chemical processes they are subjected to, including gum extraction, neutralisation, decolourisation, and heat treatments. Therefore, olive oil has been stripped of the nutrients and antioxidants found in extra virgin olive oil, such as squalene, vitamin E and other antioxidants

Olive oils alone, are blends of mostly refined oil with a splash of extra virgin olive oil. Refined oils are those that have been subject to chemical processing (see above). Refined olive oils are often labelled "Pure", "Extra Light" or "Light" which are simply marketing terms and not related to the quality or content of the oil.

Lampante oil is quite simply lamp oil, and not fit for human consumption. Don't touch this stuff unless you want to light it up!