A long-standing myth is that you shouldn't cook with olive oil.

"Olive oil is very good for you but some olives have a very low smoke point, and produce small amounts of carcinogens when heated," nutritionist Dr Glenys Jones told The Telegraph London recently, suggesting we should only use olive oil for salads and not cook with it.

So what is the truth?

The truth is simple, and it's not.

Like many a good myth, the one that says we shouldn't cook with olive oil has only a drizzle of truth.

The basic rule is that not all olive oils are equal and the acidity of the oil determines the smoke point – which is when things get hairy and not so healthy.

The fresher the olives are when crushed and turned into oil, the lower their acidity is. The lower the acidity, the higher the tolerance to heat.

Also, the better an olive oil tastes the fresher it is, the more nutrients it has which protects it when cooking, so the more heat it can handle.

So a good, unadulterated extra virgin olive oil (EVOO) will have low acidity that can tolerate heat as high as 200 to 215 degrees celsius.

This is much higher than most of us use when frying or even roasting.

On the flip side, the older an olive is by the time it is crushed and turned into oil, the higher its acidity and the lower its smoke point.

And here is where we run into sticky territory. Many cheap imported EVOO's are not only old but they are not necessarily EVOO. Or not 100 per cent EVOO.

Many imported oils labelled EVOO have been tested and found to be a refined version or mixed with corn or palm oil (which has the same appearance as EVOO).

There is no regulation of EVOO labelling so it can be tricky to tell.

In fact, the sheer number producers selling 'EVOO' when it is not EVOO, has lead to olive oil being called the world's most adulterated food.

In one instance, EVOO was in fact found to be lard.

Many Australian growers are part of the Australian Olive Association (AOA), which has been created to uphold standards and does regular, randomised testing of products to ensure adherence. Oils certified by the AOA carry a triangle symbol on the bottle's label.

When we're looking for authentic EVOOs, there are other ways to tell, says Cobram Estate's executive director, Leandro Ravetti.

He suggests looking for locally produced oil. "The closer the source, the shorter the time from tree to table," he says.

Look for a dark bottle (or clear bottle in a box) as light deteriorates any EVOO (it should always be stored in a dark, cool, dry place) and check that the harvest date of the oil is within 12 months of when you are buying it.

Finally, apply the taste test.

"When you buy an EVOO, open the bottle and have a sip," Ravetti suggests. "Good quality EVOO should feel fresh and leave no oily feeling in the mouth. If you don't like it, it is highly likely that the oil in not really good."

The other thing to consider, when choosing which oil to cook with, is how stable the oil is when heated for any length of time.

In this arena, extra virgin olive oil holds its own, in the top three behind virgin coconut oil and butter.

Ravetti says he happily deep fries and roasts using good olive oil.

This is good news, given numerous studies where olive oil has been exposed to high heat for extended periods of time have found that it exhibited strong resistance to oxidative damage and kept most of its healthful properties intact.

"Extra virgin olive oil can do so many good things and it can really do nothing bad," says Brown University's Dr Mary Flynn, who has spent twenty years studying the potential health benefits of EVOO which include cardiovascular function, anti-inflammatory properties and weight loss.

Plus, a drizzle of good oil improves the flavour and absorption of nutrients in salads and cooked vegetables.

"The more fat you eat with the carotenoids, the more you'll absorb," Flynn says.

Good olive oil is indeed liquid gold, and some like it hot. So long as you remember to get the real deal.

What you need to know about olive oil

Extra virgin, virgin, light or pure?

EVOO and VOO are two different kettles. EVOO is where the best juice from the olive is extracted with cold presses.

It is unrefined and no chemicals are used in the extraction process: it is simply the juice of the olive fruit along with the abundant antioxidants it contains and low acidity.

"Virgin" oil has higher acidity and less nutrients and is the lesser quality and fresh olives. Both evoo and vo are 'cold pressed'.

"Light", "lite" or "pure" olive oils have no fewer kilojoules and are no more 'pure'.

They have been refined with heat and chemicals, resulting in an oil with no distinctive aroma, colour or taste. They are 'light' on taste, if you like.

Why does EVOO have a higher smoke point than virgin or refined 'light' olive oil?

"EVOO has higher smoke point than virgin olive oil because VOO typically has higher levels of free fatty acids and those free fatty acids are more susceptible to thermal degradation," Ravetti explains.

"Refined olive oil has a higher smoke point than EVOO because all free fatty acids are chemically stripped with caustic soda during the refining process.

"Despite having higher smoke point, ROO is less stable than EVOO during cooking because EVOO is rich in antioxidants that protect the oil against oxidation."