Hero ingredients: olive oil

What is olive oil?

Olive oil is the main source of fat in the Mediterranean diet. It's made by crushing olives into a paste, then separating the oil from the pulp and water. About 70% of its fat is monounsaturated, a type of unsaturated fat.

A small swap with big benefits

Swapping saturated fats (from foods like butter, cream and meat) for unsaturated fats like olive oil can help reduce LDL (or 'bad') cholesterol, which in turn helps protect your heart.

A large Harvard study found that people who have more than 7 grams of olive oil a day (about half a tablespoon) have a lower risk of heart disease than people who never eat it. Even swapping one teaspoon of butter for olive oil, think drizzling it on toast instead of butter, or using olive oil to dress salads and vegetables, has been linked with a 5% to 7% lower risk of heart disease.

It's not just the fats

Olive oil is also rich in polyphenols: naturally occurring plant compounds that act as antioxidants in the body. We can't digest them directly, but our gut bacteria break them down into smaller beneficial molecules the body can use.

Extra virgin olive oils have the highest levels of polyphenols. One of the most well-known is oleocanthal, responsible for that peppery bite you feel at the back of the throat with a good extra virgin olive oil. European regulations class anything above 250 mg/kg as 'high' in polyphenols, though levels naturally drop as the oil ages.

Choosing a good olive oil

There are three main types:

• refined olive oil
• virgin olive oil
• extra virgin olive oil

When you can, choose extra virgin olive oil (EVOO). This means the oil has been extracted without heat or solvents, preserving more of those beneficial compounds.

Cooking with olive oil: your questions answered

People often wonder whether it's safe to cook with extra virgin olive oil, especially at higher temperatures. We asked our chef Matt.

Can I fry with extra virgin olive oil?

"Yes. Extra virgin olive oil has a smoke point of around 190°C, which comfortably covers everyday methods like stewing, sautéing, roasting and shallow frying. In practice, most home cooking doesn't reach these higher temperatures, and the natural antioxidants in extra virgin olive oil help keep it stable under heat."

What about deep-frying?

"You can even deep-fry with olive oil. Traditional Mediterranean cooks have done this for generations, provided you keep the temperature in the normal frying range of 160–180°C."

And roasting or slow-cooking?

"Stewing or slow-cooking with olive oil is well under these limits and entirely safe. Roasting veg at 180–200°C is also fine because the food and moisture act as a temperature buffer, although you'll want to avoid scorching or burning."

Any final advice?

"Keep a basic, cheaper extra virgin olive oil for cooking, and a higher quality bottle as a finishing oil for drizzling at the end. Avoid oil labelled as just 'olive oil', as it will contain less nutritious refined olive oil."

How to use it

A good olive oil earns its place at every stage of cooking, not just the end. Try it to:

• roast vegetables
• dress grains and pulses
• start the base of soups and stews
• drizzle over a finished dish
• splash a little over fresh, poached or stewed fruit, with or without a dollop of Greek yoghurt

How we use olive oil in our meals

We use only cold-pressed olive oil in our meals, because this retains its full flavour, aroma and nutritional integrity without the need for chemical processing or high heat. This method protects the healthy fats and beneficial compounds naturally present in the oil too. Combined with the other ingredients we use, it's one reason all our meals are low in saturated fat.

Cooking vegetables with olive oil, whether stirring through, roasting or lightly frying, can also boost your absorption of plant compounds like carotenoids and antioxidants. These nutrients are fat-soluble, and gentle heat helps release them from plant cell walls, making them easier for the body to absorb. It's one of the reasons we start many of our dishes with a soffritto: a flavoursome base of onions, carrots and celery cooked slowly in olive oil.

Try this at home

Fancy putting your olive oil to work? Matt's olive oil, yoghurt and berry cake is perfect with early blackberries making an appearance.