Check the quality of your olive oil with 1 fact almost none have on the bottle

Extra virgin olive oil is a staple of the Mediterranean diet, known for its health benefits, unique flavour, and aroma.

The natural oil, which is derived from pressing olives, has become a household staple in the UK and can be found in most local supermarkets. However, a nutrition expert is warning Britons that not all extra virgin olive oils are the same, and some could even be "fraudsters".

Health and nutrition expert and award-winning scientist Dr Megan Rossi, known as @theguthealthdoctor on Instagram, has shared five checks shoppers need to make when buying extra virgin olive oil.

Dr Rossi said not all extra virgin olive oil (EVOO) is "made equal", including the ones on your supermarket shelves.

She posted on Instagram, "Unfortunately, it’s a poorly regulated market, which is why low-quality (and even fraudster) EVOOs are constantly slipping through the net.

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"So while you may think you’re making the best choice for you and your microbes, you might not actually be getting the gut-loving EVOO properties shown in clinical trials."

According to Dr Rossi, one way to check whether your extra virgin olive oil is "fresh" is to look for the harvest date.

The harvest date should be within the last year, and the best-before date, or BBE, should be well into the future. Unlike wine, extra virgin olive oil does not get better with age, so it's important to check how fresh it is.

According to Food & Wine, most high-quality olive oils from the best producers will have the harvest date prominently displayed on the label.

Extra virgin olive oil's taste, health benefits and smell will deteriorate the longer it is not used. If the oil is more than 12 months old, it will have lost most of its quality.

If your extra virgin olive oil does not include a harvest date, this isn't necessarily a sign that the oil is of poor quality. Using oils from different harvests, harvesting olives over multiple months, and simply not wanting to confuse the consumer are some of the reasons why the harvest date may not be included on the bottle.

As well as checking the harvest date, there are four other things shoppers need to check before purchasing a bottle.

The ‘extra-virgin’ label

A bottle with "extra-virgin" labelling should indicate that the oil is less processed than standard olive oil. Other labels such as "pure olive oil", "light olive oil" or "pomace olive oil" will likely be more processed. The less processed the oil, the more polyphenols it will contain, which have been linked with numerous health benefits, including anti-inflammatory properties, reduced blood pressure and enhanced cognitive function.

Polyphenol content

Dr Rossi said some oils will include the total polyphenol/phenol content on their nutritional information panels. She added: "A phenol count above 220 is considered high but some EVOOs will contain 350+!"

Darker glass bottles or tins

The polyphenols in extra virgin olive oil start to degrade when they are exposed to light, heat, and oxygen, which is why it's better to choose an extra virgin olive oil stored in a dark glass bottle or tin. Keeping your olive oil away from heat and direct sunlight will also keep it fresher for longer.

Independent certifications

Dr Rossi said, "National and international certifications are a great marker of quality and guarantee your pick isn’t an EVOO fraudster".