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Dr. Khoi Nguyen

Olive oil has many health benefits. It has been used widely in cuisine and in the beauty industry. Here are some useful tips on how to distinguish the best products for consumption.

 Production and primary uses

There are two basic types of olive oil, extra virgin and all the others (virgin/pure/mixed).

Extra virgin oil is produced using a process called ‘cold pressing’ in which the temperature is kept below 30C degrees. Should the temperature rise above this level, the oil may be altered and can be bad for the health. Extra virgin olive oil is best used as a salad dressing. Mixed with balsamic vinegar it can be used as dipping sauce for bread but do not exceed the recommended amount in your diet.

For cooking, non-virgin olive oil can be used. Non-virgin olive oil is usually mixed with sunflower oil or soy oil. When deep frying, do not reuse the oil many times to avoid trans fats being generated, which are harmful for your health.

Good olive oil vs. bad?

Due to the many known benefits of extra virgin olive oil, its consumption is huge, and sales are estimated to be worth about $105 billion in the United States alone. Where does the supply come from and is it really extra virgin as claimed?

UC Davis Olive Center at the University of California concluded that more than 70 per cent of olive oil advertised to be extra virgin was not. The oil was mixed with a variety of other ingredients. Olive oil produced in Italy is still largely assumed by consumers to be healthy and of high quality. However, in recent years, Italy has not been able to meet the demand for extra olive oil due to prolonged harsh weather conditions.

The majority of olive oil is produced in Greece, Spain and Tunisia and shipped to other countries for consumption. According to a number of studies, a large olive oil container from Greece was found to be injected with sunflower oil or soy oil, then shipped to Italy. Chlorophyl was pumped into it to produce a green shade. A small proportion of extra virgin olive oil was mixed in, as well as some chemical ingredients to mimic the scent of authentic olive oil. It was then packaged and sold as extra virgin olive oil. The UC Davis Olive Center collected and tested many samples of olive oil on the market. They found that 75 per cent did not meet extra virgin standards. You can read the report listing all the brands tested on their website at

Tips for consumers

Unless you are from the Mediterrean, not many of us are proficient discerning genuine extra virgin olive oil.

How do you make sure you are buying a good product? Check the UC Davis Olive Center website for trusted brands. Researching quality and authentic olive oil production, I learned that the total product cost for extra virgin olive oil is 6 to 8 (Euros) a litre. This does not include other costs such as freight and taxes. The retail price of extra virgin olive oil should not be below $20 a litre.

Educate your taste buds. Quality extra virgin olive oil should smell and taste fresh, have fruity notes, and may have some bitterness and spiciness (because of healthy antioxidants).

Choose a good container as temperature and light are the enemies of freshness and decrease shelf life. Dark glass or tin are best.

Look for a quality seal on each bottle. Producer organizations such as the California Olive Oil Council and the Australian Olive Association demand stricter quality standards than the minimum USDA standards. Other seals may not offer such assurance.

There are two types of quality olive oil: filtered and unfiltered. Unfiltered olive oil is directly pressed from olives and contains residue. Shake before using. This type is very healthy as it contains fibre and is rich in nutrients. However, unfiltered oil is more likely to ferment and turn the colour.

Filtered olive oil has been poured through a cotton membrane or given a gravity spin. Once filtered, olive oil can be stored for longer. However, shelf life should not exceed two years. Seals on quality olive oil usually contain a harvest date and a best by date. Make sure to check these two dates before purchasing.

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Dr. Khoi Nguyen
Dr. Khoi holds a Science Degree from the University of Toronto and received his medical degree in 1988. He is currently seeing patients at his private family medicine practice. In 2010, he received the Canada’s Citizenship Award for his numerous contributions to the community. Bác sĩ Khôi tốt nghiệp ngành khoa học tại University of Toronto và tốt nghiệp y khoa năm 1988. Hiện nay ông đang làm việc tại phòng mạch tư chuyên về sức khỏe gia đình, và đã được vinh dự nhận giải thưởng Canada’s Citizenship Award năm 2010.