From avocado to coconut: The ABC guide to healthy oils

SINGAPORE - If you eat out often, chances are you would have had your fair share of palm oil, a cheap source of fat that is commonly used by hawkers. But palm oil is high in saturated fat, and healthier oil is now in vogue.

In July, the Health Promotion Board said it would spend millions a year on subsidies to get coffee shops and hawker centres to use a healthier mix of palm and canola oil.

A look at supermarket shelves will tell you that you have many types of cooking oil to choose from. Most are suitable for cooking, some are better for salads while others are best for deep-frying.

"Any monounsaturated or polyunsaturated cooking oil with a medium to high smoke point, such as canola oil, rice bran oil, peanut oil, soya bean oil, light or pure olive oil and corn oil, can be used for light stir-frying, pan-frying and baking," said dietitian Lauren Ho of the Singapore Heart Foundation.

"Other kinds of oil with a lower smoke point, such as most extra virgin olive oil and nut oil, are best reserved for salad dressings."

Refined and cold-pressed

The smoke point of an oil is the temperature at which it will start to break down and give off smoke and toxic fumes. That is when it will also start to lose its flavour and nutritional value.

As olive oil is believed to have a low smoke point, many people are still unsure if this heart-healthy oil can be used for cooking. The answer is "yes".

"Olive oil suitable for cooking are those that are labelled as 'light' or 'extra light' or 'pure'," said Ms Ho.

These are refined olive oil. They have higher smoke points than cold-pressed extra virgin olive oil, which is good for flavouring salads or as a finishing oil that you drizzle on cooked food.

Cold pressing is a method of producing olive oil by pressing, in which the temperature never exceeds 27 deg C, according to the International Olive Council. This intergovernmental organisation said that olive oil is ideal for frying.

"Its high smoking point (210 deg C) is substantially higher than the ideal temperature for frying food (180 deg C)," it said on its website.

Exact smoke points of different types of oil are hard to establish, as they vary according to origin and refinement.

"As a rule of thumb, the more refined an oil, the higher the smoke point," said Ms Ho.

Cold pressed, unrefined oil generally have lower smoke points than refined ones, but are richer in nutrients and flavour, she said. "Opt for healthier types of oil, such as the monounsaturated and polyunsaturated oil, but use them in moderation."

Deep-fry with the right oil

Deep-frying is not a healthy cooking method. Healthier methods include pan-frying, steaming, poaching, baking, roasting and grilling.

But if you must deep-fry your food, choose an oil with a high smoke point, as deep-frying oil can reach a temperature of more than 200 deg C.

These include avocado oil, refined canola oil, refined coconut oil, corn, soya bean and peanut oil.

Avocado oil has the highest smoke point, of about 270 deg C. This makes it suitable for deep-frying, but it does not come cheap. According to Miss Sarah Sinaram, a senior dietitian at Raffles Diabetes & Endocrine Centre, "oil which has a higher saturated fat content is usually recommended for deep-frying".

For instance, corn oil, which has less unsaturated fatty acids, is better for frying than soya bean or canola oil, which have more unsaturated fatty acids.

While butter contains a lot of saturated fat, it has a low smoke point and is not suitable for high-heat cooking.

Stay away from rancid oil

Subjecting any oil, especially the unsaturated varieties, repeatedly to high heat will break down its fatty acids, cause chemical changes in the oil and making it turn rancid, said Ms Ho.

"Rancid oil contains free radicals that can cause oxidative damage to cell DNA and damage to arteries, leading to atherosclerosis and possibly increase the risk of cancer," she said.

It is best to limit the consumption of deep-fried foods.

Said Ms Sinaram: "While rancid oil may produce damaging chemicals and substances that may not make you ill immediately, they may cause harm over time."

Know your fats

SATURATED FATS

What these are: Coconut oil, palm oil and blended vegetable oil (palm oil mixed with a mono- or polyunsaturated oil will have an overall lower saturated fat content).

Take note: They are more stable and more resistant to heat, oxygen and light than unsaturated fats. However, a diet that is high in saturated fat may increase the level of low-density lipoprotein (LDL) or bad cholesterol in our body and lead to a higher risk of cardiovascular disease.

MONOUNSATURATED FATS

What these are: Olive oil, canola oil, avocado oil, peanut oil, sesame oil, macadamia oil, hazelnut oil, rice bran oil, sunflower oil and safflower oil.

Take note: These are considered healthy dietary fats as they may confer certain health benefits such as lowering your risk of heart disease and helping with blood sugar control. But some types, such as extra virgin olive oil, are expensive and best used for salad dressings.

POLYUNSATURATED FATS

What these are: Sunflower oil*, safflower oil*, walnut oil, grapeseed oil*, flaxseed oil, soybean oil* and corn oil*.

Take note: They are also considered "good" fats as they can, for instance, help to lower your risk of heart disease.

Some of these oils are high in omega-6 fatty acids (those marked with *). It may be wise to limit our intake of such oils as our diets are already loaded with omega-6 fatty acids but deficient in omega-3 fatty acids, which can be found in oily fish.

Sources: Singapore Heart Foundation's dietitian Lauren Ho; Mayo Clinic.

joyceteo@sph.com.sg

This article was first published on MONTH DAY, 2014.
Get a copy of Mind Your Body, The Straits Times or go to straitstimes.com for more stories.