Oils ain't oils. Don't know your flaxseed from your rice bran? Read on. We pressed the experts for the insider info on cooking oils.
Nature's nectar has been associated with healing everything from constipation to cancer. The health claims are rife; the warnings are alarming. You've probably been forwarded an email declaring that coconut oil will help you lose weight. Or, that flaxseed oil staves off ADHD. Apparently, canola oil can kill you. Walnut oil nixes stress! (Actually, that last claim is partly true.)
Health & Wellbeing wades through the myths and facts so you don't have to. Here's the lowdown on five cooking oils du jour.
Why you need it: The "little black dress" of pantry staples is always in style. It's long been linked with a lower risk of heart disease and cancer. Olive oil's a key ingredient of the Mediterranean diet, which research shows increases life expectancy.
But olive oil can do so much more. A recent Spanish study published in the journal PLoS One found that a diet rich in mono- and polyunsaturated fats (including olive oil) may ward off depression. Saudi Arabian researchers have discovered olive oil protects the liver against oxidative stress. While in a study published in the Journal of Women's Health, researchers found olive oil helped 80 percent of breast cancer survivors lose weight helping prevent recurrence of the deadly disease. Phew.
Use it! Choose unrefined, extra-virgin olive oil but don't overcook. Olive oil has a low smoke point the temperature at which it starts to burn and breaks down, nutritionist Catherine Saxelby says. The best way to avoid this, suggests Lola Berry, nutritionist and author of Inspiring Ingredients ($29.95), is to add olive oil towards the end of cooking.
Bonus tip: Combine olive oil, lemon juice, balsamic vinegar and tahini (sesame seed) paste for a creamy and zesty salad dressing, Berry says.
Why you need it: Canola oil divides experts, but according to Saxelby, it has two advantages over olive: canola oil contains some omega-3, while olive oil has none; and it has a higher smoke point.
"Canola oil is a good all-rounder, as it's high in monounsaturated fats," says Dr Alan Barclay, spokesman for the Dietitians Association of Australia.
Regardless, canola oil gets a bad rap. Why? According to the US-based Mayo Clinic there's a common misperception that canola oil is made from the rapeseed plant, which contains erucic acid, high levels of which are toxic to humans. While the canola plant was developed through crossbreeding with the rapeseed plant, canola oil contains less than 2 percent of erucic acid. Nothing to worry about.
Use it! Canola oil's high smoke point and tolerance to heat means it is best suited to stir-frying. The subtle taste won't interfere with punchy Asian flavours.
Bonus tip: "Look for certified organic canola oil, so you know it's not genetically modified," Berry says.
Why you need it: While some dieticians such as Dr Barclay argue it is "hyped up", rice bran oil is polyunsaturated and free of trans fats. "It also contains vitamins and antioxidants, and is reported to help lower cholesterol and to boost the immune system," says Lee Holmes, founder of altruistic healthy recipe site, SuperchargedFood.com. A significant 2005 study published in the American Journal of Clinical Nutrition found rice brain oil can lower cholesterol levels in humans. Score!
Use it! Thanks to its delicate flavour and high smoke point, rice bran oil is more versatile than a Swiss army knife. "I like to use rice bran oil for frying and sautéing, as well as in baked goods," Holmes says.
Bonus tip: If you must deep-fry, opt for rice bran oil over the others. More and more restaurants are making the switch.
Why you (might) need it: The jury's out on coconut oil. While the Heart Foundation currently recommends avoiding it (palm oil, too), it may pose some benefits when enjoyed in moderation.
Coconut oil is 92 percent saturated fat, warns Saxelby, but not all saturated fats are created equal. "To veer from the public health message, we now know not all sat fats are bad," Dr Barclay explains.
The saturated fat in coconut oil is mostly lauric acid, also found in breast milk. "It's a proven antiviral, antibacterial and antifungal agent; easily digested and absorbed," Holmes says.
Berry agrees. "Saturated fats have people scared, but studies show coconut oil can speed up metabolism; it may be good for hypothyroidism [an underactive thyroid]".
Saxelby is not convinced. "I'm suspicious. Not enough research has been done on coconut oil and weight loss," she argues.
Use it! Employ this "sometimes food" in Thai cooking. "Coconut oil has a high smoke point, around 200°C. Look for cold-pressed or extra-virgin coconut oil, in health food stores," Berry advises.
Bonus tip: Try naturally sweet coconut oil in baking. "But it doesn't impart a coconut flavour unless you add desiccated coconut to the recipe," she says.
Why you (might) need it: Flaxseed oil boasts the highest level of the omega-3 alpha-linolenic acid (ALA) of any vegetable oil. But unfortunately it's not useful as the long-chain omega-3s, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are found in meat sources.
ALA, a short-chain omega-3, must be converted by the body into these long-chain omega-3s. "The Omega-3 Centre, the Australian authority on omega-3s, doesn't place much value on ALAs.
The best way to get omega-3s is through fish, meat and eggs," Saxelby says.
Flaxseed oil is rumoured to alleviate menopausal symptoms, ADHD and even dry eye syndrome (and more!), but the Mayo Clinic grades all flaxseed oil's health claims under C: "unclear scientific evidence for this use".
Flaxseed may help ovarian cancer patients, however. A five-year University of Illinois study of chickens who develop the cancer in a similar way to humans found that a diet enriched with flaxseed decreases the severity of ovarian cancer in hens and ups their chance of survival.
Use it! It might not save your life, but flaxseed oil certainly won't hurt you. It's delicious. "Flaxseed oil goes rancid easily, so keep it in the fridge for up to six weeks; don't expose it to light or heat. It's awesome drizzled over salad," Berry says.
Bonus tip: "Flaxseed oil is extracted from linseeds, which, I think, are always better consumed whole anyway. They're often baked into grainy bread," Dr Barclay says.
The skinny on fat
Sure, vegie oils are good for you, but don't go nuts. Whichever oil you stock your pantry with, remember, it's 100 percent fat. "There is 100g of fat in every 100 millilitres of oil," warns Saxelby. (And 37 kilojoules per gram of fat.) "There's no [recommended daily intake] of oils … but I would recommend one to two tablespoons per day, or three to five tablespoons for a very active person."