Myths about nutrition are nothing new but thanks to the internet, misinformation about food can spread like a virus as half truths are rapidly twisted into 'facts'.
Myth: Olive oil produces carcinogens when it's heated.
Fact. What's true is that when any cooking oil is heated to the point where it smokes (its smoke point) it breaks down and may produce potentially carcinogenic toxins. Different oils reach their smoke points at different temperatures. In the case of olive oil, good quality extra virgin olive oil (EVOO) has a smoke point of 180 ⁰ C to 210 ⁰C that suits most cooking techniques, including deep frying according to Lisa Rowntree, the CEO of the Australian Olive Association. Most olive oil produced in Australia is EVOO - but to be sure it's the real thing check for the triangular green and yellow certification logo (Australian Standard AS 5264-2011) on the pack.
What's the smoke point of a more refined olive oil that's not EVOO? That 's hard to answer because it depends on what sort of refining it's undergone, but the better the quality of olive oil the higher the smoke point, Rowntree says.
Bottom line: avoid heating any oil until it's hot enough to smoke.
Myth: You can reduce the risk of food allergy in children by avoiding allergenic foods in pregnancy.
Fact: Studies show that avoiding potentially allergenic foods like nuts, eggs, milk, seafood, soy and wheat doesn't prevent food allergy in children, according to the Australasian Society of Clinical Immunology. ASCIA's advice: it's best not to avoid these foods in pregnancy because of the risk of missing out on important nutrients.
Myth: Meat is so hard to digest that it putrefies in your stomach.
Fact: This is a salvo sometimes fired by vegetarians at equally misinformed meat eaters who insist that meatless diets are nutritionally inadequate. In fact, meat is fully digested and broken down into amino acids needed for cell growth and repair, says Accredited Practising Dietitian Maria Packard, a spokesperson for the Dietitians' Association of Australia. However, meat's high protein content does slow down the rate of digestion.
"On average a meal that includes meat will take three hours to leave the stomach as opposed to a glass of lemonade which takes a few minutes," Packard says.
Myth: Mushrooms are a good source of B12.
Fact: There are excellent reasons to cook up some mushrooms - just don't expect them to deliver too much vitamin B12. The main sources of this essential vitamin are animal foods like meat, fish, poultry and dairy products -this makes it difficult to get B12 from a vegan diet that excludes these foods, although some manufactured foods and soymilks are fortified with B12. Mushrooms, the only natural plant source of vitamin B12, are often claimed as a good source of this vitamin but one serve (100g -the equivalent of three average size button mushrooms) provides no more than five per cent of the daily requirement, says the Australian Mushroom Growers' Association.
Myth: Margarine is full of trans fats.
Fact: Synthetic trans fats are created by a hydrogenation, a process that turns liquid oils into a spreadable alternative to butter. However Australian manufacturers changed production methods for these spreads in the 90s so that production of trans fats in these products is reduced to negligible levels, says Packard.
Myth: Spinach is a great source of iron.
Fact: One of the stickiest myths ever. Spinach does contain iron but it also contains oxalic acid which makes the iron hard to absorb. Still, it's a good place to find the B vitamin folate, vitamin C, beta-carotene - and the antioxidants lutein and xeaxanthin important for eye health.
Myth: If you're lactose intolerant you should avoid all dairy products. Fact: People who are lactose intolerant don't produce lactase, the enzyme that breaks down lactose (the sugar naturally found in dairy food). But most lactose intolerant people can handle some lactose, Packard says.
"People with lactose intolerance vary in how much lactose they can handle, but small amounts of cheese are usually okay because cheese isn't high in lactose. Yoghurt is usually well tolerated because the bacteria in yoghurt break the lactose down. Some people can also tolerate small amounts of milk."
- Sydney Morning Herald