Fact or fiction? Are you worrying about nothing? Discover the truth about commonly held beliefs and your health.

The decisions we make regarding our health aren’t always based on truth. If you’re convinced the flu shot can give you the flu or you’ve ever blamed a child’s naughty behaviour on a sugar high, read on. Dr Ronald McCoy from the Royal Australian College of General Practitioners shatters these and some other common medical myths.

You lose most of your body heat through your head

If your mother ever warned you against going out in winter without your beanie, she probably believed this myth. It originated with a military study that saw subjects wearing arctic survival suits exposed to extreme cold.

The researchers found they lost most of their body heat through their heads, which is understandable as they weren’t wearing hats. The amount of body heat lost is proportional to the area of your body exposed to the cold and there’s nothing particularly special about your head.

The flu shot can give you the flu

This statement is definitely not true. The flu vaccine contains a tiny part of dead flu virus. Your immune system only needs to recognise part of the virus in order to neutralise it and prevent you becoming ill. It’s not possible for a dead virus to cause infection, but most people get their flu shots in autumn when there are a lot of coughs and colds doing the rounds, so some do get sick. If you feel sniffly after your flu shot, chances are it’s a head cold and nothing to do with the vaccine.

We only use 10 percent of our brains

If you’ve ever wondered how successful you’d be if only you could only learn to harness that other 90 per cent of your grey matter, you’re not alone. This is a myth often attributed to Albert Einstein and has been repeated so often that even some of the most educated among us believe it to be true.

We, in fact, use 100 per cent of our brains every day. On the other hand, if you don’t challenge your brain on a daily basis, you may only end up with 10 percent of it. There’s strong evidence that the “use it or lose it” factor applies to brain function, so staying mentally active can help to protect you from dementia.

Green mucus means you need antibiotics

If you’re coughing up or blowing out green mucus it usually means that your immune system is working as it should to rid your body of a viral infection and is not necessarily a sign that you need antibiotics. Antibiotics are of no use against viruses. But if you’re not getting better, you have a fever or the mucus is blood stained, see your doctor because you might have a bacterial infection such as sinusitis.

Sugar makes kids hyperactive

This has been studied extensively and nobody has been able to find a link between sugar and behaviour, even in children with ADHD. One study showed that parents who believed their children had been given a sugar-laden treat reported them to be hyperactive afterwards, even if they hadn’t really had any sugar.

Of course, that doesn’t mean sugar is a good thing to feed your kids there’s strong evidence that too much sugar contributes to obesity, which can actually make them less active than they should be.