So, red wine is good for you? And pregnant women should eat for two? Think again!
Caitriona Durcan puts some of our most enduring health myths to the test
True or false: wash your hands and dry under a hand-dryer to prevent the spread of germs. If you answered 'true', you could be jeopardising your health.
Researchers at the University of Bradford discovered that when it comes to reducing the amount of bacteria on your hands, not all drying methods are equal.
The standard hand blow-dryer is supposed to be more hygienic than paper towels. But while dryers reduce the amount of 'litter' on the floor, they actually increase the amount of bacteria on your hands.
It turns out that all that rubbing of your hands under the warm, blowing air actually brings the bacteria that lives within the skin to the surface.
The most effective way to dry your hands is the old-fashioned paper towel method. The second most effective method is the high-velocity dryer that doesn't require hand rubbing.
And they aren't the only myths that should be shattered.
Decaf coffee won't affect your energy levels
It may come as a shock, but decaffeinated coffee does contain caffeine -- although only a tiny 5mg compared with the normal 90mg or more in a filter coffee.
But rather than having no effect on you, research shows it may make you sleepier than no coffee.
Dr Crystal Haskell, of Northumbria University, found levels of caffeine less than 10mg actually made people feel more tired, with weaker memory skills.
She puts this down to the body countering the effect of the expected caffeine high.
Always keep fruit and veg in the fridge
You probably don't give a second thought before sticking fruit and veg in the fridge.
But by keeping things cool, you may be losing out.
Scientists in the US discovered that a watermelon left at room temperature had double the levels of beta-carotene and 20% more lycopene -- both antioxidants -- after two weeks than one stored in the fridge.
Bananas and peaches are also more nutritious at 20 degrees.
"As rule of thumb, you shouldn't store fruit and veg for long, and especially not in the fridge", says TV cook, Catherine Leyden. "After all, they aren't called fresh fruit for nothing."
White meat is lower in fat than red meat
Often, dieters eat chicken as a healthy choice, but it could be fattier than a lean cut of red meat. The myth probably dates back to when butchers' cuts were fattier, agrees nutritionist Margot Brennan.
Chicken can contain as much saturated fat as lean cuts of beef or pork. For instance, a serving of sirloin beef or pork tenderloin has less saturated fats than the same serving size of chicken thigh with skin.
Margot advises: "It is true that poultry like chicken and turkey is naturally lower in saturated fats. But it is only true if you do not eat the skin."
Eat for two during pregnancy
Pregnant women do not need to "eat for two", drink full-fat milk or even alter how much food they eat for the first six months, NHS experts say.
"The traditional advice that expectant mothers can 'eat for two' is dangerous," says a spokeswoman of the Well Woman Centre in Dublin.
"Almost half of expectant mothers are overweight or obese, and are putting themselves at a higher risk of fatal health conditions such as blood clots, pre-eclampsia, miscarriages and stillbirths."
New mothers should start shedding their baby weight six months after birth, the health watchdog advises.
A lie-in counters sleep loss
A lie-in at the weekend does not counter ill-effects of lack of sleep during the week, a study suggests.
Dr Chris Idzikowski, director of the Edinburgh Sleep Centre says: "Changing your sleep pattern suddenly has a dramatic effect on the hypothalamus part of your brain, responsible for balancing hormones which can trigger headaches. You're also likely to suffer caffeine withdrawal after sleeping through your normal early morning cup of tea or coffee.
"Try to stick as close to the same schedule as possible. If you're tired, have a nap later in the day," Idzikowski advises.
When slimming, eat little and often
Which is better for you -- three hearty meals or six little ones? Diet books might advise you to eat little and often, but you're no more likely to lose weight this way.
Australian scientist Dr Michelle Palmer compared weight loss in people eating in both ways and found they lost the same amount.
In fact, the six-mini-meal group was more likely to put the weight back on.
Palmer says: "Eating little and often can control hunger, but there's a danger that by eating more often you eat more calories."
Rinse well after brushing
Dr Philip Stemmer, consultant surgeon at the British Dental Association, says: "Leave the sink the moment you've finished brushing your teeth -- rinsing your mouth out with water washes away the protective fluoride coating left by the toothpaste, which adds hours of protection.
"Also avoid drinking any fluids for at least half an hour afterwards -- it's a strange sensation at first, but you quickly get used to it.
"I even dry my toothbrush before applying toothpaste, as there's plenty of moisture in your mouth without using extra water."
A hot toddy helps you sleep
Many people swear by a late- night tipple to help them fall asleep. However, a study by scientists in Canada suggests they may, in fact, be fooling themselves.
They have found that although a nightcap can help people escape to the land of nod more quickly -- their sleep is unlikely to be a restful one.
"They are more likely to wake up during the night and early the following morning, and are less likely to have the deep sleep they need," says Dr Chris Idzikowski.
Raw vegetables are better
While you may not fancy a raw veg diet, general wisdom maintains that the more you cook vegetables, the more nutrients they lose. But this is not necessarily true.
Carrots, spinach, mushrooms, asparagus, cabbage, peppers and many other vegetables supply more antioxidants to the body when cooked than they do when raw.
Nutritionist Margot Brennan says: "When cooked, the damage to the cells means three times as much beta carotene is released -- an anti-oxidant thought to help protect skin."
Cooking actually boosts the amount of lycopene in tomatoes. Studies have linked high intake of lycopene with a lower risk of cancer and heart attacks.
Red wine is good for your health
The National Cancer Institute of France has found that a daily 125ml glass of wine increased the likelihood of developing cancer by 168%.
Polyphenols, such as the antioxidant resveratrol, are found in the skins of red wine grapes.
"In high doses it does seem to enhance the lifespan of mice," says Professor Roger Corder, author of The Red Wine Diet. But, he adds crucially, "you need huge doses." In humans, this equates to thousands of litres of wine.
"The problem is that most supermarket wines are low procyanadin and high alcohol," he says.
"We're promoting bad wine for bad habits."