Now apples are bad for you!

An apple a day keeps the doctor away, or at least that's how the saying used to go. But now apples have been branded bad news by dentists thanks to high sugar levels and fruit acids. We reveal some more surprising facts about our diet.

MYTH

Eating apples between meals is good for you

FACT

According to the British Dental Association, the opposite may be true. Apples may actually encourage decay because their sugar content is relatively high, and has been rising in recent years with the introduction of sweeter varieties such as Pink Lady, Fuji and Braeburn. More worryingly, apples are also a source of fruit acids which can cause tooth erosion. Erosion occurs through repeated exposure to acidic foods over time. Fruit juices, fizzy drinks and vinegar are the major culprits.

MYTH

Chocolate gives you spots

FACT

Some experts believe an unbalanced diet might exacerbate acne, but there is no evidence linking chocolate with spots.

MYTH

Spinach is a fantastic source of iron

FACT

When the iron content of spinach was analysed, an error in the placing of the decimal point meant the content was hiked by ten times. Spinach is rich in iron, but no better than watercress or spring greens.

MYTH

Mouldy cheese is fine if you cut off the green bits

FACT

Some cheese, such as Stilton, contains perfectly safe edible moulds. But if the mould isn't meant to be there, you should throw it away. Cutting it off isn't adequate as traces will remain. "They won't make you acutely ill," says Professor William Waites, a food microbiologist at Nottingham University. "But it's possible that in the long-term moulds could contribute to cancer."

MYTH

Sugar causes diabetes

FACT

For people with type 2 diabetes (the type that has its onset in adulthood) it is excess calories and inactivity that are the biggest culprits, not sugar. Overweight and sedentary lifestyles make the cells more resistant to insulin, the hormone which regulates blood sugar. A diet that's generally high in refined and processed foods and saturated fats may also play a part, but it's these combined factors, not sugar per se, which causes problems.

MYTH

Vitamins give you energy

FACT

Vitamins don't contain calories, so they can't supply energy directly. Unless you have severe vitamin deficiency, which means your cells can't efficiently process food into energy, your energy levels will not be affected, says stateregistered dietitian Dr Wendy Doyle. Iron may boost your vitality if you have low levels, but it does so by increasing levels of haemoglobin that help oxygenate the blood.

MYTH

Eggs are artery cloggers

FACT

Eggs are a good source of high-quality protein and also contain iron and vitamin D for strong bones. They have a bad reputation because their cholesterol content, but the body compensates by making less cholesterol itself. When scientists at the University of Washington gave people with elevated cholesterol two eggs a day in conjunction with a lowfat diet, their cholesterol level went up slightly more. However, half of the rise was in HDL cholesterol, the "good" type that clears, rather than clogs, the arteries. MYTH

You can't eat food past its Best Before date

FACT

Best Before dates are used on non-perishable foods that may lose their eating quality, but don't become dangerous. Many people think they should throw the food away when the date is up, but if it tastes fine (and isn't growing fuzz) there's no reason not to eat it. The foods you should throw away are those that are past their Use By date. Use By dates are put on perishable foods that could become poisonous.

MYTH

Eating late makes you put on weight

FACT

According to Dr Susan Jebb, there is no truth in the theory that eating your main meal in the evening makes you fat as you sleep. Subjects monitored in a metabolic unit for 48 hours on two separate occasions were first given their main meal at lunch time, and then at 8pm. "The results showed no difference in the amount of fat stored," says Dr Jebb.

MYTH

Cheap brown bread is white bread dyed with caramel

FACT

It is illegal to dye bread according to The Colours in Food Regulations 1995. As a classification, brown bread must be made with flour containing 85 per cent of the whole wheat grain, as compared with 75 - 80 per cent for white bread.

MYTH

Fat people have a slow metabolic rate

FACT

In the vast majority of cases it's simply not true. "In fact, the bigger you are, the more calories you use up," says Dr Susan Jebb from the Medical Research Council's Human Nutrition Research Unit in Cambridge. "Your internal organs have to work harder, and you use more energy carrying extra weight." Neither is it true that yo-yo dieting makes you fatter. "Even though crash dieting isn't a good idea, there's no evidence that it actually makes the proportion of fat in your body higher," adds Dr Jebb.