Here are the facts behind some of the most common health myths.
Drink eight glasses of water a day
Drinking water is good for your health, but don't stress is you don't make the eight-glass quota daily. Remember, you also consume water when you have a glass of juice, a cup of tea, a piece of fruit and vegetables, and this is quite enough to keep your body hydrated.
Rachel Vreeman from Children's Health Services Research at the Indiana University School of Medicine in Indianapolis, USA, says, ''If you're thirsty, you should drink,'' but warns not to overdo it. While drinking water is good for you, too much can lead to hyponatremia, a condition where your sodium levels fall causing an electrolyte imbalance that can make you very ill.
Stress will turn your hair grey
''Too much stress does age us inside and out,'' says Nancy L Snyderman, chief medical editor of NBC News and author of Medical Myths That Can Kill You. So far though, no scientific evidence proves a bad day can turn your locks grey. ''We grey according to genetics,'' Snyderman says.
Reading in poor light harms your eyesight
Another myth! ''Reading in dim light can strain your eyes, as you tend to squint and that can give you a headache,'' says Snyderman, ''but you won't do any permanent damage, apart from maybe crow's-feet!''
Coffee is bad for your health
Too many cuppas can give you the jitters, but coffee also has a lot of positive health benefits too. Studies suggest it may reduce the risk of type 2 diabetes, as well as Parkinson's disease, colon cancer, cirrhosis and gallstones. A good brew also gives your brain a boost.
Two to three cups a day is fine for most people, says Stacy Beeson, a wellness dietician from Idaho, USA, but cut back to decaf if your suffer from a racing heart, anxiety or sleeplessness. If you're pregnant or low on calcium see your doctor first.
Fresh is better than frozen
''Frozen can be just as good as fresh because the fruits and vegetables are harvested at the peak of their nutritional content and frozen on the spot, locking in their nutrients,'' says Beeson. And unless produce is picked and sold on the same day it may lose nutrients because of heat, air and water.
Get cold and you'll catch a cold
A complete myth! You can't catch a cold unless you've been exposed to a cold virus, a simply getting wet or getting caught in the rain and wind won't affect your immunity. The exception is if your body gets so cold that your defences are destroyed, but this only happens during hypothermia.