Some medical advice gets passed down from generation to generation with such authority we never doubt their truth. They remain unchallenged mostly because they are completely plausible, despite the fact that there is no solid evidence to back them up. Plus, who would question the common wisdom of our mothers, teachers and doctors who advise us with such conviction.
Here are some unfounded, yet wildly common medical recommendations that even slip past the medical professionals.
1. Sugar makes kids hyperactive
Nothing would make a parent happier than finding the cause of hyperactive behavior. But alas, the sugar-hyperactivity myth has been debunked. There have been numerous studies looking at the role of dietary sugar in children and there is no evidence that it makes kids hyper. They tested the effects of natural sugars such as those found in fruit and added sugars like those found in candy bars. Interestingly enough, parents perceived their child as hyperactive when they were told they had consumed a sweetened soft drink, when in fact, it was sugar-free.
2. You should drink 8 glasses of water a day
This little ditty has been circulating since a 1945 guideline recommendation from the Nutrition Board of the National Research Council (NRC) read, "An ordinary standard for diverse persons is 1 milliliter for each calorie of food. Most of this quantity is contained in prepared foods."
For some reason the last sentence, which is really an important point, got cut from the story telling. Hence the 8, 8-ounce glasses of water a day rule persisted. What the board really meant was humans need 2.5 liters of fluid a day (assuming a 2500 calorie diet). But fluid comes from many sources, not just water alone, including other beverages such as coffee and from fruits, vegetables, yogurt and rice.
Healthy people at rest naturally maintain a water balance and what you don't use you excrete as urine. Still, if you consume too much water too quickly, you can get water toxicity, a potentially life-threatening situation where the kidneys just can't manage processing large quantities of fluid all at once.
3. You lose most of your body heat through your head
If you check the US Army Survival Manual's basic principal of cold weather survival it says to always keep your head covered because you can lose 40-45% of your body heat from an unprotected head. Tell that to the guy standing outside with no pants on. Truth is you lose no more heat from your head than any other portion of your body. Any part of your body exposed to the cold will drop core body temperature. When emergency medical technicians treat for hypothermia, they apply heat to the chest, neck, armpits and groin. The head? Not so much.