Back in 2007, two doctors, Dr. Rachel C. Vreeman and Dr. Aaron E. Carroll, from the Indiana University School of Medicine, compiled a list of medical myths that even some doctors believe. They published the entire list in the BMJ (British Medical Journal). I'll share some of them with you today:
1. People should drink at least eight glasses of water a day
The authors found no scientific evidence to support this recommendation. The source may be a 1945 article published by the National Research Council, part of the National Academy of Sciences, which notes that the “approximate amount” of water for adults is 2.5 liters per day, although the final sentence notes that a significant portion of this is already contained in the food we eat.
If the final, crucial sentence is ignored, the statement could be interpreted as an instruction to drink eight glasses of water per day. Existing research shows that adequate fluid intake is typically met through typical daily consumption of juice, milk, and beverages, including caffeinated ones.
2. We only use 10 percent of our brain.
The belief that we only use 10 percent of our brain has persisted for nearly a century. This statement is sometimes attributed to Albert Einstein, but no such statement has ever been recorded. In their study, the authors found references to this myth in a source dating back to 1907 and noted that it is often repeated by people advocating self-improvement.
The authors stated that data from studies of brain-damaged patients proves that people use significantly more than 10 percent of their brains. Numerous brain studies have not yet identified a single completely inactive region of the brain. And no one has yet found a completely inactive 90 percent.
3. Hair and nails continue to grow after death
This myth is often repeated in movies and talk shows, but it's not true. Hair and nail growth requires “complex hormonal regulation,” which ceases after death. The persistent nature of this myth may be due to dehydration after death and the subsequent contraction of soft tissue, which can create the illusion of hair and nail growth.
4. Shaving makes hair grow faster, darker and coarser
This common belief is often repeated in the media. A 1928 study found clinical evidence that shaving does not affect hair growth, a conclusion supported by later studies. When hair grows back after shaving, it appears coarser because it lacks the tapering characteristic of pre-shaved hair. The hair appears darker because it has not been exposed to sunlight, as previously unshaven hair would.
5. Reading in dim light damages your eyesight.
In poor lighting, it's difficult to concentrate, and you blink less often, leading to dry eyes. So, reading in dim light is uncomfortable, but it doesn't cause any permanent damage.