Ask any American for some medical advice and you're sure to get an earful. Everybody, it seems, has a surefire cure for the common cold, hangover or sore throat. But how much can you trust that advice? Maybe not so much. In a world where, according to one survey by the Pew Health Group, almost half of the respondents thought antibiotics were effective against the common cold or flu (the answer to that is a big fat no, in case you were wondering), one should be exceedingly careful about the source of one's medical information.

The truth is that Americans are not so smart about medicine, which makes us exceedingly vulnerable to hucksters peddling remedies. We don’t know much about heart disease despite the fact that it kills 1 out of 4 of us. We don’t even know the appropriate place to go for medical help. Only 18% of Americans are proficient in health literacy. An equal number of us have below basic health literacy and the rest of us are somewhere in the middle. Women fare a bit better than men, with 22% being proficient, while youth aged 18 to 24 fare the worst, with a third of them below basic health literacy.

Not every medical belief amounts to a life-or-death scenario (although our ignorance does add to the nation’s rising medical costs), but it is interesting to take a snapshot of some medical myths and dissect them to see who believes them, and why. That is exactly what the online insurance quote company, Insurancequotes.com, did, surveying over 2,000 people to see where they stand on a few widespread medical myths.

Below are seven of the most commonly believed medical myths.

1. Probiotics improve digestion for everyone who takes them.

In the survey, heading the list, over 83% of respondents thought that probiotics improve digestion for everyone who takes them.

While probiotics can help alleviate certain conditions like inflammatory bowel disease, childhood diarrhea and irritable bowel syndrome, most healthy people won’t experience any digestive benefits from consuming them.

People of all ethnicities buy into the probiotic hype. In the survey, Caucasians and Asian Americans tied at 84%, and African Americans and Hispanics tied at 80%.

2. Creativity is controlled on the right half of the brain, logic on the left.

Almost 68% of respondents bought into this myth, but it isn’t true. It originated in the 1960s, when epileptic patients had surgical procedures on their brains that effectively walled off one side of the brain from the other. Researchers then found which sides of the brain were involved with language, math, drawing, and other functions. Pop gurus extrapolated from this information that one side of the brain was creative and one logical.

Studies since then debunk that notion. In fact, one recent study from the University of Utah of over 1,000 brains found no evidence that people are left-brained or right-brained.

3. Carrots give you better eyesight.

Nope, although over 68% believe otherwise.

Unless you have a severe shortage of vitamin A, eating a lot of carrots might turn you a bit orange (maybe our president likes carrots), but it won’t do anything for your eyesight.

4. When women live together, their periods become synchronized.

The myth that women in close proximity to one another for long periods of time begin experiencing their periods at the same time had its origin in an early 1970s study. Although subsequent studies seemed to bear this out, more recent studies say it is not true.

Still, more than 62% buy into the myth. Here’s a surprise: more men (44.6%) than women (29.8%) knew this myth was false.

5. Sitting close to the television set will cause poor eyesight.

Almost 61% of the respondents believed this to be true, but it is not. Although it could cause eyestrain, sitting close to the TV won’t cause any permanent damage to your eyes.

6. Myth: Women who are menstruating can’t get pregnant.

Women knew this one was false by a large margin, 72.7% to 57.6% for wishful thinking men.

Interestingly, Asian Americans believed this myth more than any other racial group, at 38%, followed closely by African Americans at 36% and Caucasians at 35%. Hispanics aren’t buying it, though, with only 30% believing this.

7. Myth: Vaccines are not effective at helping the body ward off disease.

Belief in the efficacy of vaccines (they are overwhelmingly safe and effective) has taken a hit in the past few years thanks to the misguided anti-vaxxer movement, which claims vaccines can cause autism (they don’t).

A sizable chunk of people (though, thankfully, still a minority) believe that vaccines are not effective, with 33% of African Americans believing this dangerous myth, followed by 22% of Hispanics, 20% of Asian Americans, and 13% of Caucasians.

Sources of health information

Based on the survey, it is clear where medical information is coming from. By far, the source of health information (or misinformation) is the internet. Seventy-one percent of Asian Americans report they get their health information online, followed by 59% for Caucasians, and 58% for both African Americans and Hispanics.

Given the fact that almost anyone can create a “health” website, including those with a business or political agenda, this may be a cause for concern.

Other health info sources include family and friends, and doctors. Asian Americans are least likely to get their information from a physician (18%), while Hispanics are most likely (35%). African Americans are most likely to follow the medical advice of family or friends (14%), while Hispanics are least likely (7%).

Health knowledge by profession and education level

Some professions, it would seem, are more easily taken in by myths than others. People in the marketing and advertising industry are the least likely to correctly identify medical myths, with only 52% accurately calling them out. They were tied with broadcasting and journalism, which should give us pause (FAKE NEWS!).

The military professions were most able to identify myths, at 62%. Somewhat shockingly, they beat out the scientific professions, who came in at 59%, barely ahead of homemakers at 58%, who disconcertingly in turn beat out the medical profession at 57% (apparently working in the field does not assure protection from incorrect medical information).

People with professional degrees led the pack in being able to accurately identify medical myths, at 61%. Overall, college degrees beat out those with only a high school degree or GED equivalent (who came in at 54%). The surprise here was that PhDs just barely beat out the high school crowd at 55%.

See the entire survey results.