Table 1 Folk theory veracity assessment and endorsement summary.
From: The pervasiveness and policy consequences of medical folk wisdom in the U.S.
Folk theory | Evidence | % Endorsed |
|---|---|---|
“Exposure to cold weather can cause you to catch a cold” | Exposure to rhinoviruses, irrespective of weather conditions, causes people to catch colds1. People are more likely to catch colds in winter5, but that’s because we spend more time indoors3. Cold weather is associated with decreased immune responsiveness in mice2, and more favorable survival conditions for viruses6, but there is little evidence that exposure to cold weather causes colds | 49% (S1), 46% (S2) |
“Consuming more than the daily recommended amount of vitamin C can prevent illnesses like influenza and the common cold” | A recent meta-analysis found that vitamin C, and excess consumption of it (e.g., via supplements), does not reduce incidence of the common cold4 | 55% (S1), 49% (S2) |
“Eating chicken soup can help people recover from illnesses more quickly” | Eating chicken soup may reduce respiratory inflammation, but it has no known medicinal benefits regarding its ability to fight infections7 | 66% (S1), 63% (S2) |
“Not washing one’s hands can help increase immunity to disease” | Hand washing is an effective way8 to prevent the transfer of germs that cause disease. Poor hygiene and not washing one’s hands does not9,10 act as a natural form of inoculation | 38% (S1), 37% (S2) |
“Taking multivitamins daily can help prevent catching illnesses like the common cold” | Neither vitamin C11, nor multivitamins19 have been shown to reduce cold incidence. Some studies12 find beneficial effects of Zinc when taken immediately at the outset of a cold, but with the important caveat13 that (1) these claims are disputed, and (2) Zinc does not prevent colds | 62% (S1), 72% (S2) |
“Carbonated drinks, like ginger ale, can cure stomach aches” | Ginger in its natural form can have health benefits14. However, there is no evidence15 that sugar sweetened beverages like ginger ale offer much relief | 63% (S1), 62% (S2) |
“Women cannot become pregnant by having sex during menstruation (or “on their period”)” | While women may be less likely16 to become pregnant while having sex during menstruation, sex during menstruation can result in pregnancy17 | 30% (S1), 28% (S2) |
“White spots on one’s fingernails are indicative of not consuming enough Vitamin C” | Although white spots (known as leukonychia) can occur for a number of different reasons, the most common is minor injury18 to the fingernail area. Vitamin deficiencies are not thought20 to be responsible for leukonychia | 58% (S1), 54% (S2) |
“Showering after sex is an effective way to prevent pregnancy” | Showering after sex will not21 help prevent pregnancy. In fact, research suggests that the act of rinsing the vagina after sex may actually push sperm further up through the cervix22. That said, cleaning yourself after sex can protect from some infections like UTIs23 | 15% (S1), 13% (S2) |
“Cracking one’s knuckles can cause arthritis” | Consistent medical research24,25 suggests that cracking knuckles is not correlated with degenerative changes associated with arthritis | 49% (S1), 47% (S2) |
“Not eating when one has a fever (sometimes called “starving a fever”) can reduce the amount of time it takes to recover” | While the idea of fasting to stop a fever dates back to the 1500 s, it is not based in scientific consensus26,27. Fevers increase body temperature and metabolism and thus burn more calories. Eating can actually help to replace the calories that are lost due to the fever. That said, research in mice28 suggests the importance of eating may depend on the root cause of the fever, with it proving beneficial for influenza but detrimental for bacterial infections | 37% (S1), 33% (S2) |
