Debunking 4 Common Coffee Myths, According to Popular Science
Popular Science highlights how research is rewriting what we thought we knew about coffee—debunking myths about roast strength, dehydration, heart health, and more.
Coffee is one of the most widely consumed beverages in the world, yet it remains surrounded by misconceptions. From the idea that dark roast has more caffeine to the belief that coffee causes dehydration or heart issues, myths persist despite scientific evidence to the contrary.
In a recent feature published by Popular Science, journalist Justin Pot examined four of the most common coffee myths and presented what the science really says. Here’s a breakdown of those myths—and the research that dispels them.
1. Dark Roast Doesn’t Mean More Caffeine
Contrary to popular belief, dark roast coffee isn’t stronger in caffeine content than light or medium roast. While the taste of a dark roast is more intense, it doesn’t correlate with higher caffeine levels.
According to a 2017 study cited by Popular Science and published in Nature, researchers Megan Fuller and Niny Z. Rao from Thomas Jefferson University found that medium roast Arabica beans actually had higher caffeine concentrations than dark roast when measured by mass. The longer roasting process reduces caffeine slightly, meaning that the darker the roast, the less caffeine it may contain.
2. Coffee Doesn’t Stunt Growth in Children
Another widespread myth is that drinking coffee can stunt a child’s growth. However, no scientific research supports this claim.
Popular Science references Dr. Roy Kim of the Cleveland Clinic, who clarified that “caffeine doesn’t impact growth.” While caffeine may slightly suppress appetite, this does not translate into any significant effect on child development or height. However, excessive caffeine consumption in children may cause sleep issues, moodiness, or heart palpitations—reasons why moderation is still advised for young coffee drinkers.
3. Coffee Does Not Dehydrate You
Because caffeine is known as a diuretic, many assume that drinking coffee leads to dehydration. This idea, though popular, has been largely debunked.
A 2014 study by researchers at the University of Birmingham, published in PLOS ONE and highlighted in Popular Science, compared hydration markers in men who consumed either coffee or water. The findings revealed no significant difference in hydration between the two beverages, showing that coffee contributes to fluid intake similarly to water. This is because coffee is mostly water—offsetting any mild diuretic effect from the caffeine.
4. Coffee Doesn’t Cause Heart Disease—It May Even Help
Many people worry that regular coffee consumption might increase the risk of heart problems due to its stimulating effects. However, research paints a very different picture.
As noted by Popular Science, a major 2022 study by the European Society of Cardiology found that drinking two to three cups of coffee per day—whether instant, ground, or decaf—was linked to a reduced risk of cardiovascular disease and lower overall mortality. The study involved more than 500,000 participants and supports the idea that moderate coffee consumption is not only safe but potentially beneficial for heart health.
Bottom Line: Science Supports Your Morning Cup
Coffee has long been misunderstood, but studies continue to show that many of the concerns associated with it are unfounded. Whether it’s fears about caffeine levels, dehydration, or long-term health effects, Popular Science makes it clear: coffee in moderation can be part of a healthy lifestyle.
Before making any significant changes to your caffeine intake, it’s always best to consult with a healthcare professional—especially if you have existing conditions. But for most people, that daily cup of coffee is not just safe—it may even be doing you good.
