Belly button lint

Dear Alice,

Okay, so this may be a little weird, but what is belly button lint? Where does it come from, and why do I have it?

— Curious

Dear Curious,

Rest assured that your questions are not weird at all — many have pondered these fuzzy questions! Belly button lint is the collection of tiny fibers of clothing that get channeled into the navel where they compact into a felt ball. And, there are actually scientists who have researched belly button lint! In 2002, Australian scientist Karl Kruszelnicki won an Ig Nobel Prize, a parody of the Nobel Prize award that “honors achievements that first make people laugh, and then make them think”, for his year-long belly button lint study of some 5,000 individuals. His main finding was that belly button lint is more prevalent in people with stomach hair, affects more men than women, and is made up of clothing fibers (more on that later). Thanks to Dr. K’s work, many others have explored the depths of the navel and have provided more insight on what all the fuzz is about.

You might be wondering how the fuzz funnels its way into your belly button. The main engine of this process is belly hairs that act similar to a conveyer belt directing the fibers into the navel. Studies have shown that shaving the hair around the belly button results in less accumulation of fuzz. What else causes frequent fiber buildup? Deep navels, poor hygiene, and obesity may result in more lint. Biological males tend to have more belly hair and deeper navels than biological females, which can result in this being considered more of a phenomenon among the males of the species. Additionally, when it comes to belly button lint, not all navels collect fuzz equally. As might be expected, people with "innies" are more likely to find fuzzy accumulation in their buttons than people with "outies”. However, even those with bigger buttons need not worry! Navel accumulation tends to be pretty small with an average mass of 1.82 milligrams.

The fibers also play a role in lint accumulation. Older t-shirts and dress shirts tend to produce less navel fuzz because they have fewer stray fibers available to maneuver. In addition, different types of washing machines may effect the amount of fuzz on your clothes. Top-loading machines tend to be rougher on clothing than front-loading machines resulting in larger quantities of dislodged fibers that remain on the clothing, which then can result in more lint. You also may be curious about colors. If you tend to wear a particular color of shirt, your lint is more likely to be that color. If you wear a variety of colors the lint will typically take on blue-gray hue, similar to lint you may find in your dryer's lint trap. 

The depths of the belly button continue to be studied — and more than fuzzy fibers are being observed. Belly button biodiversity is a long-running, volunteer-based study that has found 2,368 different groups of bacteria growing in the navels of 60 volunteers. Surprisingly, 80 percent of the volunteers had only six of these groups in common, meaning the rest were unique to a few individuals. Also, those common groups found were similar to bacteria already known to live on other parts of the skin. So, lint isn’t the only thing to be found in your belly button!

Lastly, since you're searching for details on the inner sanctum of the navel: while belly button discharge and inflammation in adults is rare, it can be caused by infections due to hair tufts and foreign bodies. The best way to avoid such infection and rid your belly of fuzzballs is to practice proper hygiene and keep that navel clean — which can easily be taken care of with regular showers or baths.

All this to say, though the stuff in your navel might be fluff, the science behind the goings-on in your belly button isn't!

Last updated Jan 22, 2016
Originally published Mar 01, 2002