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Question of the fortnight: Why do you get fluff in your belly button?

Blogging science to life

Wed 15 September 2010, Written by: Nicole

Why do you get fluff in your belly button?

Question asked via twitter @bristol_citizen

The origin of belly button fluff (BBF) or naval lint, as it is also known, has been puzzling men, women and children the world over for years. To find out where these fluffy deposits come from and what causes them we must consider the relationship between the belly button and our clothes. Interestingly there have been a few surveys about this...

Dr Karl Kruszelnicki conducted a survey of nearly 4000 people, who collected their BBF, results of which show that BBF is made up of mostly fibres from clothing, some dead skin cells and hair. (Yuk!)

Throughout the day our clothing rubs on our skin and this friction causes some fibres to be dislodged from your clothes. The hairs on your body catch and collect these clothing fibres. Your body movements throughout the day channel the fibres along the hairs of the stomach towards the belly button, or umbilicus, where it collects and forms a visible ball of fluff or lint.

Why these fibres collect in the belly button alone is undecided; Dr Donald E. Smith has suggested that the belly button could secrete a substance which catches whatever lands by it. However Dr Bhupendar S. Gupta suggests it is the ‘microclimate’ between clothing and your stomach which forms a flow of air carrying the tiny particles towards your navel.

It seems the amount of fluff collected depends on a few factors:

1) How hairy the person is - as the more hair the more fibres collected. This is why it is more common for men to be afflicted by BBF.
2) The size of the belly - the larger the stomach the more surface area for the fibres to collect on and the larger the belly button for them to be collected in.
3) Different types of fabrics – some fabrics are more likely to shed fibres. It has been suggested older fabrics shed less fibres than new ones.
4) The shape of your belly button – if you have an ‘innie’ belly button you are more likely to have navel lint. Where as if you have an ‘outie’ this prevents build up of clothing fibres. Piercings also prevent the build up of fibres resulting in less belly button fluff.

Another thing of note is the colour of BBF deposits. They are commonly bluish-grey in colour due to the fact that a lot of our clothes are made with colours of blue and white, even black clothing dye is actually just very dark blue.
However that is not the case for Graham Baker, who holds the Guinness World Record for the world’s biggest collection of one person’s navel lint. Most of Graham’s collection is yellow or red, even though apparently he rarely wears those colours! See his collection here

Hope this answers your question bristol_citizen! If you have any interesting stories about BBF we would love to hear about them!

With thanks to: Graham Barker, quizzical.com and wikipedia

You can find out even more weird and wonderful facts about the human body when All About Us opens!

Every fortnight, we are answering your science questions about the human body. It's all part of finding out how amazing you are, in the run up to the opening of our new exhibition All About Us in February 2011.