A scientist’s guide to life: how to smell nice

A scientist’s guide to life: How to smell nice It’s whiffy, it’s unpleasant, and many of us have suffered from the embarrassment it causes, but what is the best way to deal with body odour? Dr Chris Callewaert, aka Dr Armpit, tells all.

What causes body odour? Lots of factors are involved – what you eat, your body mass index, the weather, your clothes and your genetic makeup, but the most important factor is the bacteria that live in your underarms. They feed on the lipids, amino acids and other molecules in our sweat. Some bacteria are better at breaking these materials down than others. Some leave unconverted molecules behind that start smelling bad. This causes body odour.

Everyone has their own unique cocktail of bacteria in their armpits. There are ‘good’, non-smelly bacteria, and ‘bad,’ stinky bacteria. The balance is different for everyone.

Which underarm products work the best? There are two main types of product. Deodorants contain perfume and antibacterial ingredients. These work well for most people.

Antiperspirants have an extra ingredient – aluminium salts – which go into the sweat pores and help prevent sweating. These are good for people who sweat excessively.

Are natural deodorants and creams any good? There’s a trend for these products at the moment. Natural deodorants contain ingredients like essential oils that smell nice and kill bacteria.

These can work well, but some of the creams contain high concentrations of silver ions which could eradicate the microbiome. We need these bacteria. They help to protect us from pathogens. We’ve evolved with them. It’s a futile idea to think that we can go on without them.

What other products are in the pipeline? We’ve been doing bacterial transplants. You take the bacteria from people that smell good and ‘transplant’ or wipe them into the clean armpits of smelly people. The new bacteria colonise their armpits and the body odour is reduced.

It can work well for a couple of weeks, so now we’re developing a bacterial spray that people could use daily. It’s currently in clinical trials.

Which fabrics make body odour worse? Synthetic fabrics like nylon and polyester capture moisture and odours, and selectively grow some bad, odour-causing bacteria. Natural fibres, like cotton, tend to be better and smell less.

What foods can help me smell better? People who eat more vegetables smell better and have more of the good bacteria. People who eat more fast foods and meat smell worse and have more of the bad bacteria.

Will I smell more if I get stressed? Some people do. When we’re stressed, we release adrenaline which leads to more sweat production. This means that more lipids and amino acids are pushed out from the sweat glands and hair roots into the underarm. With all the bacteria that are already present there, this can lead to a burst of malodour.

The only way out is not to get stressed about it. Psychology is a big part of this. Our research shows that women smell a bit better than men, and yet stress about body odour more. We need to use good products and try to worry less.

NEED TO KNOW… If you don’t sweat much, deodorant should keep you smelling sweet. Avoid polyester and nylon. Stick to natural fibres like cotton. Don’t stress! The more you worry about body odour the worse it will get.

Dr Chris Callewaert ( @DrArmpit ) is a microbial ecologist at the University of Ghent, Belgium.

Interviewed by Dr Helen Pilcher.

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