When bad breath is a sign you need to see a doctor

Although fit and toned, thanks to his love of rugby and athletics, Duke Al Durham, then 23, was suddenly plagued by a series of minor, niggling health issues in the summer of 2017.

His mouth was constantly dry, he was more thirsty and tired and he developed thrush (a common fungal infection). But he only really became concerned when his partner pointed out that he had also developed another rather strange and embarrassing symptom — bad breath.

‘She said it smelled really strongly of pear drops, a sickly sweet odour that was very powerful and noticeable,’ says Duke Al, who is now 29 and a rapper and spoken-word artist from South Wales.

‘I hadn’t eaten or drunk anything that would make it smell like that — it was a bit of a mystery, so I immediately went online and looked it up.’

He discovered that pear drop breath is a characteristic sign of type 1 diabetes, an autoimmune disorder that affects around 400,000 people in the UK and means the body is unable to process sugar properly.

The smell is caused by diabetic ketoacidosis, a serious condition where the body, unable to use sugar for energy — because it’s not producing enough insulin to help cells mop it up — starts to burn fat. As a result, it produces chemicals called ketones, which have the distinctive pear drop smell, and these are emitted through the breath and sweat.

By the time someone has developed it, they may be only hours away from slipping into a potentially fatal diabetic coma.

Armed with this worrying information, Duke Al went straight to his GP — and sure enough blood tests revealed that he had type 1 diabetes.

A jab of the hormone insulin restored his sky-high blood sugar levels back to normal — and he has been on daily insulin jabs ever since.

‘At the time, the other symptoms — thirst and fatigue — didn’t really register with me as anything particularly serious but when my girlfriend told me my breath smelled strongly of pear drops, it was so unusual it prompted me to look into it further,’ says Duke Al. ‘I’m so glad I did.’

According to charity the Juvenile Diabetes Research Foundation (JDRF), around one in four cases of type 1 — a condition that usually emerges in childhood or early adulthod — is diagnosed only when a patient has already developed diabetic ketoacidosis.

‘When that happens, you must call 999 immediately as it’s vitally important that the child is seen as soon as possible and started on insulin to bring blood glucose levels down,’ says Josie Clarkson, the research communications lead at the charity.

Bad breath (medically known as halitosis) affects around 30 per cent of people at some point, with a number of potential causes, including, obviously, spicy or strong-smelling foods, gum disease (which allows bacteria to thrive in the mouth and taint the breath), smoking and nasal congestion.

It can have a damaging effect on self-esteem, relationships and wellbeing — and for some, like Duke Al, it is a valuable warning sign of something more serious.

‘Fishy’ breath (and sweat, too), for example, can be a sign of poor kidney function. The foul smell derives from a chemical called trimethylamine which builds up when the kidneys fail to clear waste from the bloodstream.

A sour breath can be due to acid reflux, a condition affecting up to one in four adults in the UK, where a faulty valve allows stomach acid to leak back up into the oesophagus (or food pipe); a sweet, slightly ‘mouldy’ aroma often develops on the breath of patients who have severe cirrhosis, scarring of the liver linked with drinking too much alcohol. ‘There are numerous causes of bad breath, but if it is a chronic ongoing problem then you really should get it checked out — initially with a dentist and then with an ear, nose and throat (ENT) specialist, as it can be a sign of a serious underlying condition,’ says Adam Frosh, a consultant ENT surgeon at The Lister Hospital in Stevenage.

‘The problem is that people are often reluctant to seek help about bad breath due to embarrassment. The other problem is that it isn’t the person with bad breath who normally notices it — it is those around them, so detecting the problem tends to rely on the honesty of those around you.’

Mr Frosh says anything that blocks the nose — such as allergies — can lead to bad breath because it encourages breathing through the mouth, which can create a ‘perfect storm’; a dry mouth leads to bacteria in the mouth colonising it more; these in turn produce byproducts, malodorous ‘sulphurous’ compounds that become more concentrated, while ‘potentially smelly food particles aren’t washed away as normal’.

A related problem is ozena. ‘This causes a foul smell emanating from the nose, normally as a result of a fungal or bacterial infection within the nose or sinuses and this can have a knock-on effect of bad breath,’ he adds.

Some people may be more genetically prone to halitosis. Scientists have discovered that those who carry mutations in the SELENBP1 gene are more likely to develop ‘cabbage breath’.

According to a report in Nature Genetics in 2017, this gene may have a role in breaking down sulphurous compounds: the faulty gene means they then build up.

‘This gene mutation affects up to 3 per cent of the population — although not everyone who carries the gene will have the cabbage breath,’ says Mr Frosh. ‘For those who are affected, it is really unfortunate.’

Treatment of bad breath usually involves regular use of mouthwash to cover the smell or addressing the root cause of the problem — such as gum infections.

But new potential treatments are emerging that could banish bad breath altogether.

Recently, scientists at Ohio State University in the U.S. discovered that eating plain yoghurt straight after a meal containing garlic effectively traps the molecules that give off the smell, sealing them inside the body rather than letting them escape via the breath.

The secret is the yoghurt’s high levels of fat and protein, both of which appear to be very good at trapping garlic odours in the gullet so they do not contaminate the breath, according to a report published in the journal Molecules in September.

Meanwhile, there is considerable interest in the role probiotics — supplements containing good bacteria — might play in tackling halitosis.

A major review published in the journal BMJ Open in December 2022 by experts at Sichuan University in China, concluded that certain strains — Lactobacillus salivarius, Lactobacillus reuteri, Streptococcus salivarius and Weissella cibaria — seem to banish bad breath in under a month.

These types of bacteria are found naturally in foods such as sourdough bread and miso soup, and it’s thought they work by neutralising so-called volatile sulphuric compounds, gases produced by mouth bacteria.

In a separate development, small studies have found that a laser treatment called photodynamic therapy could tackle chronic halitosis by zapping the volatile compounds at the back of the tongue.

First, a light-sensitive chemical is applied to the middle and back of the tongue — when the laser is directed onto it for just a few seconds, this triggers a chemical reaction that damages only the molecules that produce the volatile sulphuric compounds.

However, it’s not yet clear whether the effects are long-lasting and the treatment is not currently available in the UK.

Duke Al believes his type 1 was triggered by a severe bout of food poisoning he suffered while on holiday in Bali earlier in 2017.

After flying home, he became increasingly unwell, with a sky-high temperature and a thumping headache. He was admitted to hospital and diagnosed with sepsis.

His recovery was slow and he was too weak to continue his job as a landscape gardener.

It was a few months later that his girlfriend pointed out his breath was sickly sweet.

‘Pear drop breath is a vital warning sign, but it’s one that’s often overlooked, I’ve since learned,’ says Duke Al, who raises awareness of the symptoms of type 1 diabetes on behalf of the JDRF.

‘If there’s any sign of it, you need to seek medical attention immediately because it means your blood sugar levels are dangerously high.’

Dr TikTok

This week: The egg diet for weight loss

What social media says: There are more than 124 million views for videos of this trend, which involves eating only eggs for ten days.

Some videos feature slimmed-down dieters praising the regimen, but others cover side-effects including increased hunger, low energy, headaches and irritability.

The expert’s verdict: ‘This is one of the few social media trends I’ve seen with some evidence to back it up, though not as the only food you eat,’ says dietitian Dr Carrie Ruxton. 

‘Eggs — at breakfast or lunch — make us feel fuller for longer, leading to fewer calories being eaten across the day.

‘This is probably because the rich protein content stimulates hormones that control fullness, such as GLP-1, and inhibits hormones that increase hunger, such as ghrelin.

‘But I wouldn’t recommend eating only eggs at every meal as this will lead to a diet lacking in iron, fibre, vitamin C, potassium, calcium and carbohydrates.

‘Instead, try two boiled eggs for lunch, with a baked potato or pasta salad, plus veg.’