Some like it hot – especially when it comes to food. Surveys show one in five of us tuck into curry at least once a week, while demand in the UK for hot sauces loaded with fiery chilli flavours are on the increase, fuelled by the popularity of celebrity-backed brands, such as Tingly Ted’s, launched by music megastar Ed Sheeran.
But can spicy food fire up our health?
Compelling evidence comes from a recent study in the British Journal of Nutrition, which quizzed more than 50,000 adults on how often they ate fresh chillies, chilli sauce or added dried chillies to their cooking.
The results showed those tucking into a spicy dish just once a week reduced the risk of a life-threatening ischaemic stroke (where a clot forms in the narrow blood vessels in the skull, shutting off blood flow to the brain) by 13 per cent compared with those who rarely or never ate spicy dishes.
And those eating hot food three times a week or more were almost 20 per cent less likely to suffer a blockage, according to the study by Guangxi Medical University in China.
This effect was particularly prominent in obese people too – and obesity is a major risk factor for stroke; researchers said: ‘Obese people may benefit from a higher frequency of consuming spicy food.’
Ischaemic strokes affect more than 100,000 people a year in the UK – killing more than a third and leaving many more permanently affected by speech problems and immobility.
One theory is that the health benefits are down to the effects of capsaicin – the ingredient which gives chillies their heat. Capsaicin increases metabolism, or the rate at which the body expends energy, by about 8 per cent – and in turn this wards off obesity.
And even those who do have a stroke may still benefit – a study in the Journal of Stroke and Cerebrovascular Diseases in 2019 found stroke patients given a capsaicin supplement were much less likely to suffer with dysphagia, a problem which affects up to 80 per cent of stroke victims, which makes swallowing food and drink difficult.
The spicy compound has been shown to stimulate receptors in muscles in the throat, making them contract more easily – aiding swallowing.
Dr Louise Flanagan, head of research at the Stroke Association, said: ‘More than 90,000 people survive a stroke every year in the UK, and its devastating impact can leave people unable to move, see, speak or even swallow. We welcome studies like these, which look at modifiable stroke risk factors like diet. But these studies have limitations and people’s definition of “spicy” may vary.’
Spicy food has been shown to benefit our wellbeing in other ways, too. For example, have you ever noticed how your nasal congestion seems to clear up when you enjoy a hot, spicy meal?
That’s because capsaicin in chillies releases a vapour that irritates the mucus membranes that line the nostrils: this delicate layer traps incoming germs and releases mucus to remove them from the nose.
Capsaicin triggers the release of mucus, which can clear congestion and make breathing easier for a short while.
In some countries doctors prescribe a capsaicin-based nasal spray for non-allergic rhinitis, a condition that affects up to six million people in the UK and where nasal stuffiness is caused by a cold or irritation from pollutants such as cigarette smoke.
In clinical trials, the chilli sprays – which are not licensed in the UK – eradicated symptoms in around 40 per cent of patients.
Chillies could be good for the heart, too. In one of the biggest studies into the health benefits of a spicy diet, reported in 2020 at the American Heart Association conference, researchers found those regularly eating dishes containing chillies were 26 per cent less likely to die from heart disease than those who rarely, or never, ate them.
The study, by the Cleveland Heart, Vascular and Thoracic Institute in Ohio, analysed the eating habits of more than 570,000 people who’d taken part in several studies on diet and health. Previous research suggests chillies can dampen down inflammation, which can affect blood vessels around the heart leading to blockages that ultimately cause a heart attack.
But the US researchers stressed it’s too early to say for sure that eating spicy food saves lives, as their study did not account for the amount or type of chilli (some are hotter than others) that volunteers were eating.
Meanwhile, research suggests regularly eating chillies may protect against dementia.
For example, a 2020 study in mice by scientists in Canada found that feeding them treats made with capsaicin protected against the formation of amyloid plaques, the harmful deposits thought to be responsible for the symptoms of Alzheimer’s, including memory loss and mood swings.
Writing in the journal Translational Psychiatry, the researchers said, as well as blocking plaque formation, capsaicin appeared to dampen down inflammation in the brain, also linked to cognitive decline.
But the jury is still out – another study, by the University of South Australia in 2019, found eating more than 50g of chilli a day can double the risk of memory decline and poor cognition.
The 15-year investigation, involving more than 4,500 volunteers, concluded that too much spicy food might in fact damage brain cells, predisposing them to the onset of Alzheimer’s.
What is well accepted is that capsaicin from chillies can relieve pain – it acts on pain-sensing nerves, making them less sensitive. For example, a skin patch made with capsaicin is often used on the NHS to treat neuropathic pain, such as that suffered by people with diabetes, where poor circulation to the legs and feet can damage nerves.
Studies show the chilli-based patch, which contains a liquid made with capsaicin that seeps through, can reduce neuropathic pain by up to 50 per cent.
Even just eating capsaicin on a regular basis can increase our tolerance for pain, according to a 2020 study in the Journal of Pain.
Researchers gave 60 students either a sugary snack or a chilli-based one, then measured their ability to withstand pain when their hands were plunged into ice-cold water.
Those given the spicy snack were able to withstand the pain for longer and the effects lasted for weeks after the test – suggesting it improved long-term pain tolerance.
Susan Brain, a professor of pharmacology at King’s College London, says: ‘If you eat a hot chilli and get the burning sensation, it’s the capsaicin that causes it by binding to and activating nerve fibres in the body that transmit pain signals.
‘But that pain soon goes away as the capsaicin desensitises them.’
It’s not all positive news. In 2021, researchers at Nanjing University of Chinese Medicine reviewed data from 16 previous studies on chillies and gastric tumours and found those eating them several times a week had a 50 per cent greater risk of stomach cancer than occasional eaters – possibly because excessive capsaicin intake can irritate the stomach lining.
And eating too much spicy food could turn the temperature down in the bedroom. A recent study of 373 men found that those who ate spicy foods three times a week or more had reduced libido – and were two-and-a-half times more likely to suffer erectile dysfunction than those who consumed hot dishes less than once a week.
One reason may be the effect on male hormone levels.
Writing in the journal Translational Andrology and Urology in September, the researchers said: ‘Testosterone levels decreased significantly with an increase in spicy food consumption frequency.’
But the scientists, from the University of South China, also suggested that eating lots of fiery food could be a marker for a fattening diet and obesity, both of which can reduce sex drive.
Professor Brain says: ‘The take-home message here is to eat sensible amounts – as part of a healthy, balanced diet with lots of fresh fruit and vegetables, chillies certainly won’t do you any harm.’
