Our taste buds actually have an important role in defending us against diseases
Taste receptors have recently been found in organs such as the brain and lungs
Research suggests this discovery could lead to new treatments for conditions
Without a sense of taste the world would be much duller, but scientists believe taste buds also have an important role in defending us against diseases.
And it’s not simply that taste buds stop us eating food that might harm us, such as something that’s gone off.
Taste receptors have recently been found in organs all around the body — from the brain to the lungs and the bladder.
And research suggests this discovery could lead to new treatments for conditions such as sinusitis and even diabetes.
Whether people enjoy bitter foods such as Brussels sprouts may indicate how strong their bitter receptors are and their immune response
‘Taste receptors on the tongue detect five basic types of tastes: sweet, bitter, salty, sour and umami [savoury],’ says Carl Philpott, a consultant ear, nose and throat surgeon at the James Paget and Norfolk & Norwich University Hospitals.
‘But emerging research suggests the exact same receptors outside the tongue have more complex roles.’
Taste buds are small clusters of cells, specialised proteins called ‘receptors’ on the tongue and the roof of the mouth.
These feed back signals about food flavours to the brain via nerves. The brain analyses this information and decides whether it’s OK to swallow or if we need to spit it out.
The average person is thought to have about 10,000 taste buds on the tongue, each made up of 50 to 150 taste receptor cells. It’s unclear how many taste receptors there may be elsewhere in the body.
Their role on the tongue — reacting to substances and triggering a response — lines up with the emerging theory that taste receptors are involved in the immune response (the body’s reaction to foreign invaders such as bacteria).
But the taste receptors around the body, unlike those in the mouth, don’t send signals to the brain. Instead, they send signals to the nearby tissue and organs to trigger a physiological response locally.
Scientists at the University of Iowa discovered cilia, hairlike structures found in the airway that help push out harmful substances, have bitter taste receptors on them.
Tastes described as ‘bitter’ are the result of the brain perceiving them as unpleasant. Receptors have evolved to recognise potentially harmful chemicals that ‘taste’ bitter.
In other organs such as the lungs, receptors detect ‘bitter’ compounds such as certain products secreted by bacteria.
Those who taste bitter tastes strongly are less receptive to pseudomonas aeruginosa infections, or sinusitis
Studies found that when activated by bitter compounds, these taste receptors increase the speed of the cilia movements and trigger an immune response to kill the bacteria within seconds or minutes.
This is much faster than immune cells, which can take hours, days or weeks to create antibodies. We have just one type of taste receptor dedicated to recognising sweet, salty, umami and sour, but 25 different types of bitter taste receptors on the tongue and round the body.
Bitter receptors have been found in the brain, nose, sinuses, windpipe, heart, breasts, lungs, small intestine, colon, testicles and urethra, so far.
A study in 2012 found bitter taste receptors in the testes of mice.
When mice were bred not to express the genes responsible for these receptors, they had smaller testes and no sperm — suggesting a role for bitter taste receptors in fertility.
‘Sweet’ taste receptors have different roles. For example, those found on cells of the intestine are thought to be involved in the release of the hormone insulin from the pancreas.
People with more sensitive bitter receptors tend to hate bitter foods because they taste unpleasant. They could also have better immunity
Whether people enjoy bitter foods such as Brussels sprouts may indicate how strong their bitter receptors are and their immune response.
People with more sensitive bitter receptors tend to hate bitter foods because they taste unpleasant.
They could also have better immunity, as these receptors can better detect harmful bacteria and trigger a fast response to kill it off.
A study on a bitter receptor known as T2R38 found it was activated by the bacteria Pseudomonas aeruginosa.
Found in hospitals, it can cause skin lesions, fever, blood infections and chronic sinusitis.
Dr Andy Turnbull, a clinical research fellow at Imperial College London, who is researching bitter receptors, says: ‘The gene involved in determining the function of this bitter receptor exists in two forms: taster and non-taster.
‘People with two copies of the taster gene — 20 per cent of the population — detect bitter tastes strongly.
Studies suggest they have a powerful immune response against Pseudomonas aeruginosa infections and stronger clearance of the bacteria. As a result, when they get sinusitis, it’s less severe.’
Dr Turnbull is looking at bitter taste receptors in cystic fibrosis patients, who are vulnerable to lung infections, particularly with Pseudo-monas aeruginosa.
And identifying how the gene is involved could lead to new therapies in upper airway diseases such as chronic sinusitis.
Source: Daily Mail