In the mood for that food

[Guest guest]

How you feel affects the way a meal tastes, say scientists. Kate Wighton investigates sprouts, stress and serotonin If you’re already anxious about having to eat a compulsory portion of Brussels sprouts with your Christmas dinner, take heart. The fact that you’re worried about it means that it may not taste so bad. In a paper published this month in The Journal of Neuroscience, researchers at the University of Bristol say that taste is affected by our mood. If we’re feeling stressed or anxious, our ability to

taste salt and bitterness diminishes. So the taste of bitter sprouts won’t be so strong. On the other hand, if we’re happy, the report suggests that our taste buds will be enhanced and we will be able to detect the subtlest of flavours. The research results form part of a growing body of evidence that suggests that taste is not constant throughout our life. Instead, how food tastes to us changes according to how we are feeling week to week; even moment to moment. The Bristol study, and others like it, could not only improve medication for depression but also pave the way for taste-enhancing technologies. Dr Jan Melichar, a psychiatrist involved in the study, says: “We found that people who had been anxious in

the past few weeks had a blunted sense of taste when it came to salt and bitterness. So if someone had been anxious in the weeks up to Christmas, they would need more salt on their food.” As well as believing that stress and anxiety affect taste, Dr Melichar and the team at Bristol also think that taste is changed by two brain chemicals, serotonin and noradrenalin. Both control mood and are low in depressed people. “We found that when we increased the level of serotonin in our healthy volunteers, their sensitivity to sweet and bitter tastes increased. When we increased the amount of noradrenalin the subjects were more sensitive to bitter and sour things,” he says. Dr Melichar hopes this discovery of a connection between mood and taste will ensure better and faster treatment for depression. By testing a patient’s taste, doctors may be able to tell whether they are lacking noradrenalin or serotonin. This would make it easier for the correct drug to be

prescribed first time, something that doesn’t always happen. Depressed people are usually lacking more of one chemical than the other — either serotonin or noradrenalin — and the drugs that treat them raise the levels of the relevant chemical. “At the moment, patients are given the right drug 60 to 80 per cent of the time,” says Dr Melichar. “If doctors get the drug right, that’s fine. But if they get it wrong, then people can stop taking the drug. And, often, do not return for help to their doctors. This is important because the longer someone goes without getting treatment, the harder it is to bring them out of depression. It’s like having a broken leg. The longer you walk on it, the harder it is to fix, and the more you get used to walking with a limp.” Dr Melichar predicts that a depression taste test could be available in five years’ time, after further trials. It might not guarantee that a patient would always gets the right prescription from the

outset but it would increase the chances. “Even a 5 per cent increase in people getting the right drug first time could make a difference. With the one in ten people being affected by depression in the UK, this could mean tens if not hundreds of thousands more people are getting the right drug.” Depression aside, Dr Melichar believes he has found something more surprising — that everyday levels of stress and anxiety in those not suffering from depression can affect our taste buds. The Bristol researchers say that people who had been stressed for a prolonged period of time — perhaps by a stressful project at work over few weeks — have a diminished ability to taste salt and bitterness. This could be why some highly stressed individuals shovel down salty snacks or guzzle bucketloads of coffee, unable to detect its bitter taste. By the same logic, the Bristol team say that being happy, and having more serotonin dancing around your body, may tantalise your taste buds and

make food taste delicious. Indeed, food and mood are a hot topic among scientists. Professor Francis McGlone, a neuroscientist for the global food company Unilever, the maker of Ben & Jerry’s ice-cream, Flora margarine and Hellmann’s mayonnaise believes that our mood and hence our brain have a powerful influence on how we taste food. “The area of the brain where taste is processed is linked to other parts of the brain, such as ones that deal with emotion,” he says. So if we feel better, food tastes better. Surrounded by friends and family, with great music and soft lighting, food will taste yummier than, say, if you were eating exactly the same thing in your work canteen, thinking about the busy afternoon ahead. How emotions affect our mood is big business, and companies are turning to science to see how they can make our culinary experiences pleasurable. Serotonin has been used in a number of food studies, says Professor McGlone. In one such

study, people were asked to rate the sweetness of a drink and then given a chemical that, in effect, temporarily stopped the body’s production of serotonin. A few hours later they were asked to rate the sweetness of the same drink again. The results showed that they found the drink less sweet than before. “Serotonin colours all of our sensory experiences,” says Professor McGlone. Dr Melichar doesn’t rule out the possibility of a taste-enhancing pill, although perhaps not in the near future. “Maybe one day we could spray something on to our tongues, or take a designer taste-tablet, just to make that steak taste juicier or that pudding a little sweeter,” he says. But when it comes down to the nitty-gritty of the biology behind our changing experience of taste, it’s unclear whether all the action takes place at the taste-bud stage, or in the brain. The Bristol researchers suggest that serotonin is found in the taste bud, where it acts as a signalling

device, and so low levels of this hormone could mean fewer taste signals sent to the brain. However, Professor McGlone believes that taste is computed in our brain, so it is here that the low serotonin levels would weaken a food’s taste. The taste buds, he believes, wouldn’t have an effect, as they’re merely passive detectors that send information to the central hub of the brain, where the data is processed. And although taste is an important consideration in discussing over-eating in people with depression, many other factors are involved. One theory for over-eating, especially in people suffering from seasonal affective disorder (SAD), who feel low during the winter months, is that over-eating is fuelled by a craving for carbohydrates. If sufferers can’t taste the full sweetness of this food group, says Dr Melichar, that may be why they eat so much of it. However, this theory has yet to be fully investigated. As for over-indulging in sprouts at the

Christmas dinner — remember, if you want them to taste better, start worrying now.Peter H

 

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