DR MICHAEL MOSLEY: Artificial sugars can kill the bugs in your gut that keep you healthy
Scientists found that those knocking back more than two sugary drinks a day were 17 per cent more likely to die prematurely than those who rarely had them
It’s no secret that extra helpings of sugar, be it in fizzy pop or flavoured yogurt, are bad for both our waistlines and our teeth. So surely replacing the stuff with artificial sweeteners that contain zero calories is better for us?
Apparently not. A study published last week suggests that they may, in fact, be worse. As part of the research, reported in the JAMA Internal Medicine journal, more than 451,000 middle-aged people filled in questionnaires 16 years ago and they’ve been followed ever since.
The scientists found that those knocking back more than two sugary drinks a day were 17 per cent more likely to die prematurely than those who rarely had them. The risk of premature death was even higher in people who consumed drinks containing artificial sweeteners. A preference for artificial sweeteners was also found to increase the risk of heart disease by 40 per cent.
Two other big studies this year reached similarly shocking conclusions. One found that for obese women, just two diet drinks daily doubled the risk of stroke.
So why do they spell such havoc for your body? After all, the whole point of them is that, unlike sugar, the sweeteners are not absorbed, so they don’t cause excess weight gain – or at least that was what we were told. But what most are not aware of is the damaging effect on the 100 trillion microbes (microbiome) in our guts. It’s these microbes that, thanks to the signals they send to the brain, have perhaps the most profound impact on our health…
Sweeteners blitz your gut bacteria
I often write about the benefits of healthy, thriving gut bacteria for warding off a whole host of diseases, such as diabetes. And research surrounding artificial sweeteners – and their effect on these important gut bugs – provides further evidence of the bacteria’s importance to overall health.
Artificial sweeteners are not absorbed in your small intestine as most nutrients are. Instead, they travel to your large intestine, also called the colon, which is the home of the gut bacteria.
A few years ago, doctors from the Weizmann Institute in Israel conducted a series of experiments looking at the impact of consuming artificial sweeteners on the microbiome. Mice were split into three groups – some were given water, some sugary water, and some water laced with a type of sweetener called saccharin.
Mice in the saccharin group developed an inability to metabolise glucose – a precursor to diabetes. Those in the other two groups remained perfectly healthy. Next, they took faecal samples in the gut bacteria from mice in the saccharin group, and transferred it to other normal mice. Within six days, these healthy mice also developed glucose intolerance. The guts of the transplanted mice also grew higher quantities of the sort of bacteria associated with obesity and diabetes. Scientists concluded that the sweetener had transformed both the type and quantity of gut bacteria in the mice, causing significant health problems.
And what about in humans? Well, another experiment by the same team asked volunteers who don’t usually eat artificially sweetened food to consume a high dose for a week. Just like the mice, the participants began to show signs of glucose intolerance.
Why? Scientists aren’t certain but it is thought that gut bacteria reacts to the sweetener and produces chemicals that provoke an inflammatory response, which can encourage obesity and diabetes.
And researchers at the National Institutes of Health in the US reported that women with gestational diabetes (raised blood sugars brought on by pregnancy) who had consumed at least one artificially sweetened drink a day during pregnancy were more likely to have children who were obese by the age of seven compared to those born to unwell mothers who had drunk water. The link, according to scientists, was likely to do with the microbiome.
… And they won’t help shift pounds
A recent study looking at the eating and drinking habits of more than 7,000 American teenagers found that those who favoured low-calorie or zero-calorie diet drinks also consumed 200 extra calories a day, compared to their contemporaries who drank water.
And compared to students who stuck to the original, sugary version, there was little difference in overall calorie intake.
It is thought that consuming something sweet-tasting tricks the brain into expecting a sugar hit.
Hormones such as insulin are then released, driving blood sugars down. But when nothing calorie-laden arrives, your body feels cheated, so the brain responds by releasing hormones that trigger hunger pangs.
Avoid the fakes – and go cold turkey
The studies I’ve referred to so far mainly involve drinks laced with artificial sweeteners such as aspartame, sucralose and saccharine. These are the most familiar ‘fake’ sugars. But there is one newly developed sweetener that, in studies, doesn’t seem to have a detrimental effect on the gut.
Leaves of the stevia plant have been used as a sweetener for centuries in countries such as Brazil. Powdered stevia is now widely available in supermarkets. As it’s intensely sweet, you need only a pinch. So if, like me, you can’t go without sweet stuff, there is an alternative. But my advice is to go cold turkey rather than relying on artificially sweetened foods. If you opt for water and unsweetened tea and coffee, your body will thank you for it.
Bubbles can make you fat too
Fizzy water could make you more hungry
Fizzy water fans don’t get off scot-free.
Some research suggests that, regardless of sweeteners, the fizz alone could have worrying health implications.
A few years ago I took part in an experiment with Dr James Brown, from Aston University, to test the impact of bubbles on hunger.
Volunteers consumed a fizzy, sugary drink, a glass of the same drink but flat, and a glass of fizzy water, and one of flat water.
When results were analysed, James found that levels of the hunger hormone ghrelin were higher when participants had the fizzy drinks compared to flat – even water.
In other words, consuming a fizzy drink makes you hungrier than drinking the same drink, but flat.
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