I will admit it – I fell for the promise of diet drinks. A few years ago, when I was trying to get healthier, I switched from my standard two cans of full-fat cola per A&E shift to two cans of the diet version.
Of course, I never expected to end up looking like the diet cola models you’d see on advertising billboards in the early 2000s. But I did expect to lose some weight. Sadly, I didn’t, and until a couple of weeks ago, I never really understood why.
That’s when a new paper was published in the academic journal Cell Metabolism with very little fanfare or publicity. But I believe it is hugely significant and something everyone should know about.
Essentially, it shows that we in the medical profession got it wrong about artificial sweeteners, diet drinks and their ‘benefits’ for health.
On paper, using artificial sweeteners to make sugar-free gum and diet drinks seems like a win-win: they provide the taste of sugar without the impact on blood-sugar levels or calorie intake. And cutting sugar means reducing the risks of obesity, type 2 diabetes, cancer, heart attack, stroke and tooth decay.
But just because something doesn’t have calories doesn’t mean it’s harmless – as this new study has shown.
Researchers from Shandong University in China and the Karolinska Institute in Sweden found that the sweetener aspartame led to raised levels of insulin in the blood as well as atherosclerosis (clogged arteries).
In the first of a series of clever experiments, the scientists gave mice one of three doses of aspartame to drink – in similar concentrations to what humans would consume if they had three cans a day of diet drinks.
We in the medical profession got it wrong about artificial sweeteners, diet drinks and their ‘benefits’ for health, writes DR ROB GALLOWAY
The researchers found that the more aspartame the mice consumed, the higher their levels of insulin. And, as we already know, higher levels of insulin can lead to weight gain and all the complications associated with that, such as type 2 diabetes.
It seems that aspartame activates the vagus nerve, the main nerve in the body that runs from the brain to the abdomen, which causes more insulin to be secreted from the pancreas. How do we know this? Because mice that had had the nerve severed did not have a rise in insulin.
And before anyone retorts that ‘mice aren’t people’, monkeys given aspartame-laced water showed the same spike in insulin – strong evidence that the effect isn’t limited to rodents and is highly likely to be seen in humans too.
But it wasn’t just the raised insulin. When the researchers looked at mice’s arteries, those that consumed the larger amounts of aspartame and had higher insulin levels also had higher rates of atherosclerosis. This raises the risk of stroke, heart attack and dementia.
There was another key finding: when the researchers looked at the mice’s genome (their gene blueprint), they found that the protein cytokine CX3CL1 – which regulates inflammation in the body and too much of which is not a good thing – was massively ‘upregulated’. In other words, the aspartame had activated a gene that causes inflammation and atherosclerosis.
Again the scientists checked this using mice bred without the receptor for this cytokine. Those given aspartame showed no increase in atherosclerosis.
This complicated but compelling science experiment proved that the sweetener drives atherosclerosis through increased insulin levels which, in turn, drives the pro-inflammatory cytokine CX3CL1. The scientists concluded that this all suggested a new and novel approach to tackling atherosclerosis.
But in fact the paper showed something much more profound: artificial sweeteners are not the benign alternative you might think they are.
A few years ago, when I was trying to get healthier, I switched from my standard two cans of full-fat cola per A&E shift to two cans of the diet version
This latest paper explains the findings from a 2022 study published in the British Medical Journal involving more than 100,000 French adults which meticulously tracked their dietary habits and health outcomes over several years.
The findings were alarming: people who consumed higher amounts of artificial sweeteners had a 9 per cent increased risk of cardiovascular diseases. Delving deeper, specific sweeteners were linked to specific effects: aspartame was linked to a 17 per cent higher risk of brain-related events such as strokes. Acesulfame potassium was associated with a 40 per cent increased risk of coronary heart disease and sucralose with a 31 per cent increased risk of the condition.
What this study didn’t show was proof of causation. But having read the Cell Metabolism paper, I am confident we now have this.
Don’t just trust the lab studies: we’re seeing an effect in terms of weight gain in the real world, too.
A recent study led by the University of Minnesota Medical School showed that long-term consumption of certain artificial sweeteners may be contributing to increased body fat and a higher risk of obesity.
Researchers analysed the dietary habits of more than 3,000 adults over a 20-year period, focusing on artificial sweeteners.
The findings were alarming: regular and long-term use of these sweeteners was linked to greater volumes of body fat, particularly harmful visceral fat – the type that is stored around organs such as the liver.
It’s not just their impact on insulin levels that could explain artificial sweeteners’ effect.
When you consume something sweet, your brain expects calories. When they don’t arrive, cravings for real sugar may increase, leading to later overeating.
Rats given saccharin-sweetened diets later overate real sugar or high-calorie foods, suggesting their brains were compensating for the ‘missing’ energy.
There is evidence that this may happen in humans, too. MRI studies show that artificial sweeteners activate the brain’s reward system, but with a weaker ‘hit’ of dopamine (a feel-good chemical messenger) than real sugar. This may leave the brain ‘unsatisfied’, prompting additional cravings.
Then there is evidence suggesting that artificial sweeteners alter the balance of gut bacteria, leading to insulin resistance (where the cells don’t respond as well to the hormone, so the body has to produce more). A study in 2014 in Nature showed this can happen in humans as well as rodents.
Finally, there is evidence in animals that artificial sweeteners interfere with hormone regulation, particularly those involved in hunger and satiety, such as leptin and ghrelin.
But for me the most compelling thing is that these days we drink more diet drinks, but we’re now heavier than ever.
Since the introduction of the sugar tax in 2018, aimed at reducing sugar consumption and addressing rising obesity rates, sugar levels in drinks fell, as manufacturers reformulated their products. Diet soft drinks’ share of the market increased from 44 per cent in 2011 to 72 per cent in 2023.
One year after the tax was introduced, the average adult was consuming 10.9g less sugar a day (and children 4.8g less). So you would have expected obesity levels to fall.
But a House of Commons report published last month showed that in 2023 a shocking 64 per cent of adults were classified as overweight or obese – that’s 1 per cent higher than when the sugar tax was introduced.
For children the picture is more mixed. Research from Cambridge University showed obesity rates fell among ten to 11-year-old girls by 8 per cent, but for boys of the same age, there was no change, for instance.
But please don’t think that all this means is that you should give up diet drinks and drink full-fat versions. In fact, full-fat cans of pop are definitely not good for our health.
However, while cutting your sugar intake is vital for health, replacing it with artificial sweetened drinks is not the answer.
The healthier drinks are tea, coffee, diluted fruit juices and milk. But, best of all, drink water.
