Concerns about the effect sugar can have on weight and teeth are fueling demand for products made with calorie-free artificial sweeteners based on chemicals such as aspartame, acesulfame K, saccharin, sorbitol, sucralose and xylitol.
These products, considered a marker for a healthy lifestyle, are found in everything from soft drinks and ready meals to pastries and toothpaste, and the British spend about 68 million pounds a year on them.
But while there is no doubt that they reduce the risk of tooth decay, there are questions about how healthy they are as a weight loss aid – with suggestions that they can actually make our cravings for sweet and fat foods even worse.
Concerns about the effect that sugar can have on weight and teeth are fueling demand for products made with calorie-free artificial sweeteners based on chemicals such as aspartame, acesulfame K, saccharin, sorbitol, sucralose and xylitol.
Several studies in recent years have found that regular consumption of sweetened foods and beverages can make it harder, not easier, for some people to lose weight because of the way chemicals interact with the brain.
Now scientists think they know why.
A revolutionary new study suggests that the cells in the gut tell the brain that we have eaten sugar – and therefore calories – do not do this for sweeteners, leaving us still craving sweet foods.
Other studies show that the brain itself reacts differently to sugar sweeteners.
One of the most recent, in 2021, was conducted by experts at the Institute of Diabetes and Obesity at the University of Southern California in Los Angeles, who scanned the brains of 74 men and women after consuming sucralose – a widely used alternative to sugar. and which is 600 times sweeter than sugar.
During a series of laboratory experiments, volunteers were asked to drink either plain water, a beverage containing sucralose, or a beverage flavored with sugar.
After each drink, they underwent an MRI scan to measure blood flow to different areas of the brain at the same time while looking at images of high-calorie foods, sweet treats or spicy snacks.
The researchers stressed that their findings do not represent a clear and humiliating sentence for sweeteners – on the one hand, increased appetite is observed mainly in women and not in men.
The results, published in the September 2021 issue of the JAMA Network Open, reveal higher levels of blood flow – a sign of increased nerve (brain) activity – in areas of the brain responsible for food hunger, such as the hippocampus, after a fall. sweetener-based drink than sugar.
In a separate test, the volunteers were also told to help themselves with everything you can eat at the buffet two hours after consuming the same drinks. They ate the most after the sweetener-based drink.
Researchers emphasize that their findings do not represent a clear and humiliating sentence for sweeteners – on the one hand, increased appetite is observed mainly in women and not in men.
One theory is that the women in this study were in the first years of birth, when their brains may be harder to look for more high-calorie foods to support their chances of successful reproduction and survival.
But summing up the study, lead author Dr. Kathleen Page, an endocrinologist, said: “Based on these findings, I would suggest that sucralose may not be as effective in women as it is in reducing appetite and food cravings.”
Other research questions if effects are limited to women.
In a 2019 study at the University of Leiden, the Netherlands, researchers performed an MRI scan of the brains of healthy young men.
After a sweet drink, there was an immediate response in the hypothalamus, the part of the brain responsible for signaling satiety – or fullness – that reduced appetite in minutes.
But after a drink made with the sweetener sucralose, this response is significantly smaller and more fun, increasing the likelihood of consuming more calories later to feel full. But why would the brain react so differently to a chemical sweetener than to sugar?
The latest study, published in January in Nature Neuroscience, may provide vital evidence.
Researchers at Duke University in North Carolina have found that humans and animals have specific cells in their gut that can differentiate between the two, more like taste buds that distinguish between sweet and sour.
These “sensory” cells – which the research team called neuropods – then trigger different messages to the brain, depending on which substance they find.
For example, within a second of detecting sugar in the gut, these neurops secrete a chemical called glutamate, which sends a signal to the brain via the vagus nerve.
This is the body’s main “highway” for electrical signals that travel between the brain and many of the body’s major organs.
This signal immediately tells the brain that the body’s caloric needs are reduced due to the “shock” of sugar.
But such an increase in glutamate levels does not happen when the gut finds sweeteners, so the thirst for calories remains.
Other studies question whether replacing sugar with sweeteners is of any medical benefit to people with diabetes; sweeteners have been shown not to cause an immediate spike in blood sugar levels like sugar.
Indeed, a statement on Diabetes UK’s position on sweeteners says: “They can be used to control weight and diabetes, as long as they replace [for sugar] does not lead to later compensation with increased energy intake. ‘
The British Dietetic Association says that sweeteners can “help” with weight loss and diabetes.
However, Cochrane’s 2020 review of the evidence for sweeteners and diabetes, which looked at data from more than a dozen large studies, concluded: “Available data do not show a clear difference between sweeteners and sugar for blood sugar or body weight. ‘
Some experts go further. Mike Lean, a professor of human nutrition at the University of Glasgow, an authority on diabetes who has written about the role of sugar in the obesity epidemic, says questions remain about the long-term benefits of sweeteners.
“There is no convincing evidence of better results than using artificial sugar sweeteners in normal amounts,” he said. “International guidelines say keep added sugar below 10 percent of calorie intake. And even that is to protect teeth, not to control diabetes or avoid weight gain: the evidence for this is very weak.
Professor Tim Specter, an expert in genetic epidemiology at King’s College London, author of The Diet Myth – The Real Science Behind What We Eat, agrees, saying the experiments show little or no weight loss or reduced risk of diabetes in those which range from sweet carbonated drinks to those that contain sweeteners.
“There’s no obvious benefit to switching to a diet drink – except when it comes to your teeth,” says Professor Specter. “These people need to lose weight, but they are not.”
He says that something else must be happening in the body; he says that either the brain is “reset” at the neuronal level (ie between brain cells) by the chemicals in the sweeteners so that it does not react like sugar, or artificial products affect the body’s intestinal microbiome – intestinal “soup” , made up of trillions of organisms that are thought to play a major role in everything from our appetite to our immune system.
“Our gut microbes may not know how to deal with chemicals we should never have eaten,” he said.
Proponents of stevia claim that it has an advantage over other sweeteners because it is plant-based and not created in a laboratory.
But Professor Specter believes that the very idea of replacing sugar with super-sweet alternatives is wrong. “We need to wean people, especially children, from oversweetened foods and teach them to enjoy other tastes instead,” he said.
Under the microscope
Former Jamaican cricketer Michael Holding, 67, meets our health test
Can you run up the stairs?
This is not a problem for me – I have no serious problems with playing cricket. But I can’t say that I have a lot of fitness these days, because the daily walks I did are now very sporadic.
Do you get your five a day?
I eat healthy: lots of fresh vegetables in salads and lots of fruit. I do not drink soft drinks, and if I drink beer and wine it is only with dinner.
Have you ever been on a diet?
No. I’m lighter now than when I played [he retired in 1989] – My parents gave me good genes. When I was playing, I worked out a lot in the gym and I had a lot of muscle, but I never gained too much weight. I weigh 187 pounds (13th 5 pounds) and am 6 feet 3½ inches.
Any vices?
I love racing and horses and just watching them. People would say it’s a vice because I bet on them. I don’t need to drink wine or beer, but horses, I would hardly stop being interested in them.
Any family illnesses?
There is a history of prostate cancer in my family. My father got it in the ’80s, even though he didn’t kill it. As my sister, a doctor, said, he will die before prostate cancer has any effect. Five years ago, my brother got prostate cancer and it killed him. I have an annual checkup that includes my prostate, but this has been going on for a long time.
The most serious illness / injury?
I had several cricket injuries. I tore the muscles in my right shoulder in 1979 and had my cartilage removed from my left knee in 1982. I resumed my career after both. I’m very lucky – I was quite healthy. As I told so many of my friends, one day I will just fall dead; I can’t imagine being sick.
Have you ever had plastic surgery?
No. What God has given me, I am pleased with.
Have you tried alternative remedies?
Only vitamin D. I was advised to take it because of the coronavirus [to boost immunity]. I get a lot of sun anyway, so I take in less power than most people.
A cure for a hangover?
I don’t drink enough for that.
What keeps you awake?
Sometimes I lay awake thinking about the future and my children [he has three], and even myself and what the future holds. But at my age there is not much future, so I do not stay awake and think about it.
Do you want to live forever?
Definitely not. I watch what is happening in the world today and most of the time I am so grateful that my parents are not around to see it. I don’t want to be around when people do what they want and no one holds them accountable. This is the direction in which I am moving.
n Why We Kneel, How We Rise, by Michael Holding (Simon and Schuster, £ 20).