Written by Charlotte Green
Currently, there is much attention being paid to reducing our sugar consumption, both for our general and metabolic health, especially considering the global rise of obesity and other lifestyle associated diseases such as type 2 diabetes. In fact, one of the most significant risk factors for type 2 diabetes is a Western diet, high in sugar, saturated fat, and processed foods (1). Consequently, in recent years, the consumption of artificial sweeteners has risen dramatically.
What are artificial sweeteners?
Artificial sweeteners are chemical substances which are used a sugar alternative to sweeten food and drinks. Artificial sweeteners can be up to around 600 times sweeter than sugar (in the case of sucralose), meaning they can be used in much smaller quantities (2). They are also known as non-nutritive sweeteners because they generally contain little or no calories.
Where are they found?
There are seven types of sweeteners approved for use in the UK; acesulfame K, aspartame, saccharin, sorbitol, sucralose, stevia and xylitol. These can be found in:
Common sweeteners found in the supermarket include brand names such as Canderel (containing aspartame) and sweetex (containing saccharin). Stevia, a natural sweetener alterative from the South American plant Stevia rebaudiana, is also becoming a popular sugar alternative.
Despite strict safety controls, there still remains considerable controversy surrounding artificial sweeteners, particularly in the media. As a consumer, it is often confusing to decide whether artificial sweeteners are a healthy choice. Here we will explore the evidence to try and make it a little clearer.
Artificial sweeteners and body weight
Although artificial sweeteners have been used to try to tackle rising obesity, some studies have found that they may in fact contribute to weight gain and inflammation, particularly sucralose (3,4). Artificial sweeteners can bind to sweet taste receptors in the tongue, intestines, and fat tissue, just like sugar. This triggers a variety of signalling pathways to communicate to the brain that food has been consumed and produce feelings of fullness. However, the signals induced by artificial sweeteners are weaker, which may be due to the lack of calories. It has been suggested that this could lead to compensatory consumption of extra calories (5).
Nevertheless, the majority of the research demonstrating that artificial sweeteners may cause weight gain were carried out on animals, which may not represent their action in humans (3). In fact, most human studies show that artificial sweetener consumption is not generally associated with weight gain (6).
Artificial sweeteners and the gut microbiota
Previously it was thought that artificial sweeteners were not broken down by the body and passed through unchanged. However, this is no longer believed to be the case, as evidence suggests that they can be broken down by the gut microbiota (7). The gut microbiota is the community of microorganisms residing in the gastrointestinal tract, necessary for a variety of important processes in the body, from digestion to immunity (8).
Some artificial sweeteners, such as sucralose and saccharin, can directly interact with the gut microbiota. The microbiota may be able to utilise artificial sweeteners as an energy source, leading to the growth of these species of bacteria (9). Thus, artificial sweeteners have the ability to modify the composition of the gut microbiota and wider processes in the body (7).
A recent important study investigated the effects of a two-week consumption of a variety of artificial sweeteners in volunteers who had previously been complete abstainers from artificial sweeteners. They found that sucralose and saccharin significantly altered the gut microbiota, causing dysbiosis, an imbalance of the “good” and “bad” bacteria. This change in the gut microbiota resulted in higher blood sugar levels (10), which could be due to inflammation induced by gut microbiota dysbiosis (7).
It is also important to note that some artificial sweeteners may affect digestion and cause uncomfortable gut symptoms such as bloating. Sweeteners ending in "-ol", such as sorbitol and xylitol, often found in sugar-free sweets, are classed as being high in FODMAPs, a fermentable carbohydrate known to cause gut symptoms in individuals with irritable bowel syndrome (IBS) (11). These products should therefore not be consumed in excessive amounts.
Natural vs artificial sweeteners
"Natural" sweeteners, such as stevia are derived from plants where as "artificial" sweeteners are chemical substances. "Natural" sweeteners are gaining popularity, but are they healthier than artificial sweeteners? Evidence seems to suggest that stevia does not have the potential to alter blood sugar levels, unlike some artificial sweeteners (12).
Furthermore, because stevia is derived from the leaves of the Stevia rebaudiana plant, it contains many other compounds besides the sweetener, which may have beneficial anti-inflammatory properties, although further research in human trials is necessary (13).
However, stevia, just like artificial sweeteners, has the ability to modify the gut microbiota, meaning it could have, as yet unexplored impacts on human metabolism (10).
Are artificial sweeteners bad for us?
At the moment, the evidence on artificial sweeteners is still inconclusive. Although some studies show that artificial sweeteners may have detrimental effects on weight, blood sugar control, and the gut microbiota, these studies tend to have been carried out in animals. The results in human trials are much more varied, with some showing a neutral effect on health or even some benefits when considering obesity (14).
The huge variation in conclusions could be due to the type of artificial sweetener investigated, as they all react differently in the body. Therefore, it is not helpful to generalise that all artificial sweeteners are categorically “bad”. It could be that some are more beneficial or detrimental than others. More long-term studies in humans are required to accurately determine the effects they have on our health.
For now, it is important to remember, like most things when considering the diet, moderation is key. Artificial sweeteners are not necessarily something to be feared, and can have a place in a healthy, balanced diet, when consumed consciously.
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Charlotte Green is a postgraduate Dietetics student at the University of Chester, after graduating with a degree in Biological Sciences from Durham University. She is passionate about the role of nutrition in health and longevity, the gut microbiome and the link between food and mood. Charlotte looks forward to supporting others live a healthier life in her future role as a registered Dietitian.
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