Are Sweeteners Safe?
Sweeteners are sweet food additives that are often added to foods in the place of sugar to provide that sweet flavour we love, with a fraction of the calories - or even no calories!
Could they actually be too good to be true?
Are sweeteners safe?
All the sweetness of sugar, minus the calories...Are artificial sweeteners too good to be true?
Some popular artificial sweeteners you may have heard of are aspartame, saccharin, sucralose and acesulfame-K. Some natural sweeteners you may have heard of are stevia or monk fruit and some sugar alcohols you may have heard of are xylitol and erythritol.
However, there is wide scale debate about the safety of sweetener consumption, particularly the artificial ones.
There is some evidence that the brain has a different response to sweeteners than sugar, increasing appetite for sweet foods. When fruit flies were given sweetener, in addition to their normal fruit fly diet, over a prolonged period of time they increased food and calorie intake (1). Although they didn’t observe any weight gain (yes they used tiny little fruit fly scales)! This increased food intake is thought to occur because the brain typically associates a sweet taste with an influx of calories. When the body doesn’t get those calories (like when you’re eating low calorie sweeteners) it can trigger a particular fasting response in the brain, upping appetite and the need for sugar! FYI, this theory would also apply to natural sweeteners.
And it is true that sweetened or ‘diet’ beverage consumption is higher in people who are over weight or obese (2). Although this does not mean that the sweetened drinks cause obesity, that would be a very simplistic conclusion to draw, it merely states that more overweight people are drinking diet sodas. This could be due to lots of different factors including this demographic being more likely to choose drinks marketed as ‘diet’.
In really good quality, well designed human studies, where more variables can be controlled (called randomised control trials, RCTs), there is a big lack of evidence for sweeteners causing weight gain. In fact in many trials, sweeteners have been found to help with weight loss (3).
It would appear that in humans, sweeteners have little effect on appetite and can promote weight loss if used as a tool to reduce calorie intake as part of a weight loss plan. Although, theoretically high intakes of sweetened food and drink over a prolonged period of time could promote cravings and an increase in food intake. Sweeteners' effect on body weight probably comes down to the context of its role in the overall diet.
Sweeteners do not increase blood glucose (sugar) after consumption therefore they can be a good sugar substitute for people with diabetes. There is controversial evidence that people with diabetes tend to drink more sweetened beverages than those without diabetes, but again this could be due to reverse causation. I.e. ‘Diet’ drinks didn’t cause diabetes, diabetes caused the ‘diet’ drinks.
It has been suggested that sweeteners can jack up your insulin, creating cravings and increasing risk of insulin resistance. However there is also a plethora of research showing zero to minimal insulin secretion following sweetener ingestion. This could actually be helpful for diabetics who need to carefully control insulin levels. Also if insulin levels were spiked by sweeteners we would expect to see effects of hypo-glyceamia after ingestion. The insulin would lower the much needed baseline level of blood sugar by promoting uptake into the body's cells in lieu of actual ingested glucose (sugar).
There is some evidence that consuming high amounts of sweeteners can however disrupt your ability to clear blood glucose as efficiently following ingestion of actual sugar (4). This was however only found in 4 people out of a total 7 participants in a study, so clearly more evidence is needed, but it does highlight that our biological response to sweeteners may be very individualised. If you happen to be one of these responders to sweeteners it may actually affect your blood glucose regulation and perhaps increase your risk for diabetes.
Sweeteners don’t seem to affect blood glucose or insulin levels however there is a small amount of evidence that they can affect some people's ability to efficiently clear blood glucose after a high sugar intake.
Interestingly, the 4 people in the study mentioned earlier, who had impaired blood glucose regulation after sweetener ingestion, also had changes in gut microbiota (4). Again out of the 7 participants, just 4 saw this effect, which may mean that some people will see a shift in gut microbes and some won’t. Further research has highlighted a change in 4 of the 39 gut bacterial groups in those using sweeteners. This was associated with reduced levels of short chain fatty acid in the gut, which can be beneficial for a healthy weight, reducing insulin resistance and improved blood fats (5). Although other studies show very little change in gut microbes following sweetener use (6).
In a recent 2019 review of sweeteners and gut microbes it was stated that “so far, only saccharin, sucralose and stevia change the composition of the gut microbiota”. This review also highlighted the dire need for more human studies in this area, however so far rodent studies suggest we should at least be wary (7). Having said that rodent studies have a habit of using huge amounts of sweetener, that is not realistic to the human diet.
There is a lot of research showing changes in gut microbes following sweetener use in mice. We have seen some changes in human gut microbiota too but we need more convincing evidence. The knock on effects this may have to human health is not yet fully understood.
There has long been speculation that artificial sweeteners can cause cancer. This stems from one particular study in the 1970’s that found that bladder cancer increased in rats given saccharin. However, since then it has been highlighted that this was due to a rat specific problem in metabolising saccharin and therefore does not apply to humans. Other than this, there is a lack of evidence for sweeteners' involvement in cancer risk in rats (8) and in humans (9), including a review looking at almost 600,000 people (10). Cancer Research UK says “the best evidence shows that artificial sweeteners in our food and drink, like aspartame, do not increase the risk of cancer.”
Sweeteners have been linked to cancer in rodent models using extremely high doses however this does not seem to translate biologically to humans.
Which sweeteners to use and which to avoid?
Acceptable daily intakes (ADIs) are set for all sweeteners and they are much lower than the amount it would take to be toxic and much higher than people tend to consume on a daily basis. For example, if you drank around 15-20 cans of diet drink per day you would still be within the safe range. Interestingly stevia has one of the lowest ADIs at 4 mg per Kg of body weight. With this being said there may be a few things you want to consider when choosing which sweetener to use. Read on below to find out more about the different types.
Which sweeteners to use and which avoid?
Aspartame may be linked to headaches in those predisposed to migraines, lower mood in those predisposed to depression and increased brain activity in children with epilepsy. Those with the rare metabolic disorder phenylketonuria (PKU) cannot metabolise an amino acid in aspartame. You should avoid aspartame if you belong to any of these groups.
Baking with sucralose is probably a bad idea, as the sucralose can react at high temperatures creating potentially carcinogenic compounds called chloropropanols. Sucralose may also alter the gut microbiome.
Saccharin may alter the gut microbiome.
Stevia has been found to lower blood pressure in people with hypertension and lower blood sugar in people with diabetes. Stevia may alter the gut microbiome.
Erythritol has been linked to improved blood vessel health, but can cause gas and diarrhoea in large doses.
Xylitol has been linked to improved tooth health and reduced dental decay. It can cause gas and diarrhoea in large doses. It is also toxic to dogs.
Consistently eating large amounts of nutrient void, processed foods whether sweetened with sugar, artificial or natural sweeteners is probably not a good idea if it is creating persistent cravings or displacing healthy foods out of your diet. If you are avoiding nutrient dense foods regularly in favour of these nutrient void processed options, you should consider making some changes. Drink less sugar or sweetened beverages by choosing water or whole fruit smoothies, and reduce the amount of weight watchers/ diet snacks you eat by including more naturally occurring sweetness in fruit and yoghurt etc. Sweeteners, like sugar, and like anything in our diet, can have a detrimental effect if eaten to excess and if you develop an unhealthy habit around it. Sweetened food can be included in a diet as a sometimes food or drink ideally with the focus predominantly on nutritious, whole foods.
You are unlikely to reach the toxic consumption level for any of the sweeteners, however some sweeteners may have health concerns for particular individuals. Natural sweeteners seem to have less reported side effects. However, it is not a good idea to displace healthy, nutritious foods from your diet in favour of processed foods, whether it’s ‘diet’ or full sugar options.
Let’s Sum It Up
Sweeteners are low or no calorie food additives used as sugar substitutes. They can help with weight loss if you swap sugar containing foods for sweetened versions to reduce calories. Although, including a high amount of sweeteners regularly may increase your sweet tooth. Sweeteners do not increase blood glucose or insulin. More research is needed to investigate the effects of sweeteners on glucose regulation. Sweeteners may change the gut microbiota but more studies are needed. All available evidence suggests no link between sweeteners and cancer. Some people should avoid certain sweeteners and generally speaking natural sweeteners have reported side effects and can have health benefits. Sweeteners can safely be used in your diet however you would ideally prioritise nutrient dense foods over processed nutrient void options.
Want to know more? Watch our latest DediKate Eat Great chat with Amy - Ep #38 Are Sweeteners Safe?
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