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Artificial Sweeteners: partners or enemies?

Updated: Feb 24, 2020

Artificial sweeteners have been blamed for causing obesity, diabetes, Parkinson’s disease, and cancer. Are artificial sweeteners safe alternatives to sugar?

diet soda
Diet soda - safe alternative to sugary drinks?

Artificial sweeteners (AS) are high potency sweeteners without the carbohydrate calories – and are marketed as the healthier alternative to sugar.

Recently, there have been controversial discussions whether artificial sweeteners may cause or worsen weight gain or have detrimental effects on glucose metabolism via alterations of the intestinal microbiome, and cause or worsen diabetes.

Artificial sweeteners have been the subject of debate for decades, and the available data is far from being clear, hence, it is worthwhile to have a critical look at artificial sweeteners in the right context.

Can artificial sweeteners cause weight gain?

Artificial sweeteners have been long suspected to cause weight gain and diabetes via appetite increase (Blundell, Lancet, 1986), however, large meta-analyses (e.g. Bellisle et al, Eur J Clin Nutr, 2007) have failed to conclusively establish a causal link between artificial sweeteners, increased appetite and weight gain. In contrary, in some studies, obese subjects who were allowed to drink artificially sweetened beverages lost more weight than those only allowed to drink water. Thus: no, artificial sweeteners cannot cause weight gain.

Can artificial sweeteners cause insulin spikes?

Insulin spikes, as seen with sugary drinks, have never been proved in humans. If this were true, drinking beverages with artificial sweeteners in a fasting state would lead to low blood sugar levels (hypoglycemia).

Thus: no, artificial sweeteners cannot cause insulin spikes.

Can artificial sweeteners cause diabetes?

A large study done recently, the San Antonio Heart Study, wrongfully linked consumption of diet soda to type 2 diabetes, creating a lot of confusion. When looking at the data, however, it becomes obvious, that this is a misinterpretation. People were asked, if they consume sugar or artificially sweetened drinks, and those who answered “artificial sweeteners” had more often type 2 diabetes than those who answered “sugar”. This is a so-called prospective study that cannot rule out a "reverse causality: people with type 2 diabetes are much more likely to use artificial sweeteners than sugar, with hopes of losing weight and controlling their blood glucose levels. This does not mean that artificial sweeteners cause diabetes. As the authors correctly state: a causality cannot be established.

Can artificial sweeteners destroy the human microbiome and lead to prediabetes and obesity?

Recently, saccharine and sucralose (not aspartame) in very high doses were shown to alter the intestinal microbiome and to lead to glucose intolerance and obesity. However, these results were only shown in mice, data in humans is still very ambiguous, and it seems that genetic susceptibility plays a big role here. Mouse experiments are rarely able to mimic the complexity of human physiology, and studies linking changes of the intestinal flora to weight gain in humans are virtually non existent – except for a preliminary report from 2017 linking sucralose and acesulfame-K with gut dysbiosis and increased intestinal glucose absorption. Thus, this question cannot yet be answered unambiguously and, while caution is warranted, there’s no reason for concern.

Can artificial sweeteners cause cancer?

This has been, yet again, a question that has lead to a heated debate and a lot of confusion. The overall conclusion is: while there is evidence to link very high-dose artificial sweetener use (the equivalent of hundreds of cans of diet beverages daily) with cancer in animals, there is no evidence to support such a link in humans.


The concern: Studies of laboratory rats in the 1970s linked high doses of saccharin with the formation of bladder stones that can lead to bladder cancer.

The evidence: These results however could not be replicated in mice and it has been determined that the increase in bladder cancer risk in rats is due to the way the rat urinary system is built.

Human studies that examined the rates of cancer among populations who are more likely to consume artificial sweeteners (people with diabetes) found that the risk of cancer was no higher than the general population.


The concern: A report in the 1990s suggested that the increase in number of people with brain tumors may be associated with the introduction and use of artificial sweetener in the United States.

The evidence: An analysis of the US National Cancer Institute statistics showed that the incidence of cancers began to rise eight years before the approval of aspartame and mainly among people aged 70 and older, a group not exposed to the highest doses of aspartame.

Data from the Diet and Health Study from more than half a million retirees found that increasing consumption of aspartame-containing beverages was not associated with the development of cancer.


The concern: After studies in rats suggested that cyclamate might increase the risk of bladder cancer in humans, cyclamates were banned in the US in 1969 by the Food and Drug Administration (FDA).

The Evidence: Re-examination of data concluded that cyclamate does not cause cancer. Cyclamates are still banned in the US; however the FDA’s concerns about cyclamate are not related to cancer.


There’s undoubted evidence for the harms of excess dietary sugar. The key word here is: excess. Water should be the basis of hydration and replacing excess sugar with excess artificial sweeteners is the wrong signal. However, those people who struggle to lose weight, and in whom the occasional consumption of an artificially sweetened beverage helps resist cravings for other, calorie-rich sweets, may use them: occasionally and like a stimulant. Because, as with everything: the dose makes the poison.

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