Let’s start by noting that the World Health Organization (WHO) recently warned against using artificial sweeteners for weight control. [1] What? I thought that was the whole purpose; I hear you saying. Well, not quite. Saccharin was initially hailed, even canonized, by patients with diabetes who required limiting their sugar intake for metabolic reasons. Early questions of safety were jettisoned when the diabetic patients revolted at an imminent ban. [2] And from then on, dieters joined those with diabetes in fake sugar consumption, aiming to reduce calorie intake.
But the WHO’s latest guidelines, issued in July, say that’s not a good idea.
The WHO’s guidelines were issued following a major meta-review of the literature on weight loss and artificial sweeteners published in April. While not final and still open to comment, the guidelines are anything but equivocal. The WHO advises against using artificial sweeteners for dieting purposes.
That hasn’t stopped the diet-food industry and my skinny-seeking friends from advocating guzzling diet beverages by the liter – specifically for weight-control purposes. Sure, there’s always been a razz on the “artificials.” Some of the old trusties, most recently aspartame, have been attacked as “cancer causers,” claims recently debunked by my colleague and friend, ACSH’s Susan Goldhaber. Does that mean they are safe or even effective?
The WHO says no. And a recent study reported in Cell magazine agrees.
Artificial sweeteners don’t work on a long-term basis.
“Higher NSS (non-sugar sweetener) consumption by adults led to lower body weight and BMI … when assessed in short-term randomized controlled trials, but was associated with increased BMI and risk of incident obesity in long-term prospective observational studies.” [emphasis added].
Their recommendation: lay off the stuff.
Tempering their recommendations, the WHO did not say the products themselves were toxic or unsafe. Instead, it claims that their use fostered an unhealthy diet. But who cares about that – if it means I won’t lose weight?
Industry stakeholders were outraged and are fighting back (including noting the effects of sugar on rotting teeth). These folks have both much clout and a lot at stake. According to Market Data Reports, globally, the artificial sweetener market reached 7.2 billion dollars and is expected to reach 9.2 billion in the next five years. Industry analysts project this to be a growth area predicated on society’s concern for health and consumer demand. Except the WHO report just threw a monkey-wrench into the hype, especially when it noted an association (not necessarily causal) with some untoward medical conditions – and increased death rates.
“Long-term NSS use was also associated with increased risk of type 2 diabetes, cardiovascular diseases, and mortality in prospective cohort studies conducted in adults….” - WHO Draft Guidelines
The Calorie Control Council, which counts suppliers and manufacturers among its members, was “disappointed” and fired back: claiming that “low and no-calorie sweeteners have been proven to assist in body weight and blood glucose level management, as well as calorie and sugar intake restriction,” highlighting that the draft guidelines are only conditional and that most of the evidence relied on was ‘very low’ to ‘moderate’ in quality. Other industry groups echoed the sentiment, alleging the WHO does a “disservice to public health” by failing to recognize the role of sugar/energy reduction and weight management.”
Dr. Rachel Cheatham, the founder of food and nutrition consultancy, the Foodscape Group, tried to put a good face on things, apparently looking for loopholes:
“Beyond the basics of safety and not raising blood sugar, there may be metabolic differences among them [the NSS] involving the gut microbiome, for instance, that are not yet fully understood….[and so t]his doesn’t mean consumers should necessarily try to completely avoid non-sugar sweeteners in their diet.”
- Dr. Rachel Cheatham.
The gut microbiome contains the trillions of microbes that can alter a person’s glucose metabolism and blood sugar levels. Unfortunately, for Dr. Cheatham and industry supporters, we now have serious evidence that artificial sweeteners, at least some of them, wreak havoc on our gut microbiome.
Two weeks ago, Dr. Jotham Suez and his collaborator Professor Eran Elinav published the results of their randomized controlled study and follow-up experiments in the journal Cell, evaluating saccharin, sucralose, aspartame, and stevia intake for two weeks in doses lower than the acceptable daily intake.
The results: All four artificial sweeteners tested “distinctly altered stool and oral microbiome and plasma metabolome,” each in their own way, closely correlated with the alterations in glucose tolerance. Worse, though, was the effect of saccharin and sucralose, which “significantly impaired glycemic responses.”
This means that the metabolic deficiencies saccharin was designed to correct in individuals with diabetes may actually be made worse by its use. The finding supported a conclusion reached in earlier preliminary experimental work published in Nature, linking NSS use to alterations in the gut microbiome and consequent obesity in animal studies.
This time the researchers went further. After evaluating the changes in humans, they conducted further animal experiments. To investigate whether the changes in the human microbiome were, in fact, responsible for the impaired glucose tolerance, gut microbes from 40 trial participants were transplanted into specially bred “sugar-naive” mice (which had never been exposed to artificial sweeteners).
“Our trial has shown that non-nutritive sweeteners may impair glucose responses by altering our microbiome, and they do so in a highly personalized manner."
The mice reacted by showing glucose tolerance patterns reflecting that of their human donors. Follow-up studies were conducted to determine how the different sweeteners affected the prevalence of different species of gut bacteria. Both saccharin and sucralose were found to alter glucose metabolism – but in highly individualized ways. This means that because each person’s microbiome differs, the effects of artificial sweeteners will vary, and based on the evidence we now have, it’s impossible to predict individualized responses.
“These findings reinforce the view of the microbiome as a hub that integrates the signals coming from the human body’s own systems and from external factors such as the food we eat, the medications we take, our lifestyle and physical surroundings.”
Clearly, for some NSS, particularly saccharin and sucralose, the alterations in the gut microbiome affect the body differently from the way intended.
And one last thought.
To those advocating across-the-board-solution of weight-loss by calorie cutting: Not all cases of excess fat are due to calories. For those who aren’t over 50 and have never been a female – calorie counting won’t do diddly for menopause-related weight gain. A little sensitivity, please.
[1] High-intensity artificial sweeteners currently in use also include neotame, acesulfame-K, and advantame. Cyclamate, dulcin, and alitame have not been approved by the FDA.
[2] The saccharin wars first surfaced in 1907. The early 1900s saw increased attention to newly created food additives by scientists, businesses (fearing competition), and the law. Shortly after the publication of Upton Sinclair’s, The Jungle, which exposed some of the rampant practices of food adulteration, Congress passed the 1906 Pure Food and Drugs Act. This gave the Bureau of Chemistry (the forerunner of the FDA) the power to “prohibited the interstate transport of unlawful food and drugs under penalty of seizure of the questionable products and/or prosecution of the responsible parties.”
Sources: Personalized microbiome-driven effects of non-nutritive sweeteners on human glucose tolerance Cell DOI: 10.1016/j.cell.2022.07.016
