Sue's Blog

Artificial sweeteners can cause diabetes and obesity? Wait, I thought they were supposed to prevent …

Well, researchers at the prestigious Weizman Institute of Science in Israel have shown that the opposite is true.
Unlike other universities, the Weizmann Institute is open only to graduates and has produced three Nobel laureates and three Turing Award laureates, so as you might expect, it’s a comprehensive study, described as an “elegant and home run experiment that shows causality in mice,” by the author of an accompanying editorial in the world’s top journal Nature.

The researchers showed that mice given water sweetened with commonly used artificial sweeteners - aspartame, sucralose or saccharin - had elevated blood-glucose levels after 11 weeks compared to mice given either a similar glucose solution or water alone.  (Elevated blood glucose - also called blood sugar - levels can lead to type 2 diabetes).

Next, the researchers transferred the gut microbiota from mice that consumed artificial sweeteners to other mice, and found that the recipient mice now had glucose intolerance:  conclusive proof that changes to the gut bacteria are directly responsible for the elevated glucose levels. The microbiota changes in these new mice are known to be associated with potential to develop obesity and diabetes.

Can it happen in humans?

Yes. First, the researchers looked at the largest human trial on the connection between nutrition and microbiota ( They found an association between consumption of artificial sweeteners, personal gut bacteria, and the potential for glucose intolerance.
Next they asked 7 young, healthy volunteers who did not normally consume artificial sweeteners to use saccharin. After just one week, 4 of the volunteers had begun to develop glucose intolerance. They also showed a different gut microbiota profile. The other 3 had no change in blood sugar levels or microbiomes.

Further reading: Suez J et al, Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature, 2014; DOI: 10.1038/nature13793


According to DiabetesAustralia, to lower your risk of diabetes you need to reduce your intake of fat, salt, and sugar.  “A healthy eating plan for diabetes can include some sugar. However, it is important to consider the nutritional value of the foods you eat. In general, foods with added sugars should be consumed sparingly …   In particular, high energy foods such as sweets, lollies and standard soft drinks should not be consumed on a regular basis.”

If you already have diabetes, we note that they recommend “intense sweeteners” (also known as artificial sweeteners) instead of sugar. Obviously we cannot now agree with that.  As the Suez et al study has shown, instead of preventing diabetes as previously thought, artificial sweeteners can actually CAUSE glucose intolerance in a substantial proportion of people by altering beneficial bacteria in the gut.
Sugar and diabetes (and obesity) - two ways to reduce your risk

1. Don’t use artificial sweeteners

Use sugar sparingly, as part of a healthy balanced meal but NOT in drinks.  

2. Don’t drink sugary drinks (especially soft drinks, energy drinks, sports drinks etc)

Sugar can contribute to obesity, especially when consumed in sweetened drinks. This is because people who drink sweetened drinks  do not feel as full as if they had eaten the same calories from solid food and do not compensate by eating less.
“What can I drink instead?”

What people used to drink before BigFood took over the world: mostly water (tap, filtered, mineral water, plain soda water); coffee (or decaf if you react to salicylates); tea and herbal teas (if you don’t react to salicylates).

“I can’t drink plain water. I am addicted to sugar.”

We often hear this, most recently from a man who explained that he can only drink Coke and beer. In our experience, sugar addiction is usually a side effect of dietary salicylates. You can get rid of it in three weeks by following the RPAH elimination diet that we recommend.  Yes, you will experience withdrawal symptoms for a few days. See more
By the way, contrary to popular belief, sugar does NOT cause children’s behaviour problems. The children are either reacting to additives such as colours and preservatives in sugary foods or they are reacting to dietary salicylates and the sugar addiction is part of that.  See more 

"I’m wondering whether Stevia has the same effect. It is claimed to be '100% natural'"

Only one small study has been done regarding Stevia in this area, and it appeared to produce similar findings:
Denina I and others, The influence of stevia glycosides on the growth of Lactobacillus reuteri strains. Lett Appl Microbiol. 2014 Mar;58(3):278-84.

While this study isn't definitive, the fact is that many studies over the years have showed that when people switch from sugar to low-calorie sweeteners in an effort to lose weight, for most of them it doesn't work as well as expected. Scientists have puzzled over this for years.

According to NY University gastroenterologist Ilseung Cho, who researches the role of gut bacteria in human disorders:

“We've suspected for years that changes in gut bacteria may play some role in obesity ... We know that we don't see the weight-loss benefit one would expect from these nonnutritive sweeteners, and a shift in the balance of gut bacteria may well be the reason"

- from

Basically, the jury is still out about Stevia and other "natural" non-nutritive sweeteners and food-industry lobbyists will do everything they can to cast doubt on any findings.

"What can I eat instead?"

You could use natural failsafe sweeteners such as white sugar, maple syrup and rice malt syrup (raw sugar and honey are high in salicylates). Eat them in moderate amounts with healthy foods. If you want to lose weight, avoid sweetened drinks and reduce your intake of sweetened foods. I myself am working on weight loss right now (I'm halfway through losing the 5 kg I gained while we were in Europe recently for 2 months walking the Camino and eating cakes). I don't drink sweetened drinks. There are many days when I don't have any sweeteners. I eat sweetened desserts as part of a healthy meal on weekends and have an occasional sweet treat e.g. like Blondies at the failsafe supper after the Crows Nest talk. It has taken me a while to change my taste buds but it worked, and now desserts seem more special.

Scientific references

Suez J et al, Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature, 2014; DOI: 10.1038/nature13793

Swithers SE. Artificial sweeteners are not the answer to childhood obesity. Appetite. 2015 Mar 28. pii: S0195-6663(15)00129-4.

Ludwig DS and others, Relation between consumption of sugar-sweetened drinks and childhood obesity, Lancet. 2001;357(9255):505-8.

and many more references in  Harvard school of Public Health: Sugary Drinks and Obesity factsheet "The Problem: Sugary Drinks Are a Major Contributor to the Obesity Epidemic ..."

Wolraich ML et al,  Effects of diets high in sucrose or aspartame on the behavior and cognitive performance of children. N Engl J Med. 1994 Feb 3;330(5):301-7. (Sugar does NOT cause children's behaviour problems)

See factsheet on sugar free sweeteners