by Marion Nestle
Sep 19 2014

Do artificial sweeteners cause–not cure–glucose intolerance?

The big nutrition scare last week was the study in Nature finding that in mice and, maybe, humans, artificial sweeteners mess up the microbiome and make some people even more intolerant of glucose.

The authors conclude that their results call for a reassessment of massive use of artificial sweeteners.

The study is complicated and difficult to read but the Wall Street Journal has a nice summary.  It explains why the study is getting so much attention:

The new Nature study marks a significant advance because it brings together two separate areas of research—the role of sweeteners in raising blood sugar levels, and the complex workings of the vast colonies of bacteria that inhabit the gut. Individuals can have differing bacterial colonies in their gut, meaning people respond differently to what they consume.

The study involved several experiments.  These found:

  • Mice fed saccharin, sucralose, or aspartame had significantly higher blood-glucose levels than mice whose diet included sugar, or just water.
  • Mice with sterilized digestive tracts, who were given bacterial transplants from artificial-sweetener-fed mice, displayed higher blood sugar levels than those receiving bacterial transplants from sugar-fed mice.
  • People who typically use artificial sweeteners have different kinds of bacteria in their intestines than those who do not.  They also are more glucose intolerant.
  • Seven volunteers fed artificial sweeteners for four days displayed higher blood-sugar levels as well as altered populations of bacteria in their gut.

The Wall Street Journal quotes the Calorie Control Council (the trade association of makers of artificial sweeteners).  The CCC said:

The results from the mouse experiments may not apply to humans, while the human experiments had a small sample size. It said further research was needed.

Despite my lack of enthusiasm for artificial sweeteners, I think the Calorie Control Council has a point.

The excellent report by Kenneth Chang in the New York Times explains why.

At present, the scientists cannot explain how the sweeteners affect the bacteria or why the three different molecules of saccharin, aspartame and sucralose result in similar changes in the glucose metabolism.

Chang ends with this:

Dr. Frank Hu, a professor of nutrition and immunology at the Harvard School of Public Health who did not take part in the study, called it interesting but far from conclusive and added that given the number of participants, “I think the validity of the human study is questionable.”

Here’s why I’m not fond of artificial sweeteners:

  • They taste bad (to me)
  • They have no demonstrated effectiveness in helping people lose or maintain weight.
  • They are artificial, and violate my rule to “never eat anything artificial.”

Do they mess up the microbiome and cause glucose intolerance, insulin resistance, and metabolic syndrome?

That would be fascinating, but I’m reserving judgment pending further research.

In the meantime, I’ll take sugar—in moderation, of course.

  • Melodie Kelly

    Hello Ms. Nestle,

    I just wanted to say how much I enjoy receiving your blog – it
    is my e-mail indulgence at work.

    I felt I had to comment on this post as it resonated with
    me. My mother, who is addicted to diet coke suffers from severe crohn’s
    and has had several bowel resections. The only other people I know
    that have had bowel resections (3 others) have also been addicted to diet coke (consuming at least one a day). I know it is very anecdotal but I do not know anyone else who drinks diet coke (because it tastes awful). The
    correlation that I have observed between consuming diet coke on a regular basis and bowel surgery frightens me. I am thankful that there are people such as yourself and the author of this study that are willing to do research which will hopefully lead to better policies and decisions in regards to what is allowed to be considered food.

    Thank you on behalf of me and my family for all of the great
    work you do and for educating us one blog post at a time.

    All the best,

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  • Eric Potter

    Ms. Nestle,
    I just began reading your book food politics and thought I would explore your foodpolitics site. My son’s type I diabetes has taken us on a journey of investigating nutrition for him and for the rest of our family, so the issues you address in this post are quite intriguing. We have seen other research hinting at problems with artificial sweeteners, so had given up sucralose months ago.
    Thanks for your hard work in this arena. I look forward to learning more from your writings and applying it to my family’s health as well as in my integrative medical practice, Sanctuary Medical Care and Consulting in Tennessee.
    Eric Potter MD
    Wholistic Healthcare for the Glory of God

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  • Timar

    How about sugar alcohols, particularly xylitol? It has exactly the same taste and texture and is not any more artificial than refined sugar (naturally occurs in fruits and vegetables). Yet it is lower in calories, has a much lower GI, acts as a fermentable prebiotic fiber and actively inhibits caries causing bacteria instead of promoting them. Too good to be true? Not if you ask PubMed…

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  • endmathabusenow

    I have a few problems with the study. The parts that actually examine the bacteria use only saccharin as the artificial sweeteners. The figures that show glucose response and other metabolic measurements for the three artificial sweeteners does not appear to show any pattern that separates the group of artificial sweeteners from water, glucose, and sucrose. See figure 5c of their extended set of figures (the full article is behind the pay wall)

  • I heard about this study, and it might be the start of concrete proof that drinking 2-3 liters of Diet Coke every day isn’t good for you. But, I’ll probably never stop this daily addiction, because I don’t see many immediate negative consequences from drinking it.

    I do everything else (diet, exercise, weight) right, if not perfect, so I allow myself this habit. I do drink water when I’m serious about hydration (before and during hard workouts), but I immediately pound the Diet Coke afterwards.

    A few people often preach to me how bad the stuff is, but I still think they do more good than harm.

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  • Emaho

    Hi Eric Potter,

    I have had Type 1 diabetes for 49 years and, in my opinion, I’m a live and not blind today because of Dr. Richard Bernstein and his book, ‘Diabetes Solutions’. I read the book in 2004 and my A1c went from an average of 7.1 to 5.7. I highly recommend that you read it.

    BTW, eating a high carb diet as a diabetic can led to gastroparesis in 10 to 20 years. This is a quiet but deadly complication for insulin dependent diabetics.

  • Emaho

    “… I’ll take sugar—in moderation, of course.” Some people produce huge amounts of insulin in response to a few carbs in the diet and others just the opposite. As Dr. Atkins’ excellent work shows moderation in the consumption of carbs, especially refined carbs, depends on the individual metabolism of the person. For more insulin-resistant people, correctly following his dietary plan, especially that in the newest version, ‘The New Atkins diet for the new you’ will help you find out how many carbs is a moderate amount for your individual metabolism..

  • plky

    yeah, my brother-in-law was like you. Drank 2-3 litres of Diet Coke every day, was a serious runner, ate all the right foods, until he was diagnosed with osteoporosis before the age of 50. Ingesting the combination of caffeine and phosphorous found in diet cola causes a hormonal reaction that leaches calcium from your bones. If you haven’t had a bone density test, I’d get one if I were you.

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  • Thanks, I’ll look into that!

  • Rashed

    Hi Nestle,

    Thanks for your nice article.

    It’s my view to follow an effective guide to lose fat and gain muscle.

    Read more :

  • AS a huge supporter of the AdvoCare brand I am going to watch this study very close as they use sucralose as their main sweetener! I have been on them for some time as well as put my personal training clients on some and it seems to improve not only weight but overall well being of those to take it. So until the studies say otherwise I am going to continue on! Great Read!

    Lucas Hale, CPT

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