artificial sweeteners

Study: Gut Bacteria on Artificial Sweeteners
Artificial Sweeteners

Artificial Sweeteners

Since nearly everyone consumes artificial sweeteners in something (toothpaste, protein shakes, diet sodas), there’s impressive coverage of any new study on the topic. This of course is an incentive for the study authors to take their conclusions a bit further than they really should, and the headline writers then compete to jump to even more unwarranted conclusions.

So this Israeli study is everywhere: this writeup, “Saccharin solution? Sugar substitutes may mess with gut bacteria—causing obesity in the process,” from The Economist, is among the responsible ones that carefully mention the context of other studies showing no such effects.

In short, researchers gave mice water with sugar substitutes, sugar, or nothing. These researchers were especially interested in the microbiome and investigated the effects on gut bacteria of the different diets; after a week they dosed them with glucose and noted that the mice on sugar substitutes had higher blood sugar, meaning they had not processed the glucose as effectively (which normally occurs by release of insulin.)

They then killed off the gut bacteria in the mice, and the processing of glucose returned to normal, which supports the theory that the gut bacteria themselves had changed in the presence of artificial sweeteners to increase insulin resistance.

This is very interesting and suggests lots more research possibilities on the influence of our biomes on body processes; it tells us something about mice and artificial sweeteners. But it also reminds us that the response of mice to saccharin was the reason cited to attempt to ban it in the US, but further research in primates showed no significant health concerns at reasonable levels of consumption (though it still tastes bad!)

Reaching for significance (and headlines), the researchers then did something very interesting before publication: they tried to tie their results to human obesity. Noting that some correlation studies show consumption of artificial sweeteners is correlated with weight gain, they suggest the possibility (without claiming it) that human obesity is caused by artificial sweeteners interacting with the gut biome. They recruited 7 (7!) nonusers of artificial sweeteners, gave them maximum allowed doses of saccharin, and observed changes in the gut biomes of 4 of the 7 which looked much like the changes seen in the mice. This result, even if accurate, barely reaches statistical significance.

What can we conclude here? That 90% of human nutrition studies can’t be replicated, meaning no single study means much; that there may well be some very interesting research to be done on the gut flora and fauna, since there are many clues showing the microbiome significantly affects digestive and metabolic processes; that researchers are tempted to direct their results toward headlines which get them notoriety and funding; and that since most studies show reasonable use of artificial sweeteners to substitute for sugar is an aid to weight loss and critical for real diabetics, no one should change their habits because of this study.

Let’s look at the headlines generated by the study:

NYTimes: “Artificial Sweeteners May Disrupt Body’s Blood Sugar Controls”
FT: “Israeli researchers link artificial sweeteners with obesity”
Israel Hayom: “Artificial sweeteners may drive diabetes, Israeli study finds”
ABC: “Study: Artificial Sweeteners May Promote Diabetes”
CBC: “Artificial sweeteners linked to obesity epidemic, scientists say”
WSJ: “Research Shows Zero-Calorie Sweeteners Can Raise Blood Sugar”

Note the better-quality publications (NYTimes, WSJ) avoid sensationalizing the results–it’s especially reprehensible to suggest diabetics should be terrorized and stop using artificial sweeteners, which allow them some semblance of sweetness and have been used for decades without causing problems. The weasel word “linked” in “Artificial sweeteners linked to obesity epidemic, scientists say,” should be a clue to the lack of scientific backing for that headline’s claim.

For further reading, I can recommend the WSJ’s relatively cautious coverage: “Research Shows Zero-Calorie Sweeteners Can Raise Blood Sugar,” by Gautam Naik:

“The scope of our discovery is cause for a public reassessment of the massive and unsupervised use of artificial sweeteners,” said Eran Elinav, a physician and immunologist at Israel’s Weizmann Institute of Science and lead author of the study, which appeared Wednesday in the journal Nature….

They transplanted bacteria from artificial-sweetener-fed mice or sugar-fed mice into other mice that were bred to have no gut bacteria of their own and that had never consumed a sweetener product. They found that the bacterial transfer from the sweetener-fed mice raised the blood sugar levels in the transplant recipients—suggesting that the gut microbes had triggered the higher sugar levels in mice fed fake sweeteners.

Was the same link true for people? Dr. Elinav and his colleagues examined the relationship between long-term consumption of artificial sweeteners and various metabolic measurements in some 380 nondiabetic people.

They found that the bacteria in the gut of those who regularly ate fake sweeteners were notably different from those who didn’t. In addition, there was a correlation between the sweetener consumption and a susceptibility to glucose intolerance, which is a disturbance in the blood glucose level.

Correlation, however, doesn’t necessarily mean causation. In the next experiment, seven volunteers who normally didn’t consume fake sugar were asked to consume products high in the sweeteners. After four days, four of them had significantly higher blood-sugar levels as well as altered populations of bacteria in their gut—an outcome similar to what was seen in mice.

“This susceptibility to sweeteners [can now] be predicted ahead of time by profiling the microbes in the people,” said Eran Segal, a co-author of the study and computational biologist at the Weizmann Institute.

The results need to be corroborated through a study with many more participants.

Our lead author certainly wants to take artificial sweeteners away from people, or at least require prescriptions! Can’t have anything go unsupervised. Such attitudes tend to indicate a less-than-objective scientist.

Here’s a blog post from Suppversity which goes into detail–they have actually read the paper, while I have only seen pieces. Not all the mice suffered ill effects, and the paper’s authors also managed to not publicize the fact that the effects were seen most strongly with saccharin, less with sucralose, and hardly at all with aspartame. So the news trumpeted around the world was (to be charitable) incomplete.

More on Diet:

Getting to Less Than 10% Body Fat Like the Models – Ask Me How!
Starbucks, Jamba Juice Make You Fat
Fat Doesn’t Make You Fat. Government Guidelines Did!
‘Fed Up’ Asks, Are All Calories Equal?
Fructose: The True Villain?
More on “Fed Up”, Sugar Subsidies, and Obesity
Another Study on Diet Drinks
LeBron James Cut Carbs for Lean Look
Why We’re Fat: In-Depth Studies Under Way
Almonds: Superfood, Eat Them Daily for Heart Health
Fish Oil Supplements Ward Off Dementia
More on Diet Drinks: Best Studies Show They Aid Weight Loss
Vani Hari: “Food Babe” and Quack
Cleanses and Detox Diets: Quackery
Sugared Soft Drinks: Health Risk? (and What About Diet Soda?)
Gluten-Free Diets: The Nocebo Effect
Acidic Soft Drinks and Sodas: Demineralization Damages Teeth
Fish and Fish Oil for Better Brain Health
Salt: New Research Says Too Little May Be Unhealthy
Bulletproof Coffee: Coffee, Oil, and Butter for Breakfast?

More on Diet Drinks: Best Studies Show They Aid Weight Loss
Sugar in Processed Foods

Sugar in Processed Foods – UCSF

One theme we’re going to return to over and over here is the bad science we see in media every day. Media needs content, so even bad studies with no control groups and self-reporting are trumpeted as news, which is one reason why we are assaulted by supposed proof of a diet or health question one day, then fed “proof” of the opposite the next. It’s all to keep you clicking and getting views to pay for the news site; the study promoters want the world to think their results are meaningful so they’ll get funding to do more. Incentives to hype are great, and so hype is what we get.

You can learn to read the studies for yourself to understand which to pay attention to. Or you can read specialty publications that have a record of understanding how real science works so you can rely on them when they say a study’s conclusions are really valid. That’s what I’m trying to do here — I read all the press releases so you don’t have to.

Today’s example is a large meta-analysis by Paige Miller and Vanessa Perez of the Center for Epidemiology, Biostatistics, and Computational Biology, Exponent Inc., published in The American Journal of Clinical Nutrition. A meta-analysis is a statistical study of a basket of other studies which attempts to discern a better answer to questions raised than the individual studies by combining them; techniques for doing this are complex, but the usual result is to quantify a trend in answers over a much larger examined population. The abstract [with my annotations]:

Background: Replacement of caloric sweeteners with lower- or no-calorie alternatives may facilitate weight loss or weight maintenance by helping to reduce energy intake; however, past research examining low-calorie sweeteners (LCSs) and body weight has produced mixed results. [They will go on to show only unreliable studies show diet drinks induce weight gain.]

Objective: The objective was to systematically review and quantitatively evaluate randomized controlled trials (RCTs) and prospective cohort studies, separately, that examined the relation between LCSs and body weight and composition. [A prospective cohort study identifies a sample, characterizes each element of the sample typically by measuring or questioning, then follows the sample to try to show what initial conditions lead to what outcomes.]

Design: A systematic literature search identified 15 RCTs and 9 prospective cohort studies that examined LCSs from foods or beverages or LCSs consumed as tabletop sweeteners. Meta-analyses generated weighted mean differences in body weight and composition values between the LCS and control groups among RCTs and weighted mean correlations for LCS intake and these parameters among prospective cohort studies.

Results: In RCTs, LCSs modestly but significantly reduced all outcomes examined, including body weight (−0.80 kg; 95% CI: −1.17, −0.43), body mass index [BMI (in kg/m2): −0.24; 95% CI: −0.41, −0.07], fat mass (−1.10 kg; 95% CI: −1.77, −0.44), and waist circumference (−0.83 cm; 95% CI: −1.29, −0.37). Among prospective cohort studies, LCS intake was not associated with body weight or fat mass, but was significantly associated with slightly higher BMI (0.03; 95% CI: 0.01, 0.06). [Emphasis mine: only the unscientific prospective cohort studies showed weight gain for diet drink consumers.]

Conclusions: The current meta-analysis provides a rigorous evaluation of the scientific evidence on LCSs and body weight and composition. Findings from observational studies showed no association between LCS intake and body weight or fat mass and a small positive association with BMI; however, data from RCTs, which provide the highest quality of evidence for examining the potentially causal effects of LCS intake, indicate that substituting LCS options for their regular-calorie versions results in a modest weight loss and may be a useful dietary tool to improve compliance with weight loss or weight maintenance plans.

So what we can see here is that self-promoters who wanted to show low-calorie sweeteners had negative effects on body weight and metabolism were citing poor, uncontrolled studies. They explained this supposed effect by claiming these sweeteners confused metabolism by triggering insulin release through their effect on taste buds, but there was no evidence of that. One plausible explanation for the studies showing weight increases for those who reported drinking diet sodas is that such people are already aware of their tendency toward weight gain, and are more likely to consume diet drinks as a result; other factors about them create the weight gain, and their knowledge of their propensity to gain weight is the cause for their choosing to drink diet sodas. Those other causes of weight gain continue during the study, so naturally this population gains more weight than the unconcerned.

Our meta-takeaway from the meta-analysis: correlation is not causation. If you personally want to change some practice or undergo a procedure to improve something about yourself, pay very little attention to studies which are not randomized, controlled trials or their equivalent. Another good example of this is the constant drumbeat of Conventional Wisdom claiming that going to college increases your future earnings; the figures cited are almost always ignoring the fact that people who complete college have thereby been screened for aptitude for admission and then screened again for the ability to stick to a plan. If you are trying to decide whether or not to go to college, your aptitude and fortitude are already determined, and the effect of going vs. not going for you is much less, especially when you evaluate the opportunity costs: what you could be doing instead of college to educate yourself and grow your earnings capacity. Some people (and you might be one of them) would earn more by starting their own business or going to a high tech startup and skipping higher education. Not that earnings are the most important thing; one common pattern is to gain admission to a prestigious school with excellent networking connections and use those ties to jump into a business without bothering to finish school (the route of Bill Gates and many other entrepreneurs.)

Learn to recognize the lies and distortions in the Conventional Wisdom, and chart your own course.

Now it’s likely true that simply drinking water or tea instead of any soft drink is the healthiest option. But for those who appreciate the carbonation and sweet taste of a diet soda, you should feel free to indulge, in moderation. Diet sodas are far better for your body than sugared sodas, large servings of fruit juice, or jazzy Starbucks or Jamba Juice concoctions.

For more on this topic:

Sugared Soft Drinks: Health Risk? (and What About Diet Soda?)
Another Study on Diet Drinks
Fructose: The True Villain?
More on “Fed Up”, Sugar Subsidies, and Obesity

More on science-based diet for health and fat loss:

Getting to Less Than 10% Body Fat Like the Models – Ask Me How!
Starbucks, Jamba Juice Make You Fat
Fat Doesn’t Make You Fat. Government Guidelines Did!
‘Fed Up’ Asks, Are All Calories Equal?
LeBron James Cut Carbs for Lean Look
Why We’re Fat: In-Depth Studies Under Way
Almonds: Superfood, Eat Them Daily for Heart Health
Fish Oil Supplements Ward Off Dementia
Vani Hari: “Food Babe” and Quack
Cleanses and Detox Diets: Quackery
Sugared Soft Drinks: Health Risk? (and What About Diet Soda?)
Gluten-Free Diets: The Nocebo Effect
Acidic Soft Drinks and Sodas: Demineralization Damages Teeth
Fish and Fish Oil for Better Brain Health
Salt: New Research Says Too Little May Be Unhealthy
Bulletproof Coffee: Coffee, Oil, and Butter for Breakfast?

Another Study on Diet Drinks
Sugar in Processed Foods

Sugar in Processed Foods – UCSF

Some experts think artificial sweeteners trick the body’s feedback mechanisms and increase cravings for food; if so, using them would not be helpful in weight loss. But as a previous study showed, there’s little evidence of that aside from unscientific studies showing that people who drink diet drinks tend to gain weight; correlation not proving causation, more studies are needed.

A new study featured in this Reason piece by Ronald Bailey is closer to scientific in that it compares results against an otherwise similar control group which was not asked to use diet beverages, and it shows a small weight-loss effect by drinking diet beverages instead of water, presumably because the artificially-sweetened beverages were more satisfying and reduced other food consumption.

I personally enjoy a diet soda (currently favoring ginger ale) for its refreshing effect; a little carbonated sweet flavor is very satisfying. And I have very low body fat as a result of a low-carb diet.

For more on diet and weight loss:

Getting to Less Than 10% Body Fat Like the Models – Ask Me How!
Starbucks, Jamba Juice Make You Fat
Fat Doesn’t Make You Fat. Government Guidelines Did!
‘Fed Up’ Asks, Are All Calories Equal?
Fructose: The True Villain?
More on “Fed Up”, Sugar Subsidies, and Obesity
LeBron James Cut Carbs for Lean Look
Why We’re Fat: In-Depth Studies Under Way
Almonds: Superfood, Eat Them Daily for Heart Health
Fish Oil Supplements Ward Off Dementia
More on Diet Drinks: Best Studies Show They Aid Weight Loss
Vani Hari: “Food Babe” and Quack
Cleanses and Detox Diets: Quackery
Sugared Soft Drinks: Health Risk? (and What About Diet Soda?)
Gluten-Free Diets: The Nocebo Effect
Acidic Soft Drinks and Sodas: Demineralization Damages Teeth
Fish and Fish Oil for Better Brain Health
Salt: New Research Says Too Little May Be Unhealthy
Bulletproof Coffee: Coffee, Oil, and Butter for Breakfast?