Added sugars are bad news.

It's very clear that they promote diabetes, weight gain, and cardiovascular disease.

A 2013 study found a close link between the amount of sugar sold in a country and its diabetes rate.

For every additional 150 calories of sugar – the amount in a typical 12 oz can of soda – sold per person, a country's diabetes rate rose by one percent.

Given the scary stats, it's no wonder many seek out non-caloric alternatives.

Those choices seem smart on the surface, especially for folks who fear weight gain, diabetes, and their sickening ripple effects in the body. 

But are the sugar-free options really better for you? And are some better than others?

For starters, it helps to learn more about these sweet substances and where they come from.

A primer on sweeteners
Sweeteners fall into five main categories:
  1. Artificial sweeteners – synthetic chemicals such as aspartame, sucralose, and saccharin
  2. Novel sweeteners – Natural, non-sugar compounds like stevia (sold as Pure Via and Truvia)
  3. Natural sweeteners – Cane sugar, honey, maple syrup, and agave nectar are the most common, and all four deliver one or both of the same natural sugars: fructose and sucrose (a chemical that's half glucose and half fructose).
  4. Semi-natural sweeteners – The most prominent is high fructose corn syrup (HFCS), which is made by chemically tweaking natural corn syrup to adjust its proportions of fructose and glucose. Much like the sucrose in cane sugar, HFCS is about one half glucose and one half fructose (The proportions vary modestly among different kinds of HFCS).
  5. Sugar alcohols – Xylitol and sorbitol are the most common. They occur naturally in fruits and fibers and are added to sugarless toothpastes and chewing gums.
When it comes to the artificial stuff, three super-sweet chemicals dominate:
  1. Aspartame (the stuff in Equal and most diet sodas), which is low-calorie and 200 times sweeter than sugar.
  2. Saccharin (the stuff in Sweet n'Low), which can be up to 700 times sweeter than sugar.
  3. Sucralose (the sweetener behind Splenda), which is created by modifying the sugar molecule to make it 600 times sweeter.
Early evidence linking some artificial sweeteners to cancer has since been discredited, but other concerns linger, with varying degrees of credibility.

And people's fear of obesity and diabetes tend to outweigh their anxiety about possible adverse effects from artificial sweeteners.

Artificial sweeteners: Do they make matters worse?
Surprisingly, there's little evidence that substituting sugars with artificial sweeteners results in significant weight loss (Roberts JR 2015).

And growing evidence suggests that artificial sweeteners mess with the body's ability to regulate blood sugar.

Impaired ability to regulate blood sugar – called glucose intolerance or insulin resistance – inevitably lead to diabetes and weight gain.

These are the very conditions that users of artificial sweeteners hope to avoid, but that hope may be a false one.

Two years ago, researchers in Israel studied how artificial sweeteners change the human microbiome.

The microbiome is the diverse collection of microbial colonies that populate your gut, from where they influence your digestive system, metabolism, and immune system … even your mood and brain functions.

Fake sweeteners caused blood sugar problems in mice
To test artificial sweeteners against the real stuff, the researchers added either table (cane) sugar or artificial sweeteners (aspartame, sucralose, or saccharin) to the water supply of mice.

After just one week, the mice given artificially sweetened water developed a marked intolerance to glucose.

In contrast, the mice given regular sugar water suffered no such harm.

When the researchers examined the animals' microbiomes, they found that artificial sweeteners had changed these miniature ecosystems to a striking extent (Suez J et al. 2014; Suez J et al. 2015).

However, they couldn't be certain that people suffer the same adverse effects from artificial sweeteners, so they conducted two tests in humans.

Same bad effects seen in people
The Israeli scientists then examined 381 non-diabetic volunteers.

Disturbingly, they found a link between the participants use of any kind of artificial sweeteners and signs of glucose intolerance.

In addition, the gut bacteria of those who used artificial sweeteners were different from those who did not.

Next, the Israeli team recruited seven volunteers and added saccharin to their diets, at the highest level recommended by the U.S. Food and Drug Administration.

In less than a week (six days), more than half of the participants suffered a spike in blood sugar levels.

And one in two of the volunteers had begun to develop glucose intolerance, just like the mice.

The Israeli researchers performed two other experiments that confirmed that changes in the microbiome caused by artificial sweeteners were the cause of glucose intolerance:
  • When the researchers treated the mice with antibiotics, killing much of the gut microbiome, the glucose intolerance went away.
  • When they injected human gut bacteria colonies altered by artificial sweeteners into the intestines of mice, the animals developed glucose intolerance.
These tests confirmed that the effect of artificial sweeteners was the same in mice and humans.

It remains to be seen what, if any, other negative health effects might result from microbiome changes caused by these synthetic chemicals.

Natural, artificial, or novel?
Given the rather conflicting and confusing evidence, what's the healthiest choice?

If you want to reduce your diabetes risk, stay away from natural and artificial sweeteners alike.

Fortunately, the natural, plant-derived, non-caloric sweetener stevia doesn't seem to affect the blood-sugar control system.

Sadly, it took the FDA many years to approve sale of stevia in the U.S., despite clear evidence of its safety.

(Stevia belongs to the same family as lettuces, dandelions, sunflowers, artichokes, thistles, and ragweed. People who are allergic to any of those may experience an allergic reaction to stevia, although this appears to be quite uncommon.)

We don't want to believe that the agency's foot-dragging was linked to political influence from the makers of artificial sweeteners ... but it's hard to draw any other conclusion.

  • Gardner C. Non-nutritive sweeteners: evidence for benefit vs. risk. Curr Opin Lipidol. 2014 Feb;25(1):80-4. doi: 10.1097/MOL.0000000000000034. Review.
  • Miller PE, Perez V. Low-calorie sweeteners and body weight and composition: a meta-analysis of randomized controlled trials and prospective cohort studies. Am J Clin Nutr. 2014 Sep;100(3):765-77. doi: 10.3945/ajcn.113.082826. Epub 2014 Jun 18.
  • Roberts JR. The paradox of artificial sweeteners in managing obesity. Curr Gastroenterol Rep. 2015 Jan;17(1):423. doi: 10.1007/s11894-014-0423-z. Review.
  • Suez J, Korem T, Zilberman-Schapira G, Segal E, Elinav E. Non-caloric artificial sweeteners and the microbiome: findings and challenges. Gut Microbes. 2015;6(2):149-55. doi: 10.1080/19490976.2015.1017700. Epub 2015 Apr 1. Review.
  • Suez J, Korem T, Zeevi D, Zilberman-Schapira G, Thaiss CA, Maza O, Israeli D, Zmora N, Gilad S, Weinberger A, Kuperman Y, Harmelin A, Kolodkin-Gal I, Shapiro H, Halpern Z, Segal E, Elinav E. Artificial sweeteners induce glucose intolerance by altering the gut microbiota. Nature. 2014 Oct 9;514(7521):181-6. doi: 10.1038/nature13793. Epub 2014 Sep 17.