Glucose intolerance, or pre-diabetes, affects an estimated 41 million Americans. It’s the gateway to type 2 diabetes…and as obesity rates rise, more and more people are stepping through. A brand new study published in the weekly science journal Nature reports: artificial sweeteners linked to glucose intolerance…the very condition these sugar substitutes are supposed to treat!
What Is Glucose Intolerance?
When consuming a food or beverage high in sugar, a healthy individual with properly functioning glucose controls will experience a spike in glucose (blood sugar), followed by a decline as insulin is released from the pancreas. Insulin tells the cells to either burn the excess glucose as energy, or store it as fat.
When your cells stop listening to the instructions insulin is giving them, they become insulin resistant, and don’t let glucose enter. Blood sugar levels remain chronically elevated, and this state of glucose intolerance eventually manifests as full-blown diabetes if left unmanaged.
The Link Between Artificial Sweeteners and Glucose Intolerance
Motivated by the emerging link between artificial sweeteners and obesity, researchers from the Weizmann Institute in Israel set out to explore the possible association between artificial sweeteners and glucose intolerance.
Young healthy mice received one of three sweeteners in their drinking water—saccharin, aspartame, or sucralose—at a dose equivalent to the FDA’s maximum daily suggested allowance for artificial sweeteners. The researchers compared this variable group to two controls: young healthy mice who received plain drinking water and young healthy mice who received regular sugar in their drinking water.
After 11 weeks, researchers tested glucose tolerance by giving the mice a drink high in sugar, and then taking blood samples. The mice who consumed artificial sweeteners exhibited dramatic elevations in blood-glucose levels…much higher than the mice in the control groups. Furthermore, blood-glucose levels in the variable group took significantly longer to stabilize back to normal. Researcher Eran Segal explains, “They showed significant glucose intolerance at levels comparable to a metabolic disease.”
Artificial Sweeteners Affect Gut Bacteria
Researchers speculate that glucose intolerance may be caused by the effect artificial sweeteners have on gut bacteria. To test this theory, they cleared out gut bacteria using antibiotics (which destroy both good and bad microflora). They then tested saccharin’s effects. With no gut bacteria, the artificial sweetener demonstrated no substantial influence on glucose tolerance. However, when they transferred the gut bacteria of mice who had been feed saccharin into the mice with previously bacteria-free guts, the mice became glucose intolerant!
An examination of gut bacteria before and after the experiments confirmed that the mice fed artificial sweeteners demonstrated a dramatic increase in several different types of gut bacteria, particularly those associated with obesity.
Researchers then attempted to connect the results of this animal study to its applicability to humans. They reviewed data from 381 people and determined that there was indeed a link between artificial sweeteners and glucose intolerance, but they couldn’t determine what came first…the obesity, glucose intolerance, and then artificial sweeteners in an attempt to manage the metabolic conditions…or the artificial sweeteners, then the obesity, then the glucose intolerance.
To help solve the mystery, they put seven healthy individuals who did not normally eat artificial sweeteners on an artificial sweetener regimen that matched the FDA’s daily saccharin allowance. The result? Four out of seven people saw a dramatic increase in glucose intolerance, while three people experienced no significant change. The four who were affected had different gut bacteria than the three who were not. Moreover, those exhibiting glucose intolerance showed significant rises in deleterious gut bacteria.
So, what to take from this groundbreaking study? Co-author Eran Elinav perhaps sums up the findings the best: “The most shocking result is that the use of sweeteners aimed at preventing diabetes might actually be contributing to and possibly driving the epidemic that it aims to prevent.”