Concern on artificial sweeteners: a ‘wolf in sheep’s clothing’?

(First of two parts)

A wolf in sheep’s clothing! That was how Dr. David Johnson, professor of medicine and chief of gastroenterology at Eastern Virginia Medical School in Norfolk, Virginia, described artificial sweeteners in his commentary that came out earlier this week in the Medscape Internal Medicine publication.

Dr. Johnson is just one of many medical specialists who have expressed concern about the possible harmful effects of artificial sweeteners, which are used in “diet” soft drinks, and a variety of other foods and drinks. They are recommended for better weight control, and for patients with diabetes since they’re supposed to be noncaloric and don’t contain any absorbable sugar.

However, based on some studies, they may not really be the healthier alternative many had hoped for. There are even studies suggesting that they may increase the risk of stroke, myocardial infarction (heart attack), and vascular death  (related to narrowing of the arteries).

Several years ago, Dr. Hannah Gardener, the lead investigator of a research paper from the University of Miami, Florida, reported during the annual congress of the American Stroke Association that people who had diet soda every day experienced a 61-percent higher risk of cardiovascular complications than those who reported not taking diet soda as a usual practice.

Other studies have likewise linked diet-soda consumption and the risk of developing metabolic syndrome and diabetes. Metabolic syndrome is composed of several risk factors including obesity, high-blood pressure, cholesterol and blood-sugar problems. This syndrome has been associated with serious complications like heart attack, stroke and premature deaths.

One should interpret all these “observational” studies with caution though. At most, they suggest an association but not a conclusive causal relationship, which more strictly designed, prospective clinical trials can provide.

In his commentary, Dr. Johnson cited a series of experiments from the Weizmann Institute of Science in Rehovot, Israel, that showed worsening of the metabolism including blood-sugar control in experimental animals.

He attributed these potentially harmful effects to the interaction with the microflora in the intestines. The hypothesis is that the intestinal microflora can convert the artificial sweeteners to fermented substances that may be harmful to the body’s metabolism. Pretreating the experimental animals with antibiotics that kill the intestinal microflora prevent this reaction.

The research group correlated these findings in humans, using a database with nutritional profiling in a large number of patients. They specifically looked at associations with blood-sugar control and ingestion of noncaloric artificial sweeteners. They noted increases in prediabetes, reduced blood-sugar tolerance, impaired fasting blood sugar, and increased body weight and waist-to-hip ratios, and hemoglobin A1c, which is an indicator of diabetes.

Central obesity pattern

“So, there was this central obesity pattern seen in metabolic syndrome. These changes were all related to this exposure to noncaloric artificial sweeteners, and there seemed to be a dose-related effect. In other words, those people who used more of these noncaloric artificial sweeteners had even more pronounced effects,” said Dr. Johnson.

The researchers then evaluated seven healthy, lean participants and fed them the FDA-recommended acceptable daily intake of an artificial sweetener (saccharin). They looked at the blood-sugar effect as a response only to the saccharin ingestion, with standardized meals. Four out of the seven participants showed impaired glucose or carbohydrate tolerance (IGT), and Dr. Johnson described the blood-sugar response as “strikingly aberrant” compared to baseline values. IGT is an established precursor to diabetes.

“As we strive to try to improve these disease states, we actually may be making them worse,” said Dr. Johnson. “To conclude, buyer beware to patients with diabetes or obesity. These artificial sweeteners certainly may be a part, if not the crux, of the problem, and patients should discuss using these sweeteners with their physician. Physicians who recommend these sweeteners need to take a step back and really reevaluate their recommendations, especially among their patients with diabetes and obesity. In fact, we may be dealing with a wolf in sheep’s clothing,” he warned.