Scary Sweets

Antibiotics are effective against diseases caused by bacteria because they kill or inhibit the growth of the causative bacteria. Antibiotics have made it possible to treat a wide variety of infectious diseases. However, since 1980, the number of “antibiotic-resistant” bacteria that do not respond to conventional antimicrobial agents has increased worldwide, making it increasingly difficult to prevent and treat infections. The Centers for Disease Control and Prevention (CDC) states that “antibiotic resistance is one of the greatest public health challenges of our time,” with at least 2.8 million people in the United States developing antibiotic-resistant infections each year and over 35,000 people dying as a result. Failure to halt infections caused by antibiotic resistance can lead to dangerous and life-threatening complications such as sepsis. Did you know artificial sweeteners contribute to the creation of antibiotic-resistant bacteria?

Global consumption of commonly used artificial sweeteners (saccharin, sucralose, aspartame, and acesulfame potassium) is estimated at approximately 117,000 tons per year. After ingestion with foods and beverages, artificial sweeteners pass through the human digestive system without being metabolized, and their concentration estimates can be tens of mg/L in human urine and hundreds of mg/L in the human digestive tract. These artificial sweetener spread antibiotic resistance genes (ARGs) in intestinal bacteria, contributing to an increase in fatal infections. 

The emergence of ARGs is driven by a process called horizontal gene transfer (HGT). (Normally, organisms copy chromosomes “vertically” from mother cells to daughter cells through cell division, but horizontal transmission (propagation) is the transfer of genes from one individual to another, or from one species to another, without passing through reproduction, such as from parent to offspring.) The mechanism is to increase ARGs by transferring genetic material from one bacterium to another.  In a February 2021 publication in the peer-reviewed journal The ISME Journal (International Society for Microbial Ecology), the research team described the process as “the equivalent of sexual reproduction or mating in bacteria, in which direct contact between two bacteria transfers resistance genes from donor to recipient. Direct contact between the two bacteria results in the transfer of resistance genes from the donor to the recipient,” and the recipient may become multidrug-resistant (i.e., ineffective against many drugs). It has also been found that consumption of such artificial sweeteners is associated with changes in the intestinal microbiota similar to those caused by antibiotics. 

The number of ARGs in the bacterial population within the human microbiota is said to be immeasurable. For example, a study titled “Assessing the global health risks of antibiotic resistance genes,” published in Nature, found 2,561 ARGs that collectively confer resistance to 24 different antibiotics on the human gut microbiota. As the study concludes, “Our results show that 23.78% of ARGs, especially those that confer multidrug resistance, pose a health hazard.” 

A study published last month (December 2022) in the medical journal “Gut Bacteria” found that all four artificial sweeteners tested (saccharin, sucralose, aspartame, and acesulfame potassium) increased the production of reactive oxygen species (i.e., free radical damage) and promoted a function called “plasmid-mediated conjugative transfer to gut bacteria. This is a form of horizontal gene transfer (HGT) that speeds up the adaptation of bacteria to different substances, such as antibiotics and artificial sweeteners, by exchanging key genes. Additionally, synthetic sweeteners may be more conducive to the development of bacterial resistance than antibiotics, with artificial sweeteners overcoming barriers and creating superbug genes in bacterial strains that normally cannot exchange antibiotic resistance genes (ARGs). 

Artificial sweeteners are full of really scary stuff and are pervasive in processed foods and beverages.  They are used in most “zero sugar” beverages, “sugar free” products, and in many soft drinks such as Calpis, sports drinks, energy drinks, and canned or bottled coffee.  Chewing gums , candy, dressings, alcohol and even medicines are also commonly made with artificial sweeteners.  So be sure to check the names of the ingredients. Note that aspartame is often labeled as “L-phenylalanine compound,” so please look carefully.


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