The year was 1665 and the Black Plague came calling on the city of London. The disease first appeared in Britain in 1348 and had been a constant threat with cases sprouting up here and there but never really causing wide-spread panic. When the plague ravished Holland in 1663, King Charles II of England forbade all trade with the Dutch, partly out of concern that the plague might spread but also because England was engaged in a trade war. Nevertheless, by the spring of 1665, London saw a spike in cases of the deadly disease. When spring gave way to one of the hottest summers on record, the Black Plague overwhelmed the impoverished neighborhoods of London, claiming the lives of approximately 1,000 people per week.
Then, the Lord Mayor of London, Sir William Lawrence, made a fateful decision that seemed prudent in the moment but in hind sight, proved disastrous for the population of London. Believing that the disease was being spread by pets, he ordered all of the dogs and cats in the city to be exterminated. Approximately 40,000 dogs and 200,000 cats were killed and almost immediately the death rate rose from 1,000 per week to 6,000 per week.
Sir William had the best intensions in mind when he ordered the deaths of almost a quarter million animals but as sometimes happens when people make important decision based on intuition rather than known facts, unintended consequences soon followed. Had Sir William known that the disease, caused by a bacterial pathogen known as Yersinia pestis, was spread by fleas found on rats, the people of London would have been better off had the Lord Mayor employed more dogs and cats to kill off the rats. Without the presence of natural predators, the rat population in London exploded and soon the sewers and city streets were overrun by rats carrying multitudes of tiny disease-filled fleas.
I offer the above example as a means to show that while people may have good and noble intentions while making policy, the consequences of decisions made on misinformed intuition can have devastating consequences. With this concept in mind I’d like to offer a modern example of how things can go terribly wrong even under the guise of good intentions.
For over a century now, non-caloric artificial sweeteners have been introduced into our foods as a means to provide that sweet taste that everyone loves and craves without the associated high energy content of caloric sugars. It’s a good idea, right? Artificial sweeteners are low cost and manufacturers claim that they support weight reduction and normalization of blood sugar levels. If you drink diet sodas and sugar-free desserts you are consuming artificial sweeteners and despite controversial data regarding the benefits and pit-falls of artificial sweetener consumption, our government has approved at least six products for use in the United States. And if the FDA says that they are safe, then they’re safe, right?
Not so fast. Let’s take a look at what scientific studies have to say about artificial sweetener consumption and let’s do so in the context of what these products do to our gut flora. After all, if you’ve followed the Gut Hero blog, you’ll know that our gut flora, also known as the gut microbiota, plays a central role in the health of an individual. The gut microbiota is found in your colon and is composed of approximately 40 trillion microorganisms, weighing roughly three pounds. Some have called the gut microbiota the forgotten organ and it plays a role in your digestion, immunity, hormone production, brain function and a myriad of other systems.
The goal of artificial sweetener manufacturers is to provide a substance that tastes good yet passes through the body without any consequences. At first glance, this goal seems fairly benign. After all, if you can get a substance that has a desirable taste through the consumer’s body without any caloric impact you have the perfect recipe for weight loss; not to mention a great money making opportunity for the manufacturer, especially when the word “Diet” is plastered all over the label in bold letters. So most artificial sweeteners pass through the human gastrointestinal tract without being digested. The problem is that the undigested substance comes into direct contact with the gut microbiota and research shows that this impact has a profoundly negative effect on our health.
For example, Suez, et al., evaluated the impact of artificial sweeteners on the gut flora and metabolism of laboratory mice and human subjects. They found that consumption of commonly used artificial sweeteners has a significant effect on the functional and compositional make-up of the gut microbiota. Remember that the 1,000 or so species of microorganisms in the intestines are in constant competition with each other for available nutrients and when a substance is introduced into the gut environment, it will promote the growth and proliferation of organisms that are either beneficial or detrimental to the health of the host. High fiber-content fruits, vegetables and legumes promote a diverse and healthy gut microbiota while highly-processed junk food reduces diversity and promotes an unhealthy imbalance, favoring microorganism populations that have been associated with metabolic disease and obesity.
In the Suez research, the scientists found that the compositional change in the gut microbiota population brought on by the introduction of commonly used artificial sweeteners resulted in an unhealthy reduction of microbial diversity and induction of glucose intolerance in the host. Glucose intolerance is a hyperglycemic condition (i.e., high blood glucose levels) that is considered a pre-diabetic state associated with increased risk of cardiovascular disease and obesity. This research suggests that artificial sweetener consumption contributes to metabolic disease and so rather than helping the consumer to lose weight, these products may very well be contributing to chronic disease.
I realize that some readers may complain that I’m an alarmist by comparing the disastrous but well-intentioned decision by the Lord Mayor to exterminate all cats and dogs during the 1665 London epidemic with the good-intentioned decision to allow the mass production of artificial sweeteners to promote weight-loss. Perhaps, but allow me to make the following point…
The Lord Mayors decision did not cause the epidemic but it certainly exacerbated the problem. Can’t the same be said about the mass production and consumption of artificial sweeteners? According to the National Institutes of Health, the obesity epidemic is the second leading cause of death in the U.S. and causes an estimated 300,000 deaths per year. By comparison, the London Black Plague epidemic of 1665-1666 claimed only approximately 100,000 people. Artificial sweeteners have not caused the current obesity epidemic but if they significantly alter the composition of the gut flora to favor an unhealthy population of microorganisms, as suggested by the Suez research, then they are certainly exacerbated the problem.
To be fair to food manufacturers and the FDA, there are scientific studies that claim to show beneficial results of artificial sweetener consumption without elevated blood glucose levels (Tordoff, et. al.). But in situations like these where experts cannot agree and where the data is equivocal, my advice is to take a cautious approach and simply abstain from the substance.
Remember that good-intentioned decisions regarding your health by policy makers and so-called experts aren’t always the best decisions. Sometimes these decisions, as described above, have unintended consequences. When it comes to the rapidly evolving field of gut health and the impact of microorganisms on our wellness, the best approach is to stay informed the best you can. The Hero Gut Blog was created to help in that effort. So stay informed and remember that scientific studies have shown that people with a diverse set of gut microorganisms tend to be less obese and are less likely to develop chronic metabolic diseases. To learn more ways to promote gut microbiota diversity, visit our blog.
Suez, et. al., Artificial sweeteners induce glucose intolerance by altering the gut microbiota. 2014. Nature: 514:181-186
Tordoff, et. al., Effect of drinking soda sweetened with aspartame or high-fructose corn syrup on food intake and body weight. 1990. Am. J. Clin. Nutr. 51:963-969