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Artificial Sweeteners - Good For Your Gut?

07/28/2016

Can we have our cake and eat it too? 

Sugar sweetness without the calories – until Sweet N Low, Equal and Splenda – was the holy-grail for food manufacturers.  The new miracle sweeteners were working fine until some scientists pushed back and claimed “artificial” sweeteners were unhealthy, caused cancer, or worse – made us even fatter! The current opinion of the FDA is that artificial sweeteners are “safe,” but should be used in moderation.  However, as recently as 2014, a research group led by Eran Segal & Eran Elinav, at the Department of Immunology, Weizmann Institute of Science, Israel, showed a clear link between artificial sweeteners, gut bacteria, and adverse health outcomes.

So, what is it in these sweeteners that makes them so controversial?

The five FDA approved sugar substitutes are acesulfame potassium, aspartame, neotame, saccharin, and sucralose.  They are synthetic molecules, which are arranged by chemists to trick your taste buds into thinking they are sugar.  They can be up to 80,000 times sweeter than sugar, and so a small amount can deliver that sugary taste without the customary bolus of calories. 

The study referred to above and also reported on in Nature, Scientific American and the New York Times, demonstrated that when mice were fed a daily dose of aspartame, sucralose, or saccharin, they developed high blood sugar and glucose intolerance, both prediabetic indicators. The unhealthy signs were not seen in the control group fed with the natural sugars, sucrose, or glucose. The study also showed that the effect of the artificial sweeteners could be reversed by clearing the gut of the treated mice with antibiotics, and allowing their gut microbiata to return to normal. 

In my opinion, unlike much of the previous research that linked artificial sweeteners with cancer, this is the first compelling evidence that shows artificial sweeteners can cause serious (diabetes related) health issues.

What’s actually happening in your body?

Although there is ever increasing evidence linking artificial sweeteners with aberrant glucose metabolism and obesity, it has not been definitively studied. However, recent research into weight management and gut bacteria by Dr. Jeffrey Gordon at the Center for Genomes Sciences, Washington University School of Medicine, St. Louis, showed that there is a relationship between obesity and gut microbiata. The study demonstrated that weight management is closely related to two species of gut bacteria: Bacteroidetes and Firmicutes. Obese mice had more Firmicutes, and lean mice had more Bacteroidetes. Interestingly, the proportion of Bacteroidetes to Firmicutes could be reversed by feeding obese mice with a calorie-restricted diet to increase the proportion of Bacteroidetes.

The link between the two studies is that artificial sweeteners also stimulate growth of Firmicutes in gut bacteria – the very same species that were shown to cause obesity in the Washington University mouse study. 

Dr. Gordon, leader of the Washington University study, suggests that the link between gut bacteria and weight is that certain species of gut bacteria, e.g., Firmicutes, are more efficient at extracting energy from a given diet than other gut bacteria species. This in turn allows the human gut to absorb relatively more nutrients, where the excess amount is stored as fat.

Therefore, when taken together we see a picture forming of how artificial sweeteners are far from helping in diet and weight control, and can aggravate the very problems they are trying to solve by changing the make up of our gut microbiome.

With this much evidence on the side effects of artificial sweeteners, how are we going to have our cake and eat it too? Until the food industry comes up with a sweetener that neither humans or our gut bacteria can digest, my advice would be: in moderation.

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