Ulcerative Colitis and Stevia
New research points to some potential downsides to Stevia use in products containing certain strains of Lactobacillus Reuteri
Research on Stevia and Gut Bacteria
I have always had an interest in digestive disorders, both from personal experience, and that of family and friends. My story started a few years ago with a recurring abdominal pain on the right. Some days it would be there, similar to a menstrual cramp, but obviously not due to recurrence and timing. My doctor tried a variety of things, none of which really seemed to help. Finally he instructed me to start a food log, and to see if anything seemed to correlate. I followed his advice for a couple of months, and a pattern started to emerge: fats. If I had a ton of avocados, or a bunch of fried food, or a super fatty steak, soon enough the abdominal pain would show up. So, for a month or so, I wiped out fats, but it did not really seem to be helping, so I started to look at what I also had in the meals that were fat heavy. They turned out to mostly contain wheat, so for the next month I started to reduce (but not eliminate) wheat heavy foods, such as breads, donuts, pancakes, etc. THAT started to make a difference, and I eventually realized that if I did not consume significant wheat products, I could go back to eating avocados and fried food without the pain. I have been following a similar diet ever since, and so far, the pain has not returned.Between family and friends, I am close to a couple folks with Ulcerative Colitis, and one with Crohn's. Ulcerative Colitis dietary modifications have remained pretty stagnant over the years since closest family member was diagnosed: wheat is fine, dairy is questionable, eat fiber, but not too much, and hope you can identify your problem foods and avoid them. Fiber was easy as my family has always been full of avid gardeners, and its easy to have veggie rich meals when all you need to do is take a trip to the garden for the majority of the year. Even with Ulcerative Colitis advice remaining mostly static, regular dietary advice started to change. Instead of demonizing fats, we started to demonize wheat, which then moved to demonizing sugar. With the demonization of sugar came a wave of artificial sweeteners with questionable digestive system effects. Soon a natural alternative emerged: Stevia - it was from a plant! So, what is any reasonable UC sufferer to do? Perhaps, swap to stevia, it seemed the safest in regards to both UC directives and according to general nutrition advice of the time, but until recently, there had not really been any studies on what effects our new found additive might have on those with compromised digestion systems. Luckily, that is just beginning to change.
Before we get too far into the results of that study, lets talk about how Stevia is made: Stevioside and Rebaudioside A are glycosides commonly sold as "Stevia Extract" and are 250 to 300 times sweeter than sucrose (the extract from sugar cane). As described by the Global Stevia Institue, they are extracted from the Stevia plant by drying the leaves and steeping them in water. The resulting liquid is then purified either with water or alcohol (which is removed as part of the process), leaving the pure stevia extract behind. It is worth noting that many commercially available stevia products also contain erythritol, a sugar alcohol, in addition to the stevia.
Now, onto the recent study, full text available via the US National Library of Medicine - National Institutes of Health, and published in Letters in Applied Microbiology. The researchers question: does the presence of stevia compounds affect Lactobacillus Reuteri strains growth ability. To talk about why that is important, lets first talk about Lactobacillus Reuteri. As nicely summarized by the Wikipedia article, it is a common natural gut bacteria, and is also commonly used in probiotics. It is also considered to be the most common strain of gut bacteria of healthy individuals (and many animals). OK, so we know it is really common in healthy folks, but why. Researchers in the '80s found that the strain creates a substance that is a natural broad-spectrum antibiotic. This substance can also kill "good" gut bacteria, in addition to the "bad", but the researchers invoved in that study found that it took five times more of it to do any harm to the good guys. The effective summary of this is that a healthy level of Lactobacillus Reuteri can effectively combat overgrowths of bad fungi, yeast, and protozoa. As an example, it can inhibit the growth of E.coli in the gut.
Now, onto the recent study, full text available via the US National Library of Medicine - National Institutes of Health, and published in Letters in Applied Microbiology. The researchers question: does the presence of stevia compounds affect Lactobacillus Reuteri strains growth ability. To talk about why that is important, lets first talk about Lactobacillus Reuteri. As nicely summarized by the Wikipedia article, it is a common natural gut bacteria, and is also commonly used in probiotics. It is also considered to be the most common strain of gut bacteria of healthy individuals (and many animals). OK, so we know it is really common in healthy folks, but why. Researchers in the '80s found that the strain creates a substance that is a natural broad-spectrum antibiotic. This substance can also kill "good" gut bacteria, in addition to the "bad", but the researchers invoved in that study found that it took five times more of it to do any harm to the good guys. The effective summary of this is that a healthy level of Lactobacillus Reuteri can effectively combat overgrowths of bad fungi, yeast, and protozoa. As an example, it can inhibit the growth of E.coli in the gut.
The objective was to test this in-vitro (in the lab, not in an intestine), primarily to determine if stevia use in foods aiming to include Lactobacillus Reuteri would affect the growth ability of the bacteria. They tested six different strains, and the results proved to be quite interesting. Some strains appeared to be mostly unaffected by the presence of stevia extracts, but others had growth rates reduced by nearly two-fold (as measured by the production of lactic and acetic acid, a by-product of sugar consumption by the bacteria). This should not be inferred to mean that the researchers stole the bacteria's normal food and replaced it with stevia. Actually, they supplemented the mixture used to feed the control group with stevia, so stevia was in addition to the sugars the bacteria normally feed upon.
I think this study is interesting for a couple of reasons. First, if reproducible, it may show that stevia is not an acceptable way to sweeten fermented foods, as it may partially negate the good bacteria that is one of the best reasons to go for yogurts. Secondly, it makes me wonder if there are valid considerations for people who have difficulty maintaining healthy gut flora to begin with, such as sufferers of Ulcerative Colitis or Crohn's. Note, the researchers do not make any assumptions that their results will expand to in-gut similarities, but will future research show that significant stevia consumption hinders intestinal growth of Lactobacillus Reuteri as much as it does in-vitro? Only time will tell, but for now I think I am going to stick with honey.
I think this study is interesting for a couple of reasons. First, if reproducible, it may show that stevia is not an acceptable way to sweeten fermented foods, as it may partially negate the good bacteria that is one of the best reasons to go for yogurts. Secondly, it makes me wonder if there are valid considerations for people who have difficulty maintaining healthy gut flora to begin with, such as sufferers of Ulcerative Colitis or Crohn's. Note, the researchers do not make any assumptions that their results will expand to in-gut similarities, but will future research show that significant stevia consumption hinders intestinal growth of Lactobacillus Reuteri as much as it does in-vitro? Only time will tell, but for now I think I am going to stick with honey.