By Betty Zou, PhD
In the world of dental care, X stands for xylitol, a type of sugary alcohol extracted from plants. Over the past decade, xylitol has become increasingly popular as an alternative to common sweeteners such as sucrose and glucose. Take a stroll through your local supermarket and you’ll find xylitol in a wide range of products—from toothpaste and mouthwash in the oral care section to sugar-free candies and drinks in the snack aisle.
Much of xylitol’s appeal comes from its benefits for both oral and overall health. The simple sugars in the food and drink we consume also feed the bacteria in our mouth. The harmful cavity-causing bacteria, in particular, are able to ferment these sugars to produce acid that damages tooth enamel. Xylitol, however, is a nonfermentable sweetener, which means that microbes can’t metabolize it. This property helps to maintain a healthy balanced pH in the mouth while starving the destructive bacteria. Another feature of xylitol that contributes to oral health is its anti-adhesive ability. By preventing bacteria from sticking to hard surfaces like tooth enamel, xylitol can also prevent and reduce plaque formation.
The effects of xylitol on the body continues to differ from that of simple sugars once it makes its way past the mouth and into the gut. Unlike glucose, xylitol is not absorbed well in the gut. The absorption efficiency of xylitol is estimated to be 20-30% that of glucose.
The inefficient absorption of xylitol is a double-edged sword. On the one hand, because xylitol uptake in the gut is so poor, it doesn’t produce the same spike in blood glucose levels as simple sugars. With a low glycemic index, this makes xylitol a great alternative sweetener for people with diabetes.
On the other hand, the slow and ineffective absorption of xylitol means that much of it remains in your lower intestines. Normally this isn’t an issue but when you have exorbitant amounts of common substances like vitamin C, salt or lactose sitting in your gut, it can create an imbalance between the concentrations within the gut and in the rest of the body. In an effort to dilute the excess material, your body pumps water into the gut resulting in what’s known as osmotic diarrhea.
Does this mean you should stay away from xylitol-containing products? Not at all. Since the 1970s, numerous studies have been done to examine the health effects and safety of xylitol. In and gradually increased their dose. Researchers observed no incidence of gastrointestinal pain or diarrhea until the daily dose surpassed 90 grams. If you wanted to test your own limit and consume 90 grams of xylitol in one day, you’d have to eat 18 of these sugar-free lollipops or drink 12 bottles of qii.
How a person responds to xylitol also depends on factors like body weight and fiber consumption, which helps absorb the excess water pumped into the gut. Even with individual variations, results from available studies indicate that most healthy adults can tolerate between 30 and 40 grams of xylitol in a single dose before there is any real risk of gastrointestinal discomfort. That upper limit is likely higher in individuals who regularly consume xylitol-containing products and have gradually built up their tolerance. The bottom line: when consumed in moderation, xylitol is a safe and effective way to maintain good oral health.