Sweet treats often raise concerns about dental decay, leading many consumers to seek sugar-free candy as an alternative. Whether these products cause cavities is not a simple yes or no answer, but depends on the complex interplay of ingredients and oral chemistry. Removing sucrose eliminates the primary fuel for cavity-causing bacteria. However, the replacement sweeteners and other components introduce both dental benefits and potential risks. Understanding these nuances is necessary to determine if “sugar-free” truly means “cavity-free.”
How Sugar Substitutes Affect Dental Plaque
Traditional sugar creates cavities when the bacterium Streptococcus mutans metabolizes fermentable carbohydrates like sucrose into organic acids, such as lactic acid. These acids rapidly lower the pH in dental plaque, causing the demineralization of tooth enamel. Sugar substitutes circumvent this process because oral bacteria cannot effectively break them down.
Most sugar alcohols (e.g., sorbitol and maltitol) and non-nutritive sweeteners (e.g., sucralose and aspartame) are considered non-cariogenic. This means they are not fermentable by the acid-producing bacteria in dental plaque. Since the bacteria cannot consume these substitutes for energy, they do not produce the destructive acid that initiates decay. This absence of acid production is the main reason sugar-free candies are less likely to cause cavities than their sugar-filled counterparts.
Specific Ingredients That Protect Teeth
Some sugar substitutes offer active therapeutic benefits for dental health beyond being non-cariogenic. Xylitol, a five-carbon sugar alcohol, is known for its direct anti-cariogenic effect. S. mutans attempts to metabolize xylitol but cannot complete the process, resulting in a futile energy cycle that inhibits bacterial growth and survival.
Regular consumption of xylitol reduces plaque adhesion and decreases the overall population of harmful bacteria in the mouth. Erythritol, another polyol, also demonstrates active benefits and may be more effective than xylitol in managing oral health factors. Studies show erythritol can reduce dental plaque weight and lower the counts of S. mutans. Another element is that the sweet taste of many sugar alcohols stimulates salivary flow, which naturally helps neutralize acids and aids in the remineralization of early enamel lesions.
Hidden Risks to Tooth Enamel
Despite the benefits of non-fermentable sweeteners, sugar-free candy is not without risk to tooth enamel. A primary concern is the presence of food acids used for flavoring, particularly in sour varieties. Sour candies often rely on high concentrations of acids like citric, malic, or tartaric acid to achieve their characteristic tang.
These added acids can directly cause enamel erosion, a process independent of bacterial activity. Enamel begins to soften and dissolve at a pH level below 5.5, and some sour candies have been measured with a pH as low as 1.6. The physical properties of some sugar-free candies also pose a threat. Hard or sticky confections prolong the oral exposure time to these acids, giving the erosive acids more time to demineralize the enamel.
Other Health Effects of Consumption
While the dental impact is the primary concern, consuming large amounts of sugar-free candy can lead to non-dental health issues. Many sugar alcohols, including sorbitol, maltitol, and mannitol, are poorly absorbed in the small intestine. When these compounds reach the large intestine, they are fermented by gut bacteria.
This fermentation process can produce gas and cause gastrointestinal discomfort, such as bloating and cramping. Unabsorbed sugar alcohols also create an osmotic effect, drawing water into the digestive tract. This can result in a laxative effect or diarrhea, especially when consumed in excess. Erythritol is an exception among the sugar alcohols, as most of it is readily absorbed before reaching the large intestine, making it better tolerated.