A polyol is a sugar alcohol, a type of carbohydrate whose molecular structure sits somewhere between a sugar and an alcohol, though it contains no ethanol and will not get you drunk. Polyols include familiar names like xylitol, sorbitol, erythritol, maltitol, mannitol, isomalt, and lactitol. They show up in sugar-free gum, diabetic-friendly chocolate, protein bars, cough syrup, skincare products, and even industrial coatings. The reason for that range is their unusual chemistry: they taste sweet but behave differently from sugar once they enter your body, your mouth, or a manufacturing process.
The Basics of Sugar Alcohols
Despite the name, polyols are not sugars and not alcohols in the way most people use those words. Their chemical structure partially resembles sugar and partially resembles a simple alcohol, but they lack the ethanol group found in alcoholic beverages.1Journal of Nutrition & Food Sciences. Sugar alcohols: Chemical structures, manufacturing, properties and applications What makes them useful is that this hybrid structure gives them sweetness, usually somewhere between 25% and 90% as sweet as table sugar depending on the specific polyol, while limiting how much your body can absorb and metabolize.
Some polyols occur naturally in fruits and fermented foods. Erythritol, for instance, is found in melons, watermelons, pears, grapes, cheese, and soy sauce.2PubMed Central. Erythritol: An In-Depth Discussion of Its Potential to Be a Beneficial Dietary Component The amounts in nature are tiny, though, so commercial production relies on different methods. Erythritol is typically made through fermentation using yeast or yeast-like fungi fed glucose, fructose, or other sugars.2PubMed Central. Erythritol: An In-Depth Discussion of Its Potential to Be a Beneficial Dietary Component Other polyols like sorbitol and maltitol are more commonly produced through chemical hydrogenation, a process that converts sugars into their corresponding sugar alcohols at industrial scale. Extracting erythritol from its natural fruit sources is impractical because concentrations are so low, and chemical synthesis for erythritol specifically requires high temperatures and a nickel catalyst, making it cost-ineffective with poor yields.3PubMed Central. Erythritol as sweetener—wherefrom and whereto? Fermentation ended up being the winner for erythritol, which is why its production pathway looks more like brewing beer than refining sugar.
How Your Body Handles Polyols
This is where polyols diverge most sharply from regular sugar. Table sugar is almost completely absorbed in your small intestine and converted to glucose. Polyols are only incompletely digested there. Whatever your small intestine does not absorb passes into the colon, where gut bacteria ferment it or it leaves the body in stool.4PubMed. Clinical tolerance, intestinal absorption, and energy value of four sugar alcohols taken on an empty stomach This incomplete absorption is the key to most of their benefits and most of their side effects.
The degree of absorption varies between polyols. Sorbitol, when consumed on its own, is absorbed at roughly 80% in the small intestine, while maltitol is digested at about 90%.5PubMed. Digestion and absorption in the human intestine of three sugar alcohols Erythritol is the outlier: around 90% of it is absorbed in the small intestine but then excreted unchanged in urine, meaning very little reaches the colon and very little is metabolized for energy. This makes erythritol nearly calorie-free. The others carry real calories, though fewer than sugar. Sorbitol, for example, provides roughly 3.6 calories per gram, and maltitol about 3.5 calories per gram, compared to sugar’s 4 calories per gram.5PubMed. Digestion and absorption in the human intestine of three sugar alcohols The calorie savings are real but modest for most polyols, which is something the “sugar-free” label can obscure.
Blood Sugar and Diabetes Management
The incomplete absorption of polyols means they produce a smaller and slower blood sugar rise than regular sugar. This has made them a fixture in foods marketed to people with diabetes for decades.1Journal of Nutrition & Food Sciences. Sugar alcohols: Chemical structures, manufacturing, properties and applications The glycemic index of most polyols is substantially lower than that of sucrose. Erythritol has a glycemic index near zero. Xylitol, sorbitol, and isomalt sit in the low range as well. Maltitol is the exception among the common polyols; its glycemic index is higher than its siblings, roughly half that of sugar, which means it can still produce a meaningful blood sugar response if you eat enough of it.
Reviews of the evidence confirm that polyols generally produce beneficial effects on blood sugar management, though the picture comes with caveats. While some polyols barely raise plasma glucose at all, others (particularly maltitol) do produce a measurable insulin and glucose response, and the side effects associated with normal or higher dosages have prompted the FDA to issue usage guidelines.6PubMed Central. Suitability of sugar alcohols as antidiabetic supplements: A review So while polyols are generally friendlier to blood sugar than sucrose, treating them all as equivalent is a mistake. If blood sugar control is the reason you are choosing a polyol, which specific one matters quite a bit.
Why Dentists Like Xylitol
The dental benefits of polyols, and xylitol in particular, are probably the best-known aspect of sugar alcohols for most people. The mechanism is straightforward: the bacteria that cause tooth decay, especially Streptococcus mutans, thrive on fermentable sugars. Polyols are not easily fermented by these bacteria, so replacing sugar with a polyol starves them of fuel. Xylitol goes a step further. It appears to actively reduce the population of cavity-causing bacteria rather than simply denying them a meal.
In a randomized crossover trial, subjects who chewed xylitol gum for three weeks saw their salivary levels of S. mutans drop by about 27% and S. sobrinus drop by about 21%, both statistically significant reductions compared to baseline.7PubMed Central. Effect of xylitol on cariogenic and beneficial oral streptococci: a randomized, double-blind crossover trial A systematic review looking across multiple studies found that xylitol gum significantly decreased mutans streptococci counts compared with sorbitol gum in the vast majority of trials, reduced plaque accumulation in over half the studies examined, and lowered cavity occurrence in the majority of caries trials.8PubMed Central. Specific effects of xylitol chewing gum on mutans streptococci levels, plaque accumulation and caries occurrence: a systematic review Xylitol has even been described as promising for reversing the process of early-stage cavities.9PubMed Central. The effect of xylitol on dental caries and oral flora
Chewing sugar-free gum in general also boosts salivary flow, which helps neutralize acids and wash away food debris. Studies comparing xylitol, sorbitol, and isomalt candies in children found that all three polyols significantly increased salivary flow rates compared to a control.10PubMed Central. A Comparative Evaluation of Xylitol, Sorbitol, and Isomalt-containing Candies and Their Effects on Salivary pH and Salivary Flow Rate in Children Aged 6–12 Years: An Ex Vivo Study The combination of reduced bacterial activity, increased saliva, and a higher oral pH makes xylitol one of the more evidence-backed “functional” food ingredients out there, and the reason the ingredient appears in so many sugar-free gums and mints.
Gastrointestinal Side Effects
The same incomplete absorption that makes polyols lower in calories and gentler on blood sugar is also what causes their most common complaint: digestive trouble. Polyols that reach the colon draw water into the gut through osmosis and get fermented by bacteria, producing gas. The result, depending on how much you consume and how sensitive your gut is, can be bloating, flatulence, abdominal cramps, or diarrhea. These symptoms are dose-dependent.11PubMed Central. A Systematic Review of the Effects of Polyols on Gastrointestinal Health and Irritable Bowel Syndrome
The good news, if you can call it that, is that research and clinical experience have found no actual pathological damage to the intestinal lining from polyol-induced osmotic diarrhea. The gut mucosa retains its normal structure even in extreme instances.12PubMed Central. Gastrointestinal Disturbances Associated with the Consumption of Sugar Alcohols with Special Consideration of Xylitol: Scientific Review and Instructions for Dentists and Other Health-Care Professionals In other words, polyol-related GI distress is uncomfortable but not harmful. Your gut is not being damaged; it is just unhappy about the water and gas.
Tolerance varies widely between individuals and between polyols. Erythritol is generally the best tolerated because so little of it reaches the colon. Sorbitol and maltitol tend to cause more symptoms at lower doses. Many people also find that regular consumption builds tolerance over time, as their gut microbiome adjusts. Still, for anyone eating a “sugar-free” chocolate bar sweetened with maltitol for the first time, the experience can be memorable in the wrong way.
The FODMAP Connection
Polyols are one of the categories in the acronym FODMAP, which stands for fermentable oligosaccharides, disaccharides, monosaccharides, and polyols. These are poorly absorbed carbohydrates that increase water content in the bowel through osmosis and boost gas production via colonic bacterial fermentation.13PLoS ONE. Low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diet improves symptoms in adults suffering from irritable bowel syndrome (IBS) compared to standard IBS diet: A meta-analysis of clinical studies For people with irritable bowel syndrome or other functional gastrointestinal disorders, FODMAPs as a group can trigger significant symptoms.
A low-FODMAP diet, which restricts all five categories including polyols, has been shown in meta-analyses to improve IBS symptoms compared to a standard diet.13PLoS ONE. Low fermentable oligosaccharides, disaccharides, monosaccharides and polyols (FODMAP) diet improves symptoms in adults suffering from irritable bowel syndrome (IBS) compared to standard IBS diet: A meta-analysis of clinical studies If you have been diagnosed with IBS and your dietitian has put you on a low-FODMAP elimination plan, polyol-containing foods and sugar-free products are among the things you will be asked to cut. During the reintroduction phase, you can test individual polyols (sorbitol and mannitol are the two usually tested separately) to learn your personal threshold. Some people with IBS tolerate erythritol well while reacting strongly to sorbitol, which makes sense given how differently the two are absorbed.
Polyols in Baking and Food Manufacturing
Replacing sugar in food products is harder than it sounds, because sugar does far more than just sweeten. In baked goods, sugar contributes to browning, texture, moisture retention, and structure. Polyols can handle some of these jobs but not others. Because they are non-reducing compounds, sugar alcohols do not participate in the Maillard browning reaction during baking. A cookie made entirely with polyols will tend to come out paler and may have a different texture than its sugared counterpart.
Food scientists have found that the best results come from combining polyols with other sweeteners rather than using them alone. One approach pairs a bulk polyol like xylitol, which provides the physical mass and mouthfeel that sugar would normally supply, with a tiny amount of a high-intensity sweetener like monk fruit or thaumatin for extra sweetness. These “balanced” formulations maintain sweetness equivalence while minimizing the off-flavors and structural issues that arise when any single sugar substitute carries the entire load.14PubMed Central. Sensory Characterization of Cookies With Sugar Replacement by Sweeteners Using the Check‐All‐That‐Apply Method If you have ever noticed that commercial sugar-free products often list multiple sweeteners on the ingredient panel, this complementary approach is the reason.
Polyols also have a characteristic cooling sensation on the tongue, especially erythritol and xylitol. That cooling effect works well in mints and chewing gum but can be distracting in a warm brownie. Maltitol, which has a less pronounced cooling effect and behaves more like sugar in baking, is why it is the polyol most commonly found in sugar-free chocolate and candy, despite being the one most likely to cause GI problems.
Cosmetic and Pharmaceutical Uses
Polyols show up well beyond the food aisle. In skincare, they function as humectants, meaning they attract and hold water. Research has demonstrated a strong correlation between polyol concentration in cosmetic formulations and skin moisture levels. At concentrations up to 30%, higher polyol content led to measurably more hydrated skin and reduced skin surface roughness.15PubMed. Influence of polyol and oil concentration in cosmetic products on skin moisturization and skin surface roughness Glycerol, the simplest polyol, is one of the most widely used moisturizing ingredients in the world and appears in everything from lotions to serums to lip balms.
In pharmaceuticals, polyols serve as excipients, the inactive ingredients that help deliver the active drug. Sorbitol and glycerol are common vehicles in oral solutions, syrups, and liquid medications, where they add sweetness and help keep the drug in solution. This role is not without complications, however. Some drug substances can chemically react with polyol excipients. Cetirizine, a common antihistamine, has been found to readily form ester compounds when formulated with sorbitol or glycerol in liquid products.16PubMed. Reaction between drug substances and pharmaceutical excipients: formation of esters between cetirizine and polyols These reactions can degrade the active ingredient over time, which is why pharmaceutical chemists have to carefully test stability when polyols are used as carriers.
Industrial Polyols Are a Different Animal
If you search for “polyol” in a chemistry or materials science context, you will find a world that has little to do with chewing gum. In industrial chemistry, “polyol” refers broadly to any molecule with multiple hydroxyl (–OH) groups, and these compounds serve as essential building blocks for polyurethanes. When a polyol reacts with an isocyanate, the result is polyurethane, the material behind rigid foams, flexible foams, coatings, adhesives, and elastomers found in construction, automotive manufacturing, and furniture.
Researchers have synthesized polyols from mixtures of metasilicic acid and cellulose to produce rigid polyurethane foams.17PubMed Central. Polyols and Polyurethane Foams Obtained from Mixture of Metasilicic Acid and Cellulose Polyester-based polyurethane coatings, which rely on polyol chemistry, are widely used in automotive, construction, and plastics industries for their mechanical strength, adhesion, and chemical resistance.18Coatings. Effects of Different Polyols with Functions on the Properties of Polyester Polyol-Based Polyurethane Coatings These industrial polyols share the same defining chemical feature as the sugar alcohols in your protein bar, multiple hydroxyl groups on a carbon backbone, but they are not food-grade and not remotely edible. The overlap in terminology confuses people who encounter “polyol” in ingredient lists and also in materials science, but the two applications are connected only by molecular architecture.
The Erythritol Cardiovascular Debate
Erythritol, long considered the mildest and best-tolerated polyol, has recently attracted scrutiny over potential cardiovascular risks. A widely discussed 2023 observational study from the Cleveland Clinic linked elevated blood erythritol levels to increased rates of heart attack and stroke, generating considerable media attention. That research has since prompted further investigation. A Mendelian randomization analysis, which uses genetic variation to probe causal relationships, found that genetically predicted higher erythritol levels were associated with modestly increased risks of coronary heart disease, ischemic stroke, and deep vein thrombosis.19PubMed Central. Role of erythritol in coronary heart disease, ischemic stroke, and venous thromboembolism: A Mendelian randomization analysis
The odds ratios in that analysis were small, in the range of 1.08 to 1.16, meaning the increases in risk are not large in absolute terms.19PubMed Central. Role of erythritol in coronary heart disease, ischemic stroke, and venous thromboembolism: A Mendelian randomization analysis And there is an important nuance: elevated erythritol in the blood may reflect metabolic processes in the body rather than dietary intake from sugar-free foods. Your body produces erythritol endogenously through the pentose phosphate pathway, and people with metabolic syndrome or diabetes tend to have higher endogenous erythritol levels, which could confound the relationship. The science here is genuinely unsettled. Regulatory bodies have not changed their stance on erythritol’s safety as a food additive, but the findings have prompted calls for long-term clinical trials to clarify whether dietary erythritol actually contributes to cardiovascular events or whether the association is explained by something else entirely.
Labeling and Regulatory Status
In the European Union, foods containing more than 10% added polyols must carry the warning label “excessive consumption may produce laxative effects.” EFSA has reviewed this requirement, including the question of whether erythritol should be exempted from the warning given its lower GI impact, but has maintained that the laxative warning remains valid for polyols as a class.20EFSA Journal. Re-evaluation of erythritol (E 968) as a food additive In the United States, the FDA does not require that specific warning, but sugar alcohols must be listed on the Nutrition Facts panel. When a product makes a “sugar-free” claim, the sugar alcohol content must be declared separately.
A point of confusion for consumers is that sugar alcohols are counted as carbohydrates on nutrition labels but are sometimes excluded from “net carb” calculations on products marketed to low-carb dieters. The logic is that because polyols are incompletely absorbed, their effective carbohydrate contribution is lower than the label number suggests. This is roughly true for erythritol but less accurate for maltitol, which is metabolized more completely. If you are tracking carbohydrates closely, knowing which polyol you are eating matters more than trusting a “net carb” number on the front of a package.
Xylitol and Dogs
One critical safety issue that catches many pet owners off guard: xylitol is severely toxic to dogs. In canine metabolism, xylitol triggers a massive release of insulin, causing dangerous hypoglycemia within minutes to hours of ingestion. At higher doses, it can cause acute liver failure. Even small amounts, the quantity found in a few sticks of gum, can be life-threatening to a medium-sized dog.21Journal of Advances in VetBio Science and Techniques. Hypoglycemic shock and acute liver injury in a dog associated with xylitol toxicity
As xylitol has become more prevalent in sugar-free products, peanut butters, baked goods, toothpaste, and even some medications, the risk of accidental canine exposure has grown. Dogs metabolize xylitol in a fundamentally different way than humans do; this is not a sensitivity or an allergy but a species-specific metabolic difference that makes an ingredient harmless to you potentially lethal to your dog. If you keep xylitol-containing products in your home and also have dogs, store those products where your pet cannot reach them, and check ingredient labels on peanut butter before using it in treat recipes or Kong toys. Other polyols like erythritol and sorbitol do not appear to carry the same risk for dogs, but xylitol specifically requires vigilance.