Understanding Sugar Alcohols vs. Ethanol
Sugar alcohols, also known as polyols, are a type of carbohydrate with a chemical structure similar to both sugars and alcohols, but they are not the same as the ethanol found in alcoholic beverages. Ethanol is metabolized in the liver, entering the bloodstream and affecting the central nervous system. In contrast, most sugar alcohols are only partially absorbed by the body. For example, erythritol is well-absorbed but excreted largely unchanged in the urine, while xylitol is only 50% absorbed. This metabolic difference is the primary reason that consuming sugar alcohols does not cause inebriation.
Common Sources of Sugar Alcohols
Sugar alcohols are widely used as lower-calorie sweeteners and bulking agents in a variety of products marketed as 'sugar-free' or 'diet'. These include:
- Sugar-free gum and mints
- Diet sodas and energy drinks
- Sugar-free candies and chocolates
- Protein bars and other snack foods
- Toothpaste and certain mouthwashes
- Baked goods designed for low-carb or keto diets
- Some cough syrups and medications
The Problem with Mouth Alcohol and Breathalyzers
The potential for a false positive from sugar alcohols lies not in the systemic metabolism, but in a phenomenon known as 'mouth alcohol'. Some breathalyzer devices, particularly older models, are designed to detect any type of alcohol present in the breath, not just ethanol. If sugar alcohol residue from gum, toothpaste, or a recent snack is still in the mouth when a breath sample is given, it can be misinterpreted as ethanol by the machine, leading to an artificially high reading. Anecdotal evidence and some tests have shown this effect, with readings as high as 0.04% reported from chewing sorbitol gum.
To combat this, law enforcement typically uses a 15-20 minute waiting period before administering a breath test. This allows any residual mouth alcohol to dissipate. Modern evidential breath test devices often use more advanced filtering technology to be more specific to ethanol, reducing the likelihood of a false positive from sugar alcohols. However, this is not a guarantee, especially with roadside screening devices.
Comparison of Common Sugar Alcohols
This table outlines the key differences between some of the most common sugar alcohols and their potential impact on alcohol testing.
| Sugar Alcohol | Relative Sweetness (vs. Sucrose) | Absorption Rate | Impact on Blood Alcohol | Breath Test Potential Issue | Common Products |
|---|---|---|---|---|---|
| Erythritol | ~70% | Well absorbed, excreted in urine | None | Low (unless residue is in mouth) | Keto products, diet drinks, sweeteners |
| Xylitol | ~100% | Partially absorbed (50%) | None | Moderate (if oral residue is present) | Sugar-free gum, mints, dental products |
| Sorbitol | ~60% | Slowly and incompletely absorbed | None | High (known false positive risk from mouth residue) | Toothpaste, sugar-free foods, gum |
| Maltitol | ~75-90% | Incompletely absorbed | None | Moderate (if oral residue is present) | Sugar-free candies, baked goods |
What About Other Alcohol Tests?
While breathalyzers are the most common roadside test, other methods are used for more conclusive evidence. Sugar alcohols pose no threat to the accuracy of these tests.
Blood Tests
Blood tests are highly specific and considered the gold standard for measuring blood alcohol concentration (BAC). A gas chromatography test can accurately differentiate between ethanol and other alcohols, including sugar alcohols. Since sugar alcohols are either not absorbed or not metabolized into ethanol in the bloodstream, they will not cause a positive blood alcohol reading.
Urine Tests (EtG/EtS)
Urine tests, particularly EtG (ethyl glucuronide) and EtS (ethyl sulfate) tests, are designed to detect the metabolic byproducts of ethanol consumption. Sugar alcohols do not metabolize into these specific markers, so they will not trigger a positive result on an EtG or EtS test. The only way a urine sample could contain alcohol from sugar (not sugar alcohol) would be through post-collection fermentation, which is unrelated to consuming sugar substitutes.
How to Avoid a False Positive
If you consume products containing sugar alcohols, particularly before driving, there are a few simple precautions you can take to avoid any potential issues with a breathalyzer test. The core principle is to eliminate any mouth alcohol residue.
- Rinse Your Mouth: The most effective and easiest method is to rinse your mouth thoroughly with water after consuming any sugar-free gum, mints, or other products.
- Wait a Few Minutes: Allowing a few minutes to pass after consuming the product will give any residual mouth alcohol time to dissipate. A law enforcement officer should observe a 15-20 minute period before testing anyway.
- Request a Blood Test: If you are confident you have not consumed alcohol but fail a breathalyzer, you can request a more specific blood test, which will not be affected by sugar alcohols.
Conclusion
While the names sound similar, sugar alcohols like erythritol and xylitol are not the same as ethanol and do not cause intoxication or a systemic blood alcohol reading. The primary risk of a false positive from sugar alcohol is a temporary, localized effect caused by mouth alcohol residue on less sophisticated breathalyzer devices. Blood and urine tests, which analyze the body's systemic state, are not affected. By understanding the mechanism and taking simple precautions like rinsing your mouth, you can confidently consume sugar-free products without fear of a misleading alcohol test result.
Lack of response of breath alcohol screening devices to sugar alcohols contained in chewing gum
