Like fiber, sugar alcohols are partly resistant to digestion. While this is good news when it comes to blood sugar and insulin levels, it’s not such great news when it comes to things like gas and bloating. Because sugar alcohols make it to your small intestine partly intact, they become a source of food for the bacteria that live there. These bacteria feast on the sugar alcohols and create gases as a byproduct. These gases are then released into your digestive tract and can cause bloating, stomach pain, and excess flatulence.
If you’re experiencing any of these symptoms on the keto diet, check your labels and make sure you’re not overdoing it on the sugar alcohols. Chewing gum, sugar-free candy, keto-friendly protein bars, and any processed foods that have “no sugar added” or “low in net carbs” claims on them likely contain sugar alcohols. Look for names like sorbitol, xylitol, mannitol, and maltitol, which are the most common, but any ingredient with an “-ol” at the end is likely a sugar alcohol.
Certain sugar alcohols, like maltitol and sorbitol, cause more digestive upset than others, like erythritol, which is well tolerated by most people and considered an exception to this rule. Of course, everyone is different, so pay attention to how you feel after you consume sugar alcohols, and if your stomach doesn’t feel good, skip them—or at least limit them to very occasionally.