If you've ever eaten a protein bar that's labeled "sugar free" yet tastes suspiciously sweet, then you've likely had multiple run-ins with sugar alcohols. These compounds are sacred in the health food industry — they mimic the taste of sugar without adding excess calories. But if sugar alcohols aren't actually absorbed by the body, then what happens? Are they really as "healthy" as they seem?
The good news:
If you too have survived the organic chemistry pilgrimage, a sugar alcohol is exactly what its name implies. It is not the sugar found in alcoholic beverages, but instead is an hybrid of a simple carbohydrate and an alcohol. This unique structure allows it to bind to taste receptors on the tongue that respond to sweetness while evading complete digestion in the body — meaning that 1 gram of sugar alcohol provides significantly less calories than 1 gram of sugar.
This characteristic makes sugar alcohols particularly enticing to diabetics. The Diabetes Training Center at the University of California San Francisco advises patients to count each gram of sugar alcohol as 1/2 of a carbohydrate, granting individuals more freedom to enjoy food that would traditionally be "too sweet." Furthermore, since bacteria in the mouth cannot use sugar alcohols are a source of energy, these sugar-substitutes are FDA-endorsed to help promote healthy oral hygiene practices (look for xylitol on your chewing gum labels!)
One thing to note: sugar alcohols are NOT the same product as artificial sweeteners. Those pastel packets lining the edge of hole-in-the-wall breakfast dives have no calories, while sugar alcohols still provide energy. With this being said, artificial sweeteners have issues of their own – stay tuned for a later article.
The bad news:
Just because sugar alcohols don't spike the blood sugar doesn't mean that they're the holy grail of processed food. For those attempting to stave off excess pounds while still satisfying a sweet tooth, sugar alcohols may be something of a double-edged sword. While they may not cause a dramatic spike (and subsequent crash) in blood sugar, they could potentially hijack the same neural addiction pathway that makes sweet snacks so enticing in the first place.
Sugar facilitates the release of dopamine and opioids in the brain — two neurotransmitters that are associated with drug addiction. In a study conducted with rats, the group that was deprived of sugar exhibited withdrawal-like symptoms that mimic those of an opioid user. Any sugar alcohols that also elicit this neural reaction could perpetuate an individual's sugar addiction regardless of the fact that the compound is absorbed less readily by the bloodstream.
Furthermore, because they aren't easily digested by the human body, excessive consumption of these sugar-like compounds can cause an amalgam of adverse side effects. Un-digested sugar alcohols arrive in the intestine largely intact and therefore susceptible to fermentation. The gas produced by this process can cause bouts of gastrointestinal distress, as well as a potential disruption of the gut microbiome. Additionally, large quantities of sugar alcohols can pull water out of the body and into the gut, resulting in an upset stomach or diarrhea.
As with most things, the best way to approach the onslaught of sugar alcohols is to enjoy them in moderation. The most common sugar alchols are xylitol, manitol, sorbitol, and lactitol, although there are many others currently on the market (look for the "-ol" ending). However, the easiest way to recognize them is with your intuition — if the label says "sugar-free" but it tastes like a chocolate chip cookie or a raspberry cheesecake, there's a good chance it contains a sugar alcohol.