Sugar Alcohols

=O to -OH

While there are many types of sugar substitutes out there, this post will focus on the sugar alcohols. First, what are sugar alcohols? Molecularly, sugar alcohols are sugars (glucose, fructose, etc.) that have their double-bonded oxygen hydrogenated. If you can’t picture that, it’s okay, here’s what it looks like: =O becomes -OH
Now, this may not seem like a significant change to us, but it makes quite a difference in the sweetness and the fermentability of the sugar. Sugar alcohols are less sweet and the bacteria in your mouth are incapable of fermenting them; plus, they also don’t produce as much energy as regular sugar (aka: they’re lower in calories). To prevent blood sugar spikes, these sugar substitutes and the ketogenic diet are recommended for diabetics. Lots of perks to replacing sugar with these alternatives!

Testing for reducing sugars (and other stuff). Biochemistry is so pretty!

Browning Deliciousness

Now the downsides. See, the problem with not being real sugar is that these substitutes don’t react like sugar. Because sugar alcohols don’t brown, you can forget about making caramel with it. The Maillard reaction, responsible for producing the delicious odor of baked goods, only occurs between sugars and proteins. Sugar alcohols do not partake in the Maillard reaction. This is quite unfortunate because that smell is the reason I go into bakeries. Plus, if we all switched to sugar alcohols in baking, I’m pretty sure it would single-handedly destroy the French p√Ętisserie and boulangerie business.

Gas and Bloat

Not all sugar alcohols go through our digestive system the same way. While they are all absorbed at a slower rate than regular sugar, some stay in our large intestines long enough for bacteria to ferment them. This means lots of gas and possibly even diarrhea if you eat too much. Maltitol is the most famous gas-causing culprit (see Amazon’s reviews for Haribo sugarless gummy bears).


Erythritol is an up-and-coming sugar alcohol that you’ve probably read about. Similar to xylitol, erythritol doesn’t cause cavities because it cannot be used for energy by the bacteria in our mouths. Most of it is absorbed before the large intestine and therefore doesn’t cause gas or diarrhea. In the bloodstream, cells don’t use erythritol in cellular respiration and it ends up just being excreted by the kidneys. I’ve seen someone devour 2 pints of Halo Top Ice Cream (in under 20 minutes) and be perfectly fine. What can I say, he had a craving.

Next time you’re contemplating sugarless treats, be sure to look at the ingredients to see which type of sugar alcohol you’re consuming. From there, you can either give yourself a limit or go nuts. Personally, I prefer real sugar, in moderation.

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