If you eat protein bars, or low sugar foods, you’ve probably seen sugar alcohol listed among the ingredients in many popular brands.
Sugar alcohols are found most commonly in food products labeled “sugar-free,” including hard candies, cookies, chewing gums, and soda, but have recently become very popular in “health foods”.
Do you really know what you’re consuming? Is sugar alcohol bad for you? The short answer to the latter question is “no”, sugar alcohol is not bad for you, but it is not intrinsically healthy either.
What Is Sugar Alcohol?
Sugar alcohol gets its name because of its molecular structure, which is a hybrid between a sugar molecule and an alcohol molecule. Biochemically speaking, sugar alcohols are structurally similar to sugar but are either poorly digested (e.g., maltitol), or poorly metabolized (e.g., erythritol).
Sugar alcohol has grown in popularity as a “sugar replacement” in foods such as protein bars because they contain few calories, minimally impact insulin levels, are safe for those with diabetes, and are better for your teeth.
Here’s a list of some popular sugar alcohols so you can identify them when you look at a nutrition label:
- Hydrogenated starch hydrolysates
The two major sugar alcohols found in protein bars and most low sugar foods are maltitol and erythritol, which are explored in more detail below.
Sugar Alcohol #1: Maltitol
Maltitol, the more popular of the two, has only 2.1 kilocalories per gram (compared to 4 for sugar) and is comprised of glucose and sorbitol (see image on right).
Only 80% as sweet as sugar, maltitol has 47% fewer calories…and won’t rot your teeth! The downside of maltitol is its poor absorption. In high doses, it will cause a laxative effect (i.e., diarrhea). This isn’t a concern in protein bars with less than 20 grams, but down a couple of the bars with over 20 grams and you might spend the afternoon in the restroom; fortunately, most companies are listing sugar alcohols directly on the label.
If “sugar alcohols” aren’t listed as a separate category under carbohydrates, check the ingredients list. You shouldn’t have to look very far because sugar alcohols will be one the first ingredients on the list.
Safety & Metabolic Effects of Maltitol
One study estimated the maximal safe dose to be 30 grams.1 40 grams caused very mild GI upset, but still no diarrhea. Furthermore, if you’re watching your weight, take comfort in the fact that maltitol causes minimal insulin secretion. This is important for maintaining blood sugar, which is a significant factor in controlling your body’s hunger. In the figure to your right, the response to 50 grams of either glucose (solid lines) or maltitol (dashed lines) is shown.2
For the record: 1) 50 grams is far more than what is found in any food products; and 2) these volunteers exhibited no side effects to 50 grams of maltitol, suggesting that the 30 gram limit mentioned above might be person-specific (i.e., some people can tolerate more than others).
Last but not least, maltitol promotes healthy gut bacteria!3
Sugar Alcohol #2: Erythritol
Erythritol, another popular sugar alcohol, is: 1) virtually calorie-free (0.2 kcal/g); 2) not a laxative; and 3) still 70% as sweet as sugar.
Erythritol is used in foods because its physical properties mimic sugar. It’s not more widely used because it has a slight cooling effect, kind of like mint, which is undesirable in some foods. This can be countered by the addition of inulin,4 a super-fiber that promotes healthy gut bacteria and I suspect companies who are trying to reduce the carbs in their protein bars will be doing more of this in the future…less sugar and more super-fiber, what more could you ask for?
Safety & metabolic effects of Erythritol
Erythritol lacks maltitols laxative and pro-gut bacteria effects because it is almost completely absorbed (~90%).
One group looked at the insulin response to a chocolate snack containing either erythritol or sugar.5 The figure to your right has been color-coded and edited for simplicity. Red = 24 grams of sugar; blue = 48 grams of erythritol.
After breakfast (Time = -2 h), which was identical in both groups, insulin went up to a similar degree confirming that subjects in both groups had a normal insulin response. After the snack (Time = 0 h), however, insulin only increased in the subjects who ate the sugar-containing chocolate (red line). And at twice the dose, the erythritol-containing chocolate snack was probably much sweeter. As mentioned above, unlike maltitol, erythritol has no GI side effects… it’s almost completely absorbed. But the other half of the story is that it is excreted almost completely intact (it’s not metabolized by the body, which accounts for its lack of calories). Did I forget to mention erythritol has virtually no calories?
So Should You Eat Sugar Alcohol?
While sugar alcohol might be better for you than actual sugar (what wouldn’t be?) it is still not intrinsically healthy. If you’ve got an insatiable craving for something sweet, sugar alcohols are the lesser evil, but in terms of healthy-eating, you would be much better off grabbing a piece of fruit than downing a protein bar full of this stuff.
- Storey DM, Koutsou GA, Lee A, Zumbe A, Olivier P, Le Bot Y, Flourie B. Tolerance and breath hydrogen excretion following ingestion of maltitol incorporated at two levels into milk chocolate consumed by healthy young adults with and without fasting . J Nutr. 1998 Mar;128(3):587-92. ↩
- Secchi A, Pontiroli AE, Cammelli L, Bizzi A, Cini M, Pozza G. Effects of oral administration of maltitol on plasma glucose, plasma sorbitol, and serum insulin levels in man . Klin Wochenschr. 1986 Mar 17;64(6):265-9. ↩
- Beards E, Tuohy K, Gibson G. A human volunteer study to assess the impact of confectionery sweeteners on the gut microbiota composition . Br J Nutr. 2010 Sep;104(5):701-8. 2010 Apr 7. ↩
- Lagakos, B. taking the fun out of FODMAPs . The poor, misunderstood calorie. 2012. ↩
- Bornet FR, Blayo A, Dauchy F, Slama G. . Gastrointestinal response and plasma and urine determinations in human subjects given erythritol . Regul Toxicol Pharmacol. 1996 Oct;24(2 Pt 2):S296-302. ↩
Beans, beans the magical fruit. The more ya eat the more ya _____. Sugar alcohol wreaks more havoc on your digestive system than beans and you know what that means….
Congrats on your first post, Bill. Informative article with solid research.
Nice timing, eating a protein bar now. Thanks for the information. Rather the sugar alcohol than dealing with an insulin spike. Oh, Steve, HAHA, my 98 year old grandmother says that all the time.
Marc what’s your opinion of intermittent fasting
@Jay – check out answer #2 in this article Weekly Q&A
I think organic brown sugar would be better since it is from the pure cane.
What are the brand names of the products that contain these substances, and how many grams of sugar alcohol are in each?
@John – There are an innumerable amount of brands and products that have sugar alcohol in them. Literally almost every protein bar, many protein shakes and powders, many low sugar bars, just look around on nutrition labels and you will see them on many low sugar products.
Great article! I eat low carb protein bars often and have always wondered about the sugar alcohols but haven’t taken the time to really research them yet, I’m glad to hear that they are safe, i was kinda worried that they might be bad for you
Sorbitol is the sugar alcohol in diabetes that is related to osmotic death of cells lining capillaries. This fact alone should be a red flag.
What about Splenda? My nutritionist told me that the human metabolism treats it like alcohol once inside the system so it works hard on getting rid of it first and foremost instead of working on the fat…
I’m confused… you claim that sugar alcohol is healthier than sugar; however, you conclude by suggesting fruit over sugar-alcohol-containing protein bars.If I’m not mistaken, once it has reached the small intestine, it doesn’t matter if its a natural sugar or refined sugar. The only major difference is how rapidly it is metabolized prior to reaching to duodenum (mainly due from fruit containing fiber, preventing the spike you see with refined sugars), so why would you suggest natural sugars over sugar alcohols? Is it just because it comes from a natural source?
Thank you in advance,
We actually need to update parts of this article. While it’s true that sugar alcohols don’t have the same impact on insulin as regular sugar, they can cause GI upset and can negatively affect the composition of your gut microbiome. Studies have also shown that consuming sugar alcohols could increase your appetite and cravings for sugar. The consumption of sugar alcohols has also been linked to increased incidence of weight gain and obesity.
Fruit is a better option than sugar alcohols for multiple reasons: (1) fruit contains fiber, and fiber slows the digestion of sugar so it doesn’t all hit your bloodstream at once, (2) fruit is full of vitamins, minerals, and antioxidants, and (3) it contains a lot of water. The water and fiber in fruit make it a filling and satisfying food, and the nutrients provide a lot of health benefits.
Does that clarify why fruit is the better option?
-Kristin, BuiltLean Coach & Managing Editor
True about the fruit having fiber but the fruit doesn’t have the protein.
You’re correct. Fruit contains very very small amounts of protein. That’s why we often recommend eating fruit with something more protein-rich, such as greek yogurt, a small handful of nuts, or a protein shake. That way, you’re getting both fiber and protein in one meal or snack.
-Kristin, BuiltLean Coach & Managing Editor
Thanks for the information.. I’ve been told to stay away from sugar and to watch how much sugar alcohols I digest. Now I understand why. Thanks again! Great article!
For someone who is on a low carb high protein diet, what is the recommended grams of sugar/sugar substitute a day
How many total grams of carbs are you having? What kind of sugar? Added sugars should be kept as little as possible and whether you are getting the carbs from an apple (sugar) or a price of bread will not have substantially different impact, especially if you are eating around 50 grams or less of carbs a day (not sure how many you are having).