Sugar Alcohols: The Bitter Truths

Ryan Dickey: Microbiologist, Husband, Dad, Doer of Things Healthy.
Last Updated: 02-12-2019

In Sugar Alcohols: Sweet and Simple Answers, I discussed the basics of what sugar alcohols are, and their most fundamental qualities. In this post I’m going to be diving deeper. I will still do my best to keep it all in layman’s terms so that all can understand, but some parts are going to get a little science-intensive, consider yourselves warned.

I’ve divided the list based on their chemical structure, the ones that are produced from simplistic sugar structures are listed first, and getting into larger sugar sources, and therefore, larger sugar-alcohols, as we move down the list. Their size has a lot to do with indigestible qualities, and their glycemic index.

The Monosaccharide Derivatives

Erythritol aka E968

Erythritol Molecule
  • Calories per gram: 0.2 or less
  • Glycemic Index: 0
  • Approximate Sweetness: 70% of sucrose
  • Industrial source: Glucose from Corn Starch by Fermentation with Yeast

I admit it, I’ve listed Erythritol first out of my own personal bias (it is the only one on the list we use at home!). While it has the same basic qualities that all sugar alcohols share, it also has a lot of beneficial effects on our bodies that put it in a class all its own.

Beneficial for diabetics. Boston university school of medicine published a study showing that erythritol consumption, both immediate and long- term ingestion, led to improvement in patients with diabetic mellitus.

It’s an Antioxidant! Which is a plus for hyperglycemia and heart health. Maastricht University published findings that indicate erythritol might be a powerful enough antioxidant to help protect against vascular damage from hyperglycemia.

No gut distress and no glycemic index. Omiya Research Lab published a study that demonstrated that erythritol does not produce a blood glucose or insulin response, and that 90% or more of what is ingested is excreted in urine. While a study reported in Regulatory Toxicology and Pharmacology found that about 78% of erythritol consumed is excreted in urine after being absorbed in the small intestine.

Where most sugar alcohols pass through the small intestine and are then fermented by gut bacteria in the large intestine (the source of bloating and gas that accompanies other sugar alcohols), erythritol leaves the intestinal tract early on, but is not metabolized in the body.  And finally, another study from the Swiss Federal Institute of Technology found that the small amount of erythritol that does make it to the large intestine is not fermented by our gut bacteria.

And if you’re concerned about what that erythritol is doing while it’s floating around your in your system before being excreted, the answer is nothing. Erythritol is a natural metabolite of adiposity, meaning our bodies make it ourselves, you’ve had it floating around in you every time you’ve made a new fat cell. Your body knows full well what to do with it, it goes out with the garbage.

In summary, erythritol is produced by natural fermentation, is an antioxidant that assists with vascular healing, has no gastrointestinal distress, no glycemic index, and functionally zero calories!

Wow! If only it baked like sugar, oh right, it does!

So, what are the cons of erythritol again?

The unfamiliar flavor, and the cooling effect bother some people, although it’s not an unpleasant flavor, it is different than the sugar we are all accustomed to.

And, unfortunately, a rare group of individuals do have a sensitivity to it, and will still experience some gut discomfort, and some have even reported headaches.

And, then, even if you’re not one of the rare individuals with an erythritol sensitivity, and you like the flavor, we still cannot dismiss how new it is to the mass food market (introduced in the 1990’s). There’s been a lot of good research on it, but it is still relatively unknown. However, if the studies continue with the same trend, this sugar alcohol might just become the ultimate sugar replacement.

Xylitol aka E967

Xylitol Molecule
  • Calories per gram: 2.4
  • Glycemic Index: 7
  • Sweetness: 100% of sucrose (just as sweet!)
  • Industrial source: Xylan-Hemicellulose from birch or corn-cob hydrolyzed to xylose then to xylitol by hydrogenation

Good old Xylitol, the one that kills dogs.

Yep yep, don’t let your puppers snack on any xylitol products; or really, don’t let any pets snack on it for that matter. It is harmful to most pets, but is particularly deadly for dogs. A fact that was realized too late after certain peanut butter manufacturers started replacing the sugar and corn syrup in their products with the new and amazing xylitol.

While it has been deemed safe for human consumption, there have been some complaints outside of the expected gut complications. One common one is reports of experiencing dizziness or headaches after consuming xylitol. Another, less common complaint is heart palpitations . Although, there have not yet been any scientific studies to explain these reactions, and it seems to be very rare. The heart palpitations could be a sign of an underlying condition.

On top of all of that,  the industrial source on this stuff looks pretty nasty, but really, it’s not as bad as it seems when you understand it. The hemicellulose source is split in two with the addition of water and heat (hydrolyzed) to get its components, xylose, a simple sugar. Then hydrogen is added with a catalyst (Hydrogenation) to get xylitol.

Ew, hydrogenation, right? Well, there’s a difference between using hydrogenation to create a molecular form that is human-made (like hydrogenated vegetable oils that clog arteries) , and using it to refine a sugar into a a naturally occurring polyol. Refined xylitol isn’t any less natural than refined sugar.

You’ll also hear some people stating that it’s mostly derived from corncob instead of the healthier choice of birch, which is a little absurd, it’s a refined molecule. The end result is identical to the xylitol that is found in the plums and raspberries in your kitchen, regardless of its source. Corn can be farmed far easier than birch trees, and the corncob method also doesn’t use sulfuric acid in the process, which is required from birch extraction, generating an unusable waste product.

Okay, we’ve discussed the negatives, let’s look at the brighter side of Xylitol. As it turns out,  there are many health benefits, as long as you’re not a dog.

Various studies have found that xylitol fights candida albicans, one such study carried out by the shiraz university of medical science found that a 99.5% reduction in colony forming units was observed after exposure to xylitol.

More well known is that xylitol fights tooth decay, but it can also help fight ear infections by the same mechanism, as was observed in several trials that were reviewed in a paper published by the University of Toronto.

And in a big win for xylitol, it might slow the proliferation of cancer cells; findings include a study at Pusan National University where it was found to be effective against lung cancer, and a study published in Nutrition and Cancer by researchers in Thailand found that it was effective against oral cancer.

So that’s many cons and many pros for xylitol. Whether the benefits outweigh the detriments really depends on how they personally effect each individual.

If it seems like a sweetener that fits perfectly to your lifestyle, then have at it. I myself will chew xylitol gum, and have used a xylitol mouthwash, but I won’t purchase any to use as a sugar replacement: I don’t want the gastrointestinal problems, and I’ve got those puppers and kiggies at home.

Mannitol aka E421

Mannitol Molecule
  • Calories per gram: 1.5
  • Glycemic Index: 0
  • Sweetness: 60% of sucrose
  • Industrial source: Fructose from Starch by Hydrogenation

Mannitol has many medical uses, which make it an invaluable sugar alcohol for human health, but should it really be used as a sweetener?

It’s common medical uses include use as diuretic, where it assists with urination in patients with kidney failure. It can be used to diagnose asthma and other lung conditions. And it’s often used to reduce swelling around the eyes and brain after physical trauma.

This is all great stuff, but not very relevant to dietary applications, outside of it being a diuretic, and on that note it has been found that in high doses it can lead to dehydration and can even cross to the fetus in pregnant women resulting in fetal dehydration; findings detailed in Essentials of Neuroanesthisia and Neurointensive Care, 2008.

It is also very talented at being a laxative, so eating this stuff really sounds like a bad idea to me. Perhaps we just leave the mannitol for the doctors to administer.

Sorbitol aka E420, or glucitol

Sorbitol Molecule
  • Calories per gram: 2.5
  • Glycemic Index: 9
  • Sweetness: 60% of sucrose
  • Industrial Source: Glucose from starch by Hydrogenation

Definitely avoid sorbitol, seriously. The are no real pros here, just a long list of cons and better alternatives.

Possibly the winner of the worst offender award for gut problems, although this has it’s practical applications for treating constipation, for which it is recommended.

Sorbitol does occur naturally in people from the metabolism of glucose, but only in low levels, and is a known problem molecule that can accumulate too quickly leading to health complications when there’s an over abundance of glucose in the body. Health Complications such as blood-vessel, kidney, and eye damage due to the accumulation of too much sorbitol. This is a common occurrence in untreated diabetes.

Fortunately, due to it’s large size, not much of what you eat actually makes it into your system. Instead it nearly all goes to your large intestine, where it is fermented by your gut bacteria resulting in very bad gas and loose stool. Bad enough that it can potentially lead to hospitalization. What little is adsorbed through the intestines is converted to fructose in the liver.

It does have practical applications in large scale food production, given that it retains moisture well, and also act as a plasticizer when baked, a combination that prevents baked good from going stale as quickly. But glycerol also does a good job at this, and might be a more logical choice of a sugar alcohol.

This all leaves some question as to whether something that is so potentially harmful should even be considered fit for human consumption; however, as it stands, it is still in regular use commercially. I wouldn’t eat the stuff, but, as always, you do you.

The Disaccharide Derivatives

Maltitol aka E965

Maltitol Molecule
  • Calories per gram: 2.7
  • Glycemic Index: 36
  • Sweetness: 70% of sucrose
  • Industrial Source: Maltose from Starch by Hydrogenation

Maltitol in its crystalline form isn’t so horrible as some of its nastier cousins in this list, but with such a high caloric count, and high glycemic index, once you make up for it only being 70% as sweet as sugar, then you’ve eaten something just as unhealthy as sugar but that gives you gas and indigestion.  Maybe just eat sugar.

On the up side, it is still better for oral health than sugar. Still not sure that makes it worth the discomfort and blood- sugar levels…

There are better choices out there.

Lactitol aka E966

Lactitol Molecule
  • Calories per gram: 2
  • Glycemic Index: 6
  • Sweetness: 40% of sucrose
  • Industrial Source: Lactose from whey by hydrogenation

Lactitol, unlike other sugar alcohols in this list,  is an artificial sweetener.  It does not occur naturally, but is human-made. Although derived from lactose, it doesn’t appear to cause problems for those with lactose intolerance.

It is often prescribed as a laxative, on account of how well it gets things moving. And is also a candidate for being a good prebiotic substance for use to improve gut health.

Lactitol has also been described as very stable, and great for baking. I’m assuming these people must be making laxative cookies and brownies.

But at only 40% the sweetness of sugar, to match that sweetness would result in a higher caloric count if substituting with lactitol.

Greater calories, and more diarrhea! What more could anyone ask of an artificial sweetener?!

Isomalt aka E953

Isomalt Molecule
  • Calories per gram: 2.1
  • Glycemic Index: 9
  • Sweetness: 50% of sucrose
  • Industrial Source: Isomaltulose (A disaccharine) from glucose by enzymatic transformation, and then hydrogenation to Isomalt.

Isomalt is the pretty one. It is very popular among people who need an alternative to sugar for making sugar art. It doesn’t brown or caramelize when heated like sugar does, and it holds it’s form very well.

On the down side, it has 50% the sweetness of sugar and just a little more than half the caloric count; so, it’s in the same boat as lactitol, and very distressing for the gut. By the time you’ve doubled the amount you would use if using sugar in order to get the sweetness you need, you’ve got more calories than if you had used sugar, and it’s a treat that gives you a tummy ache. Yea, sure world, let’s make suckers out of this stuff, makes sense to me.

For people who need to find a sugar free alternative for making sugary sculptures, beads, and other artwork, this stuff is hands down awesome. And most professionals who use it know to cut it with something a little sweeter that doesn’t bother the gut so that it can go a little further. Not that you couldn’t make pretty clear candy gems from just isomalt without mixing in other sweeteners; if you do, just, maybe don’t actually eat them.

The Polysaccharide Derivatives

Maltitol Syrups aka E965ii, or lycasin, or Hydrogenated Starch Hyrolysate (HSH)

  • Calories per gram: 3
  • Glycemic Index: 48-53
  • Sweetness: 25-50% of sucrose
  • Industrial Source: Various carbohydrates from corn syrup by hydrogenation

Aside from having no cooling effect to its flavor, and it’s ability to stabilize other sugar alcohols in solution , there are not many benefits for using maltitol syrups over good old classic sucrose, with a glycemic index of 53, vs sucrose at 65, and 3 calories per gram vs sucrose at 4 calories per gram, by the time you make up the sweetness deficit, you’ve accomplished nothing good.

Maltitol syrup is just not significantly different than classic syrup,  although,  arguably still better than high fructose corn syrup (but, short of poisons, most things are).  So,  save yourself some gut distress and just use syrup or honey,  leave the maltitol alone.

Additionally, maltitol syrup is a mixture of different sugar alcohols and contains a large amount of sorbitol, which, as stated above, isn’t the greatest stuff.

Polyglycitol aka polyglucitol, or Hydrogenated Starch Hyrolysate (HSH)

  • Calories per gram: 2.8
  • Glycemic Index: 39
  • Sweetness: 30% of sucrose
  • Industrial Source: Various carbohydrates from corn syrup by hydrogenation

Polyglycitol is the same stuff as maltitol syrup (read above), just at different concentrations, if less than 50% by dry weight is maltitol, then it is labeled as polglycitol or polyglucitol syrup, but if greater than 50% maltitol, then it’s labeled as maltitol syrup. HSH is the general label that is used for all variants of this sticky concoction.

A Lipid Derivative

Glycerol aka E422, Glycerin, or Glycerine

Glycerine Molecule
  • Calories per gram: 4
  • Glycemic Index: 3
  • Sweetness: 60% of sucrose
  • Industrial Source: Triglycerides from plant or animal fats by hydrolysis, saponification, or transestrification.

Glycerol has a lot going for it in the food industry, it’s unique properties give a wide range of application, and it is often considered a healthier alternative to sugar with a lower glycemic index, and, like other sugar alcohols, it doesn’t contribute to cavities.

However, it’s not much different than some of the other sugar alcohols we’ve discussed, in that the sweetness is so much lower than sugar, that once you’ve matched that sweetness level, you’ve got a food with a greater calorie count.

And, it does still have that pesky laxative effect and gut irritation that most other sugar alcohols have, the exception being erythritol. So there’s that.

What it does have going for it is the heating effect to it’s flavor instead of a cooling effect, and is suggested as a balance for sweeteners like erythritol to remove that unwanted cooling effect.

It is also great at holding in moisture, which is it’s primary function in most food applications; aiding in keeping foods from drying out or going stale. It has also been shown to help retain moisture in people during extreme workouts, and some people have been known to add a little to their water before their workouts.

Outside of food, it is also used in many medical applications: for relieving pressure around the eyes and brain, as a laxative, and as an additive to many pharmaceuticals as a carrier or delivery substance.

In Conclusion

A few sugar alcohols on this list are either acceptable sweeteners or have their functions that justify their use: Erythritol (sweetener), Xylitol (oral care and medical), Mannitol (medical), Isomalt (decorations), and Glycerol (humectant, sweetener additive, industrial, and medical). But many are not very logical choices for finding an alternative to sugar.

I would love to be able to tell you which of these you should avoid, and which are okay for you, but that’s really something that only you can find out. With so many different effects and uses, each one of these sugar alcohols is as unique as the people consuming them. How they effect you, only you can determine (or choose not to), but I do hope that I’ve at least provided you with some guidance in making your decisions.

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