The “ol” ending in the names of some sweeteners is no accident—that’s the result of chemists trying to keep things consistent. Sorbitol, erythritol and xylitol are known as sugar alcohols. That doesn’t mean they’ll get you drunk—they won’t. It means that they have a chemical resemblance to alcohol. They’re best known for their use in sugar-free chewing gum. They don’t promote tooth decay because most microbes can’t use them for fuel. Humans can use some sugar alcohols for fuel, but they don’t pack as many calories per gram as sugar. Unfortunately, most sugar alcohols are not well absorbed from the digestive tract, and what isn’t absorbed can lead to bloating and diarrhea. The sugar alcohols are found in nature, but most of the products available commercially are created through industrial chemical processing of sugars. While sugar alcohols are found in nature, they’re not found in the kind of quantity that sugar is in a typical sweet-toothed Western diet.
The relevant questions here: Are they a healthier alternative than:
b) artificial sweeteners such as NutraSweet (aspartame) and Splenda (sucralose)?
c) glucose (dextrose)?
and do the sugar alcohols (such as released when chewing sugar-free gum) cause an insulin response?
While none of the sugar alcohols has a smoking-gun kind of badness about it, I’d like to point out that none of these sugars has been a major component of food for anyone for a lifetime. That means that over time, any of these products could cause trouble that no one can detect in short-term lab studies. The same goes for any product you use. Consumer products just don’t get tested that way—if they did, it would be decades before any new product could be on the market. If that sort of testing were customary, then products like sugar, high fructose corn syrup, aspirin and fruit juice might never have been allowed on sale.
What Do We Know About Erythritol?
A 1996 study sums up the following: Erythritol is about 60-70 percent as sweet as sugar. It’s 60-90% absorbed by the intestine. The portion that is absorbed can’t be used as fuel or broken down (metabolized) by humans, so it circulates in the bloodstream until it is excreted by the kidneys in urine. The 10-40% remaining in the intestine may be fermented in the colon if bacteria adapt to its presence as observed in rats, but there’s some debate about whether that happens in humans at typical intake levels. The subjects in the study showed an insulin response to the sucrose snack, but not to the 0.8g/kg erythritol. Some of the test subjects eating the higher dose of erythritol reported hunger, nausea and flatulence to a greater degree than those in the lower dose and control groups.
A second study from 1996 looked at ingestion of 1g/kg per day of erythritol over the course of a week. The erythritol was generally well tolerated and 7 of the 12 subjects had a significant increase in urine calcium and protein excretion, including a 25% increase in beta-2-microglobulin excretion.
A chronic toxicity study in rats fed massive doses (10% of intake) of erythritol found some indicators of mild kidney damage including kidney enlargement and nephrocalcinosis.
If a sweetener is a must, then erythritol appears to be a reasonable choice. It’s mostly absorbed from the intestine, so bloating, diarrhea and flatulence are less likely than with other sugar alcohols. It’s not metabolized, so it has no actual calorie content. It appears unlikely but possible that chronic use of erythritol could contribute to kidney damage. Used in small amounts and only occasionally, the chance of such damage would be reduced. Frequent use of erythritol may allow bacteria in the colon to adapt to ferment the non-absorbed portion, producing gas (flatulence). It was the tendency of the authors of all of these studies to minimize the significance of the negative effects, so I have concerns about bias. The healthiest choice is to work on losing the sweet-centered taste that makes sugar and sugar substitutes necessary.
If I wanted to sweeten a no-calorie drink during a fasting window, I would consider erythritol roughly equivalent to stevia. I’d use it in the smallest tolerable amounts, and would prefer it to the major sugar substitutes such as aspartame, sucralose and saccharin. I would not prefer it to glucose (dextrose) or even sucrose for sweetening food because of the amount required.