Today we will talk about sugar alcohols which are a popular low calorie sugar substitute. We will talk about xylitol, which is the most popular and most researched, but we will also cover other sugar alcohols, such as sorbitol and erythritol. Xylitol and sorbitol are commonly used as sugar substitutes, but are they safe?
What exactly are sugar alcohols like sorbitol
The sugar alcohols are a type of 'low digestible carbohydrate ", a category that includes fiber and resistant starch. Sugar alcohols are found naturally in many fruits and are also known as 'polyols', which you may recognize as FODMAPs.
Unlike artificial sweeteners, sugar alcohols are not completely calorie-free, because we are able to digest and absorb them to some degree.
The rate of absorption varies among sugar alcohols, from about 50% for xylitol to almost 80% for sorbitol, depending on the individual. The erythritol is absorbed almost completely but not digested, so almost no calories.
Compared to artificial sweeteners, sugar alcohols have very few safety and toxicity studies, and are generally accepted as safe. (1)
In a long-term human study, 35 participants consumed xylitol as their main dietary sweetener for two years, and no adverse effects other than gastrointestinal upset were observed, and gastrointestinal symptoms dissipated after the first two months. (2) The amount of xylitol consumed during this test typically exceeded 100 g per day, often exceeding 200 g per day, depending on the participant.
Metabolic effects of sugar alcohols
Sugar alcohols are a popular option for weight loss due to their low-calorie content and for diabetics due to their low glycemic index.
There isn't as much research on the metabolic effects of sugar alcohols as there is on artificial sweeteners, but the evidence we do have suggests that sugar alcohols like sorbitol and xylitol are at least harmless and possibly beneficial.
Sorbitol and xylitol do not raise blood sugar
For the most part, sugar alcohols do not cause appreciable changes in blood glucose or insulin in humans, and sorbitol and xylitol have not been found to increase blood glucose after consumption.
In diabetic rats, 5 weeks of xylitol supplementation (as 10% of their water taken) reduced body weight, blood glucose, and serum lipids, and increased glucose tolerance compared to controls.
(3) Two other studies in rats also found that rats supplemented with xylitol gained less weight and fat mass compared to control rats, and had better glucose tolerance.
Sugar alcohols like sorbitol do not have a strong flavor
Because sweetness does not predict the caloric value in sugar alcohols, one might expect them to cause the same “metabolic confusion” that is seen with non-caloric artificial sweeteners.
Unfortunately, there is not enough evidence to draw a conclusion on this, but it could be that this is not a major problem for sugar alcohols.
For one thing, sugar alcohols like sorbitol are not 'strong sweeteners' like artificial sweeteners, which are hundreds of times sweeter than sugar.
In fact, many are less sweet than sugar. Also, sugar alcohols offer some calories, so there isn't much of a discrepancy between the caloric load that your body expects and the caloric load that you actually get.
Does xylitol prevent tooth decay?
The best-known health benefit of xylitol is easily its effect on dental health, and the evidence for xylitol's ability to prevent tooth decay is pretty strong. (4) A couple of trials have found xylitol to be more effective in preventing cavities than fluoride, and benefits of xylitol consumption have even been seen in child mothers chewing gum containing xylitol.
Unsurprisingly, the most drastic effects are seen when xylitol replaces sucrose in diet or gum, but significant reductions in cavities have been seen when xylitol is simply added in addition to a normal diet.
Although some effects of xylitol are undoubtedly due to non-specific factors such as increased saliva production or sugar substitution, it appears to have specific properties that promote dental health.
Xylitol is not fermentable by common oral plaque-forming bacteria like sugar, so it does not provide a food source. Additionally, xylitol actively inhibits the growth of these bacteria. It also forms complexes with calcium, which can aid in remineralization.
Sugar alcohols and digestive health
While sugar alcohols appear to be safe and potentially therapeutic, they are also notorious for causing digestive problems. Because sugar alcohols are FODMAPs and are largely indigestible, they can cause diarrhea by carrying excess water into the large intestine.
Fermentation of sugar alcohols by gut bacteria can also cause gas and bloating, and sugar alcohols can decrease fat absorption from other foods.
(5) However, most of the evidence indicates that people can adjust to regular alcohol and sugar consumption, and adverse gastrointestinal effects reported in studies tend to fade after the first month or two.
Erythriol, the best intestinal tolerated sugar alcohol
Erythritol is probably the best tolerated sugar alcohol, and some human trials have found that if the amount of erythritol increases gradually and the doses are spread throughout the day, many people can tolerate large amounts (up to 1 g / kg of body weight) of erythritol without gastrointestinal distress.
(6) The average tolerance for xylitol and sorbitol is lower; Most study subjects were able to tolerate approximately 30 g per day without problems, but significant adaptation was required to increase the xylitol content in the diet.
Some studies indicate that sugar alcohols may have a prebiotic effect. This is not too surprising, considering the prebiotic effects of other low-digestible carbohydrates like fiber and resistant starch.
Xylitol causes good intestinal bacteria
Animal studies have found that xylitol causes a change from gram-negative to gram-positive bacteria, with fewer Bacteroides and higher levels of Bifidobacteria.
A similar change has been observed in humans, even after a single dose of xylitol. (7) In addition, the observed changes allowed a more efficient use of sugar alcohols by intestinal bacteria, which largely explains the reduction in gastrointestinal symptoms after a few months of regular consumption.
In addition to the potential metabolic, dental, and prebiotic benefits already discussed, xylitol shows promise for preventing age-related decline in bone and skin health.
Xylitol increases collagen in the skin
An interesting study found that supplementation with 10% xylitol for 20 months increased collagen synthesis in the skin of elderly rats, resulting in thicker skin.
Preliminary studies in rats have also shown that xylitol can increase bone volume and mineral content and protect against bone loss. (8)
In general, sugar alcohols appear to be safer than artificial sweeteners with several potentially therapeutic effects. Although the metabolic and weight loss benefits of sugar alcohols have not been as widely studied, sugar alcohols are recommended in place of artificial sweeteners to anyone in need of a low-calorie sweetener, although it would not be recommended to anyone consume large amounts of them.
Also, it would be interesting to see additional research on their ability to alter the gut microbiome and alter biofilms, because this could make sugar alcohols a useful tool for certain patients.
At this point, there doesn't seem to be any major problem with sugar alcohols, so if it's something that interests you, experiment with your own tolerance and see how they affect you.
However, people with chronic gut problems should be careful around sugar alcohols like sorbitol.
Normally, blood glucose levels increase after you eat a meal. When blood sugar rises, cells in the pancreas release insulin, causing the body to absorb glucose from the blood and lowering the blood sugar level to normal. When blood sugar drops too low, the level of insulin declines and other cells in the pancreas release glucagon, which causes the liver to turn stored glycogen back into glucose and release it into the blood.