Sugar alcohols are a great way to get your hit of sweetness without doing damage to your Keto diet. Regular sugar is a big no no on the Keto diet so it’s necessary to satisfy your cravings from other sources.
You have may have read our previous article on natural or artificial sweeteners, which touched on sugar alcohols. Similarly to these sweeteners, sugar alcohols provide a sweet taste at a significantly reduced caloric value in comparison to sugar. As a result, they are a good alternative to sugar and can help keep your Keto diet on track.
But what are sugar alcohols and how can they be incorporated into your Keto diet?
Table of contents
What are sugar alcohols?
Sugar alcohols are a type of carbohydrate commonly used as a sugar substitute in a variety of food products
These food products sometimes combine sugar with sugar alcohols in order to reduce the total sugar, or use sugar alcohols as a complete sugar-substitute. Products that completely replace sugar with sugar alcohols are often suitable for individuals on a ketogenic diet.
Unlike artificial sweeteners, sugar alcohols are naturally occurring compounds that are commonly found in fruits and vegetables, such as berries and mushrooms[1].
However, for commercial uses, sugar alcohols are generally produced through the hydrogenation of sugars[1].
Sugar alcohols provide fewer calories than sugar, are metabolized more slowly, and have a lower glycemic index, making them a popular alternative for individuals looking to reduce their sugar intake or follow a low-carb or ketogenic diet[1].
Sugar alcohols can be separated into 3 broad categories, depending on the number of saccharides (carbohydrate units) present in the molecule;
Monosaccharide-derived sugar alcohols: e.g. xylitol, sorbitol and mannitol – derived from xylose, glucose and mannose respectively
Disaccharide-derived sugar alcohols: e.g. lactitol and maltitol which are derived by the hydrogenation of lactose and maltose respectively
Polysaccharide-derived sugar alcohols mixture: e.g. Isomalt
When ingested, sugar alcohols are only partially digested (ranging from 0% – 80%) in the intestines[1].
The remaining undigested sugar alcohols are fermented by colonic bacteria, often resulting in the production of gas that can be responsible for bloating and stomach cramps. The fermentative breakdown of sugar alcohols by bacteria results in the formation of short-chain fatty-acids, which can then be utilised by the body for energy[1][2].
This partial digestion means that sugar alcohols have a lower caloric value compared to sucrose, meaning they are a good option for reduced-sugar products.
Commonly used sugar alcohols
Isomalt
Isomalt is a polysaccharide-derived sugar alcohol (a mixture of 2 disaccharide alcohols) that has a white, odourless, crystalline structure, and is soluble in water[3].
As a sugar alcohol, isomalt is commonly used as a sweetener and flavouring agent in products such as sugar-free gum, lozenges and sugar-free sweets for diabetics. In addition, isomalt has unique properties that mean it can be used in a wide variety of pharmaceutical applications, including tablets, capsules and suspensions[3][4].
Isomalt is about half the sweetness of sucrose, but contains significantly less energy per gram, and can be combined with other sweeteners to match the sweetness of sugar. Given its low glycemic index and negligible impact on insulin, Isomalt can be used on the Keto diet as well as for those with diabetes[3][4].
Lactitol
Lactitol is a disaccharide-derived sugar alcohol created by the hydrogenation of the sugar lactose, using a Raney nickel catalyst[5].
It is commonly used as a sucrose substitute, but is also used medically as an excipient and a laxative.
Apart from being a sweetener, lactitol is used medically as a laxative to treat chronic idiopathic constipation (CIC) (which means constipation with an unknown cause). It acts by bringing water into the colon and improving peristalsis (colonic contractions), which can improve bowel movements[5].
Lactitol is only around 30-40% as sweet as sucrose, so is often used as a bulk sweetener for lower calorie food options.
Common uses as a sweetener include sugar-free confectionary and ice cream. As lactitol is poorly absorbed compared to sugar, it has approximately half the caloric value by weight, making it a popular sugar-replacement. In addition, lactitol is also used as a sweetener on the Keto diet as it has a low glycemic index and does not lead to an increase in insulin secretion[5].
Sorbitol
Sorbitol is a monosaccharide-derived sugar alcohol, that naturally occurs in fruits and vegetables as well as seaweed and algae[6].
For commercial purposes, sorbitol is produced from glucose through a reduction reaction (aldehyde group to a hydroxyl group).
Sorbitol is used in numerous food and beverage products as a sweetener, but is incredibly versatile. In addition to a sweetener, sorbitol is used as stabiliser, bulking agent, and thickener for foods as well as numerous uses within cosmetics and pharmaceuticals[6].
Sorbitol is about half as sweet as sucrose but contains significantly fewer calories. In addition, sorbitol has a low glycemic index and has a minimal impact on insulin, making it a Keto-friendly option[6].
Maltitol
Maltitol is a disaccharide-derived sugar alcohol formed by the hydrogenation of the sugar maltose[7].
It is commonly used as a sugar-substitute and a sweetening agent as well as used as a laxative.
As well as being used as a sweetener in food and beverage products, e.g. sugar-free chewing gum, chocolates, ice cream etc., maltitol is extensively used in pharmaceutical applications, specifically use in different dosage forms such as tablets and capsules[7].
Maltitol is often used as a bulk sweetener, and given its sweetness is approximately the same as sucrose, it can be used in similar proportions to sugar[7].
Unlike sugar however, it has a more favourable glycemic profile, and a reduced impact on insulin. It should be noted however that maltitol does impact insulin levels to a greater extent than other sugar alcohols and should therefore be avoided or minimised when following a strict Keto diet[7].
Mannitol
Mannitol is a monosaccharide-derived sugar alcohol, formed by the reduction of mannose[8].
As it is poorly absorbed in the intestines, it is a good low-calorie sugar-substitute, and is consequently used in a number of different food applications.
Naturally, mannitol may be extracted from the flowering ash plant (manna) but in most commercial applications, mannitol is produced from the electrolytic reduction of monosaccharides such as mannose and glucose[8].
Mannitol also has a number of medical applications.
These include use as a diuretic as well as a treatment for glaucoma, due to its ability to reduce intra-ocular pressure. In larger doses, mannitol may also act as a laxative[8].
Given its low glycemic index and negligible impact on insulin, mannitol can be consumed as a sugar-substitute on the Keto diet.
Erythritol
Erythritol is a very popular sugar alcohol, that is commonly used in a number of food products.
It naturally occurs in a number of fruits and fermented foods but for commercial applications, erythritol is manufactured through fermentation of glucose or sucrose. Due to its sweet properties, erythritol can be used in a number of applications, including cakes, sugar-free sweets as well as beverages and ice cream[9].
Erythritol is also commonly used within the pharmaceutical industry as an excipient, and is often prepared in solid dosage forms such as tablet fillers and coatings. In large enough doses, erythritol has a laxative effect (similar to many sugar alcohols)[9].
Given its low glycemic index, as well as no impact on insulin, erythritol is a great sweetener to use on the Keto diet[9].
It is approximately 50-60% as sweet a sucrose, so may require larger volumes to obtain the desired level of sweetness.
Check out our in depth guide on erythritol here.
Xylitol
Xylitol is a monosaccharide-derived sugar alcohol, commercially produced by the hydrogenation of xylose, using a Raney nickel catalyst[10].
While xylitol naturally occurs in a number of fruits such as strawberries and plums, most commercial operations utilise hydrogenation or industrial fermentation.
Xylitol has a sweetness value that is commensurate with sucrose, and is commonly used in sugar-free products. Xylitol is commonly found as a sugar-substitute in sugar-free chewing gym, toothpaste as well as an excipient in pharmaceutical products[10].
As well as being equivalent in sweetness to sucrose, xylitol contains 40-50% less caloric value, resulting in a good sugar-substitute to those looking to lose weight[10].
In addition, a low glycemic index and minimal impact on blood insulin means that xylitol can safely be consumed on the Keto diet.
Check out our in depth guide on xylitol here.
Do sugar alcohols impact insulin and blood sugar levels?
Impact on insulin and blood sugar
A key component of the Keto diet is to maintain a state of ketosis, which requires controlling blood glucose and insulin levels.
Given most sugar alcohols have a negligible impact insulin, they are generally compatible with the Keto diet.
Numerous studies have demonstrated that consumption of sugar alcohols have no discernible impact on blood glucose or insulin secretion[11].
A study conducted with both lean and obese individuals found that sugar alcohols had a negligible impact on blood glucose or insulin levels.
In this study, participants were either given a supplement of glucose, erythritol or xylitol in a 300ml solution with water. The study found that, as expected, sugar ingestion led to an increase in both plasma glucose and insulin levels[12].
However, with erythritol, there was no impact on plasma glucose or insulin, with only minor affects noticed with xylitol[12].
Longer term impact on metabolic profile
Similarly, longer term studies with sugar alcohols demonstrate an overall improvement in metabolic control as a result of replacing sugar.
A 12-week study investigating the impact of replacing sucrose with the sugar alcohol isomalt found improvements in markers of metabolic controls. The study included patients with type II diabetes and found that those supplemented with isomalt (rather than sucrose) displayed significant reductions in fasting blood glucose, insulin and insulin resistance[13].
The literature clearly demonstrates that sugar alcohols have minimal impact on blood glucose and insulin levels, and can be used as effective sugar-substitutes for diabetics or those following a Keto diet.
What are the health benefits of sugar alcohols?
Weight control and improved metabolic profile
Sugar alcohols like xylitol can provide sweetness to foods and beverages but at a fraction of the caloric value of sugar. As a result, using sugar alcohols as a sugar-substitute can significantly reduce overall daily caloric intake, leading to a reduction in body fat[12][13].
In addition, sugar alcohols have a significantly lower glycemic index and insulin response, resulting in greater metabolic control. As a result, sugar alcohols can be used freely by both diabetics and those following low carbohydrate diets like Keto[12].
Improved dental health
Use of sugar alcohols (particularly in chewing gum) has been associated with improved dental health and caries prevention.
This likely occurs due to 2 main reasons; firstly the replacement of sugar in the diet with sugar alcohols, reduces the total amount of dental damage – consumed sugar that remains in the mouth is fed on by oral bacteria, which create an acid that slowly dissolves tooth enamel[14].
The second reason is that sugar alcohols are able to repair and remineralise dental caries.
A number of clinical studies have demonstrated that sugar alcohol consumption, notably sorbitol and xylitol, are strongly associated with re-hardening of artificial as well as genuine caries[14].
As a result, sugar alcohols are often recommended as sugar-replacements by dentists, and are commonly found in toothpastes.
Side effects of sugar alcohols
Gastrointestinal symptoms
Now that you’ve heard about all the wonderful features of sugar alcohols, you may be wondering, what’s the catch?
As mentioned earlier, some sugar alcohols can be used as medical laxatives. This is due to their ability to draw water from the body into the gut, which can also result in something called osmotic diarrhea. This can occur with excessive consumption and can contribute to dehydration, especially in hotter environmental conditions[15].
In addition, overconsumption of sugar alcohols has been linked to a number of gastrointestinal issues such as flatulence, bloating and abdominal cramps[15].
This is because sugar alcohols are incompletely digested in the gut, resulting in gut bacteria feeding on them.
As a by-product, the bacteria produce gas, which can lead to bloating and abdominal cramps. The larger the amount ingested, the more significant the abdominal symptoms[15].
Does this mean you should swear off sugar alcohols? Absolutely not!
Sugar alcohols can be a great way to maintain your Keto diet and enjoy sweet treats.
The key is to consume them in moderation and slowly increase the amount in your diet, and therefore give your body time to adjust.
How to integrate sugar alcohols into your Keto diet
Sugar alcohols can be used in a number of different food and beverage products.
This can include baked goods, sugar-free sweets and ice creams.
It is important consider what the use of the sweetener is as some sugar alcohols are more stable and respond better to heat and therefore would be more suitable for baking or frying.
Why not check out some of our Keto recipes utilising sugar alcohols, or check out our article for a complete guide to what you can eat on the Keto diet?
The amount of sweetener required will vary depending on the type of sugar alcohols you use.
For example, xylitol is approximately the same level of sweetness as sucrose, so can generally be replaced in a 1:1 ratio. However, sugar alcohols with a lower level of sweetness may require larger amounts, or combination with other sweeteners.
As mentioned, excessive consumption can lead to gastrointestinal distress. To mitigate this, it is recommended to consume sugar alcohols in moderation, as well as slowly introducing them into your diet, giving your body a chance to adapt[15].
If you are interested in learning more about sweeteners that can be used on the Keto diet, why not check out our guides on natural sweeteners and artificial sweeteners.
WARNING: Some sugar alcohols, e.g. xylitol, can be poisonous for dogs and other pets.
So please ensure that these are kept away from you furry friends!
