Coming to the keto diet from a former diet rich in sugar and carbohydrates can be a difficult thing. Trust me, I’ve done it.

With so much information out there and so many alternative sweeteners in foods, it’s challenging to always know what exactly is safe for the keto diet, and what should be avoided at all costs.

In this article, I’ll be doing a deep dive on the sugar alcohol known as mannitol, will discuss it’s pros and cons, and will give some insight into just how keto-friendly it really is.

But first, let’s breakdown exactly what mannitol is.

What Is Mannitol?

Mannitol is a type of sugar alcohol that is used for both prescription medications and as an alternative sweetener for sugar in a lot of pre-packaged food products.

As a medicine, it’s often prescribed to help with decreasing pressure around the eyes for conditions like glaucoma, and can also function as a prescribed laxative for those with more extreme cases of digestion issues.

It’s most commonly found in foods that are marketed toward those with diabetes, because it has a low glycemic index, and the carbs it comes with are not digestible by the body.

Like most types of sugar alcohols, you’re likely to find mannitol in some of the following foods:

• Sugar-free juices and sodas
• Sugar-free candies
• Chewing gum
• Dairy products like ice cream and yogurt

Is Mannitol Keto-Friendly?

Because of its low digestible carb content, low glycemic index value, and low calorie count, mannitol makes for a perfectly keto-friendly sugar alternative.

Mannitol is generally hard to come by in stores, and it is most commonly found in “sugar-free” pre-packaged foods and drinks.

One caveat to mannitol on keto is that because its often pre-packaged, sometimes it can come with other non-keto and high glycemic sweeteners such as maltitol, dextrose and maltodextrin, so you should always read the full list of ingredients whenever considering eating or drinking something that contains mannitol.

Now that we know it’s safe to use on a keto diet, let’s get into both the benefits and drawbacks that you’ll want to consider when adding it to your daily or weekly meal plans.

Benefits of Mannitol

• Stimulates bowel movements

Mannitol, like a few other types of sugar alcohols, has been proven to be very effective when it comes to stimulating bowel movements because of its laxative-like properties.

This may be a positive or a negative depending on your individual digestion situation, but because constipation tends to be a common symptom of keto, especially for those who are just starting out with keto, it can be a great choice to help improve the regularity of your bowel movements.

• Good for oral health

Sugar alcohols, such as mannitol, are beneficial for our dental health because they are resistant to being metabolized by oral bacteria. Because of this, they also don’t contribute to an increase in the acidity of the mouth after being ingested, unlike regular table sugar.

This means consuming sugar alcohols will not directly contribute to the development of cavities or the erosion of tooth enamel. The Food and Drug Administration (FDA) has approved the use of a “does not promote tooth decay” health claim for labeling all sugar free products that use mannitol as their active sweetening ingredient.

• Low in calories

One of the clearest benefits of using foods that contain mannitol instead of sugar is simply because of its low calorie counts. Sugar is highly caloric, and is largely responsible for the rapid weight gain we’ve been seeing in western countries over the last century.

By switching to sugar substitutes that are low in calories, you can help promote weight loss, and reduce the risk of developing a variety of metabolic cardiovascular diseases such as heart disease, high cholesterol, high blood pressure, and type 2 diabetes.

• Lowers blood sugar levels

Mannitol is especially beneficial for those who struggle with diabetes and keto dieters alike because of its effects on blood sugar levels. As an alternative sweetener, mannitol has a very low glycemic index (GI) value, which means that you won’t experience spikes in blood glucose after eating.

Mannitol is in fact one of the best types of sugar alcohols in this department, because it only has a GI of 2, compared to table sugar’s GI of 65.

It’s important to try and aim for low glycemic index values in everything you eat on the ketogenic diet, because even if you’re well within your net carb limits, spikes in blood sugar have been known to take people out of ketosis.

Side Effects of Mannitol

• Dizziness

Dizziness is a pretty concerning issue when it comes to mannitol. When it comes to dizziness from a sugar alcohol, it will usually also come with symptoms like nausea, dehydration, blurred vision, insomnia, chills, fever, and a persistently dry mouth.

It’s important to keep an eye on the other symptoms that arise with mannitol use, because they can often be indicators of much more serious conditions as well. It’s generally advised to see a doctor if you end up experiencing prolonged dizziness.

• Digestion issues

Along with the added benefit of stimulating more regular frequency of bowel movements, too much mannitol can quickly make this a bad thing.

As seen in other types of sugar alcohols as well, getting too much mannitol can end up over-hydrating your intestines, which can result in discomfort, bloating, and in more extreme cases diarrhea. You should always keep track of just how much mannitol you’re consuming, just to be safe

• Allergic reactions

Mannitol can lead to a variety of allergic reactions as well. These can range from mild to severe, including symptoms like a runny nose, itchy skin, trouble breathing, hives, and in most extreme cases, anaphylaxis.

If you have any known fruit allergies or already know that you have allergic reactions to other types of sugar alcohols, you should consult with a doctor before adding mannitol into your diet.

• High in FODMAPS

Polyols (sugar alcohols) are characterized as foods that are high in FODMAPS.

FODMAPS are characterized as a group of fermentable carbohydrates, which can come with their own set of issues not only for those on the keto diet, but for any humans.

FODMAP stands for Fermentable Oligo-, Di-, Mono-saccharides and Polyols, and foods that are high in these have been heavily linked to digestive issues.

That doesn’t mean that you should stray away from sugar alcohols altogether, but you should always evaluate how you feel after attempting to add a certain type of sugar alternative into your diet.

Mannitol vs Other Alternative Sweeteners

• Monk Fruit

Monk fruit is by far my most perferred option out of all sugar substitutes that are safe to eat on the keto diet.

As an alternative sweetener, it is about 100 to 250 times sweeter than table sugar, meaning just a little can definitely go a long way, especially when it is compared to a sugar alcohol like mannitol, which only has about 60% of the sweetness of sugar.

If you’d like to learn more about monk fruit and keto, you can check out my full guide on it here.

• Sucralose

Sucralose, which is more popularly known as Splenda, is a pretty common sugar substitute, but unfortunately it isn’t always the best option when it comes to trying to maintain a state of ketosis.

When used as a sweetener by itself, sucralose contains zero calories and zero glycemic index, which is great in theory, but when sold as a powder (like in splenda packets), or mixed into pre-packaged foods, it’s often blended with other sweeteners that can easily contribute to your overall carb counts.

• Allulose

Allulose, while often thought of as just a normal sugar alcohol, is actually characterized as a monosaccharaide, which is a rare type of natural sugar.

As a substance that comes from nautre, it is completely organic, and is usually found in dried fruits such as raisins, jackfruit, and figs, but really only in trace amounts.

When allulose is made for human consumption, it is generally processed into a fine extract, so that it can be used as an effective substitute for sugar.

Similar to other sugar alcohols like mannitol and sorbitol, allulose has roughly 60-70% of the sweetness of sugar.

• Erythritol

Erythritol, like mannitol is a fairly popular kind of keto-friendly sugar alcohol.

One of the important differentiators for erythritol from other sugar alcohols is that it occurs in nature much more prevalently, and generally has lower glycemic index values and calorie counts than other alternatives. It’s commonly found in a lot of keto recipes because it can come as a liquid or as a confectionary powder for baking, popularized by keto products like Swerve.

• Xylitol

Xylitol, like mannitol is another type of sugar alcohol that is often used by a lot of people on the keto diet.

Generally, xylitol is perfectly fine to use on the keto diet in moderation, but when it comes to sugar alcohols I’m more likely to recommend erythritol over xylitol or mannitol for frequent use because of the known side effects for each.