Food companies have recently capitalized on the keto diet’s rise in popularity by creating innovative, keto-friendly foods and snacks.

To make these items keto-friendly, many manufacturers utilize a sugar substitute called allulose.

Still, you may wonder whether allulose can help you maintain ketosis, the process by which your body primarily burns fat for fuel rather than carbs. You may also want to know whether it’s safe.

This article takes a closer look at allulose to explain whether it’s truly keto-friendly.

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Allulose is a type of sweetener that’s found naturally in some fruits (1).

Allulose is commonly referred to as “rare sugar” because it’s naturally present in small quantities in just a few foods, including jackfruit, figs, and raisins.

It shares the same chemical formula as fructose, a simple sugar, but its molecules are arranged differently. As such, your body metabolizes allulose differently than it metabolizes fructose and other sugars (1).

Instead of being absorbed and metabolized like other sugars, leading to a rise in your blood sugar and contributing energy (calories), it passes through your body and is ultimately excreted in your urine and feces.

Gram for gram, allulose contains about 90% fewer calories than sucrose, or table sugar, and is about 70% as sweet (1).

These qualities make allulose an excellent low calorie alternative to sugar.

Its sweetness level and calorie content (0.2–0.4 calories per gram) are similar to many sugar alcohols, including erythritol, sorbitol, and mannitol (2).

Today, most allulose is mass-produced using an enzymatic process to convert fructose from corn, beets, and other vegetables into allulose (3).

Summary

Allulose — a sugar naturally found in only a few foods — contains only a fraction of the calories of sugar but is almost as sweet.

Because allulose passes through your body largely unmetabolized, it doesn’t increase your blood sugar or insulin levels.

In fact, allulose has been shown to moderately improve blood sugar and insulin regulation in people with and without diabetes (4).

As such, it’s perfectly suitable for the keto diet, as well as those seeking to manage diabetes or lose weight. Food manufacturers favor allulose as a sugar substitute for making keto-friendly products ranging from protein bars to frozen dairy desserts to syrups.

You can also purchase allulose in bulk. It acts like sugar in many recipes and can be added to beverages like coffee or tea.

When substituting allulose for sugar, you will need about 30% more allulose than the sugar called for in the recipe. In other words, every 1 teaspoon (4 grams) of sugar should be replaced by 1 1/3 teaspoon (5.5 grams) of allulose.

However, allulose is quite expensive, costing 5–7 times more per ounce than sugar.

To reduce costs, many food manufacturers combine allulose with other natural, low calorie, keto-friendly sugar substitutes like monk fruit and stevia, as well as with artificial sweeteners like sucralose and aspartame.

Since monk fruit and stevia are 100–400 times sweeter than sugar, much less allulose is required to achieve the desired sweetness level when these sweeteners are also used (5).

Summary

Allulose doesn’t affect your blood sugar or insulin levels, making it a keto-friendly alternative to sugar. It’s easy to use in baking and food manufacturing since it behaves like sugar.

With the safety of sweeteners — both natural and artificial — constantly under scrutiny, you may wonder whether allulose has any side effects.

The Food and Drug Administration (FDA) considers this additive safe to use in food (1).

Human studies have used up to 10-gram doses of allulose without tying it directly to any negative side effects (6, 7).

However, one study associated a single dose of 0.23 grams per pound (0.5 grams per kg) of body weight and a daily intake of 0.45 grams per pound (1 gram per kg) of body weight of allulose with diarrhea, bloating, nausea, headaches, and stomach pain (8).

To avoid these effects, researchers suggest a maximum single dose of 0.18 grams per pound (0.4 grams per kg) of body weight and a maximum daily intake of 0.41 grams per pound (0.9 grams per kg) of body weight (8).

For a 150-pound (68-kg) person, that’s equivalent to a single maximum dose of 27 grams or a total daily dose of 61 grams — or about 2 and 5 tablespoons — respectively.

Summary

Consuming too much allulose may cause stomach pain, diarrhea, and bloating, among other uncomfortable side effects.

Allulose is a natural sugar that shares the same molecular formula as fructose.

However, unlike fructose and other sugars, allulose doesn’t raise your blood sugar or insulin levels, making it keto-friendly.

While allulose is generally well tolerated, it may cause stomach issues if consumed in high amounts.