If you have spotted a new sweetener in protein bars, low-sugar ice cream, or
sugar-free syrups, there is a good chance you were looking at allulose. Once a
laboratory curiosity, this so-called “rare sugar” is now appearing
across U.S. supermarket shelves — and behind the marketing is a small but
growing body of research that suggests it behaves more like fiber than like
table sugar inside the body.
What Is Allulose?
Allulose, also called D-psicose, is a monosaccharide that occurs naturally
in tiny amounts in foods like figs, raisins, jackfruit, and maple syrup. It is
chemically almost identical to fructose, but one small structural difference
changes how the body processes it. According to the U.S. Food and Drug
Administration, allulose provides about 0.4 calories per gram — roughly
one-tenth the calories of table sugar — while delivering about 70% of
sucrose’s sweetness.
In a 2019 guidance update, the FDA announced that allulose can be excluded
from the “Total Sugars” and “Added Sugars” lines on the
Nutrition Facts label because studies indicate it is not metabolized to
glucose. That single labeling decision helped spark the wave of allulose-based
products now on shelves.
Why Researchers Call It “Rare”
The term rare sugar refers to monosaccharides that exist in nature only in
small quantities. Most commercial allulose is produced by enzymatically
converting fructose from corn. Once it reaches the gut, research published in
the Journal of Nutritional Science and Vitaminology indicates that
about 70% of the dose is absorbed in the small intestine and excreted unchanged
in the urine, while the remainder passes to the colon. Unlike fructose,
allulose is not used for energy production in a measurable way.
Blood Sugar and Insulin: What Studies Show
The most consistent finding in allulose research is its neutral effect on
blood glucose. A 2018 randomized crossover trial in Nutrients
reported that single doses of 5–10 grams of allulose taken before a
carbohydrate-rich meal lowered the post-meal glucose peak in adults at risk for
type 2 diabetes, compared with placebo. A 2020 systematic review and
meta-analysis published in the European Journal of Clinical Nutrition
pooled data from multiple trials and concluded that allulose modestly
attenuates post-meal glucose response without raising insulin.
These findings have prompted interest from the diabetes research community,
though authors caution that most studies are short term and involve small
sample sizes. The National Institutes of Health database PubMed lists a
growing number of ongoing clinical trials examining allulose in people with
prediabetes and metabolic syndrome.
Weight and Body Composition
Animal and early human research suggests allulose may influence fat
metabolism. A 12-week randomized trial published in Nutrition &
Metabolism in 2018 reported that overweight adults who consumed about 14
grams of allulose per day showed small but statistically significant
reductions in body fat mass compared with a sucralose control group. A 2023
review in Nutrients noted that the proposed mechanism may involve
increased fat oxidation and reduced lipogenesis in the liver, but the authors
stressed that long-term human data are still limited.
In other words, allulose is not a weight-loss drug. Research suggests it
may help when it replaces caloric sugar in a diet that is otherwise calorie
controlled.
The Gut: Where Allulose Behaves Like Fiber
Because a portion of allulose reaches the colon undigested, it interacts
with the gut microbiome similarly to certain soluble fibers. Small
fermentation studies have observed modest increases in short-chain fatty acid
production, which research suggests may support gut barrier function.
However, the same property explains the most common side effect: gastrointestinal
discomfort, including bloating, gas, and diarrhea at higher doses.
A 2018 tolerance study published in Food and Chemical Toxicology
estimated a single-dose threshold of roughly 0.4 grams per kilogram of body
weight — about 27 grams for a 150-pound adult — before noticeable
GI symptoms emerge. Daily tolerance was lower, around 0.5 grams per kilogram
spread across the day. Most packaged foods deliver far less than this per
serving, but stacking several “low-sugar” products in one day can
add up quickly.
Safety and Regulatory Status
Allulose holds Generally Recognized as Safe (GRAS) status with the FDA for
use in foods and beverages. Health Canada has also accepted it as a novel food
ingredient. Regulators in the European Union, however, have not yet authorized
allulose for general food use, citing the need for more safety data — a
reminder that the global evidence base is still maturing.
For people with diabetes, current research suggests allulose does not raise
blood glucose, but the American Diabetes Association recommends individuals
discuss any meaningful dietary change with their care team, particularly when
adjusting medications such as insulin or sulfonylureas.
How Allulose Compares to Other Sweeteners
Versus Sugar
Allulose offers similar taste and bulk to sugar with roughly 90% fewer
calories and minimal glycemic impact, which is why food scientists like it for
baking and frozen desserts. It browns and crystallizes more like sucrose than
most sugar substitutes.
Versus Artificial Sweeteners
Unlike aspartame or sucralose, allulose is a real sugar molecule, not a
synthetic high-intensity sweetener. Studies indicate it does not appear to
cause the cravings or microbiome shifts that some research has linked to
certain artificial sweeteners, though direct head-to-head comparisons remain
limited.
Versus Sugar Alcohols
Compared with erythritol or xylitol, allulose appears to be better
tolerated by most people at modest doses but can still trigger GI symptoms when
overconsumed.
Practical Takeaways
- Allulose is a low-calorie sugar that research suggests does not meaningfully raise blood glucose or insulin.
- Most studies report benefits at doses of 5 to 15 grams per day, often replacing other added sugars.
- Going much above about 0.4 grams per kilogram of body weight in a single sitting raises the risk of bloating or diarrhea.
- Allulose can be a useful tool for people working to reduce added sugar intake, but it is not a metabolic cure.
- If you live with diabetes, take blood sugar medication, or have a chronic GI condition, consult your healthcare provider before changing sweetener habits.
As more long-term trials are completed, the picture should sharpen. For now,
the available evidence supports allulose as one of the more interesting
sweetener alternatives to emerge in years — not a miracle, but a sugar
that, in moderation, may genuinely behave more like a fiber than a fuel.
Disclosure: This content is for informational purposes only and is not
medical advice. Always consult a qualified healthcare provider before making
changes to your health regimen.