Allulose is commercially made from corn. Manufacturers use enzymes to convert corn-derived fructose into allulose through a multi-step process. While allulose does exist naturally in small amounts in foods like raisins, dried figs, wheat, brown sugar, and molasses, the quantities are far too small to extract at scale, so virtually all allulose on store shelves comes from enzymatic conversion of corn or corn stover.
How Allulose Differs From Regular Sugar
Allulose is technically a sugar, sharing the exact same chemical formula as fructose. The difference comes down to the arrangement of atoms at a single point in the molecule: allulose is what chemists call the “C-3 epimer” of fructose, meaning one group of atoms is flipped to the opposite side. That tiny structural change is enough to completely alter how your body handles it. While fructose is fully metabolized for energy, allulose largely passes through without being used as fuel.
This is why allulose tastes like sugar (about 70% as sweet) but contributes very little energy. The FDA assigns allulose a caloric value of 0.4 calories per gram, compared to 4 calories per gram for regular sugar. That’s 90% fewer calories.
The Enzymatic Production Process
Making allulose at commercial scale requires converting one sugar into another using a chain of specialized enzymes. The starting material is typically corn starch, which gets broken down into glucose. From there, an enzyme called glucose isomerase converts glucose into fructose. Then a second enzyme, D-tagatose 3-epimerase, rearranges fructose molecules into allulose by flipping that single atomic group.
The conversion isn’t perfectly efficient. Research using corn stover (the stalks and leaves left after harvest) as a starting material found that about 18% of glucose was ultimately transformed into allulose, which is close to the theoretical maximum for this enzymatic reaction. Manufacturers compensate for this modest yield through large-scale processing and purification steps that isolate the allulose from leftover fructose and glucose in the mixture.
Some newer production methods skip corn starch entirely and start with cellulose from agricultural waste like corn stalks. The process is the same in principle: break plant material into glucose, convert glucose to fructose, then convert fructose to allulose. The enzymes do all the heavy lifting, which is why allulose is often marketed as “naturally derived” even though it’s produced in a factory.
What Happens to Allulose in Your Body
About 70% of the allulose you eat gets absorbed in your small intestine. But unlike regular sugar, your body doesn’t break it down for energy. Instead, the absorbed allulose circulates briefly in your blood and then gets filtered out by your kidneys. Between 50% and 70% of the absorbed dose ends up excreted unchanged in urine. The remaining 30% that isn’t absorbed in the small intestine passes into the large intestine, where gut bacteria may partially ferment it.
This unusual metabolic path is why allulose doesn’t raise blood sugar the way regular sweeteners do. A meta-analysis published in PLOS ONE found that taking just 5 to 10 grams of allulose alongside a meal significantly reduced the post-meal blood sugar spike, with the best-controlled study showing roughly a 13 to 14% reduction compared to a control group.
FDA Labeling Rules
Because allulose behaves so differently from other sugars in the body, the FDA made an unusual decision: allulose does not have to be counted under “Total Sugars” or “Added Sugars” on nutrition labels. It still appears in the ingredient list, and its calories (calculated at 0.4 calories per gram) are included in the total calorie count. This means a product sweetened with allulose can legitimately show lower sugar numbers on the label than an identical product made with table sugar, even though allulose is chemically classified as a sugar.
Digestive Tolerance Limits
Allulose is generally well tolerated, but eating too much at once can cause bloating, gas, or a laxative effect, similar to sugar alcohols like erythritol. Research in healthy adults found the threshold for digestive symptoms is about 0.4 grams per kilogram of body weight in a single sitting. For a 150-pound person, that works out to roughly 27 grams at once. The threshold where laxative effects become noticeable is slightly higher, around 0.55 grams per kilogram of body weight (about 37 grams for that same person). Staying below these amounts in a single dose keeps digestive issues unlikely for most people.