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Short Summary
Main recommendation: Dr. Leonid Kim says allulose is a sweetener he would recommend over any other currently on the market, provided you monitor for frequent urinary tract infections or GI symptoms at lower doses. He reviews small human trials showing allulose does not raise blood sugar and can blunt the glucose and insulin response to other carbohydrates, while noting that human safety data remain limited.
Key Points
- Allulose is a rare sugar found naturally in small amounts in raisins, figs, and maple syrup. It is about 70 percent as sweet as sucrose and has no chemical aftertaste like aspartame or Splenda.
- Nearly 90 percent of absorbed allulose is excreted by the kidneys without being converted to energy. The FDA stopped classifying it as an added sugar in 2019.
- A 2020 Clinical Nutrition meta-analysis of 40 trials (about 400 subjects) found small doses of allulose lowered postprandial glucose and insulin after ingesting other carbohydrates.
- A 2018 randomized Korean study of 121 subjects found allulose supplementation significantly reduced body fat percentage and abdominal fat mass (measured by CT) compared with placebo, according to Dr. Kim.
- The main safety caveat is limited human data. The FDA classified allulose as generally recognized as safe in 2012, and a 2019 Fundamental Toxicological Sciences study showed no clinical problems over 12 weeks in people with borderline or type 2 diabetes.
Details Worth Noting
- Concrete instructions: Keep total allulose intake below about 0.4 grams per kilogram of body weight to avoid nausea and diarrhea in most people. For example, a 70-kilogram (154-pound) person can consume up to about 28 grams before GI upset is expected. Individual tolerance varies, and some people feel symptoms at lower doses. Use it for coffee or tea, where quantities are usually small. Cooking may require larger amounts, so monitor more closely. If you have frequent UTIs or yeast infections, or develop GI symptoms, stop and check whether allulose is the cause.
- Allulose is excreted in urine and works somewhat like SGLT2 inhibitors (Farxiga, Jardiance, Invokana), which carry an FDA warning for severe UTIs. Dr. Kim argues the glucose load from allulose is a small fraction of that from SGLT2 drugs, and he notes that subsequent SGLT2 safety monitoring studies have not shown an increased risk of UTIs.
- A British Journal of Nutrition paper raised concern that allulose could promote overgrowth of Klebsiella pneumoniae, which can cause serious infections in people with weakened immunity or lung disease. Dr. Kim considers this unsupported, as the evidence is only from in vitro (test tube or petri dish) studies.
- Dr. Kim names monk fruit as his next-best alternative. It is often blended with other sweeteners, so finding pure monk fruit extract can be harder. He offered to cover monk fruit evidence in a future video if viewers ask for it in the comments.
Bottom Line
Allulose appears to behave like a sugar that the body largely excretes, with promising short-term human data on glucose, insulin, and fat mass, but long-term human safety data remain limited. Dr. Kim's view is that it is a reasonable choice for most people, with attention to dose, GI tolerance, and urinary infections.
