Benefits
Improved glucose tolerance in metabolic syndrome
In BMI>=23 subjects, 10 g/day trehalose vs sucrose significantly decreased post-OGTT glucose at 2 hours vs baseline. A stratified analysis of the subjects with higher truncal fat reported more favorable changes in body weight, waist circumference and systolic blood pressure, but that was a subgroup inside a 34 person trial, so it is a lead to follow rather than a finding. The control group took sucrose, not an inert placebo, and every author was an employee of the company that manufactures trehalose.
Maintained glucose homeostasis at low dose in healthy adults
In healthy adults, 3.3 g/day trehalose maintained 2-hour post-OGTT glucose unchanged from fasting (no excursion), while the sucrose group showed expected post-glucose-load elevation. A subset with higher baseline postprandial glucose showed a lower 2 hour reading than the sucrose group, but that is a subgroup inside a 50 person trial and should be read as preliminary. Across the whole group, the paper reports no differences between trehalose and sucrose in body composition or blood chemistry.
Autophagy induction (mechanism with therapeutic implications)
Trehalose is an mTOR-independent autophagy inducer — activates TFEB and FOXO1 transcription factors driving lysosomal biogenesis and autophagy genes. In animal models, this clears mutant huntingtin, alpha-synuclein, and TDP-43 aggregates. This work is in animals and cells. The review cited on this page says the autophagy explanation is disputed, and that one careful study found trehalose blocked the last step of autophagy rather than driving it. The one large human test of the idea used trehalose given by weekly infusion in a clinic and did not meet its main endpoint.
Lower glycemic and insulinemic response than sucrose
Trehalose's α-1,1 bond produces slower digestion than sucrose's α-1,2 bond. The acute human measurement was made against glucose, not sucrose: 25 g of trehalose produced a slower glucose rise and lower insulin and GIP than 25 g of glucose. It is still fully digested to glucose. Effects on fat cell growth and insulin sensitivity have been seen in mice, not in people.
Mechanism of action
Autophagy induction via TFEB and FOXO1 (proposed, and still disputed)
Trehalose activates the master transcription factor TFEB (transcription factor EB) and FOXO1, both of which drive transcription of autophagy and lysosomal biogenesis genes. In animal and cell models this has been linked to clearance of misfolded protein clumps, to changes in diet driven fatty liver and artery models, and to anti-inflammatory effects in macrophages. The review cited on this page reports that the mechanism is still unsettled, that cell results have been inconsistent, and that one careful study found trehalose blocked autophagy at its final step. The mechanism is mTOR-independent — distinguishing trehalose from rapamycin and explaining its lack of immunosuppressive effects.
Protein structural stabilization via vitrification
Trehalose forms a glassy, anhydrous matrix around proteins that prevents denaturation under stress (heat, freeze, oxidation, dehydration) — basis for its industrial use in vaccine and biologic stabilization. In neurodegenerative contexts, this may also protect against protein misfolding and aggregation, an effect distinct from autophagy induction.
Slower digestion via α-1,1 glycosidic bond
Trehalose is hydrolyzed by intestinal trehalase (rather than amylase or sucrase-isomaltase). The α-1,1 bond is more thermostable and has slower enzymatic cleavage than α-1,2 (sucrose) or α-1,4 (maltose). That slower cleavage is why an oral dose raises glucose and insulin less sharply than the same weight of glucose. Published glycemic index estimates for trehalose vary widely and are not consistently below the figure usually quoted for sucrose, so it should not be called a low glycemic sugar.
Nrf2-mediated antioxidant response
Trehalose increases p62/SQSTM1 expression, leading to enhanced nuclear translocation of Nrf2 and induction of antioxidant response element (are) gene products including heme oxygenase-1 (HO-1) and NAD(P)H quinone dehydrogenase 1 (NQO1). This represents a fourth mechanism contributing to cellular protection beyond autophagy induction alone.
Clinical trials
Double-blind trial in which the control group took sucrose rather than an inert placebo (Mizote A, Yamada M, Yoshizane C, Arai N, Maruta K, Arai S, Endo S, Ogawa R, Mitsuzumi H, Ariyasu T, J Nutr Sci Vitaminol 62(6):380-387, doi:10.3177/jnsv.62.380).
34 subjects with BMI ≥23 (metabolic syndrome risk factors). Divided into two groups; assigned to ingest 10 g/day trehalose or sucrose (control) with meals for 12 weeks. Body composition and biochemistry measured at 0, 8, 12 weeks; washout at 16 weeks.
Trehalose group: blood glucose 2-h post-OGTT significantly decreased after 12 weeks vs baseline (sucrose group did not change significantly). In stratified analysis of subjects with truncal fat percentage near upper end of normal: body weight, waist circumference, and systolic BP changes were significantly more favorable in trehalose vs sucrose group. The authors concluded that 10 g a day improved glucose tolerance. Two cautions belong with that: the main result was a change from baseline within the trehalose group rather than a significant difference between the two groups, and all of the authors worked for Hayashibara, the company that manufactures trehalose.
Randomized, double-blind trial with a sucrose control rather than an inert placebo (Yoshizane C, Mizote A, Arai C, Arai N, Ogawa R, Endo S, Mitsuzumi H, Nutr J 19(1):68, doi:10.1186/s12937-020-00586-0).
50 healthy Japanese adults randomized to 3.3 g/day trehalose (n=25) or sucrose (n=25) for 78 days (12 weeks). 75-g oral glucose tolerance tests at baseline and 12 weeks.
Sucrose group: 2-h plasma glucose significantly higher than fasting after 12 weeks. Trehalose group: 2-h and fasting plasma glucose remained similar (no postprandial elevation). In subset with above-mean baseline 2-h PG/FPG ratio, trehalose group's 2-h PG was significantly lower than sucrose group's. The authors suggest a teaspoon a day may help maintain glucose balance in healthy people. Across the full group, though, there were no differences between trehalose and sucrose in body composition or blood chemistry, and all eight authors were employees of Hayashibara, the study sponsor and a trehalose manufacturer.
Acute crossover comparison (Yoshizane C, Mizote A, Yamada M, Arai N, Arai S, Maruta K, Mitsuzumi H, Ariyasu T, Endo S, Nutr J 16(1):9, doi:10.1186/s12937-017-0233-x).
20 healthy Japanese volunteers in a crossover study, each taking 25 g of trehalose or 25 g of glucose in water after an overnight fast, with blood sampled over 3 hours.
Trehalose did not cause a rapid rise in blood glucose and stimulated less insulin and less active GIP than an equal 25 g load of glucose, while active GLP-1 ran higher from 45 to 180 minutes. The comparison was against glucose, not against table sugar or maltose. All authors were employees of the trehalose manufacturer.