Benefits
Helps moderate post-meal blood sugar in small tests
In a placebo-controlled crossover test, 1.5 g of young barley leaf powder taken with a bowl of rice lowered the 30-minute glucose reading, but only in volunteers whose glucose normally ran higher after meals. A separate crossover study found 3 g taken with a small biscuit blunted the snack's glucose rise. Both were single-meal tests in healthy adults, and the first was co-written by staff of a powder maker.
Supports antioxidant defenses, based on short trials
Two trials from one Taiwanese research group gave 15 g a day of young barley leaf extract for four weeks and reported lower free-radical readings in blood and LDL that resisted oxidation longer, but neither had a placebo group. In a 12-week placebo-controlled trial, a concentrated barley sprout extract lowered urinary malondialdehyde, a lipid-peroxidation marker, while the main antioxidant enzymes did not change.
Cholesterol lowering not confirmed against placebo
A four-week study without a placebo group reported lower total and LDL cholesterol in people with high cholesterol taking 15 g a day of young leaf extract. When a 12-week randomized trial compared 500 mg a day of barley sprout extract with placebo in healthy adults, total and LDL cholesterol did not differ between the groups. The early positive result has not been repeated under placebo control.
Studied in heavy drinkers with fatty liver
In habitual drinkers with fatty liver, 480 mg a day of a saponarin-standardized barley sprout extract for 12 weeks was followed by less liver fat and lower GGT, but the placebo group improved too and the gap between groups was too small to count as an effect. This concentrated extract is not the same product as barley grass powder, and it is no substitute for drinking less.
Superfood claims versus the evidence
Promotional material describes barley grass as a complete food that detoxifies the body; those ideas have not been tested in human trials. A recent independent review concluded the clinical data remain preliminary: most trials are small and brief, preparations are not standardized, and animal studies use doses far above a normal serving. Nutritionally, it is best understood as a dried leafy green.
Uric acid support, from one open-label trial
Adults with raised uric acid who added a concentrated barley leaf powder and tablets to a balanced diet for three months saw serum uric acid fall by about 55 micromol/L, against about 25 on the diet alone, a borderline difference. There was no placebo or blinding, nearly one in five dropped out, and the product's maker funded the trial.
Mechanism of action
Saponarin and lutonarin flavones
The leaf's phytochemistry is dominated by two C-glycosyl flavones, saponarin and lutonarin, alongside chlorophylls and phenolic acids. In test-tube lipid oxidation, saponarin strongly inhibited malonaldehyde formation. How much reaches tissues after a gram-scale serving has not been measured in people.
Viscous insoluble fiber slows glucose uptake
In one maker's powder, 1.5 g supplied about 0.67 g of dietary fiber. In rats, the powder and its insoluble fiber fraction thickened small-intestinal contents and blunted the glucose rise, while in a test tube the fiber did not bind glucose, suggesting the fiber slows glucose diffusion toward the gut wall.
Glutathione system signaling
In cultured liver cells, a barley sprout extract activated Nrf2, the switch for several antioxidant genes, and raised glutathione synthesis. The human sprout-extract trial saw a matching rise in glutathione S-transferase, but superoxide dismutase, catalase and glutathione peroxidase did not change.
Policosanols and the cholesterol hypothesis
Barley leaves contain policosanols such as hexacosanol, long-chain alcohols proposed to reduce cholesterol synthesis. Each capsule in the placebo-controlled cholesterol trial delivered about 7.5 mg of policosanol, and cholesterol still did not move relative to placebo, which weakens this rationale at supplement doses.
Clinical trials
12-week randomized, double-blind, placebo-controlled trial of 480 mg/day barley sprout extract standardized to saponarin, with test material supplied by the Korean supplement maker Novarex (Park H, Lee E, Kim Y, Jung HY, Kim KM, Kwon O 2021, Antioxidants (Basel) 10(3):459, PMID 33804285).
76 habitual alcohol drinkers with ultrasound-diagnosed fatty liver, mostly men with a mean age of about 49.
Urinary malondialdehyde fell on the extract and rose on placebo, a significant between-group difference, and glutathione S-transferase activity rose relative to placebo. Superoxide dismutase, catalase and glutathione peroxidase did not change, and the fall in reactive oxygen species was only marginal against placebo. Liver fat and GGT fell in both groups, so the between-group difference was not statistically significant; the responder analyses that followed are exploratory.
12-week randomized, placebo-controlled trial of one 500 mg barley sprout extract capsule daily, providing about 7.5 mg policosanol (Byun AR, Chun H, Lee J, Lee SW, Lee HS, Shim KW 2015, Evid Based Complement Alternat Med 2015:473056, PMID 26101533).
66 healthy Korean adults enrolled and 51 analyzed (25 extract, 26 placebo), almost all women, average age in the early forties.
Total and LDL cholesterol did not differ from placebo after 12 weeks (p = 0.415 and p = 0.351), and neither did triglycerides, liver enzymes or creatinine. The authors concluded the study failed to show a lipid-lowering effect. Seven of the 15 dropouts cited mild itching (four on extract, three on placebo), and adverse reactions did not differ between groups.
Randomized, double-blind, placebo-controlled crossover test of 1.5 g barley leaf powder taken with 200 g of rice, reported alongside rat experiments; the powder was supplied by, and most authors work for, the Japanese aojiru maker Toyo Shinyaku (Takano A, Kamiya T, Tomozawa H, et al. 2013, Evid Based Complement Alternat Med 2013:137871, PMID 24348688).
33 healthy Japanese volunteers analyzed (29 women, mean age about 25), each tested once on powder and once on placebo.
The effect depended on how high a person's glucose usually rose. In the 12 volunteers with higher post-meal glucose, the 30-minute reading was lower on the powder than on placebo; in the 21 with lower glucose there was no difference. The subgroup split and single-meal design make this a hypothesis rather than a demonstrated daily benefit.
Partially double-blinded randomized crossover trial of 3 g powdered barley or mulberry leaves in water, taken with a small biscuit before a standardized dinner and tracked by continuous glucose monitoring; funded by the Japan Society for the Promotion of Science (Kuwahara M, Kim HK, Ozaki M, et al. 2020, Nutrients 12(6):1580, PMID 32481557).
18 healthy young adults in Japan.
Barley leaf powder blunted the glucose rise from the biscuit, and glucose area under the curve at dinner was lower than after no snack or the biscuit alone, with the dinner effect concentrated in participants who ran higher glucose. The authors noted the sample was too small for firm conclusions and that the results do not apply to older people or people with type 2 diabetes.
Three-month open-label randomized trial with no placebo: a concentrated young barley leaf powder (a 4 g packet plus 10 tablets, twice daily) with a balanced diet versus the diet alone, funded by the maker Hangzhou BOK Biotechnologies, which supplied the product (Cui M, Shao L, Zhao S, Guo Q, Liu X, Liu P 2025, Front Nutr 12:1684829, PMID 41245398).
90 adults in Beijing with raised uric acid who were not on urate-lowering drugs, randomized 2:1; 74 completed (49 barley green, 25 diet only), median age about 36.
Serum uric acid fell by about 55 micromol/L on barley green versus about 25 on diet alone, a borderline between-group difference (p = 0.049). Visceral fat area also differed between groups, and xanthine oxidase activity differed mainly because it rose in the diet-only group. No adverse events were reported. The authors flagged the lack of blinding, the small sample, baseline imbalances in glucose, xanthine oxidase and leptin, 16 dropouts and the short follow-up.