Moderate evidenceLongevity & antioxidants

Glucoraphanin

The broccoli-seed compound that the gut converts into sulforaphane, an activator of the Nrf2 detoxification pathway. Human trials show real but conditional effects on blood glucose and on clearance of some pollutants.

Evidence last reviewed: August 2026

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What the science says

Fasting blood glucose in dysregulated metabolism Moderate evidence
A randomised trial of concentrated broccoli sprout extract in type 2 diabetes reduced fasting glucose and HbA1c, with the effect concentrated in obese participants with poor control. A later placebo-controlled trial in prediabetes found the glucose response depended on the participant's baseline gut microbiota, which helps explain why results are inconsistent between individuals.
Detoxification of airborne pollutants Moderate evidence
In a randomised dose-response trial in a highly polluted region of China, a broccoli sprout beverage increased urinary excretion of benzene metabolites in a dose-dependent way. This is a biomarker of accelerated clearance, not a demonstration that disease risk falls.
Longevity or general antioxidant benefit Limited evidence
The Nrf2 mechanism is well characterised in cells and animals, but no human trial has tested glucoraphanin against ageing, mortality or hard clinical endpoints. The longevity framing is extrapolation from mechanism.

Dosage & safety

Studied doseTrials have used broccoli sprout preparations supplying roughly 100–200 micromol of glucoraphanin per day; the pollutant detoxification study used higher daily doses of up to about 600 micromol. Absorption varies widely because conversion to sulforaphane depends on plant myrosinase or on gut bacteria.

SafetyGenerally well tolerated; the commonest complaints are gas, bloating and the sulphur taste. Isothiocyanates in large amounts can interfere with thyroid iodine uptake, which matters mainly for people with low iodine intake or existing thyroid disease. Not studied in pregnancy or breastfeeding.

Scientific references

Sulforaphane reduces hepatic glucose production and improves glucose control in patients with type 2 diabetes
Axelsson AS, Tubbs E, Mecham B, Chacko S, Nenonen HA, Tang Y, Fahey JW, Derry JMJ, Wollheim CB, Wierup N, Haymond MW, Friend SH, Mulder H, Rosengren AH — Sci Transl Med, 2017
Effect of broccoli sprout extract and baseline gut microbiota on fasting blood glucose in prediabetes: a randomized, placebo-controlled trial
Dwibedi C, Axelsson AS, Abrahamsson B, Fahey JW, Asplund O, Hansson O, Ahlqvist E, Tremaroli V, Bäckhed F, Rosengren AH — Nat Microbiol, 2025
Dose-dependent detoxication of the airborne pollutant benzene in a randomized trial of broccoli sprout beverage in Qidong, China
Chen JG, Johnson J, Egner P, Ng D, Zhu J, Wang JB, Xue XF, Sun Y, Zhang YH, Lu LL, Chen YS, Wu Y, Zhu YR, Carmella S, Hecht S, Jacobson L, Muñoz A, Kensler K, Rule A, Fahey J, Kensler T, Groopman J — Am J Clin Nutr, 2019

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