Updated November 2026. Molecule data, two reviews, UK labels and Verve's label checked on 5 November 2026. Verve makes a sulforaphane capsule, covered near the end.
Sulforaphane is a sulphur-containing compound, an isothiocyanate with the formula C6H11NOS2. It forms when glucoraphanin, a glucosinolate in broccoli and some other brassicas, meets the plant enzyme myrosinase: when the plant is chopped, chewed or crushed. There is no NHS daily amount, no NRV and no authorised GB health claim for sulforaphane, so this guide covers the chemistry and the label, not effects. UK labels state it as a weight of broccoli extract, as milligrams of glucoraphanin, or as milligrams of sulforaphane, and the three are not interchangeable: 100mg of glucoraphanin can become at most about 40mg of sulforaphane (our calculation). Check with your doctor first if you are pregnant, breastfeeding, taking medication (including blood thinners) or have a medical condition.
The short answer
- What it is: an isothiocyanate (molecular weight 177.29) formed from glucoraphanin (437.49) by the enzyme myrosinase. Not a vitamin, mineral or protein.
- When it forms: on chopping or chewing. Cooking inactivates myrosinase.
- Where glucoraphanin occurs: throughout the broccoli plant, richest in the seeds. Three-day-old sprouts hold 10 to 100 times the level of the mature plant.
- On the label: extract mg, glucoraphanin mg, sulforaphane mg (sometimes "yield"), on a few products myrosinase mg. 100mg of glucoraphanin gives at most about 40mg of sulforaphane.
- From Verve: Verve Sulforaphane 40mg, 40mg of sulforaphane per two capsules, from broccoli seed extract, every batch independently lab-tested for purity, with the certificate for your batch on request, and made in the UK.
- Check first: with your doctor if pregnant, breastfeeding, on medication or with a medical condition. Not for children.
Glucoraphanin and myrosinase: how sulforaphane forms
Glucoraphanin is chemically stable. In an intact plant it never meets myrosinase: the 2018 review by Oliviero, Verkerk and Dekker describes glucosinolates stored in one set of cells and the enzyme in neighbouring "myrosin cells". Cutting or chewing brings them together. Myrosinase removes the glucose, leaving an unstable fragment that rearranges into several products, including sulforaphane. Three things decide how much forms:
- A second plant protein. Epithiospecifier protein (ESP) steers the fragment towards nitriles instead (favoured at low pH). ESP is inactivated at a lower temperature than myrosinase, so short, mild heating can favour sulforaphane.
- Heat. Boiling largely inactivates myrosinase, and 25 to 75% of glucosinolates leach into the water. Myrosinase in steamed cabbage survived two minutes but had dropped about 90% after seven. Glucoraphanin itself is much tougher.
- Your own cells cannot do it. Mammalian cells do not make myrosinase (2019 review by Yagishita, Fahey, Dinkova-Kostova and Kensler).
Where glucoraphanin occurs
Glucoraphanin is found in all broccoli tissues, with seeds richest by weight (Yagishita review). Fahey, Zhang and Talalay reported in 1997 that three-day-old broccoli sprouts contain 10 to 100 times the glucoraphanin of the mature plant, which is why supplements use seed or sprout extract. Sulforaphane is also recorded in cauliflower sprouts.
In the Yagishita review, 31 supermarket heads averaged 0.38 micromoles of glucoraphanin per gram, range below 0.005 to 1.13. By our calculation from the molecular weights, that mean is about 17mg of glucoraphanin per 100g, enough for about 7mg of sulforaphane if every molecule converted.
How UK labels state it
| Label line | What it tells you | What it does not |
|---|---|---|
| Broccoli seed, sprout or flower extract, mg (often with a ratio, e.g. 10:1) | Weight of dried extract | How much glucoraphanin or sulforaphane it holds, unless a percentage follows |
| Glucoraphanin, mg (also "sulforaphane glucosinolate" or SGS) | Weight of the precursor | How much will convert. The ceiling is about 40% |
| Sulforaphane, mg, or "sulforaphane yield" | Sulforaphane present, or the amount that could form | Which of the two, unless the label says |
| Myrosinase, mg | The enzyme is added | How active it is |
One glucoraphanin molecule (437.49) gives at most one sulforaphane molecule (177.29), and 177.29 divided by 437.49 is 0.405, so 100mg of glucoraphanin can yield at most about 40.5mg of sulforaphane, and a "yield" of 40mg implies at least 99mg of glucoraphanin. That is our calculation; a label showing both figures in that ratio assumes complete conversion.
The NRV column shows a dash because there is no NRV for sulforaphane: our guide to what NRV means on a label explains why.
Typical label figures across UK products
From brand pages, no prices:
- Extract weight: 450mg of a 10:1 extract per capsule (Peak Supps); 769mg of broccoli flower extract per two capsules (Naturecan UK).
- Glucoraphanin: 40mg per serving, with 16mg of myrosinase and 8mg of pre-formed sulforaphane (SanBroc, Time Health, also listed at Holland and Barrett).
- Sulforaphane stated directly: 2.25mg per capsule (Peak Supps); 40mg per two capsules (Verve); "of which sulforaphanes 100mg" per two capsules (Naturecan UK); 100mg per two capsules from an extract "standardized to 10% sulforaphane" (Physiomance, Therascience).
So stated sulforaphane runs from about 2mg to 100mg a day. Where a label gives an extract weight and a compound figure, ask the brand whether the percentage it implies is glucoraphanin or sulforaphane.
Purity and certificates
The University of Münster's Institute of Pharmaceutical Biology and Phytochemistry analysed 14 broccoli-based food supplements and found "very large differences in quality": some held far less glucoraphanin than declared and several held none that could be detected. A certificate of analysis (CoA) for the batch is the only way to know. Read it for the assay (measured sulforaphane or glucoraphanin, and which of the two), heavy metals (lead, cadmium, mercury, arsenic), microbiology (total plate count, yeasts and moulds, E. coli, Salmonella) and identity (broccoli, not another brassica).
Storage and stability
Glucoraphanin is stable. Sulforaphane is not, which is why the Yagishita review lists stabilised preparations, including one that holds it in alpha-cyclodextrin. A capsule stating sulforaphane itself relies on the maker having stabilised it. Store as the pack directs.
Who should check with a doctor first
There is no NHS page on sulforaphane. This list uses the wording on Verve's product page.
- Anyone pregnant or breastfeeding.
- Anyone taking medication or with a medical condition.
- Anyone on blood-thinning medication or undergoing medical treatment should speak to a healthcare professional before use.
- Children. The product is not suitable for children.
Verve Sulforaphane 40mg
Verve's label has one row: sulforaphane, 40mg per serving, NRV "-", with the note "NRV% not established unless stated". Two capsules once a day; 60 capsules, so 30 servings. The product page says it comes from broccoli seed extract standardised for glucoraphanin, in a plant cellulose capsule with no other active ingredient (gluten, dairy and soy free, vegan). The page does not state the extract weight, the glucoraphanin figure, the standardisation percentage or whether myrosinase is included. Every batch is independently lab-tested for purity; the certificate of analysis for your batch is available on request from hello@vavaverve.com.
Not suitable for children. Keep out of reach of children. Do not exceed the recommended daily intake. Consult your doctor before use if you are pregnant, breastfeeding, taking medication or have a medical condition. Those on blood-thinning medication or undergoing medical treatment should speak to a healthcare professional before use. The label is on the Sulforaphane 40mg page. UK products side by side: our sulforaphane supplement comparison. Full range: the longevity collection.
featured in this article
40mg sulforaphane per serving
From €25,56/month
Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle.
Sulforaphane: your questions
Is sulforaphane the same as glucoraphanin?
No. Glucoraphanin is the stable precursor stored in broccoli; sulforaphane forms when myrosinase splits it. Their molecular weights are 437 and 177, so 100mg of glucoraphanin gives at most about 40mg of sulforaphane.
How much sulforaphane is in broccoli?
None until the plant is cut or chewed. The glucoraphanin it forms from varies: 31 supermarket heads averaged about 17mg per 100g by our calculation; three-day-old sprouts hold 10 to 100 times the level of the mature plant.
Does cooking broccoli destroy sulforaphane?
Cooking destroys myrosinase, the enzyme that makes it. Boiling largely inactivates it; seven minutes of steaming removed about 90% of it from cabbage. Glucoraphanin itself survives cooking better.
What does "sulforaphane yield" mean on a label?
The amount that could form from the glucoraphanin in the capsule, not the amount present. The ceiling is about 40% of the glucoraphanin weight. One US brand sold in the UK states 30mg of glucoraphanin "demonstrated in vitro to yield approximately 8 mg of sulforaphane", about 27%.
What does sulforaphane do?
There is no authorised health claim for sulforaphane, glucoraphanin or broccoli extract in Great Britain, so this guide describes the compound and the label, not effects. Read yours for which compound is stated and how much.
How we checked
Molecules: Human Metabolome Database entries HMDB0005792 (sulforaphane) and HMDB0038404 (glucoraphanin). Formation, ESP, cooking and gut bacteria: Oliviero, Verkerk and Dekker, Molecular Nutrition and Food Research, 2018, 62(18), 1701069. Occurrence, broccoli figures, urinary recovery, stabilised forms: Yagishita, Fahey, Dinkova-Kostova and Kensler, Molecules, 2019, 24(19), 3593. Sprouts: Fahey, Zhang and Talalay, PNAS, 1997, 94(19), 10367-10372. Label accuracy: University of Münster, Institute of Pharmaceutical Biology and Phytochemistry, "Broccoli-based food supplements". UK labels: the product pages of Peak Supps, Naturecan UK, Time Health, Holland and Barrett and Therascience (UK site) and the BroccoMax label PDF. Verve figures: the Sulforaphane 40mg page on vavaverve.com. We searched nhs.uk and found no page on sulforaphane. All checked on 5 November 2026. Verve makes the sulforaphane capsules in this guide.
