Stabilized sulforaphane

Most supplements never contain sulforaphane. They contain glucoraphanin, the precursor, because sulforaphane is reactive and will not sit in a capsule for a year. Stabilizing it is the other way to solve that problem, and one stabilized preparation has been through three randomized placebo-controlled trials, two of them in hospital patients with outcomes like functional recovery and mortality. No other sulforaphane preparation has been tested that way, and the results are not flattering.

What does stabilizing sulforaphane involve?

Putting the molecule inside a cage. The approach with human data behind it is an inclusion complex with alpha-cyclodextrin, a ring-shaped sugar whose pocket holds one sulforaphane molecule and keeps it away from water and from other sulforaphane molecules. Swallowing the complex releases it.

Two such preparations were compared in 2017 by the Johns Hopkins group: a cyclodextrin inclusion and a commercial sulforaphane-rich supplement. Both held up better in storage than pure sulforaphane and the authors judged them comparably bioavailable, with a serum peak at 2 hours in ten volunteers. The same paper carries two results that are quoted far less often. Six of those ten volunteers reported mild stomach upset. And rubbed into the skin of SKH1 mice, the stabilized form failed to switch on the protective enzymes that pure sulforaphane switched on, so caging the molecule did not preserve everything it does.

The preparation with trial data, SFX-01, differs from a food in a way worth knowing. Its own papers describe it as a synthetic d,l-sulforaphane, meaning a manufactured mixture of both mirror-image forms of the molecule rather than material grown in a plant. No trial has compared a synthetic racemic sulforaphane against plant-derived sulforaphane in people, so this site carries no figure for whether the difference matters.

How much reaches the blood?

Between 0.43 and 2.12 µmol/L at the peak, which lands in the same range as a sprout preparation. The phase 1 study enrolled 24 healthy men and randomized them three to one against placebo across three dose cohorts, so 18 took the drug and 6 did not. One cohort took 300 mg of the complex once daily, supplying 46.2 mg of sulforaphane. The other two took 300 mg twice daily or 600 mg once daily, each supplying 92.4 mg. Dosing ran seven days.

Those peak figures are for sulforaphane plus its metabolites together, measured by validated LC-MS/MS on a QTrap 6500+ against deuterated sulforaphane and sulforaphane-N-acetylcysteine standards. The distinction matters because sulforaphane itself was mostly unmeasurable: concentrations sat at or below the assay's limit of 1 ng/mL, and the authors could not derive its pharmacokinetics separately. What circulates is largely the conjugates.

For scale, Ye and colleagues measured peak plasma dithiocarbamates of 0.943 to 2.27 µmol/l in four people given a broccoli sprout isothiocyanate preparation. So a pharmaceutical dose of stabilized sulforaphane produced blood concentrations much like a sprout dose, by a different assay. Urinary recovery across the drug cohorts ran from under 1 percent to 41 percent of the dose and did not track the dose given, which is the same wide between-person spread that sulforaphane supplements show without active myrosinase.

The doses themselves are large next to food. At a molecular weight of 177.3, the 46.2 mg in a 300 mg capsule is about 260 micromoles of preformed sulforaphane, and the 600 mg dose about 520. The Qidong trial's broccoli sprout beverage, the largest food-based preformed dose on this site, supplied 40 micromoles daily to 291 people.

Did it work?

Not in either condition where somebody looked properly, and both trials were built to answer the question.

The SAS study treated patients after subarachnoid hemorrhage, a condition where sulforaphane had improved outcomes in animal models. It was multicenter, double-blind and placebo-controlled, with 105 patients randomized, 54 to 300 mg twice daily for 28 days and 51 to placebo. There was no difference in middle cerebral artery flow velocity, in haptoglobin or malondialdehyde measured in spinal fluid, or in functional outcome on either of two scales.

The reason it failed is the more interesting part. Sulforaphane barely reached the spinal fluid: many samples fell below the limit of quantification, and what was detectable tracked the spinal-fluid-to-serum albumin ratio, meaning it crossed where the barrier was already leaky. The authors make a pointed observation about their own field: of the large animal literature on sulforaphane in neurological disease, only one study ever measured brain or spinal fluid levels, because a small fat-soluble molecule was assumed to cross freely. This was the first measurement in people, and it found the compound barely got in. Plasma concentrations were higher in people with a null GSTT1 genotype (t = 2.40, p = 0.023), which is a metabolism difference rather than a delivery one.

The pneumonia trial was stopped early for futility. It randomized 133 hospitalized patients with community-acquired pneumonia, 65 to 300 mg daily for 14 days and 68 to placebo. SARS-CoV-2 caused the pneumonia in 103 of the 133, so this was mostly a COVID-19 trial. Clinical status at day 15 on the seven-point WHO scale was unchanged (adjusted odds ratio 0.87, 95% CI 0.41 to 1.83, p = 0.71), as were time to improvement, length of stay and 28-day mortality. The trial also went looking for the mechanism and did not find it: expression of Nrf2 target genes was not significantly changed, nor were interleukin-6, interleukin-1 beta or tumor necrosis factor alpha.

That last point deserves its weight. Nearly everything written about sulforaphane rests on Nrf2 activation. Here a pharmaceutical dose of a stabilized preparation, given daily for two weeks to acutely inflamed patients and checked by cytokine panel and RNA sequencing, did not measurably move the pathway. It is the only direct human test of that mechanism, and the rest of the evidence it has to sit alongside is collected under sulforaphane benefits, where these two trials are now the largest of the eleven and the only two with a clinical endpoint.

Human trials of a stabilized sulforaphane

Every row is people. The first three rows are the same preparation at the same 300 mg unit dose, which is unusual on this site and makes them directly comparable.

Why is the side-effect count so high?

Because somebody finally counted against a placebo, at a dose far above anything in food. Across the phase 1 study, 174 treatment-emergent adverse events were recorded in 17 of the 18 men who took the drug, and every one was judged certainly or probably related to it. Abdominal discomfort appeared in 94 percent, nausea in 56 percent and vomiting in 28 percent. Two events reached moderate severity, none was serious, nobody died, and the placebo group reported nothing at all.

A 94 percent adverse event rate against zero is unusually clean as a signal, and it is the strongest evidence on this site that the digestive effects are real rather than coincidental. It does not transfer to a food portion or to a supplement capsule. The dose was roughly six times the preformed sulforaphane in the Qidong beverage, it arrived in one enteric-coated tablet rather than spread through a meal, and nobody was chewing anything. The broader picture, including the groups with a reason to ask a doctor first, is under sulforaphane side effects.

The pattern is consistent though. Nausea affected 9 of 54 patients on the drug in the subarachnoid hemorrhage trial against 1 of 51 on placebo, six of ten volunteers reported stomach upset on the cyclodextrin preparation in 2017, and in a crossover trial of 49 smokers every adverse event recorded was gastrointestinal.

Is this a supplement or a drug?

A drug, and the distinction is the practical point of this page. SFX-01 is an investigational medicine held by a pharmaceutical company, administered under trial protocols, and you cannot buy it. Nothing above describes a product on a shelf.

Supplements do use the word stabilized, and some do hold sulforaphane in a cyclodextrin. What the word cannot tell you is whether your particular product resembles anything that was tested. A commercial sulforaphane-rich supplement was measured alongside the cyclodextrin inclusion in the 2017 study, and no product is named here. No supplement has been through a randomized trial with a clinical endpoint. The usable comparisons between labels are narrow, and they are set out on the sulforaphane supplements page: which compound the label names, whether active enzyme comes with it, and whether the product itself has been in a human study.

Breast cancer is worth a separate note, because it is the use this preparation is most often associated with. That case is preclinical. A 2020 paper showed the stabilized form suppressed STAT3 signaling and reduced stem-like cell activity in patient samples and in mice carrying human tumor grafts, which is laboratory and animal work. Searching PubMed for the preparation's name alongside breast returns that paper and nothing else, so no human result in breast cancer is quoted on this page.

What the evidence supports

A narrow conclusion, which is the kind this topic usually lacks. Stabilizing sulforaphane works as chemistry: the molecule survives storage, reaches the blood at concentrations comparable to a sprout dose, and bypasses the conversion step where most of a glucoraphanin dose is lost. It is reasonable to expect a stabilized preparation to deliver sulforaphane more reliably than an enzyme-free precursor, although the head-to-head study has not been done.

What the trials do not support is any clinical benefit. Two randomized, placebo-controlled trials in acutely ill patients measured real outcomes and found nothing, one of them stopping early because continuing was pointless, and the pneumonia trial could not detect movement in the pathway the whole field is built on. Those are the only placebo-controlled sulforaphane trials with clinical endpoints in acutely ill patients, and both are negative.

Neither tested whether sulforaphane does anything over years in healthy people, which is the question most readers actually have, and neither could. The doses people reach from food and from sulforaphane powder or capsules, with the assay behind each figure, are collected under how much sulforaphane per day.