Does cooked broccoli not provide sulforaphane?

It does, but much less than raw broccoli. A study with 8 men measured a bioavailability of 37% with raw broccoli versus 3.4% with boiled broccoli. Cutting broccoli 40 minutes before cooking it, or adding mustard to the finished dish, improves the result because it provides active myrosinase before or after cooking.

Do sulforaphane supplements work?

It depends on whether they contain active myrosinase. Without it, conversion depends on gut microbiota and can be 3–4 times less efficient than with a source that retains the enzyme. Look for "myrosinase" or "active myrosinase" on the label, or for the product to state that it is made from sprouts at a low temperature.

How many broccoli microgreens are equivalent to what amount of mature broccoli?

In terms of glucoraphanin, microgreens can concentrate between 10 and 100 times more than mature broccoli (in selected cultivars). In practice, about 20–30 g of fresh microgreens can provide an amount comparable to 200–300 g of raw mature broccoli, although variability between varieties and producers is high.

Is it safe to eat broccoli microgreens every day?

In usual quantities (20–60 g/day), no adverse effects have been reported in healthy individuals. Homegrown microgreens should be washed thoroughly; there is a low but real risk of bacterial contamination. Immunocompromised individuals or those with hypothyroidism should consult their doctor.

Broccoli, sprouts, or sulforaphane supplement? What to choose

💡 Key Takeaways

Broccoli, fresh sprouts, and glucoraphanin supplements do not produce the same amount of circulating sulforaphane. The determining variable is whether active myrosinase is available to perform the conversion.

Cooked broccoli provides only 3.4% sulforaphane bioavailability compared to 37% for raw broccoli.
Fresh sprouts produce significantly higher plasma sulforaphane levels than supplements without myrosinase.
A supplement without active myrosinase is 3–4 times less efficient than a source with the intact enzyme.
The gut microbiota can compensate for the lack of myrosinase, but with great individual variability.
When choosing a supplement, look for one that indicates active myrosinase or a sprout source with the intact enzyme.

This article is based on data from human bioavailability studies, including Vermeulen et al. (2008), Clarke et al. (2011), and Fahey et al. (2015), with a comparative table of the three main sources.

Table of Contents

The question makes sense. If sulforaphane is what matters—or more precisely, glucoraphanin which the body can convert into sulforaphane—there are three main pathways: eating broccoli, consuming sprouts, or taking a supplement. Each works differently, and the difference is not small.

This article compares the three options with available bioavailability data, explains why many supplements yield far less than they promise, and provides concrete criteria for choosing.

The game-changer: myrosinase

Before comparing sources, it's essential to understand why myrosinase matters so much. Glucoraphanin—the precursor to sulforaphane—does not convert on its own. It requires the myrosinase enzyme to come into contact with it. This happens in two ways: in the vegetable itself, when the tissue is damaged by cutting or chewing; or in the colon, through the action of certain gut bacteria.

The difference in efficiency between the two pathways is substantial. When plant myrosinase is active, conversion occurs in the small intestine, rapidly and predictably. When it depends on the microbiota, efficiency varies greatly among individuals—from 10% to 40% depending on flora composition—and the plasma peak arrives hours later.

This is the criterion that structures this comparison.

Mature broccoli: the most accessible source, with conditions

Broccoli contains a reasonable amount of glucoraphanin—between 0.1 and 2.2 µmol/g fresh weight, with significant variation depending on variety and cultivation. The problem is not in the content but in what happens before it reaches the intestine.

Vermeulen et al. (2008) measured sulforaphane bioavailability in 8 men who consumed 200 g of raw or boiled broccoli. With raw broccoli, 37% of glucoraphanin was recovered as metabolites in blood and urine. With boiled broccoli, only 3.4% (DOI: 10.1021/jf801989e). This is not because boiling destroys already formed sulforaphane, but because heat inactivates myrosinase before it can act.

Raw, well-chewed broccoli is, therefore, an efficient source. Broccoli boiled for several minutes, much less so.

Strategies that improve conversion with cooked broccoli:

Cut the broccoli and let it rest for 40 minutes before cooking (myrosinase acts during this period).
Steam cook for less than 5 minutes, at moderate temperature.
Add ground mustard seeds to the cooked dish (they provide active exogenous myrosinase).

Fresh broccoli sprouts: maximum concentration

Broccoli sprouts concentrate 10 to 100 times more glucoraphanin than mature broccoli, according to data from selected cultivars (Fahey et al., PNAS 1997). Consumed raw and well-chewed, they retain active myrosinase and produce the most efficient conversion available in regular diet.

Clarke et al. (2011) compared plasma sulforaphane levels in 12 people who consumed 40 g of fresh sprouts versus the same people taking 6 capsules of a broccoli supplement without myrosinase. Fresh sprouts produced significantly higher blood concentrations, with a faster peak and greater urinary excretion (DOI: 10.1016/j.phrs.2011.07.005).

Sulforaphane or glucoraphanin supplements: depends on the label

The "sulforaphane" supplement market is broad and heterogeneous. The key distinction is whether the product contains active myrosinase or not.

Fahey et al. (2015) documented that when endogenous myrosinase is present in the source, sulforaphane is between 3 and 4 times more bioavailable than when glucoraphanin is administered without the enzyme (DOI: 10.1371/journal.pone.0140963). The same study showed that a pure glucoraphanin supplement produced metabolite excretion similar to a boiled sprout extract, where the enzyme had also been inactivated.

Supplement type	Myrosinase	Estimated bioavailability	Equivalent to
Glucoraphanin alone (without enzyme)	No	Low (depends on microbiota)	Boiled broccoli
Glucoraphanin + active myrosinase	Yes	3–4× higher than the above	Close to fresh sprouts
Freeze-dried sprout powder (with intact enzyme)	Yes (preserved)	High if freeze-drying did not apply heat	Close to fresh sprouts
Stabilized sulforaphane extract	Not necessary	Variable depending on extract stability	Depends on the process

How to read a sulforaphane supplement label:

Look for “myrosinase,” “active myrosinase,” or “active myrosinase” in the ingredients.
Be wary of products that only list “glucoraphanin” or “broccoli extract” without specifying the process.
Low-temperature freeze-dried products (freeze-dried at <40°C) may retain the active enzyme if the process is documented.

Practical comparison: the three options

	Mature broccoli	Fresh sprouts	Supplement with myrosinase
Glucoraphanin per serving	Moderate (variable)	High (10–100× broccoli)	High (product dependent)
Active myrosinase	Yes (if raw) / No (if cooked)	Yes	Product dependent
Bioavailability	37% (raw) / 3.4% (cooked)	High (~37% or higher)	High (if it has myrosinase) / Low (if not)
Ease of use	High	Medium	High
Estimated monthly cost	Low (€5–15/month)	Medium (€15–30/month)	Variable (€20–60/month)
Daily consistency	Depends on culinary habit	Requires planning	High

What makes sense depending on the context

There is no single answer. It depends on the regularity one can maintain and what is already part of one's usual diet.

Raw or lightly steamed broccoli is the most accessible option and has reasonable bioavailability. Fresh sprouts have the highest glucoraphanin density of the three options and retain active myrosinase. A quality supplement—with documented active myrosinase, or made from low-temperature freeze-dried sprouts without destroying the enzyme—offers the advantage of consistency.

For those seeking consistency without sacrificing enzymatic efficiency, freeze-dried microgreens like SYNERGIC are prepared at low temperatures precisely to preserve both glucoraphanin and myrosinase in the original plant matrix. Conversion can occur upon contact with saliva and the digestive environment, just as with fresh sprouts.

Conclusion

All three sources work, but not in the same way or with the same efficiency. The variable that most determines how much sulforaphane actually circulates is the presence of active myrosinase: without it, glucoraphanin does not convert well, whether in boiled broccoli or a supplement that only sells the precursor.

Choosing between raw broccoli, fresh sprouts, and a supplement with active myrosinase is, to a large extent, a question of which habit can be maintained consistently. Bioavailability data are a guide; consistency is what defines the real outcome over time.