Broccoli Calabrese is the microgreen that first got us addicted to growing nutrition at home.
Several years ago, I was becoming increasingly desperate to heal my gut problems, which were so severe that it occasionally affected my ability to work. All the gastroenterologists I consulted were only able to offer symptomatic relief and the restrictive FODMAP diet.
While the medication helped in the short term, I didn't want to become reliant on it for life and I wanted to get to the root of my own gut health issues. I began reading widely and came across Dr Will Bulsiewicz's seminal book, Fiber Fueled. He's a leading gastroenterologist at the forefront of the latest gut health research. His work talks about how chronic inflammation is the cause of many health symptoms and conditions that appear unrelated, and how fibre heals gut health and reduces inflammation.
I already knew that cruciferous vegetables (broccoli, kale, arugula/rocket, cabbage, cauliflower and brussels sprouts) are particularly good for us, but when I did a deep dive into the research papers cited in the book, it became clear that broccoli is much more than a tasty, healthy vegetable that holds sauces well. All because of a powerful phytonutrient called sulforaphane.
Interest in sulforaphane began in the 90s when researchers at Johns Hopkins University first reported its cancer protective potential. Today, more than 1,000 peer-reviewed studies have explored its antioxidant and anti-inflammatory properties which protect against a wide range of chronic and acute diseases, with findings that support roles in metabolic, gut, immune, cognitive, and healthy aging pathways.
What is sulforaphane and why is it like a bomb?
Sulforaphane is an internal defence system that cruciferous vegetables have developed to protect themselves against pests, diseases and environmental stress. When consumed by us, sulforaphane's antioxidant and anti-inflammatory properties similarly protect human cells against free radicals, chronic diseases and various cancers.
The building blocks of sulforaphane are an enzyme called myrosinase and compounds called glucosinolates. They are stored in separate compartments within the plant, so under normal circumstances they do not mix. But when a human bites into the plant (like broccoli for example), the separating cell chambers are broken, myrosinase and glucosinolates are mixed together like a bomb, and they form isothiocyanates (ITCs) like sulforaphane. This is what gives broccoli its somewhat pungent (sulphurous) flavour.
Here’s just a selection of what the research has found about sulforaphane, as cited in Dr Bulsiewicz's book:
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Protects us from cancer by seven mechanisms: inhibits the production of carcinogens, activates enzymes to detoxify the carcinogens that are produced, shuts down blood flow to the tumor (which is needed to fuel growth), inhibits cancer cell migration and invasion, promotes self-destruction of cancer cells (apoptosis), and even regulates cancer development through epigenetics.
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Undermines lung, colon, breast, prostate, skin, pancreatic, liver, throat, and bladder cancer, osteosarcoma, glioblastoma, leukemia, melanoma, and potentially more.
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Shuts down the pro-inflammatory pathways that are activated by bacterial endotoxin.
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Works as a powerful antioxidant to detoxify free radicals and reduce cellular damage.
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Improves mood, as well as anxiety and depression. Boosts brain function, improving memory and focus.
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Regulates the immune system, ameliorating autoimmune diseases like experimental multiple sclerosis and rheumatoid arthritis.
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Flips the body into fat-burning mode to promote weight loss by reducing pathogenic bad bacteria in the gut and limiting bacterial endotoxin release in addition to other mechanisms.
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Protects the heart by improving lipids, lowering blood pressure, inhibiting platelet aggregation, and even directly suppressing inflammation in the arteries.
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Repairs the damage of diabetes, correcting diabetic heart and kidney damage.
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Corrects gut dysbiosis by increasing healthy gut microbes, increasing butyrate release, and repairing the intestinal lining to reverse leaky gut by upregulating tight junction formation.
Why broccoli microgreens > mature broccoli for maximising your sulforaphane intake
Of all the cruciferous vegetables, there is one form that dominates all the others in terms of offering more sulforaphane: broccoli sprouts and microgreens.
The research shows that broccoli sprouts and microgreens can produce 10 to 100 times more sulforaphane than mature broccoli. What this means is that you can either eat large quantities of fully mature broccoli, or a small amount of broccoli microgreens to achieve the same sulforaphane intake.
The research shows that to maximise sulforaphane in cruciferous vegetables, you should chop them and then wait 15 minutes before eating to activate the chemical reaction between the myrosinase enzyme and the glucosinolates.
Additionally, the myrosinase enzyme is sensitive to heat, so to maximize your sulforaphane intake it's best to eat your broccoli raw, or lightly cooked on low heat.
Not all broccoli seed varieties offer the same sulforaphane content
There is one final nuance here, and it's crucial to get it right if we want to ensure that the microgreen seeds we're growing are the same ones as the researchers have studied.
In the world of broccoli sulforaphane research and broccoli microgreen seeds, three named varieties recur:
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Broccoli Waltham 29 (scientific name Brassica Oleracea var. Botrytis Waltham 29, or also called Brassica Oleracea var. Italica)
- Broccoli Calabrese (scientific name Brassica Oleracea var. Botrytis Cymosa)
- Broccoli Raab (scientific name Brassica Rapa var. Ruvo)
The studies on sulforaphane typically refer to Brassica Oleracea and not Brassica Rapa.
In fact, Broccoli Raab is not related at all to broccoli. It’s from a different species: Brassica Rapa, and is a relative of turnip and bok choy.
We prefer to source Broccoli Calabrese over Waltham 29 as Calabrese comes from the EU, while Waltham 29 comes from the United States.
Research on the sulforaphane content of the different varieties has shown that Brassica Olaeracea has significantly higher levels of sulforaphane content compared to Brassica Rapa.
Unfortunately, broccoli microgreen seeds sold by other suppliers that do not mention the variety, are almost always guaranteed to be Broccoli Raab, as it is a more common, lower cost variety. At Heirloom Garden we make a point to source only premium Broccoli Calabrese, carefully selected for its naturally higher sulforaphane content.
Food is medicine
The science is strong about the benefits of consuming sulforaphane from broccoli sprouts or microgreens.
There might be no single food that represents the idea of 'Food is Medicine' better than broccoli sprouts and microgreens.
Some of the studies referred to:
Anticancer properties of sulforaphane: current insights at the molecular level
https://pmc.ncbi.nlm.nih.gov/articles/PMC10313060/
Microgreens of Brassicaceae: Mineral composition and content of 30 varieties
https://www.sciencedirect.com/science/article/abs/pii/S0889157516300448
Broccoli Microgreens: A Mineral-Rich Crop That Can Diversify Food Systems
https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2017.00007/full
Hydrolysis before Stir-Frying Increases the Isothiocyanate Content of Broccoli
https://pubs.acs.org/doi/10.1021/acs.jafc.7b05913
Modulation of the metabolism of airborne pollutants by glucoraphanin-rich and sulforaphane-rich broccoli sprout beverages in Qidong, China
https://academic.oup.com/carcin/article-abstract/33/1/101/2463507?redirectedFrom=fulltext
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