Does sulforaphane reach the colon?

This 2020 study subject was antimicrobial activity of sulforaphane:

“This study explored the role that digestion and cooking practices play in bioactivity and bioavailability, especially the rarely considered dose delivered to the colon.

A broccoli powder soup was prepared which contained 26.5 µmol of sulforaphane per 200 ml portion. Addition of 2% mustard seed powder at the cooling stage of the soup preparation process (~ 60 °C) increased the level of sulforaphane by nearly fourfold, 102 µmol per 200 ml.

Recovery of sulforaphane in ileal fluids post soup consumption was < 1% but the addition of mustard seeds increased colon-available sulforaphane sixfold. Analysis of glucosinolates composition in ileal fluids revealed noticeable inter-individual differences.

Consumption of sulforaphane-enriched broccoli soup may inhibit bacterial growth in the stomach and upper small intestine, but not in the terminal ileum or the colon.”

https://link.springer.com/article/10.1007/s00394-020-02322-0 “Sulforaphane-enriched extracts from glucoraphanin-rich broccoli exert antimicrobial activity against gut pathogens in vitro and innovative cooking methods increase in vivo intestinal delivery of sulforaphane”


My son has often asked me about adding mustard seeds to broccoli sprouts. Papers citing one of this study’s coauthors’ series of mustard seed studies include:

I bought a 74 gram container of mustard seeds at the local grocery store, and ground down a third as pictured. A level scoop of mustard seed powder weighs 1.5 grams.

1.5 g divided by my twice-daily 65 g of microwaved broccoli sprouts = 2%, matching this study’s methods. That’s a 24-day mustard seed supply for $2.19.

I’ll add mustard seed powder immediately after microwaving broccoli sprouts when they’re ≤ 60°C (140°F). Allowing the mixture to process for five minutes potentially facilitates myrosinase hydrolization of glucoraphanin and other glucosinolates into healthy isothiocyanate compounds.


Other aspects of this study:

1. I don’t consider overcooking broccoli an “innovative cooking method.” It’s more like researchers creating an effect in order to publish “increased the level of sulforaphane by nearly fourfold” which was presented numerically and emphasized twice in text.

2. A perspective on these types of studies from Epigenetic mechanisms of muscle memory:

“Underpowered studies may only be useful to check if the experiment works, but not as much for testing and estimating effects.

3. I didn’t agree with this study’s treatment of individual differences.

I read three other papers’ study design recommendations for researchers regarding inter-individual variability, but didn’t see markedly better ideas. Most of their verbiage concerned how to reduce heterogeneous effects rather than to understand causes and signals. Where are thoughtful counters to meaningless averages / standard deviations / p values / and so on?

4. “Addition of mustard seeds increased colon-available sulforaphane sixfold” was presented numerically and emphasized thrice in text. Too often for a n=11 study.

What needed further explanations were detailed causes for each individual’s responses or lack thereof. Stratifying subgroups into unresponsive:

  • What happened in Subjects 6’s and 10’s lives to make them unresponsive to any sulforaphane dose?
  • Were Subjects 1, 2, 5, and 7 instances of zero sulforaphane actually errors in measuring or processing? If not, what were individual causes for instances of no response?

And responsive:

  • Were Subjects 4, 8, 9, 11, and 12 averages meaningful? Excluding Subject 4’s 3.14 μmol, was the four remaining subjects’ 0.19 to 0.63 μmol average 332% increased response meaningful when the sulforaphane dose increased 392%?
  • What caused Subject 4’s 872% increased response when the sulforaphane dose increased 392%?

5. Findings of sulforaphane in 11 g broccoli powder not reaching the colon may not apply to 65 g broccoli sprouts due to mass and quantity differences. Broccoli sprouts definitely pass into the colon, like any other fibrous vegetable. Unhydrolyzed products are hydrolyzed by microflora there.

I create sulforaphane from broccoli sprouts shortly before eating them, and don’t depend on metabolism after the stomach to produce isothiocyanates. These findings may assist with that effort.

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