A pair of broccoli sprout studies

This 2015 Oregon human study found:

  • “Plasma and urinary levels of total SFN [sulforaphane] metabolites were ~3–5 times higher in sprout consumers compared to BSE [broccoli sprout extract] consumers.
  • In sprout consumers, plasma concentrations were 2.4-fold higher after consuming the second dose than after the first dose.
  • Calculated SFN bioavailability from broccoli sprouts exceeded 100%.

a Following consumption of a single 200-µmol SFN dose. b Cumulative excretion of SFN metabolites from baseline collection through the 48-hr study period. c Bioavailability F calculated based on total micromoles excreted in urine. Cmax, maximum concentration observed; AUC, area under the curve; h, hour; L, liter; t1/2, half-life; Tmax, time at Cmax. Values represent mean ± SD, n = 10.”

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4394840/ “Absorption and chemopreventive targets of sulforaphane in humans following consumption of broccoli sprouts or a myrosinase-treated broccoli sprout extract”

Another way to state findings:

  1. Broccoli sprouts are better than supplements.
  2. Eating sprouts twice a day is better than eating them once a day.

No explanation was given for sprout weight variability, although one was needed, because 127.6 g / 2 = 63.8 g, not 46.8 g:

“In the divided-dose phase (two weeks later), subjects (fasting) consumed half the original dose (100 μmol SFN equivalents) at 8 AM from sprouts or the BSE and the other half (not fasting) 12 h later.”

A “SFN potential” process demonstrated sulforaphane amount equivalencies, but didn’t explain non-intuitive sprout weight measurements. Was it too difficult to control sprout variability? The difficulties were instead pushed onto other researchers trying to replicate the study, and consumers looking for practical guidance.

Regardless, I adjusted my practices to twice daily start a new broccoli sprout batch with one tablespoon of seeds rather than once a day with two tablespoons. I eat them with breakfast and dinner.

I microwave 3-day-old sprouts immersed in 100 ml distilled water on full 1000W power for 35 seconds to achieve 58°C. I immediately put them into a strainer to allow further myrosinase hydrolization of glucoraphanin and other glucosinolates into sulforaphane and other healthy compounds.

I’d overlooked the above study until I saw it referenced in its successor 2018 human study Untargeted metabolomic screen reveals changes in human plasma metabolite profiles following consumption of fresh broccoli sprouts and cited it in Reversal of aging and immunosenescent trends with sulforaphane for its DHEA findings. The clinical trial treatments included:

“Both dehydroepiandrosterone (DHEA) and metformin in an attempt to limit the “diabetogenic” effect of GH [growth hormone]. DHEA has many effects, in both men and women, that oppose deleterious effects of normal aging.”

A PubMed search on DHEA found Impact of Dehydroepianrosterone (DHEA) Supplementation on Serum Levels of Insulin-Like Growth Factor 1 (IGF-1): A Dose-Response Meta-Analysis of Randomized Controlled Trials which confirmed the clinical trial’s DHEA dose would increase IGF-1.

This study observed a significant decrease in DHEA after eating broccoli sprouts, but didn’t provide a plausible explanation for this finding, or cite relevant studies. Ten other significant decreases were related to antioxidants and fatty acids.

It isn’t clear that I needed to take DHEA anyway, since the clinical trial’s purpose for DHEA treatment was to oppose effects of growth hormone, which I’m not taking. But I’m getting good results, so I’ll just keep doing what I’ve been doing for a limited time.

The study said:

“While this study focuses largely on the potential effects of SFN, broccoli sprouts contain many other bioactive components that could be responsible for our observations as well as additional health benefits.”

Our model clinical trial Effects of long-term consumption of broccoli sprouts on inflammatory markers in overweight subjects said much the same:

“The anti-inflammatory effects observed with broccoli sprouts intake are likely due to the combined effects of all the hydrolysis products of glucosinolates.”

The 3-day-old broccoli sprouts have the optimal yields study said:

Although germination reduces SF [sulforaphane] yield to some extent, it is beneficial to the formation and accumulation of total phenol and flavonoids, ensuring the health properties of sprouts.”

Combining the pair of Oregon studies’ findings:

  1. Broccoli sprouts are better than supplements.
  2. Eating sprouts twice a day is better than eating them once a day.
  3. When in doubt, refer back to Item 1.



2 thoughts on “A pair of broccoli sprout studies

  1. I like how you boil it down to a few bullet-points at the end. Sometimes, these studies can be difficult to understand and interpret. It is nice when an author summarizes it in layman’s terms and says “basically, the study says you should do X, Y, and Z.”

    • Thanks! Appreciate it.
      These two were tough. I started out thinking Wow, great stuff, how did I miss seeing them before? And they do have good data.
      It went from 5 stars to 4-5 when I realized that the 2015 study sprout weight was way off to where neither consumers nor researchers could directly use it. Then the 2018 follow-on study finding that made me look at it in the first place from a PubMed “sulforaphane dhea” search wasn’t explained.
      It went from 4-5 stars to 2-3 stars from the study’s reference #27 that was cited for “direct evidence of an effect of SFN on DHEA levels is limited.” The referenced review didn’t say anything about DHEA!

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