What is so Great About Broccoli Sprouts?

by Aaron R. Piavis

Geisinger Commonwealth School of Medicine (GCSOM)

Master of Biomedical Sciences Class of 2021 (MBS)

June 2021

Everyone remembers when their parents told them to eat their vegetables at the dinner table. For many of us, those vegetables were green cruciferous vegetables (such as broccoli, brussel sprouts, cabbage, collard greens, and many others). When you would ask why you had to eat these foods with questionable tastiness instead of having another helping of some of those French fries, you were likely met with the universal retort “because they are good for you”; but what does “good for you” actually mean and why are these cruciferous vegetables considered healthy?

According to several studies in the past century, this “good for you” quality when it comes to consumption of cruciferous vegetables means a lower likelihood of cancer, heart disease, and all-cause mortality (1)(2)(3). The initial assumption from these findings was that the protective effects of plant-based diets were due to the presence of vitamins in the vegetables, such as vitamin A, C, E, and beta-carotene, in line with the popular theory of the 20^th century that such vitamins fought the build-up of free radicals (and with it, the hastened progression of aging)(4).

However, the biological mechanisms surrounding aging and many associated chronic diseases have been discovered to be much more complex than simply being caused by the build-up of free radicals (5). Recent studies attempting to create a more concrete causal-link between classical antioxidant supplementation (such as the above vitamins) and the improvement of cardiovascular health and diabetes prevention have yielded no effects (and sometimes even adverse effects) instead of positive effects (6)(7)(8). Additionally, until the past several decades, researchers had not considered the plethora of bioactive phytochemicals that also reside within these cruciferous vegetables that are responsible for activation of many protective cellular mechanisms in our body.

A particular of the glucosinolate phytochemical family, sulforaphane, has been isolated as one the most potent anti-inflammatory, antioxidant, and anti-cancer compounds within cruciferous vegetables that contributes to the positive health outcomes seen with cruciferous vegetable consumption.

Compared to classical antioxidants and other similar phytochemicals, sulforaphane is an exciting compound because of its relatively high potency as an anti-inflammatory, anti-cancer, and antioxidant agent and its relatively high bioavailability (how much of the compound enters the blood stream from the gut) (9)(10).

If we look at the concentrations of sulforaphane-producing vegetables, broccoli sprouts come in as containing the highest concentration of the sulforaphane precursor (11).

This turns out to be great news, because the cultivation of broccoli sprouts is very easy and costs very little time and effort. Additionally, the small sprout-like shape of the vegetable allows for an easy way to add a healthy topping to any meal with a mild taste and familiar texture. I personally see this as a method to give people (in particular picky eaters and younger children) the health benefits of green vegetables that they otherwise would not enjoy eating. In the next several paragraphs, I will lay out the steps to cultivate your own broccoli sprouts and provide my experience with adding them to various dishes.

 

Growing Broccoli Sprouts

Step 1: After acquiring broccoli sprout seeds and sprouting jars, which can be found via several online retailers, the first step in the sprouting process is to add 2-6 tablespoons of broccoli seeds to an anti-bacterial solution of water, 1 tablespoon of vinegar or apple cider vinegar, and a few drops of dish soap; let this solution sit for about 10 minutes.

Step 2: Keeping the seeds in the jar, rinse and empty water through the metal mesh lid about 15 times. After all of the anti-bacterial solution is rinsed away, fill the jar with water and let the seeds sit in the water for 8 to 12 hours.

 

Step 3: Empty the water from the top of the jar until the seeds are only mildly wet. Let the jar sit upside down into a bowl to allow more water to drain throughout the day. Now you are set to allow the seeds to begin sprouting over the course of the next 4 days. Rinse the sprouts with water and empty 2 to 3 times per day, placing the jar back into an upside-down position in a bowl. No direct sunlight is required, so leaving the jar on the counter should suffice.

Step 4: Monitor your progress. By the beginning of the second day of rinsing your sprouts, you should start to see some green showing through (bottom left image). By the end of day 4, your sprouts should be ready to harvest (bottom right image).

 

How to Broccoli Sprouts

Broccoli sprouts serve as an excellent replacement for lettuce on sandwiches, as a topping for healthy pizzas, and as an extra addition to your salad. However, there are a few important caveats to note in order to make sure that you are ingesting the bioactive sulforaphane phytochemical when you eat broccoli sprouts.

First, it is important to note that when consuming broccoli sprouts, one should keep them uncooked, because boiling or exposing the broccoli sprouts to high temperatures inactivates the enzyme within the broccoli sprout responsible for converting the glucoraphanin (the sulforaphane precursor) into the bioactive sulforaphane phytochemical (11).

 Second, it is important to keep the broccoli sprout intact within 15 minutes before consuming it. This is because damage to the plant tissue (such as by chopping, chewing, or blending) exposes glucoraphanin to myrosinase (the enzyme that converts glucoraphanin into sulforaphane). Sulforaphane will not remain in this bioactive state when exposed to the elements for an extended period of time (11).

 So now the question is how much broccoli sprouts should you be eating to get the protective effects of sulforaphane? The answer is that eating as little as about 5 servings of broccoli sprouts per month has been associated with decreased risk of lung cancer (3). However, several clinical trials showed even stronger protective effects with daily consumption of the phytochemical.

 One clinical trial involved giving what was the equivalent of 60mg of sulforaphane from broccoli sprouts slowed the progressive increase in a prostate cancer biomarker known as prostate-specific antigen (PSA) (12).

 Another clinical trial showed that 40mg of daily sulforaphane lowered serum triglycerides and decreased participants atherogenic index by 50% (the risk of developing cardiovascular disease) (13).

 Furthermore, another clinical trial showed that 40mg of daily sulforaphane ingestion reduced inflammatory biomarkers in type 2 diabetes. Reduction in inflammation in the body is closely linked to improved aging throughout the lifetime and decreased risk of age-related chronic disease, such as type 2 diabetes, cardiovascular disease, and forms of dementia (14).

 For reference, each jar of broccoli sprouts contains about 280g of broccoli sprouts, which yields between 90 to 120 mg of sulforaphane – making reaching the daily recommended levels quite a breeze.

 

References

1.         Zhang X, Shu X-O, Xiang Y-B, Yang G, Li H, Gao J, et al. Cruciferous vegetable consumption is associated with a reduced risk of total and cardiovascular disease mortality. Am J Clin Nutr. 2011 Jul 1;94(1):240–6.

2.         Bosetti C, Filomeno M, Riso P, Polesel J, Levi F, Talamini R, et al. Cruciferous vegetables and cancer risk in a network of case–control studies. Ann Oncol. 2012 Aug;23(8):2198–203.

3.         Tang L, Zirpoli GR, Jayaprakash V, Reid ME, McCann SE, Nwogu CE, et al. Cruciferous vegetable intake is inversely associated with lung cancer risk among smokers: a case-control study. BMC Cancer. 2010 Dec;10(1):162.

4.         Howes M-JR, Simmonds MSJ. The role of phytochemicals as micronutrients in health and disease: Curr Opin Clin Nutr Metab Care. 2014 Nov;17(6):558–66.

5.         Varadharaj S, Kelly OJ, Khayat RN, Kumar PS, Ahmed N, Zweier JL. Role of Dietary Antioxidants in the Preservation of Vascular Function and the Modulation of Health and Disease. Front Cardiovasc Med. 2017 Nov 1;4:64.

6.         Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C. Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases. Cochrane Hepato-Biliary Group, editor. Cochrane Database Syst Rev [Internet]. 2012 Mar 14 [cited 2021 May 4]; Available from: http://doi.wiley.com/10.1002/14651858.CD007176.pub2

7.         Bjelakovic G, Nikolova D, Gluud LL, Simonetti RG, Gluud C. Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases. Sao Paulo Med J. 2015 Apr;133(2):164–5.

8.         Bjelakovic G, Gluud C. Surviving Antioxidant Supplements. JNCI J Natl Cancer Inst. 2007 May 16;99(10):742–3.

9.         Thimmulappa R, Mai K, Srisuma S, Kensler T, Tamamoto M, Biswal S. Thimmulappa RK, Mai KH, Srisuma S, Kensler TW, Yamamoto M, Biswal S.. Identification of Nrf2-regulated genes induced by the chemopreventive agent sulforaphane by oligonucleotide microarray. Cancer Res 62: 5196-5203. Cancer Res. 2002 Oct 1;62:5196–203.

10.       Hanlon N, Coldham N, Gielbert A, Kuhnert N, Sauer MJ, King LJ, et al. Absolute bioavailability and dose-dependent pharmacokinetic behaviour of dietary doses of the chemopreventive isothiocyanate sulforaphane in rat. Br J Nutr. 2008 Mar;99(3):559–64.

11.       Fahey JW, Zhang Y, Talalay P. Broccoli sprouts: An exceptionally rich source of inducers of enzymes that protect against chemical carcinogens. Proc Natl Acad Sci. 1997 Sep 16;94(19):10367–72.

12.       Cipolla BG, Mandron E, Lefort JM, Coadou Y, Della Negra E, Corbel L, et al. Effect of Sulforaphane in Men with Biochemical Recurrence after Radical Prostatectomy. Cancer Prev Res (Phila Pa). 2015 Aug;8(8):712–9.

13.       Bahadoran Z, Mirmiran P, Hosseinpanah F, Rajab A, Asghari G, Azizi F. Broccoli sprouts powder could improve serum triglyceride and oxidized LDL/LDL-cholesterol ratio in type 2 diabetic patients: A randomized double-blind placebo-controlled clinical trial. Diabetes Res Clin Pract. 2012 Jun;96(3):348–54.

14.       Navarro SL, Schwarz Y, Song X, Wang C-Y, Chen C, Trudo SP, et al. Cruciferous Vegetables Have Variable Effects on Biomarkers of Systemic Inflammation in a Randomized Controlled Trial in Healthy Young Adults. J Nutr. 2014 Nov 1;144(11):1850–7.