Time and time again, we've been told that vegetables like broccoli, cabbage and cauliflower are crucial for our health. But do we actually know why?

While there are many vitamins, minerals and nutrients found in these vegetables that contribute to great health, one key reason is a very special compound called sulforaphane – an active compound found in cruciferous vegetables, but most especially fresh broccoli sprouts as they contain 100 times more sulforaphane than mature broccoli.

Sulforaphane actually begins as its inactive form, glucoraphanin, which is stored in broccoli sprouts (and other said vegetables). When the sprouts are chopped, chewed or damaged, the release of the myrosinase enzyme is triggered, converting glucoraphanin to sulforaphane.

Switching On Your Cellular Defence System

Once inside the body, sulforaphane activates a protein called Nrf2, a “switch” that turns on the natural defence mechanisms within our cells. More specifically, Nrf2 activation affects the expression of over 200 different genes, all of which contain the code for cellular defence against oxidative stress and ageing. In this process, hundreds of cytoprotective proteins, including phase II detoxifying enzymes and glutathione (the body’s master internal antioxidant) are induced.

Due to its ability to activate our Nrf2 pathway, sulforaphane has earned itself a reputation of being highly anti-inflammatory, anti-tumour, anti-viral and (indirectly) antioxidant, and has in recent years become widely researched for its benefits for cardiovascular health, diabetes, inflammatory conditions, autism, and even cancer.

Let’s find out what the science is saying about sulforaphane and broccoli sprouts:

1. Reduces Inflammation

We now know that chronic, systemic inflammation is the root of many modern day diseases, from rheumatoid arthritis to heart disease, and that this inflammation is actually the result of oxidative stress in the body.

Oxidative stress occurs when there is an imbalance between antioxidants and free radicals in the body, or in other words, there are too many free radicals for the antioxidants to neutralise. This can cause damage to cells and tissues, leading to chronic inflammation. 

The activation of the Nrf2 pathway by sulforaphane reduces oxidative stress in a clever variety of ways, including pumping out more glutathione to neutralise free radicals, thereby reducing inflammation. [1]

Sulforaphane further reduces inflammation by decreasing NF-kB[2], which is responsible for regulating the expression of certain proteins involved in the inflammatory response. Research has also shown that cruciferous vegetables that are high in sulforaphane significantly reduced inflammatory markers such as IL-6[3] and CRP[4] in test subjects.

2. May Help Prevent Cancer

Scientists have been looking into sulforaphane’s ability to induce apoptosis (death of cancer cells) and suppress cancerous cell cycles, and a number of clinical trials have demonstrated promising results.

A study that looked into the effects of sulforaphane from broccoli sprouts on prostate cancer treatment involved prostate cancer patients taking 60mg of active sulforaphane per day. These subjects saw a 86% slowing of the doubling rate of a cancer biomarker known as Prostate Specific Antigen (PSA).

In another clinical study done on women with breast cancer, findings showed that sulforaphane halts breast cancer cell growth.[5]

Other studies have seen positive effects of sulforaphane on cancers of the bladder[6] and colon.[7]

3. Boosts Liver Detoxification

Sulforaphane is a potent inducer of both glutathione and Phase II enzymes, supporting the liver in detoxifying potential carcinogenic compounds that enter the body.

According to this study[8], the consumption of broccoli sprout extract for two months led to improved liver markers in patients with non-alcoholic fatty liver disease, thanks to its ability to induce phase II detoxification enzymes and the synthesis of glutathione. 

Another superpower of sulforaphane is its ability to detoxify the body of air pollutants. A Chinese study on participants in a particularly air-polluted region found that consuming broccoli sprouts leads to a 61% higher excretion rate of benzene and acrolein, which are both toxic chemical pollutants[9], thereby mitigating the negative and carcinogenic effects of breathing polluted air. 

4. Improves Cardiovascular Health

Many cardiac disorders like atheslerosis and hypertension are linked to oxidative stress. So, since the activation of the Nrf2 pathway from sulforaphane helps to reduce oxidative stress in the body and reduces inflammation, the consumption of broccoli sprouts therefore lends itself well to preventing and improving cardiac disorders[10].

Other studies have found that cruciferous-rich diets reduce plasma LDL[11], which is sometimes known as the “bad” cholesterol that raise your risk for heart disease and stroke.

5. Improves Gut Microbiome

Helicobacter pylori is a bacteria that is usually responsible for stomach ulcers and even stomach cancer. Thankfully, sulforaphane has been found to be effective in treating infected patients[12]. In a study, participants infected with H. pylori were split into two groups – one eating 100g of fresh broccoli sprouts a day for two months, and the other alfalfa sprouts. The study concluded that in the former group, there was a significant decrease in bacteria, but not in the latter.[13]

Other research shows that sulforaphane can balance the gut microbiome. improve the function of intestinal cells, and positively impact bowel movements[14].

6. Improves Brain and Mental Health

Emerging research has uncovered a notable impact of sulforaphane on depression and anxiety. A study on mice found that sulforaphane decreased stress hormones and the inflammatory response, and also inhibited hyperactivity of the HPA axis, which is a common biological finding in anxiety- and depression-related disorders. 

Sulforaphane has also demonstrated neuroprotective effects through preventing various brain diseases, such as stroke, Alzheimer’s disease and even autism spectrum disorders[15], thanks to the activation of Nrf2 and its downstream antioxidative effects.[16]

In addition, sulforaphane can reduce the degree of brain tissue damage and brain cell death in cases of strokes, as well as protect brain cells from the formation of beta-amyloid clumps which are responsible for Alzheimer’s disease.[17]

7. Promotes Weight Loss

As an Nrf2 activator, sulforaphane may also promote weight loss by improving gut flora and changing how we consume energy. According to Japanese study, sulforaphane accelerates the production of brown fat that is thought to burn calories at a faster rate while balancing the amount of beneficial bacteria in the gut, together promoting healthier weight.[18]

References

[1] https://doi.org/10.4103/jomfp.JOMFP_126_19

[2] https://www.sciencedirect.com/science/article/pii/S0021925819315121

[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4195422/

[4] https://www.sciencedirect.com/science/article/abs/pii/S1756464612000953

[5] http://clincancerres.aacrjournals.org/content/early/2010/04/09/1078-0432.CCR-09-2937

[6] http://cancerres.aacrjournals.org/content/68/5/1593.short

[7] https://academic.oup.com/carcin/article/21/12/2287/2908767

[8] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4649129/

[9] https://aacrjournals.org/cancerpreventionresearch/article/7/8/813/50355/Rapid-and-Sustainable-Detoxication-of-Airborne

[10] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4637098/

[11] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4692095/

[12] https://journals.lww.com/oncology-times/fulltext/2006/01250/broccoli_sprout_consumption_reduces_h__pylori.14.aspx

[13] https://journals.lww.com/oncology-times/fulltext/2006/01250/broccoli_sprout_consumption_reduces_h__pylori.14.aspx

[14] https://www.jstage.jst.go.jp/article/jcbn/62/1/62_17-42/_article

[15] https://www.pnas.org/doi/10.1073/pnas.1416940111

[16] https://austinpublishinggroup.com/cerebrovascular-disease-stroke/fulltext/ajcds-v4-id1054.php

[17] https://www.mdpi.com/1422-0067/21/22/8637

[18] https://pubmed.ncbi.nlm.nih.gov/22819548/