Sulforaphane (SFN) is a sulfur-containing compound that naturally occurs in green and yellow vegetables. It is present in an inactive form; glucoraphanin in these vegetables. But, a family of enzymes known as myrosinase activates and converts it into activated Sulforaphane used for various health benefits. 
It is important to note that myrosinase enzymes only release and work on glucoraphanin when any damage to the plant occurs. So, if someone wants an active form of Sulforaphane, he/she must chop, chew or cut the vegetables before consumption. Plus, the raw green leafy vegetables contain high content of Sulforaphane compared to cooked vegetables.
Vegetable sources of Sulforaphane
The following leafy green cruciferous vegetables contain high content of Sulforaphane.
Mechanisms of Action
The exact mechanism of Sulforaphane is unclear; however, studies reported the following mechanisms responsible for various health outcomes. These include:
Research studies highly reported the SFN modulation of the Nrf2/ARE pathway that leads to the activation and expression of genes responsible for coding endogenous enzymes, non-enzymes antioxidant, and cardioprotective and phase 2 detoxification enzymes. The major detoxification enzymes include glutathione-S-transferase (GST), glutathione peroxidase (GPX1), thioredoxin reductase (TXNRD1), thioredoxin (TXN) glutamate-cysteine ligase (GCL), NADPH: Quinone reductase-1 (NQO1), and haemoxygenase-1 (HO-1). Thus, SFN shows potent antioxidant activity that relieves oxidative stress, promotes physiological functions, and protects vital body organs. Besides, it also positively modulates natural killer cells' activity and supports an immune function that reduces the risk of chronic medical conditions. 
Along with the antioxidant action, SFN inhibits some Phase 1 detoxification enzymes responsible for carcinogen activation. Plus, it acts as a histone deacetylase inhibitor that protects DNA damage and prevents cancer risk. Moreover, SFN arrests the abnormal cell cycle, inhibits angiogenesis, and induces apoptosis that provides the anti-cancerous activity. 
The anti-inflammatory activity of SFN involves the suppression of pro-inflammatory cytokines and regulation of the NF-κB and inflammatory inducible enzymes such as cyclooxygenase (COX-2) and NO synthase (iNOS). 
Medical research studies about Sulforaphane
Medical studies reported the following health benefits of Sulforaphane.
Various animal and lab studies reported the anticancer activity of Sulforaphane. The above-discussed mechanisms help cancer and reduce the tumor size and suppress cancer cell proliferation. Also, the antioxidant property potentiates the activity of Sulforaphane against cancerous cells via neutralizing the carcinogens. Studies also reported that SFN blocks gastric tumor formation and prevents the development of stomach cancer. Thus, an optimal amount of Sulforaphane improves cancer progression and reduces the risk of cancer, including breast cancer. [1, 2]
Studies reported that SFN inhibits adipogenesis and suppresses the synthesis of triglycerides and fat accumulation. The anti-obesity mechanism involves activating the AMPK pathway, downregulating the peroxisome proliferator-activated receptor γ (PPARγ), and suppressing the C/EBPα expression. Plus, it promotes the activity of adiponectin and increases leptin responsiveness that helps prevention of diet-induced obesity. Additionally, medical research studies showed that Sulforaphane significantly improves high blood sugar levels and helps with type 2 diabetes mellitus symptoms. It regulates the hemoglobin A1C level and reduces the lipid peroxidation that significantly helps diabetes and its complications. [3, 4]
Support Cardiovascular functions
The potent antioxidant and anti-inflammatory activity of Sulforaphane improve cardiovascular health. Animal studies showed that Sulforaphane increases the level of thioredoxin (Trx) and HO-1 (haemoxygenase-1) that provide cardioprotective properties. It supports post-ischemic ventricular function, protects cardiomyocyte against apoptosis, and decreases myocardial infarct size that promotes heart functions. Adding more, it relieves inflammation in the arteries that prevent arteries narrowing and other cardiovascular dysfunctions. 
SFN shows a bactericidal effect against Helicobacter pylori bacteria responsible for gastrointestinal complications, including gastric reflux and cancer. The antibacterial mechanism reported by studies includes the modulation of Nrf2 activators, anti-inflammatory activity, and direct bactericidal action of cruciferous vegetables. Also, the inhibition of urease by SFN support the bactericidal effect as most bacterial colonies use urease for their growth. [1, 7]
Different research studies reported that SFN alters estrogen metabolism and improves estrogen dominance. The induction of NADPH: Quinone oxidoreductase 1 (NQO1) by SFN reduces the carcinogenic estrogen metabolite, known as catechol estrogen-3, 4-quinone, and suppresses the complications associated with estrogen dominance. Moreover, SFN increases the level of glutathione-S-transferase (GST) that detoxify the estrogen via conjugation and prevent the risk of adverse physiological effects such as DNA damage and abnormal cell growth. [5, 6]
Support Brain Function
Sulforaphane shows antioxidant and anti-inflammatory activity that helps neuroinflammation and supports neurological functions. It prevents brain damage, removes reactive oxygen species, relieves oxidative stress, and reduces the risk of mental decline. Plus, studies reported that it improves autism symptoms such as verbal communication and social interactions. Furthermore, SFN Protects dopaminergic cells and delay neuronal death that helps neurodegenerative diseases, including Parkinsonism and Alzheimer’s diseases. [1, 8]
Other potential health benefits
Medical research studies also reported the Antiaging and skin protective effects of SFN. It prevents skin damage by protecting skin against ultraviolet radiation that promote skin integrity and wellness. Furthermore, Sulforaphane encourages gastrointestinal health and improves the symptoms of certain dysfunctions such as constipation. Also, it limits the activity of aflatoxin on liver cells and supports liver vitality. Plus, the induction of HO-1 (haemoxygenase-1) and phase 2 enzymes by SFN protect the lungs against oxidative agents and reduce the risk of various lung dysfunctions. [1, 8]
SFN supplementation or consumption of cruciferous green vegetables is safe for more extended periods (up to six months). However, it may cause gastrointestinal upset and weight gain. There is no reliable information about its safety during pregnancy or breastfeeding, so better to stay safe side. Plus, it may aggravate the seizure in individuals with autism.
Please don't use it concomitantly with drugs metabolized by the liver, such as zolmitriptan, olanzapine, cyclobenzaprine, theophylline, imipramine, etc. 
Please, don’t exceed the recommended doses.