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Cruciferous Vegetables: Reaping the Benefits of Sulforaphane




In today's world, preventive healthcare has become more important for maintaining a healthy life. Over the past few decades, researchers have been exploring ways to reduce the risk of cancer. One area of research that has yielded promising results is the study of plant phytochemicals. Sulforaphane, a naturally occurring compound found in cruciferous vegetables like broccoli, cauliflower, kale, bok choy, Chinese cabbage and Brussels sprouts, has received significant attention from researchers due to its potential health-promoting effects.


Numerous studies suggest that sulforaphane has several biological benefits, including cancer prevention and treatment. In this blog post, we will look at some of the available experimental and clinical data on the potential therapeutic role of sulforaphane in cancer.


What is Sulforaphane?


Cruciferous vegetables are rich in glucosinolates, which are sulfur-containing compounds responsible for giving cruciferous vegetables their unique smell and taste. Sulforaphane is formed when a particular glucosinolate (glucoraphanin) interacts with an enzyme (myrosinase) involved in the defence mechanism of plants. This enzyme is released and activated when a plant is damaged. Therefore, to activate sulforaphane, cruciferous vegetables need to be finely cut, chopped, or chewed to release myrosinase.


The highest concentrations of sulforaphane are found when the cruciferous vegetable are raw. A study has revealed that raw broccoli has ten times more sulforaphane than cooked broccoli.[1] Therefore, steaming vegetables for a short duration, typically three minutes or less, is considered an optimal cooking method for preserving sulforaphane levels. [2]


How Does It Work?


Sulforaphane has garnered attention for its potential anti-cancer properties. Many of the studies conducted that looked at the effect of sulforaphane on cancer have been in vitro, meaning in a laboratory setting, and in vivo, which involves testing on animals. This research has shown promising results.


Note: The data from clinical studies on the use of sulforaphane as a therapeutic agent in cancer treatment is limited due to the complexity of conducting such trials. Therefore, the bulk of the evidence we have on sulforaphane's effect on cancer comes from preliminary studies. It is important to consider the findings of these studies in this light and for research in this field to continue.


Sulforaphane demonstrates anticancer activity by influencing key cellular processes involved in cancer development and progression.[3] Experimental studies have shown that this compound inhibits self-renewing stem cells.[4] These cells can contribute to cancer relapse and metastasis, as well as resistance to treatments such as chemotherapy.[5] Sulforaphane has also been found to inhibit cancer growth, induce cell death, and help stop the formation of new blood vessels that cancer needs to grow.[6] Additionally, sulforaphane has been found to reverse abnormal changes in gene transcription—another powerful anti-cancer activity.[7]


At the molecular level, sulforaphane activates pathways that regulate antioxidant and detoxification genes. By activating these pathways, sulforaphane can increase the expression of several genes and proteins which provide protection to cells against harmful agents.[8] This can prevent DNA damage and oxidative stress caused by carcinogens.


Sulforaphane and Cancer Prevention


One of the most promising benefits of sulforaphane is its ability to prevent cancer development. Sulforaphane has been identified as a chemoprotective agent, along with having numerous other health benefits. Observational studies have shown that increased consumption of cruciferous vegetables can decrease the risk of various types of cancer, most notably those affecting the bladder, colon, and lungs.[9] [10]


Several studies have demonstrated that sulforaphane possesses anticancer activity against a broad range of cancer types, including prostate and lung cancers.[11] It may also be effective in protecting against pancreatic, colon and breast cancers among others.[12]


The study of the effects of phytochemicals from cruciferous vegetables, including sulforaphane, particularly in the treatment of breast and prostate cancer, is an evolving field of research. In the following sections, we will review some relevant studies in these two specific areas.


Sulforaphane and Breast Cancer


Research indicates that dietary factors are significant contributors to the development of breast cancer. Fortunately, cruciferous vegetables have been identified as abundant sources of chemopreventive compounds, with sulforaphane being one of the most extensively studied. Substantial evidence from in vitro and animal studies has found that sulforaphane has a protective effect against breast cancer through multiple pathways.[13]


Findings from both lab and animal studies demonstrate its potential to prevent breast cancer progression, recurrence, and metastasis. Sulforaphane also exhibits protective properties against the detrimental effects of cytostatic drugs on healthy cells.[14]


Note: Cytostatic refers to potent toxic substances employed in medical treatments. They act by impeding cell division, effectively retarding or halting the growth of targeted cells.


A study conducted on 54 women with abnormal mammograms, who were set to undergo breast biopsy, examined the connection between the consumption of cruciferous vegetables and certain tumour biomarkers. On average, participants consumed 81.7 grams of cruciferous vegetables per day. The study found that higher total intake of cruciferous vegetables was linked to significantly lower levels of Ki-67 (a protein widely used as a cell proliferation marker) in breast non-invasive ductal carcinoma tissues. However, this association was not observed in benign or invasive ductal carcinoma tissues. These findings suggest that consuming cruciferous vegetables may help inhibit the proliferation of breast cancer cells.[15]


A phase II clinical trial is currently exploring the impact of a propriety specialised complex of sulforaphane, on a group of 60 woman over an 18-month period. The initial findings suggest that the sulforaphane complex may have the potential to counteract resistance to endocrine therapies in patients diagnosed with ER+ HER2- metastatic breast cancer.[16]


A recent systematic review explored the protective effect of cruciferous vegetables and their glucosinolate derivatives on breast cancer. The review provides substantial evidence from in vitro and animal studies that strongly support the protective effect of sulforaphane and other isothiocyanates in breast cancer. These compounds were found to significantly reduce cancer cell viability and proliferation. The preclinical evidence suggests that sulforaphane as well as other isothiocyanates could potentially be used as therapeutic agents for breast cancer either as adjunct therapy or combined with current anti-breast cancer drugs.[17]


Sulforaphane and Prostate Cancer


Cruciferous vegetables have also been identified as a potent source of protection against prostate cancer progression. A recent clinical study showed that consuming glucoraphanin-rich broccoli soup affected gene expression in the prostates of men on active surveillance. The study found that glucoraphanin-rich broccoli soup consumption led to the down-regulation of genes involved in cancer progression pathways.[18]


After undergoing radical prostatectomy, increases in serum levels of prostate-specific antigen (PSA) are common in men with prostate cancer and are referred to as “biochemical recurrence.” In a double-blinded, randomized, placebo-controlled multicentre trial with 78 patients, a daily dose of 60 mg of a stabilized free sulforaphane was administered for 6 months. The results of the study were promising, indicating that sulforaphane may be an effective treatment in decreasing the rate of PSA progression in biochemical recurrence after definitive radical prostatectomy. These findings could have significant implications for prostate cancer patients and their treatment options.[19]


In Summary


Sulforaphane is a compound found in cruciferous vegetables such as broccoli, cabbage, and kale. Some of the benefits of sulforaphane for cancer prevention and treatment are:

  • May block mutations in DNA that lead to cancer, slow tumour growth, and reduce the ability of cancerous cells to multiply and spread.

  • It neutralizes toxins that can damage healthy cells and cause inflammation, which is linked to some types of cancer.

  • It activates antioxidant enzymes that protect DNA from oxidative stress and carcinogens.

  • It modulates the expression of genes involved in cell cycle regulation, cell death, and metastasis.

  • It inhibits the growth of various cancer cells, such as breast, prostate, colon, lung, and skin.

The best way to consume sulforaphane is through eating cruciferous vegetables, as they also contain other nutrients and phytochemicals that may work together to provide the most benefit. The good news is that consumption of these vegetables containing sulforaphane is considered safe and can easily be incorporated into a healthy diet. By adopting a plant-based ketogenic diet, such as the one detailed in Nutritious, the daily intake of sulforaphane will be elevated, thereby reaping its remarkable benefits.


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