Can Eating More Broccoli Help Protect Against Cancer?

| Introduction

A Matter of Life and Death

Claire loves nothing more than delving into the world of plant science and nutrition, to find out just how nature and our environment can react and assist in the fight against some of mankind’s most deadly diseases, in this case, some of our most deadly Cancers. 

Can eating more Broccoli and other cruciferous vegetables in your diet really assist in the fight against Cancer? 

GrowMad's resident scientist investigates

Read more...

| Broccoli and its part in the treatment of cancer

As children, we were always told- ‘eat your greens!’ Who would have thought our Mothers were actually right? All cruciferous veg have oodles of nutritional qualities and broccoli more so than most.

In this article, I will tell you all about the amazing compounds in broccoli, what good it can do for you, current scientific research, and the best way to eat and store the gorgeous green stuff.

| Now for the sciency bit...

In cruciferous vegetables, there are natural components called glucosinolates which are thought to help the plant defend against disease and pests.

The compound also provides protection against an array of other environmental challenges. Many beneficial plant compounds are more concentrated in wild plants than in commercially bred varieties. (Yagishita et al. 2019)

This principle was utilised in the development of ‘Beneforte’ super broccoli which was specifically bred to contain very high amounts of glucoraphanin in 2011. This was achieved by crossing it with an old wild type which naturally has high levels.

One of these components -Glucoraphanin, (GFN) is converted by an enzyme called myrosinase into Sulforaphane (SFN). Sulforaphane, as its name implies, is a sulphur-containing organic compound found in high levels in plants of the Brassica genus (Kaiser et al. 2021)

The myrosinase is activated when the plant is damaged, either in its natural habitat or when chewed in the human mouth. The compound is also released by the action of bacteria present in the intestines (Shapiro et al. 2001)

| So, what is Sulforaphane supposed to do?

SFN has generated a lot of interest in the scientific field as may indeed have cancer-fighting and other health-giving properties. This is part of a growing field of research into the use of plants and/or derivatives as cancer treatments, a concept known as “green chemoprevention” (Kaiser et al. 2021)

Numerous studies have been carried out on the effect of Sulforaphane (SFN) on cancer cells. These show that ingesting cruciferous vegetables- for example, broccoli may lower the overall risk of cancers such as bladder, lung, breast, colorectal and prostate. Watson et al. (2014) state that the molecule can cause prostate cancer cells to undergo apoptosis (self-destruction) and also slow disease progression. Previous studies have shown that SFN can change the programming of cancer cell cycles via a number of different mechanisms. Consumption of broccoli over a 12-month period was shown to interact with genes and cause changes to chemical reactions concerning inflammation and cancer mechanisms in the prostate.

In 2010, Polish scientists, Tomczyk and Olejnik, found that SFN showed protective properties at every stage of cancer development regardless of the primary organ. They hypothesise that this could be via activating apoptosis or by preventing the formation of blood vessels (angiogenesis), which is an important factor in how quickly and aggressively a tumour can grow. They also discovered that SFN has anti-inflammatory and antibacterial properties.

Gamet-Payrastre et al. (2000) study showed that SFN could block the formation of artificially caused tumours in rats, and also investigated the effect on human colon cancer cells. Again they saw that the SFN caused the cell cycle to be disrupted, and as they increased the concentration of SFN, the cells died.

Pledgie-Tracy et al. (2007) state that SFN can help detoxification enzymes work better and can slow down the growth of induced mammary tumours in rats. The study looked at the effect of SFN on human breast cancer cells and found that cell growth was slowed down, apoptosis was activated and various proteins that would normally cause cell proliferation were decreased.

Researchers in Australia, (Tortorella et al.) in November 2014 agree that SFN can be important as a treatment against recently found types of cancer cells that possess the ability to self-renew - these are called cancer stem cells (CSC). These CSCs are particularly nasty as can maintain the cancer and contribute towards the cells becoming drug resistant- so that normal chemotherapy will not work. SFN can cause genetic alterations in these and other cancer cells, disrupting how they grow and replicate.

The CSCs are the latest target for many therapeutic cancer therapies. Work has also been carried out on pancreatic cancer, which has the worst prognosis of all malignant cancers. Studies have indicated that people, who consumed three or more servings a week of cruciferous vegetables, had a 50% risk reduction of developing pancreatic cancer.

Also, another review showed a 50% reduction in the risk of developing metastasis (spreading) of prostate cancer, with high consumption of broccoli (Appari et al. 2014) The same researchers also showed that SFN, in conjunction with green tea extract was shown to inhibit a mutated gene (Kras) responsible for producing a growth factor implicated in cancer growth. It also encourages another gene which regulates the action of a RAS – another gene in which over signalling can lead to cancer. Both of these factors mean that cell growth is diminished.

Chan et al. (2019) showed that SFN reduced cellular proliferation, migration and invasion in
breast cancer.

Scientists now recommend a balanced plant-based diet enriched in cruciferous vegetables, rather than vegetable or broccoli supplements’ (Appari et al. 2014) This is a common theme amongst the research, that although SFN has been identified as a very probable anti-cancer compound, many of the other compounds in the vegetable may work alongside it. Therefore eating the whole vegetable will confer the best outcome. Indeed many of the recent findings are of using many compounds together.

Factors affecting the quality and quantity of GFN 

It has more recently been discovered that although GFN is abundant in the florets and aerial parts of the broccoli, the seeds are the richest source of the compound.

Vanduchova et al. (2019) described studies which show that there was around sixteen times more GFN in broccoli sprouts than in mature broccoli extract. They also note that the amount of GFN precursor-glucosinolates, (GLS) are affected by cooking. Broccoli sprouts eaten raw contained 128mg per gram, blanched broccoli 92mg/gram, and cooked 47mg/gram. However, I would say that eating the same weight of raw sprouts compared to blanched broccoli is quite a feat!

If broccoli is eaten raw, the plant's own enzymes will ensure that the SFN is released in the upper gastrointestinal tract, to be absorbed readily into the body. After cooking- and I mean light steaming, the enzyme doesn’t work. All is not lost though, as bacteria in our own colon can do the same trick and release the SFN, however, this is less efficient.

Verkerk et al. (2009) carried out a study on the levels of GLS in Brassica, with regard to growing and storing conditions. It found that GLS levels were higher in late cultivars cropped between August and January, compared to early- April- July. This they linked to possible lower temperatures.

Regarding growing conditions, they also discovered that supplementing with Sulphur between 23-92kg/ha led to an increase in GLS, whereas nitrogen supplementation caused a 70% reduction. Stressing the plant, also increased the GFN levels, which would replicate its natural wild environment. GFN doubled in response to a reduced water supply. This can be easily achieved by the home gardener who wants to increase levels in their own broccoli.

Natural organic, home-grown broccoli can also be picked and on the plate in ten minutes- thereby maintaining all its nutrients. Shop-purchased vegetables will have been processed and stored. If left at room temperature, the Verkerk study found, that after 5 days the GLS will have decreased by 64-79%, whereas storage at 4 degrees Celsius the loss was only 4-16%. Most supermarket broccoli is found at ambient temperatures.

Basically- there is a growing body of evidence to suggest that plant compounds are very beneficial to us and growing your own well-fed, less looked-after crop, will in my opinion be a better alternative than purchasing shop-brought broccoli. Alternatively sprout organically produced seed in a sprouter and sprinkle them on salads, soups, or scrambled eggs.

What are you waiting for, get out there and GrowMad!

| References