Prostate cancer is on the rise. More men are being diagnosed with it, and more men are dying from it. In 2014 it was responsible for an estimated 29,480 deaths in the US alone. In the UK, prostate cancer is the second most common cause of cancer-related deaths in men.
I will talk about the whys behind this troubling trend in a future issue of Nutrition & Healing. But today, I want to share with you my research on a remarkable, yet common, natural substance that can both help treat and prevent prostate cancer.
Quercetin is a plant pigment that belongs to a group of compounds called flavonoids. Flavonoids are a type of polyphenol, the most prevalent group of substances found in the plant world. Polyphenols give plants their bright colours, fragrances and unique tastes.
Polyphenols put up a fight against cancer
While all of nature’s polyphenols have shown some anti-cancer (and cancer-fighting) activity, you no doubt have heard of only a few of them. Curcumin (turmeric), resveratrol and plant tannins – which have been found in a number of studies to help prevent diseases, including cancer – often make the headlines. But among the polyphenols, quercetin has been one of the most studied, and yet somehow overlooked.
Polyphenols protect plants from the harmful effects of ultraviolet radiation from the atmosphere, environmental pollutants and diseases. They all share a chemical structure in common called a benzene ring that can ward off or interfere with the growth and spread of these environmental dangers. And the souped-up activity of these rings (known as ‘volatility’ in the chemistry world) is exactly what gives the plants their unique flavours, odours and colours.
Quercetin causes cancer cells to commit suicide
Quercetin has another prostate-problem-fighting trick up its sleeve. According to a study on prostatitis, published in the journal Urology, the flavonoid acts as an anti-inflammatory, significantly improving swollen prostate symptoms.
In March of 2015, a review published in the journal Oncology Reports chronicled the dozens of published studies on quercetin and prostate cancer. The researchers concluded that both in vitro and in vivo studies have proven that quercetin “effectively inhibits prostate cancer via various mechanisms.”
They noted that human clinical trials have shown promising results, and that animal studies even suggest that the powerful flavonoid has a ‘chemopreventive effect’. In other words, quercetin may be able to prevent, or slow, the development of prostate cancer.
So let’s take a look at how this plant pigment accomplishes this incredible feat.
Our immune systems react to cancer cell invasions by sending out messages that promote inflammation. Inflammation gets a bad rap, but it’s not all bad. Its purpose is to bring immune cells to the area where they’re needed. Unfortunately, however, it also promotes tissue damage. And in the cancer cell, pro-inflammatory messengers stimulate growth, and slow down their natural death process.
Much like the Borg of old Star Trek shows, cancer cells need to be in constant communication with one another, and there are signalling pathways within the cancer cells to accomplish this. One of the main growth stimulating signals used by cancer cells triggers a pathway called STAT3 (signal transducer and activator of transcription 3). Many flavonoids and other natural polyphenols fight cancer by blocking this STAT3 pathway, but few do this as effectively as quercetin.
According to a March 2015 study, quercetin blocks an important messenger called IL-6 (Interleukin 6). IL-6 is a good guy or a bad guy depending on the situation. But in the case of cancer IL-6 is generally a bad guy since (among other things) it activates the STAT3 pathway which encourages tumours to grow.
This study showed that quercetin inhibits IL-6, which in turn shuts down the STAT3 pathway. The result? The cancer cells can’t grow, and instead they essentially commit suicide in a process in medicine known as apoptosis!
Another inflammatory messenger that helps stimulate prostate (and other) cancer growth is called NF kappaB. A number of studies have shown that quercetin, and its polyphenol relatives, block NF kappaB, but one in vitro study is particularly exciting. This 2011 study used an extract of Brazilian propolis, that nearly magical nutrient-rich substance produced by bees to repair their hives. (I’m an amateur beekeeper so anything involving these fascinating creatures captures my attention). Quercetin extracted from the propolis had inhibited the NF kappaB in prostate cancer cells causing them to… you guessed it… commit suicide.
Nutrients in produce partner up against cancer
Our immune systems are constantly vigilant against cells which might be turning cancerous. Your body uses the nutrients and chemicals found in fresh fruits and vegetables, quercetin among them, to fight against cancer. They turn off inflammation, block the growth and development of potential cancer cells, and trigger the apoptosis of existing cancer cells before they can do damage. In one 2014 study using a rat model of prostate cancer, quercetin was shown to slow down or stop the growth of prostate cancer cells by FIVE different mechanisms!
Quercetin doesn’t occur by itself in nature. Flavonoids and other polyphenols work as partners to supply those captivating tastes and smells, as well as cancer-fighting activity.
Several recent studies have demonstrated that quercetin with green tea extract can be even more effective than either alone, and others have looked at quercetin combined with the soy flavone genistein. All combinations have shown positive activity against prostate cancer.
Beef up cancer-fighting benefits with a supplement
One of the great things about quercetin, and other polyphenols, is how abundant in nature they are. If you eat a diet rich in fresh fruits and vegetables (as you should, for many reasons) you’re already consuming quercetin.
Foods particularly rich in this miraculous substance include…
- various salad greens
Grapes and red wine are good sources too, but even an apple contains about 10mg
of quercetin if you leave the skin on.
In order to get the full health benefit, though, it’s probably necessary to take a quercetin supplement. Most studies use levels of the flavonoid that are higher than we can get with diet alone. And when you’re taking polyphenols as supplements (whether it’s quercetin, resveratrol, green tea extract, etc.) it’s especially important to choose a high-quality product and not just the cheapest one available.
Remember, these are highly active antioxidant and anti-inflammatory compounds, and if they’re not processed properly they will easily break down in the capsule and not give you the full benefit of their amazing cancer-fighting powers.