Exciting findings expand the tumor-taming potential of cruciferous veggies
Most mothers — and fathers — urge their kids to “eat your vegetables”.
And you may have seen bumper stickers that say, “eat more kale” — especially if you live in a foodie-culture part of the country.
Kale may not be to your liking, but fortunately, its apparent anti-cancer attributes are common to all “cruciferous” vegetables — so-called because their flowering heads form a cross or crucifer.
The cruciferous family includes arugula, broccoli, bok choy, Brussels sprouts, cabbage, cauliflower, collard greens, cress, daikon, horseradish, kale, kohlrabi, mustard greens, rutabaga, radish, turnips, and wasabi.
As we reported in To Block Cancer, Favor the Crucifer Family, population studies consistently link diets rich in cruciferous veggies to reduced risks for common cancers, including breast, prostate, colon, skin, lung, stomach, and bladder tumors.
Cruciferous vegetables contain compounds called glucosinolates that the body converts into two groups of chemicals — isothiocyanates and indoles — that display anti-cancer effects in animal and test-tube studies (see Do Cruciferous Vegetables Really Curb Cancer Risk?).
Exciting new findings uncovered unique, promising anti-cancer properties in the best-known indole compound, called I3C (indole-3-carbinol).
Cruciferous veggies may protect the body’s own anti-cancer capacity
The new study was led by Pier Paolo Pandolfi, MD, PhD, director of the Cancer Center and Research Institute at Beth Israel Deaconess Medical Center (BIDMC).
His international team included researchers from Duke University, the University of North Carolina, and various universities and hospitals around the world.
Dr. Pandolfi’s team discovered that broccoli and other cruciferous veggies contain a compound that “turns off” a tumor-promoting gene found in many common cancers, called WWPI (Lee YR et al. 2019).
The WWPI gene derails another gene — called PTEN — that would otherwise suppress the development and growth of a tumor.
That ability of a tumor cells' WWPI gene to suppress, mutate, or totally silence the PTEN gene allows it to grow, and seriously worsens a patient’s chances of survival. (Inherited mutations of the PTEN gene make a person much more susceptible to common cancers — but such mutations are extremely rare.)
Pandolfi’s team discovered that the WWP1 gene in a tumor cell produces an enzyme that suppresses normal activation of the PTEN gene, thereby crippling the body’s ability to fight cancer growth.
So, chemists on Pandolfi’s team looked for ways to block a tumor’s PTEN-suppressing WWPI enzyme.
They suspected that the I3C (indole-3-carbinol) compound common to all cruciferous veggies might inactivate a tumor’s WWP1 enzyme, thereby protecting its cells’ own tumor-suppressing PTEN gene.
To test their hunch, they conducted two experiments:
- They exposed human cancer cells to I3C from cruciferous veggies.
- They administered I3C directly into the abdominal cavities of mice bred to develop prostate cancer, every day or every other day.
And the combined results of the two studies were quite encouraging:
- The cancer-cell study confirmed that I3C suppresses the growth of tumors, at least in a Petri dish. (Things could be different inside the human body.)
- The mouse study showed that I3C suppressed the growth of prostate tumors in these animals — and that any malignancies that did develop were smaller and less deadly than normal.
Together, these results suggest that cruciferous vegetables — or commonly available I3C supplements —- may help keep tumors from suppressing the cancer-fighting PTEN gene found in their own cancerous cells.
As Dr. Pandolfi said in a press release, “We found a new important player that drives a pathway critical to the development of cancer … an Achilles’ heel we can target ...”.
While this finding may lead to new ways to treat or prevent cancer, the tumor-suppressing powers of I3C needs to be confirmed in clinical trials.
How can you exploit this discovery??
It's important to note that a daily serving of broccoli or other cruciferous veggies may not be enough to curb the risk of cancer or slow its growth.
The researchers estimated that you’d have to eat about six pounds of raw Brussels sprouts every day to get enough I3C to disable the cancerous WWP1 gene’s tumor-promoting enzyme.
However, supplements that provide highly concentrated amounts of I3C are widely available online and in drug and health food stores.
It’s tricky to translate the I3C doses given to the lab mice — which went directly into the animals’ abdominal cavities — into oral doses for people. That’s both because a person would be taking I3C orally, and because mice and people may not absorb and metabolize I3C identically.
That said, these calculations suggest that you’d need to take a daily supplemental dose of I3C totaling 1,000 mg or more:
- The mice received 20 mg of I3C per kilogram (2.2 lbs.) of body weight.
- To approximate that dose, a person weighing 120 lbs. (54.5 kg) would need to ingest 1,090 mg (54.5 x 20 mg = 1,090) of I3C daily.
- Most I3C supplements provide 200 mg per capsule, so a 120-lb person would need to take five such capsules (providing a total of 1,000 mg) or more daily.
Other new studies support crucifers’ anti-cancer potential
Two new studies from the Roswell Park Cancer Institute further strengthen the case for eating more broccoli, kale, cabbage, and other cruciferous veggies.
The researchers linked diets high in cruciferous vegetables to a lower risk for ovarian cancer (McManus H et al. 2018).
And they found that raw cruciferous vegetables may reduce the risk for stomach cancer, even after accounting for the effects of other cancer-fighting dietary factors (Morrison MEW et al. 2019).
- Beth Israel Deaconess Medical Center (BIDMC). Natural Compound Found in Broccoli Reawakens the Function of Potent Tumor Suppressor. May 16, 2019. https://www.bidmc.org/about-bidmc/news/2019/05/broccoli-reawakens-tumor-suppressor
- Lee YR et al. Reactivation of PTEN tumor suppressor for cancer treatment through inhibition of a MYC-WWP1 inhibitory pathway. Science. 17 May 2019:Vol. 364, Issue 6441. DOI: 10.1126/science.aau0159. https://science.sciencemag.org/content/364/6441/eaau0159.long
- McManus H et al. Usual Cruciferous Vegetable Consumption and Ovarian Cancer: A Case-Control Study. Nutrition and Cancer. 2018 May-Jun;70(4):678-683. doi: 10.1080/01635581.2018.1464346. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6088381/
- Morrison MEW et al. Cruciferous Vegetable Consumption and Stomach Cancer: A Case-Control Study. Nutrition and Cancer. 2019 May 16:1-10. doi: 10.1080/01635581.2019.1615100. https://www.ncbi.nlm.nih.gov/pubmed/31094219 and
- National Institutes of Health. PTEN gene. https://ghr.nlm.nih.gov/gene/PTEN
- The New York Times. A Rare Genetic Mutation Leads to Cancer. The Fix May Already Be in the Drugstore. May 17, 2019. https://www.nytimes.com/2019/05/17/health/gene-mutation-cancer.html