It’s a refrain we probably all remember from childhood: eat your vegetables. You also don’t have to look very far to find countless studies singing the praises of plant foods. And that most famous of vegetables, the cruciferous family? Their purported cancer-fighting properties have been getting a lot of air time lately. Even respected institutions like the National Cancer Institute and the American Institute for Cancer Research recommend including cruciferous vegetables in the diet to help prevent cancer. But can cruciferous vegetables cure cancer?
Let’s find out.
What Are Cruciferous Vegetables?
Cruciferous vegetables, which are often referred to as brassica vegetables, are members of the Brassicaceae, or Cruciferae, family. The moniker cruciferous comes from the cross-shaped pattern of their flowers.
Cruciferous vegetables include those with flowering heads, like broccoli, and dark green leafy varieties, like kale. Other examples of cruciferous vegetables include:
Cruciferous Vegetables and Cancer
Multiple studies have shown that regular intake of cruciferous vegetables—as part of a healthy diet of fruits, non-cruciferous vegetables, whole grains, and healthy fats—may lead to a lower risk of cancer.
And that’s because cruciferous vegetables are packed with nutrition. Not only are they great sources of vitamins A, C, E, K, and folate, as well as phosphorus, magnesium, potassium, and fiber, but they’re also chock-full of cancer-fighting phytochemicals.
Take broccoli, for example. This nutrient-rich green vegetable that’s notorious for grossing out small children has one of the most well-established ties to cancer prevention.
A study published in the Proceedings of the National Academy of Sciences of the United States of America found that broccoli sprouts contain large numbers of glucosinolates (more on these later), which protect the body against potential carcinogens.
Another study published in the journal Antioxidants & Redox Signaling found that sulforaphane—a chemical found in cruciferous vegetables in general and broccoli in particular—acts as both a chemopreventive agent and toxin to malignant cells.
And a meta-analysis of case-control studies conducted over 18 years found that weekly consumption of cruciferous vegetables was associated with a decreased risk of several cancers, including breast, upper digestive tract, kidney, and colon cancers.
Perhaps most astounding is a statement made in a study published in the journal Current Pharmacology Reports to the effect that cruciferous vegetables, with their ability to both prevent the onset of and halt tumor cell growth, may be the key to ending cancer once and for all.
Indeed, the cruciferous family of vegetables has been shown to be effective in providing protection against a number of different types of cancer, including breast, lung, kidney, thyroid, cervical, colon, prostate, and pancreatic cancers.
Let’s now take a closer look at what may be the real anti-cancer power behind the vegetables: phytochemicals.
Phytochemicals: Nature’s Secret Weapon?
Phytochemicals are found in all plants, not just cruciferous vegetables. They’re actually the biologically active compounds that help plants grow and fight off diseases, predators, and other plants. They’re also the compounds that give every plant its own unique smell, color, and flavor.
The phytochemicals in cruciferous vegetables may help fight cancer in a number of ways, including via their antioxidant, anti-carcinogenic, and anti-inflammatory effects as well as their ability to boost the immune system and aid in hormone regulation.
While every plant contains phytochemicals, the types of chemicals present vary based on species. The major phytochemical groups in cruciferous vegetables are the carotenoids, polyphenols, and glucosinolates.
Let’s take a look at those now.
The carotenoids are some of the more well-known phytochemicals. For example, everyone’s probably familiar with beta-carotene—the carotenoid that gives carrots their orange hue—and lutein and zeaxanthin are becoming more well-known for their role in protecting the eyes from macular degeneration.
Carotenoids are famous mainly for their antioxidant capabilities. Antioxidants help prevent cancer by scavenging free radicals, which lead to DNA damage and inflammation, both of which are associated with an increased risk of cancer.
Polyphenols make up the largest known category of phytochemicals and include flavonoids and phenolic acids. Like other phytochemicals, polyphenols possess antioxidant and anti-inflammatory properties as well as the ability to halt the growth and proliferation of cancer cells.
Numerous studies have demonstrated the anti-cancer effects of polyphenols, noting a direct link between consumption of these phytochemicals and a decreased risk of prostate cancer as well as breast, colon, cervical, stomach, and lung cancers.
What’s more, the flavonoid quercetin has been found to increase the effectiveness of traditional cancer treatment.
The other major group of cruciferous vegetable phytochemicals is the glucosinolates. These are the sulfur-containing compounds that give the brassicas many of their characteristic tastes and smells. Sulfur is also the third most abundant mineral in the body and replete with health benefits of its own.
Moreover, the glucosinolates are some of the main players when it comes to the chemopreventive power of cruciferous veggies. Their anti-cancer effects stem from their ability to affect a wide range of factors that contribute to the development of cancer.
And cruciferous vegetables contain a variety of glucosinolates, each of which is broken down to form various metabolites, including isothiocyanates and indoles.
One particular isothiocyanate, sulforaphane, has been found in numerous studies to protect the body from environmental carcinogens and to prevent the growth of or induce cancer cell death. It’s also the compound thought to play the main cancer-fighting role in a number of cruciferous vegetables, including broccoli.
Studies have also found that the isothiocyanates have impressive antibacterial, antiviral, and antifungal properties that may make them useful in the fight against infectious diseases.
Like isothiocyanates, indoles have also been found to prevent carcinogenesis and induce cancer cell death.
In addition, indole-3-carbinol—a type of indole—acts as an estrogen receptor antagonist, which means it can attach to estrogen receptors and block the action of estrogen. This means indole-3-carbinol may potentially modulate estrogen metabolism, thus lowering the risk of hormone-dependent cancers.
Indole-3-carbinol is also the precursor of a number of other metabolites, including diindolylmethane. While both indole-3-carbinol and diindolylmethane are available in supplement form, recent studies indicate that diindolylmethane may actually be more beneficial for chemoprevention than indole-3-carbinol.
Getting the Most from Glucosinolates
All glucosinolate metabolites are created in the presence of water and enzymes called myrosinases. This chemical reaction, which is known as hydrolysis, evolved in cruciferous vegetables as a way to protect the plants from predators. But the same process also occurs when the raw vegetables are chewed or chopped.
However, when the vegetables are cooked, myrosinase is destroyed, which greatly decreases the cancer-fighting abilities of the glucosinolates.
But since most of us probably don’t want to gnaw on raw cruciferous vegetables all the time anyway, we can take comfort knowing that there are actually a couple of tricks that can ensure myrosinase is allowed to do its job.
According to Michael Greger, MD, chopping the fresh (not frozen, which involves blanching) vegetables and then letting them sit for 40 minutes before cooking allows enough time for the water and myrosinase in the cells to come together and form the beneficial metabolites.
Yet we don’t always have time to chop our vegetables and sit around waiting for them to marinate in their enzymes either. Thankfully, we can get the same effect by simply adding some fresh cruciferous veggies to the frozen or cooked versions—or even sprinkling a bit of mustard seed or horseradish on top before serving.
So What’s the Verdict? Can Cruciferous Vegetables Cure Cancer?
While no studies have conclusively proven that cruciferous vegetable intake cures cancer, there’s strong evidence to suggest that it does reduce cancer risk, and it may even play an important role in cancer treatment.
So if you already love cruciferous vegetables, keep on eating! And if you don’t, try looking online for recipes that may appeal to you.
Just about every culture enjoys cruciferous veggies, and each has its own unique way of preparing them. Whether sweet or savory, or even spicy, there’s likely some concoction somewhere that even an avowed crucifer-phobe can learn to love.
And if telling yourself how good cruciferous vegetables are for you still isn’t enough to get you on the brassica train, you might try upping your vegetable consumption with a supplement. There are several great green drinks on the market that make good use of brassicas.
As you can see, there’s really nothing stopping you from including more of this most important family of vegetables in your diet. So what are you waiting for? Your body will thank you!