Did you know that scientists rank foods based on how effective they are at fighting diseases like cancer? All vegetables provide health benefits, but these five are the most powerful if you want to prevent cancer.

You know you should be eating more vegetables, but which ones are best to prevent cancer?
You know you should be eating more vegetables, but which ones are best to prevent cancer?
Photo Credit: unsplash.com

Remember when the salad bar was a fixture at most steakhouses?

Remember when restaurant meals always came with a side salad—at no extra charge?

Remember iceberg lettuce?

Once upon a time, iceberg lettuce dominated the salad scene in this country.  But, with a changing American palate, increasing consumer health awareness, and a subsequent demand for more sophisticated greens, the pale leaf lost its status and has been replaced by the likes of arugula, spinach, and kale, among others.

Though these darker alternatives can never replicate that satisfying crunch, they offer far more in the nutrition department than the lackluster iceberg.  Iceberg has been particularly hard-hit by the commercial farming practices that have led to depleted soil and water.  Estimates are that, on average, a head of iceberg lettuce provides 30% fewer nutrients today than a couple of decades ago. The same can be said for many other types of produce, but here’s the good news: during that same time, evidence has been amassing that compounds in certain vegetables have near drug-like benefits, particularly when it comes to fighting cancer.

According to a report complied by the World Cancer Research Fund and published in the British Journal of Cancer, roughly 40% of cancers are directly related to poor diet and lifestyle habits.  Though sensible nutrition strategies encompass more than the plants we consume, thousands of research studies support the inclusion of vegetables in our diet as a means to prevent cancer.

Like most kids, I hated veggies when I was younger.  Today, they’re my favorite part of the meal.  This is due, in part, to my discovery of more creative and flavorful methods of preparation, but also to my obsession with disease prevention.  

The way I see it, there’s a battle taking place inside my body, all throughout the day, each and every day.  Humans produce up to 500,000 of cancer cells daily and though most will not survive, our ability to destroy them before they can move to the next stage of carcinogenesis is largely dependent upon the strength of our immune systems.  That’s where diet comes in. By thinking about it in those terms, I find it much easier to muster the motivation to put more of the things in my body that I once shunned.

Hippocrates said, “let food be thy medicine.”  But it’s not enough to admonish society to eat more veggies.  That’s been drilled into our heads to the point that now we just tune it out.  And, the truth is, vegetables are not all created equal.  Some just happen to be better than others in terms of disease prevention.  So, instead of the generic lists that you find in the mainstream health magazines, we have to give people more of a reason to eat the vegetables that contain the nutrients needed for optimum health.

You already know you should be eating more spinach, carrots, and tomatoes. The veggies I present here often go under the radar and that’s unfortunate, as they are nutrition superstars with a bounty of research to back it up.  I provide a sampling of the evidence here. I focus on cancer because surveys have shown that the disease strikes more fear into Americans than pretty much anything else.

You know veggies are good for you, but perhaps you don’t know how good or why.  I find that when you give people information, when you get them to understand why something is good for them and what is actually taking place in their bodies, then they are more likely to follow the advice. And maybe it’s just me, but I think it’s pretty cool that something I eat can make a cancer cell commit suicide.

If, like some members of Congress, your idea of a vegetable is a French fry, the tomato sauce on your pizza slice, or the lettuce adorning your burger, then you may not have much interest in this blog post.  But if, like me, you want to arm your immune system with nature’s most powerful cancer fighters, start with these 5 vegetables and you’re well on your way.

Top 5 Vegetables to Prevent Cancer

1. Watercress

Up until a few years ago, the only familiarity I had with the word watercress was in the context of the sandwiches served at high tea in England. Fast forward to today and it’s a key component of my cancer-fighting strategy.

Watercress is often overshadowed by its more recognizable cousins in the cruciferous family—broccoli, cabbage, and Brussels sprouts—and it doesn’t get the notoriety it deserves.  Watercress works its magic by protecting cells against DNA damage, one of the early steps in cancer development.

  • In a study at the University of Ulster, researchers gave participants a daily serving of watercress for 8 weeks, after which there was a 17% reduction in DNA damage.
  • A compound in watercress called  nasturtiin stimulates what are known as the liver’s phase II enzymes, which are responsible for removing carcinogens from the body. Studies conducted on prostate cancer cells indicate that a derivative of nasturtiin shuts down cancer cell proliferation and the growth of tumors and actually causes the cancer cells to commit suicide.
  • Another study, this time using colon cancer cells, showed that watercress is protective against 3 stages of cancer progression.
  • A study published in the British Journal of Nutrition and Biochemical Pharmacology revealed that a compound in watercress blocks a process by which breast cancer cells are fed oxygen and nutrients by surrounding tissues. Watercress essentially turns off the signal that tumors send out to normal cells in an attempt to “hijack” them.

TIP: Eat watercress raw, as cooking appears to deactivate one of the enzymes needed to produce the beneficial compounds. I throw it in with the various other salad greens I eat each day. Sometimes, I’ll juice it or toss some in a smoothie. It’s a bit peppery, but the flavor gets masked amidst the other components.

2. Broccoli sprouts   

Sauteed broccoli with garlic and olive oil is one of my favorite vegetables, but to prevent cancer, the sprouts pack a much bigger punch.
Sauteed broccoli with garlic and olive oil is one of my favorite vegetables, but to prevent cancer, the sprouts pack a much bigger punch.
Photo credit: wholefoodsmarket.com

Broccoli is good, broccoli sprouts are better.  Way better.  So much better, in fact, that a team of researchers from Johns Hopkins Medical School has actually patented a product called BroccoSprouts.  The scientists have found that you would have to eat about two pounds of  “adult” broccoli each week in order to reduce your risk of colon cancer by about 50%.

Isothiocyanate (ITC) is a fancy term for the compound that gives veggies like broccoli its distinct flavor.  ITCs are also well-known among scientists for their ability to neutralize carcinogens and stop their spread.  Research has demonstrated that broccoli sprouts have roughly 30 times more ITCs than the florets you’re more used to seeing!

Broccoli sprouts also contain a potent level of a compound called sulphorophane, which has been the subject of over 700 research studies.  Sulphorophane activates the body’s cancer-fighting enzymes.  These Phase II enzymes, as they are called, also protect cells against the mutagenic changes caused by carcinogens.

All cruciferous vegetables contain sulphorophane, but researchers have discovered that sprouts contain 10 to 100 times more of the compound than the mature plants.  In fact, just one ounce of broccoli sprouts contain the equivalent amount of sulforaphane as one-and-a-half pounds of adult broccoli!

Research confirms the powerful effect these sprouts have on cancer cells:

  • In a study out of Stanford University, researchers found that human prostate cancer cells responded to treatment with broccoli sprout extracts and showed “dramatic” increases in their Phase II protective enzymes.
  • A 2005 study in the Journal of Nutrition highlighted the ability of sulforaphane and broccoli sprout extract to inhibit cancer in human colon cancer cells.
  • A 2001 article in Cancer Research described the ability of broccoli sprout extract and sulforaphane to cause human bladder cancer cells to self-destruct—a process known as apoptosis.
  • The Amala Cancer Research Center in India has found that sulforaphane may help not only in the prevention of cancer, but that it can also stop existing cancer from spreading.  Their animal research showed a 95% reduction in the formation of lung tumors and a 94% increase in the life span.
  • In a study at Johns Hopkins Medical School, researchers exposed mice to high levels of ultraviolet light for 20 weeks and then administered an application of sulphorophane. This resulted in a 50% reduction in the number of mice with tumorsThe number and size of tumors also decreased.
  • A 2005 study published in the journal Cancer Epidemiology showed a dramatic change in levels of a biological measure associated with increased detoxification of carcinogens from the human body, resulting in a reduced cancer risk.
  • A 2008 issue of Cancer Research reported that an extract of broccoli sprouts decreased the formation of bladder tumors in animals by more than half.
  • Other studies have demonstrated the ability of sulforaphane to selectively target the bacteria known as H. pylori, including a strain that had become resistant to treatment with antibiotics.  H. pylori  raises the risk of gastric cancer.
  • In a recent study appearing in the journal Cancer Prevention Research, scientists concluded that a daily dose of broccoli sprouts reduced levels of a biomarker used to identify the presence of H. pylori by 40 percent.

According to the lead author:

“We know that a dose of a couple ounces a day of broccoli sprouts is enough to elevate the body’s protective enzymes. That is the mechanism by which we think a lot of the chemoprotective effects are occurring.”

Jed Fahey, nutritional biochemist in the Lewis B. and Dorothy Cullman Cancer Chemoprotection Center at the Johns Hopkins University School of Medicine

Their findings further indicated a protective effect for current smokers and former smokers, as well as those exposed to second-hand smoke.

TIP: Home sprouting kits are available, but I use packaged sprouts. In my area of the country, I’ve seen them at Market Basket, Shaw’s, and Big Y supermarkets, as well as Whole Foods, which carries the patented Brocco Sprouts. Throw them on a salad. What’s great about broccoli sprouts—or, at least the beneficial compounds they contain—is that they appear to remain in our systems for several days.  So a few servings per week should be enough to super-charge your immune system.

3. Dandelion greens 

Dandelions are best known as an unwelcome weed on our lawns, but the greens have actually been used medicinally for quite some time.

  • Dandelion greens provide up to 535% of the suggested daily intake of vitamin K, which was found in one study to slow the growth of lung cancer and, in another study to stabilize the disease in liver cancer patients.
  • Dandelion greens also contain more than 110% of the recommended daily intake of vitamin A, a carotenoid with the ability to prevent normal cells from becoming cancer.  A form of the vitamin called cryptoxanthin has shown potential in protecting against the formation and progression of cancers of the mouth and lungs.
  • Dandelion greens contain Tof-CFr, a glucose polymer similar to the compound in shitake mushrooms that has been shown to fight cancer in Japan.  A 1979 Japanese study found that administration of this extract drastically reduced growth of carcinoma cells within one week after treatment.
  • The Department of Chemistry and Biochemistry at Ontario’s University of Windsor demonstrated that dandelion root extract stimulates apoptosis (cell death) in human melanoma cells without harming healthy cells.  The process forced cancer cells to begin disintegrating within 48 hours of initial treatment!
  • According to Columbia University, antibodies to several different forms of cancers have been detected in individuals after dandelion consumption.
  • A study in a 2008 issue of the International Journal of Oncology concluded that dandelion leaf extract reduced growth in tissue cultures of breast cancer cells.  In the same study, dandelion extract stopped the spread of prostate cancer. 
  • A 2011 study using dandelion root tea indicated the possible presence of a “kill switch” on leukemia cell receptors.

TIP: Use dandelion greens in salads or lightly sauteed with other leafy greens. Or experiment with them in a smoothie recipe.

4. Kale

Want to prevent cancer? Eat more kale and other cruciferous vegetables.
Photo credit: pixabay.com

It’s been theorized that the reason kale has so many nutrients is because its leaves are open, in contrast to the tighter structure of cabbage, for example.  This would allow for more sunlight exposure and increased production of phytochemicals.

Kale’s cancer-fighting benefits have recently been extended to at least five different types of cancer, including cancers of the bladder, breast, colon, ovary, and prostate. The effects have been attributed to several different compounds in kale.

You’ve likely never heard of brassinin, but it’s a potent cancer-fighter. Research from the University of Illinois at Chicago demonstrates that brassinin may reduce the development of cancerous lesions in breast and skin cells.

  • A 2013 study in Phytotherapy Research showed that brassinin effectively suppresses signaling pathways used by prostate cancer cells.

Then there’s kaempferol, one in a group of antioxidants known as flavonoids, which have been shown to help reduce the risk of lung and pancreatic cancer.

Quercetin is another flavonoid found in kale. Studies have demonstrated its ability to slow or stop the growth of breast, colon, prostate, ovarian, endometrial, and lung tumors.  In one study, participants who smoked more than 20 cigarettes per day had a lower risk of lung cancer.

  • A 2013 article in Clinical Nutrition demonstrated a protective benefit against prostate cancer.
  • A 2012 study showed anti-tumor effects on liver cancer cells.

Kale is also a source of indole-3-carbinol (I3C), a chemical which enhances DNA repair in cells and seems to interfere with the growth of cancer cells.

Recent studies have shown that the ITCs (discussed above) made from kale’s glucosinolates can help regulate detoxification processes at a genetic level.  Kale has more glucosinolates—at least four different types, to be exact—than most other foods. When we eat kale, our guts turn the glucosinolates into substances that destroy cancer cells.

Scientists have traced the path of two antioxidants in kale—lutein and beta carotene—from the human digestive tract into the bloodstream and have demonstrated the ability of kale to increase the levels of these nutrients in the blood. This is significant because both are vital nutrients in protecting us from the oxidative damage that can lead to cancer and other health problems.

TIP: Cutting and properly chewing kale is very important.  This is what causes the release of the glucosinolates and also helps activate their cancer fighting properties. When cooking with kale, avoid boiling, as it decreases the level of sulforaphane.  Briefly steaming, microwaving, or stir frying, however, do not seem to lead to significant nutrient loss.

5. Cabbage 

Compounds in cabbage and similar vegetables can prevent cancer by removing excess estrogen from the body.
Compounds in cabbage and similar vegetables can prevent cancer by removing excess estrogen from the body.
Photo credit: unsplash.com

As with its cousins in the cruciferous family, the indole-3-carbinol in cabbage halts the cell cycle in breast cancer cells without harming the healthy cells that surround them (unlike chemotherapy).

Then there are those glucosinolates again. As discussed above, glucosinolates like those found in cabbage are converted into other compounds that exhibit preventative effects for a variety of different cancers.  They attack cancer at various stages of development.  Glucosinolates stop carcinogens from being activated initially, but they can also counteract the toxicity of carcinogens even once they’ve formed and can hasten the removal of carcinogens from the body.      

One of the ways in which I3C protects against cancer is by countering the harmful effects of excess estrogen in the body. There are different types of estrogen and one of them breaks down into a metabolite that leads to an increased risk of breast cancer.  I3C increases the production of the safer form.

Red cabbage contains 36 different types of anthocyanins.  These are the antioxidants that give the vegetable its color. Anthocyanins have shown such promise in lab studies that researchers have proposed uses for them in drug development.

A recent laboratory study found that some varieties of anthocyanin have twice the antioxidant effect of vitamin C.

Cabbage also contains high levels of the B vitamin folate.  According to Dr. Shu-Dong Xiao of the Shanghai Institute of Digestive Disease, “it is possible that high dose folic acid might postpone the development of gastric cancer.”

Recently emerging evidence demonstrates an important role for folic acid in suppressing tumour-promoting substances called proto-oncogenes.

Different types of cabbage (red, green, Napa, and Savoy) provide varying patterns of glucosinolates, so try to eat a mix of cabbage types to maximize the health benefits.

TIP: For optimum nutrient retention, cabbage leaves should be cut into larger pieces and eaten raw, as smaller cuts and cooking will destroy the enzymes needed to produce the cancer-fighting compounds.  Because they’re sturdy, I use cabbage leaves as a “bun” or wrap to hold my grass-fed burgers, “sandwich” meats or taco fillings. But if the only way you’ll eat the stuff is as a slaw, then go ahead and shred it. Or perhaps you’ll prefer juicing it. Just get it in you—it’s that powerful!

Do whatever it takes to get more of these vegetables into your diet.  You may not feel anything happening, but you can be sure that you’ve improved your internal environment by giving your body some of nature’s most powerful weapons.  Think they won’t taste good? Get creative, use Google, and find some recipes.  It’s amazing what even a drizzle of a good quality olive oil will do.

Iceberg may no longer reign supreme, but I think vegetables are enjoying a rebirth of sorts. Believe it or not, there’s even some research to confirm their popularity.

A Cornell University study found that participants viewed meals served with veggies as looking more “tasty” and “loving” (I’m not really sure what that means in the context of a food but it sounds good, right?).  

The study also found that these meals had greater overall appeal and elicited a favorable perception. This is good news.  I’m not sure we would have seen a report like this a few years ago.

Though I chose to focus on cancer, there is a wealth of evidence that compounds in these vegetables help battle everything from high blood pressure and diabetes to macular degeneration and COPD. There are many processes through which disease takes hold, so it’s important to choose foods that attack it from many angles.