These Veggies Could Help Lower Colon Cancer Risk

When it comes to colorectal cancer (CRC)—cancers of the colon and rectum—we’re constantly learning more about risk reduction from new research. For example, some recent studies have suggested a diet high in processed and red meat increases your risk, but a high-fiber diet can help reduce it. There is also evidence that dairy—including probiotic-rich yogurt—may help reduce your risk of colorectal cancer, but frequent alcohol intake may increase your risk. Eating more plants may also reduce your risk. 

Scientists are always striving to learn more about colorectal cancer and ways to prevent it, especially since cases are on the rise, especially in people under 55. Not including certain types of skin cancer, colorectal cancer is the third most common type of cancer diagnosed in American men and women, with almost 150,000 new cases of colorectal cancer diagnosed in the U.S each year.

Researchers from Italy took a closer look at certain nutrients—specifically, carotenoids, pigments found primarily in fruits and vegetables—to see if they could have benefits for reducing colorectal cancer risk. The research team published their findings in the European Journal of Clinical Nutrition. Let’s break down what they found.

How Was This Study Conducted?

Researchers analyzed data from a case-control study conducted between 1992 and 1996 in Italy. A case-control study observes the differences between a group of people with a certain disease or outcome—in this case, colorectal cancer—to a group of people without the disease or outcome. The group without colorectal cancer was the control group. 

The number of participants with colorectal cancer totalled 1,953, and their ages ranged from 19 to 74, with an average age of 62. The control group had no previous history of cancer and was comprised of almost 4,200 people, ages 20 to 74, with an average age of 58. 

Questionnaires were completed by interviewers asking participants questions regarding socioeconomic status, anthropometric measurements (i.e. BMI), lifestyle (i.e. physical activity, diet, alcohol intake, smoking status) and family history of cancer. 

Researchers calculated participants’ average intake of carotenoids based on their food frequency questionnaires (FFQ). The FFQs asked participants about their average weekly consumption of foods or recipes, plus questions about alcohol intake. Participants were placed into one of five quintiles (or groups for analysis) based on carotenoid intake. 

What Did This Study Find?

Researchers ran several statistical analyses, including adjusting for potential confounders like smoking and alcohol status (both of which raise colorectal cancer risk) and found an inverse, linear association between carotenoid intake and colorectal cancer. In other words, the higher the intake of carotenoid-rich foods, the lower the rate of colorectal cancer. The specific carotenoids that showed this inverse association include alpha-carotene, beta-carotene, beta-cryptoxanthin and lutein plus zeaxanthin. 

Each carotenoid on its own was associated with a lower risk of colorectal cancer, as was total carotenoid intake. Still, beta-carotene appeared to have the largest effect on cancer risk, as eating foods rich in beta-carotene was associated with a 40% reduced risk of colorectal cancer.

And the higher the carotenoid intake, the lower the risk. For example, those in the second quintile who averaged almost 16,000 mcg of carotenoids a day showed an 18% lower risk of CRC compared to those in the first quintile, while those in the fifth (highest) quintile, averaging almost 23,000 mcg per day, were associated with a 41% lower risk of CRC. To put those numbers in context, 1 cup of boiled sweet potato (without skin) offers almost 31,000 mcg of beta-carotene, while 1 cup of carrot juice contains around 22,000 mcg.

Researchers note that the carotenoid-rich plants that were most common in this study population were carrots, citrus fruits, green leafy vegetables, tomatoes and peas. 

Based on scientific evidence, researchers suggest carotenoids have anti-tumor effects, thanks to their antioxidant properties and abilities to modulate and inhibit cancer cell growth.

However, it’s important to remember that food frequency questionnaires always present a limitation to any study, as they are dependent on participants’ memory and ability to estimate, introducing the potential for bias and inaccuracies. Observational studies also make it difficult to adjust for all potential confounders, which raises another limitation of this study.

How Does This Apply to Real Life?

It may come as no surprise that, as this study suggests, eating more plants may lower cancer risk and can benefit the gut—and more. For example, eating more plant protein, like legumes, tofu, nuts and seeds, may promote healthy aging and extend your life. If you have trouble pooping, a plant-based diet may help with that, too.

Regarding colorectal cancer, we previously reported on a study that suggests getting enough vitamin D may lower your risk of colorectal cancer. Vitamin D is found in a limited number of foods, including egg yolks, some mushrooms and fatty fish, like salmon, tuna and mackerel. But your body can also make vitamin D from exposure to sunlight—though this gets more difficult as cooler temperatures set in. For this reason, a healthcare provider may recommend supplementing with vitamin D.

According to this study, foods high in carotenoids may also reduce your risk of colorectal cancer. Take your pick from citrus fruits, carrots, sweet potatoes, bell peppers, tomatoes, cantaloupe, mango, butternut squash, broccoli, green peas and leafy greens, like spinach and kale. And, of course, we’ve got some tasty recipes for all of them. 

If you’re looking for something simple and basic, try any of our roasted vegetable recipes, like Roasted Sweet Potatoes, Maple Roasted Carrots and Roasted Broccoli.   

If you’re looking for something that’s more like a complete meal, check out our Spice-Roasted Sweet Potatoes Over Garlicky Yogurt, Warm Spinach Salad with Chickpeas & Roasted Tomatoes, Sweet Potato-Black Bean Stuffed Peppers and Marry Me Butternut Squash Steaks.

Not to be outdone by the veggies, there are several carotenoid-rich fruits that deserve a place at your table, too. (Think citrus fruits, peaches, mango and papaya, among others.) Of course, you can toss whatever fruits you like into a smoothie or overnight oats. We love this Banana-Mango Smoothie and High-Protein Mango & Tahini Overnight Oats to start our day in a healthy, energizing way. And this Citrus Salad with Pomegranate & Mint is as beautiful as it is delicious. 

If you want more structure and guidance for eating plant-based, we’ve got several meal plans to choose from. Our 7-Day Plant-Based, High-Protein Meal Plan for Beginners is a great one to start with. Or if you still want to include some animal-based foods while ramping up your plant intake, any of our Mediterranean diet meal plans would be great, including our 7-Day High-Protein, High-Fiber Mediterranean Diet Meal Plan.

Our Expert Take

This study suggests that including foods rich in carotenoids may lower your risk of colorectal cancer by up to 40%. Foods rich in these powerful plant compounds include many fruits and vegetables. This is why it’s important to eat a variety of plants and other foods, to ensure you’re getting all the nutrients your body needs—not just for lower disease risk, but for overall good health, too. 

Other habits also play a role in colorectal cancer prevention, including engaging in regular physical activity, quitting smoking and limiting or avoiding alcohol. Getting plenty of quality sleep and managing the things that stress you out will also go a long way toward a healthier body and brain.