- Yogurt, whole grains, and fiber-rich foods can all contribute to a lower risk of colorectal cancer, studies find.
In the late 1990s, colorectal cancer was the fourth-leading cause of cancer deaths in both men and women younger than age 50; the American Cancer Society now reports it has taken the top spot as the leading cause of cancer death among such men and the second leading among such women, and with rates continuing to rise.
Medical professionals are also noticing that the forms of colorectal cancer found in young people are more aggressive, leading to rising deaths among younger adults who are diagnosed. A 2017 study published in the Journal of the National Cancer Institute found that people younger than 55 are almost 60% more likely than older adults to be diagnosed with late-stage colorectal cancer, which decreases the odds of survival.
Experts aren’t certain as to why these rates have jumped for Millennials and Gen Xers, the National Cancer Institute says, but they suspect—and studies show—it could be linked to higher rates of obesity, ultra-processed food (specifically processed meats) and alcohol consumption, physical inactivity, and environmental factors.
Other potential risk factors include:
- Smoking
- Low fiber, high-fat diet
- Conditions like inflammatory bowel disease
- Genetics
It is clear, however, that diet plays a role in your overall cancer risk.
“Your habits determine your health,” American Institute for Cancer Research (AICR) VP of Research, Dr. Nigel Brockton previously told Fortune.
3 foods that may help lower your colorectal cancer risk
1. Yogurt and other calcium-rich foods
A recent study published in the journal Gut Microbes found that long-term yogurt consumption—two or more servings per week—was tied to lower rates of proximal colorectal cancer (on the right side of the colon) that were positive for Bifidobacterium. While the authors did not find a significant association between long-term yogurt intake and overall colorectal cancer risk, they did see an association with Bifidobacterium-positive tumors—there was a 20% lower rate of incidence of those tumors for long-term yogurt consumers.
“This paper adds to the growing evidence that illustrates the connection between diet, the gut microbiome, and risk of colorectal cancer,” co-author Dr. Andrew T Chan, chief of the Clinical and Translational Epidemiology Unit at Massachusetts General Hospital, said in the study’s press release.
Other research has linked calcium-rich foods and drinks, like yogurt and dairy milk, to a decreased risk of colorectal cancer diagnosis. A study of over 540,000 women, conducted by Oxford Population Health’s Cancer Epidemiology Unit found that an additional 300 milligrams of calcium each day was associated with a 17% decrease in the risk of colorectal cancers.
The American Cancer Society notes, however, that calcium—specifically when consumed in dairy—could increase risk of prostate cancer, and thus does not recommend a specific calcium or dairy intake, despite the potential benefits for colorectal cancer prevention.
2. Whole grains
The American Institute for Cancer Research found a strong correlation between eating whole grains (such as brown rice, farro, bulgur, sorghum, and quinoa) and a lower risk of colorectal cancer. Eating three servings of whole grains—about 90 grams, or twice slices of whole-grain bread and one serving of oatmeal—per day was found to reduce risk of colorectal cancer by 17%.
Researchers from a 2005 study that found whole grains reduced colorectal cancer risk in women explained that the various vitamins—especially B-vitamins—and minerals like magnesium and zinc could contribute to lower risk.
Whole grains’ high fiber content, resistant starch, and prebiotics can also improve the gut microbiome to reduce risk, researchers wrote, while “diluting potential carcinogens and promoters in the colon and decreasing transit time,” which reduces colon tissue’s exposure to harmful compounds.
Good sources of whole grains include:
- Brown rice
- Bulgur
- Whole grain pasta and bread
- Farro
- Gluten-free whole grains such as sorghum, teff, amaranth, millet, quinoa, and oats
3. Fiber-rich foods
Experts have previously cited the numerous benefits of fiber, but the nutrient plays a particularly vital role in reducing risk of colorectal cancer. Fiber feeds your gut bacteria—which strengthens your gut microbiome and immune system, Dr. Andrea Tufano-Sugarman, gynecologic medical oncologist for Memorial Sloan Kettering Cancer Center, previously told Fortune.
“The more fiber you eat—the more fruits, vegetables, legumes, whole grains—the more diverse your microbiome is,” she said. That helps lower your risk of cancer—especially colorectal cancers—by reducing the risk of chronic diseases and inflammatory illnesses in your gastrointestinal tract.
Those diseases often overlap with colorectal cancers, notes the National Cancer Institute. They add that certain chronic diseases, including irritable bowel syndrome, Crohn’s disease, and diabetes, can cause inflammation in the gut—and half of younger adults with colorectal cancer also have such inflammatory chronic conditions.
That is where the power of fiber comes in: The AICR reports that each 10-gram increase in fiber is linked with a seven percent decrease in colorectal cancer risk. One study from 2015 indicated that high fiber intake lowered risk of distal colon cancer (in the left side of the colon).
The American Cancer Society recommends at least 30 grams of dietary fiber per day to lower your cancer risk, the majority of which should be from whole plant foods, such as vegetables, fruits, whole grains, nuts and seeds. Here are some of the easiest sources of fiber to add to your diet:
- Legumes like beans, lentils, or split peas
- Fresh fruits like raspberries, blueberries, apples, and pears with skin
- Fresh vegetables like broccoli, Brussels sprouts, green peas, and potatoes with skin
- Popcorn
- Avocados
- Oatmeal
- Farro
- Chia seeds, flax seeds
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