Diet has been recognized as an important modifiable risk factor for colorectal cancer (CRC). In particular, diets consisting of high fats and carbohydrates, such as red and processed meats, are considered high-risk. Now, a large-scale cohort study among U.S. residents has revealed that high consumption of ultra-processed foods might increase CRC risk in men—the third most diagnosed cancer in the U.S.. 

For the past two decades, researchers have witnessed a significant increase in the consumption of ultra-processed foods, industrial ready-to-eat or ready-to-heat products high in refined sugars, refined starch, and trans fats. Ultra-processed foods currently contribute to 57% of the total daily calories consumed by American adults. A growing pool of evidence suggests that ultra-processed foods increase CRC risk by altering the composition and diversity of gut microbiota and increasing the risk of obesity.  Some examples of these foods include bread and rolls, breakfast bars and cereals, hotdogs and other processed meats, packaged sweet snacks and desserts, jams and jellies, and condiments, among other things.

The above-mentioned study analyzed responses from over 200,000 participants—159,907 women from the Nurses’ Health Study (1986-2015) and 46,341 men from the Health Professionals Follow-up Study (1986-2014)—across three large prospective studies in the U.S. that assessed dietary intake. The follow-up period was between 24-28 years. At the time of study enrollment, none of the participants had any cancer diagnoses. Information on dietary intake, demographic characteristics, lifestyle factors, and medical conditions of the participants was obtained through food frequency questionnaires every four years. 

Of the 206,000 participants who were followed for more than 25 years, the research team documented 1,294 cases of CRC among men and 1,922 cases among women. The study findings indicated that those who consumed the highest amount of ultra-processed foods had a 29% higher risk of CRC compared to those with the lowest consumption. However, this was not observed among women. Among women, the risk of CRC was positively associated with higher consumption of ready-to-eat or ready-to-heat mixed dishes. In contrast, higher consumption of yogurt and dairy-based desserts was linked to a reduced risk of CRC among women. 

These findings support the importance of limiting certain types of ultra-processed foods for better health outcomes. Here are some additional resources on diet and lifestyle and how they can influence your colon health and overall wellness:

  1. Healthy Inside and Out: How Diet and Lifestyle Impact Colorectal Cancer
  2. Dietary Mindfulness Can Reduce the Risk of Colorectal Cancer
  3. Diet and Nutrition to Prevent Colon Cancer

 

Kitty Chiu is a Colorectal Cancer Prevention Intern with the Colon Cancer Foundation.

Image credit: Tim Toomey on Unsplash

In past years, the rate of colorectal cancer (CRC) has become a serious public health problem in Mississippi. A study conducted in 2020 showed that Mississippi had one of the highest mortality rates from CRC as well as one of the CRC lowest screening rates between 2015 and 2019. The state also leads the nation in cardiovascular disease mortality rates as well as diabetes mortality. These are both known comorbidities for many types of cancers, including CRC. 

One theory as to why the screening rates are so low in Mississippi is that about 55% of the state’s population resides in rural locations, which may make it hard for some individuals to access regular medical care. The rural population in Mississippi has a high rate of uninsured individuals making it hard for this population to afford regular screenings. In 2016, 14% of the population under 65 were uninsured. 

Another theory as to why CRC rates are so prevalent in Mississippi is that the diet of many of the residents is high in red meat and low in fiber. This is in part due to a culture that relies on red meat and processed foods. This diet is also more prevalent in areas that have a low socioeconomic background, as it can be difficult to obtain healthy food if one lives in a food desert. 

Colorectal cancer-related mortality in those over 50 (2014-2018).
Data source: https://statecancerprofiles.cancer.gov/map/map.noimage.php.

Fortunately, the Mississippi government recognized the issue and has developed a plan to help increase the screening rate of residents in Mississippi and decrease mortality rates 70X2020 was initiated in 2014. Since the start of the program, there has been an increase in individuals who got screened, specifically in minority communities. So far, screening rates have improved from 55% in 2014 to 69.9% in 2020. For white individuals there was a compliance rate of just under 70% and for black individuals there was a compliance rate of just above 70% in 2020. 

From this case study, we are able to theorize that screening and diet play a crucial role in the development of CRC. We are also able to see that there is a strong correlation between screening rates and CRC mortality rates. 

The Colon Cancer Foundation recently had the opportunity to speak with Dr. Cynthia Sears, Professor of Medicine and Oncology, Johns Hopkins University School of Medicine; Professor of Molecular Microbiology and Immunology at the Bloomberg School of Public Health. She is also the leader of the Bloomberg-Kimmel Institute for Cancer Immunotherapy at Johns Hopkins. Her current research focus is on the microbiome and how specific bacteria can contribute to colon cancer.

Dr. Sears, received her medical degree at Thomas Jefferson Medical College and completed her training in internal medicine at the Cornell Medical School, and trained in infectious diseases at The Memorial Sloan Kettering Cancer Institute and the University of Virginia. Over the past 20 years, Dr. Sears has conducted research on colonic microbiota and colon cancer, making her an expert in this field.

Q. What enticed you to start studying bacteria and the microbiome in relation to colon cancer.  

Dr. Sears: I am an infectious disease doctor who got into internal medicine because of previous work I conducted. I conduct research on how the microbiome is impacted by organisms and bacteria. I am also looking at improving immunotherapy response among colon cancer patients, since, unfortunately, only 20% to 30% of colon cancer patients respond to immunotherapya majority of patients do not respond. I am currently working to help improve treatments for cancer patients.

Dr. Cynthia Sears

Q. Can you help us improve our understanding of the interaction between a person’s dietary habits and the gut microbiome and how it relates to colorectal cancer?

Dr. Sears: There’s been substantial research showing that diet is a major driver of the composition and function of the microbiome. Individuals who shifted from a meat based diet to a vegetarian diet can see a shift in their microbiome in the first 24 to 48 hours. This shows that we have the ability to impact our microbiome based on the foods we eat. It also shows that we all have the capacity to have a “good” microbiome. It is also important to note that each person is different in their response to a particular diet. For example, some individuals can eat ice cream and pizza and have no change in their physiology, while others may have a terrible response.

Q. Talking about the “ideal” diet, is there really an “ideal” diet? What impact does an individual’s genetics or environmental factors have on the gut microbiome?

Dr. Sears: We are not very good at targeting the individual level. As a society we can’t afford the type of testing it would require to figure out exactly what each individual should and should not be eating. We really must rely on public health and what’s best for most people. In relation to genetics, it’s published that less than 10% of the effect in our microbiome is related to our genetic makeup. There’s a lot of redundancy in the microbiome. We can have three perfectly healthy individuals and when we sequence their microbiomes, they would all look totally different. In one person a certain bug may be taking up a niche and promoting the production of short-chain fatty acids and in another individual, a totally different bug could be doing the exact same thing.

Q. There has been a lot of research comparing the Mediterranean diet with the Western Diet, with the Mediterranean diet being rich in grains, fiber, fruit, vegetables, and fish meanwhile the Western diet is high in fat and red meat. Do you have any advice for individuals on what diet they should follow?

Dr. Sears: People should try and follow a Mediterranean diet or the DASH [Dietary Approach to Stop Hypertension] diet. I’m a big fan of the idea that food is medicine.

Q. What would you like the public to know about the gut microbiome?

Dr. Sears: We are at least as many microbes as we are human cells but the microbes are just much smaller so the human cells are more evident. Microbes are critical to our overall health. Individual’s should strive to foster a good microbiome whether it’s on your skin, your mouth, or in your colon. There is also literature about the impact that exercise and physical activity can have on your gut microbiome as well as brain health and vascular health. The more an individual is focused on healthy living, the better they will be overall.

Q. What do you think is the future of this field?

Dr. Sears: The future direction in this field is immunotherapy, where we can use the microbiome as a biomarker. When you do a stool test or a plasma test the doctors will be able to tell you if you are more or less likely to respond to this therapy based on a microbial signal. This can relate to colorectal cancer because early-age onset colorectal cancer [EAO-CRC] is becoming frighteningly common but it is still rare enough that we are not doing colonoscopies on everyone under the age of 50. We can hopefully do something to see if a person is at a higher risk and then we can focus our care and try to prevent EAO-CRC. 

 

Here are some additional resources on diet and lifestyle and how they can influence your colon health and overall wellness:

  1. Healthy Inside and Out: How Diet and Lifestyle Impact Colorectal Cancer
  2. Dietary Mindfulness Can Reduce the Risk of Colorectal Cancer
  3. Could the Western Diet Be a Risk Factor for EAO-CRC?
  4. Have You Had Your Fiber Yet? Food Habits and the Risk of Colorectal Cancer

Diet and lifestyle play a large role in colorectal cancer (CRC) prevention and prognosis. Dietary factors such as consumption of meat, sugary drinks, and alcohol, and lifestyle factors such as western diet patterns, being overweight or obese, physical inactivity, and smoking can add to the risk of CRC.

Diet and the Risk of CRC

A systematic review of multiple research studies has shown that a diet high in red and processed meats and low in fiber is a prominent risk factor for CRC and can lead to DNA damage, gut epithelial damage, cell proliferation, and genotoxicity from the nitrates that are added as a preservative. A diet high in red meat and processed food can be damaging for CRC patients and survivors and can increase the risk of mortality. 

Including fiber, vegetables, and fruits in the diet is definitely healthy and can also prevent CRC. The Mediterranean dietwhich includes fruits, vegetables, fish, and whole grains is a healthy preventive option to adopt in your food habits.

Research also points to a significant relationship between the consumption of processed meat and the development of early-age onset CRC (EAO-CRC), which developed among those younger than 50 years. A rapidly rising cancer across the globe, about 20% of EAO-CRC cases can be attributed to family history, and the remaining to other factors including diet and lifestyle.

  • Consumption of two or more sugary beverages per day doubles the risk of developing EAO-CRC in women 
  • An increase in consumption of sugary beverages in adolescence is associated with a 32% increased risk of developing EAO-CRC  
  • Consumption of sugary drinks is also known to increase the risk of mortality in CRC patients 
  • Alcohol consumption (greater than 14 drinks per week) also increases the risk of developing CRC.

Lifestyle Habits and the Risk of CRC

It is a well-known fact that a healthy lifestyle promotes health and well-being, while an unhealthy lifestyle can lead to health problems. Physical activity is important for overall health and studies point to physical inactivity and a sedentary lifestyle as major risk factors for CRC. Women who reported little to no physical activity after the age of 20 had a heightened risk of developing EAO-CRC.

Reduced physical activity can contribute to several different health problems, the most evident being obesity. Obesity modifies the gut microbiota leading to an increase in inflammation that damages the intestinal barrier. Obese and overweight individuals have a 42% higher risk of developing EAO-CRC than those at a healthy weight (an individual is considered to be a healthy weight if their BMI is between 18.5 and 24.9). There is also a correlation between obesity and the development of metabolic syndrome, which is a combination of multiple conditions that increase the risk of heart disease, stroke, and diabetes. Metabolic syndrome has been identified as a leading comorbidity in the development of EAO-CRC.

Smoking is also a significant risk factor in multiple cancers including CRC. Current smokers are at a higher risk of developing EAO-CRC, while past smokers may find their risk reduced. 

It is important to understand the significant role of diet and lifestyle in disease development. Maintaining a healthy diet, such as increasing fruit, vegetable, and fiber intake as well as decreasing one’s consumption of red meat, processed meat, and sugary beverages can prevent CRC. This, coupled with a healthy and active lifestyle can significantly reduce the risk of developing CRC. 

 

Abigail Parker is a Colon Cancer Prevention Intern with the Colon Cancer Foundation.

We learn time and again that prevention is the best medicine, and this holds true for colorectal cancer (CRC). It is estimated that 50% of CRC cases can be prevented with diet and lifestyle modifications. Previous studies that looked at the relationship between CRC development and nutrition concluded that there is a strong correlation between diet and the development of certain types of cancer, specifically CRC. 

A recent study published in Preventive Medicine Reports investigated the impact that an insufficient diet plays in the development and prevalence of certain cancers as well as the effect that race and ethnicity has on diet.  Wholegrains, dietary fiber, non-starchy fruits, and vegetables, dairy products, milk, cheese, dietary calcium, coffee, and calcium supplements were found to be associated with preventing cancer development. The study examined population attributable factors and the number of excessive cases diagnosed in Texas in 2015 that were attributed to an inadequate diet, defined as a diet that does not meet or conform to the national or global dietary recommendations. 

With a diverse study population, the researchers had the opportunity to explore how race and ethnicity play into diet and thus contribute to the prevalence of cancers, specifically colorectal cancer (CRC).  

The study found:

  • While men were more likely than women to not follow guidelines on red and processed meat consumption.
  • Women were more likely to miss dietary recommendations on fiber and calcium intake.
  • A significant correlation between processed meats consumption and the prevalence of CRC and a connection between red meat consumption and the prevalence of CRC. 

There has been additional research conducted to show that there is a link between dietary fiber intake, and dietary calcium intake and the prevention of CRC. Looking at the racial and ethnic difference the study found that Non-Hispanic Whites consumed higher than the recommended dietary intake of red and processed meats. While it was found that Non-Hispanic Blacks were the most likely to have insufficient fiber and calcium intake.

In the Texas population, the authors found:

  • 3.3% of all new cancers (>3,428) could be attributed to an inadequate diet 
  • 34% of new CRC cases can be attributed to dietary insufficiencies 

The authors describe a similar correlation identified in an Australian population, where:

  • 17.6% of CRCs were related to an insufficient fiber level in diet 
  • 17.7% of CRCs were attributed to red and processed meats 
  • Men had a higher proportion of cancers attributable to an insufficient diet than women 
  • Excess consumption of processed meat contributed to 1,002 new cancer cases and red meat consumption contributed to 379 additional cancer cases 

This study along with multiple other studies conducted in relation to dietary factors and their contribution to cancer highlight the importance of dietespecially insufficient fiber intake and excess red or processed meat intakeon overall cancer burden.

 

Abigail Parker is a Colon Cancer Prevention Intern with the Colon Cancer Foundation.

Slow-transit constipation (STC) is reported to occur in 15-30% of people in the U.S. The most widely accepted definition of STC is two or fewer bowel movements per week or straining at stool more than 25% of the time. Research continues to point to STC as a risk factor for colorectal cancer (CRC).

A study published in 2020 that looked at 2,165 patients (median age 54 years), found that the cumulative probability of CRC was 0.2% 5 years after STC diagnosis and 0.4% 10 years after STC diagnosis. This was not significantly different (p=0.575) than among those without STC diagnosis. However, this may be due to the small number of patients (5) who were diagnosed with CRC.

Although the authors of the 2020 study did not find a significant difference among those with and without STC diagnosis, it is well established that STC increases CRC risk. Gurérin et al. in their 2014 study of over 100,000 patients identified a statistically significant risk of CRC among those with STC:

  • 56% higher for CRC
  • 260% higher for benign neoplasm
  • 256% higher for benign neoplasm in colon
  • 262% higher for anal and rectal polyps

Current management options for STC range from dietary counseling, pharmacological therapy, and surgery. 

While the etiology of STC remains unclear, there is increasing evidence that it is caused by an imbalance in the gut microbiome. Zhang et al. in their 2021 review published in Gastroenterology Report found that gut microbiota may play a major role in modulating colonic motility, secretion, and absorption. However, there is still much research needed to understand how the gut microbiome modulates movement of fecal matter through the small intestine and colon.

Conversations about the role of the gut microbiome in CRC development were a part of the Early-Age Onset Colorectal Cancer Summit held by the Colon Cancer Foundation in May 2022.

 

Gargi Patel is a Colon Cancer Prevention Intern with the Colon Cancer Foundation.

 

A recently conducted systematic electronic search investigated keywords relating to colorectal cancer (CRC) and nutrition to define the association between diet and CRC. We summarize their findings here. 

What Can Change in My Dietary Habits?

According to the World Cancer Research Fund and American Institute of Cancer Research, 50% of CRC cases can be prevented by dietary and lifestyle modifications. While previous research studies concluded that high-fat and high-calorie diets had a carcinogenic effect, new research is showing that there is a specific role for nutrients such as fiber, vitamins, and minerals on intestinal metabolism. Consuming whole grains, dietary fiber, and dairy products decreases the risk of CRC, while consuming red and processed meats and fats increases the risk of CRC. Dietary interventions have increasingly been used over the past decade to reduce the occurrence and progression of CRC.

While there are some dietary habits that can reduce the risk of CRC, others can increase that risk. High-risk diets include those with red and processed meats, and diets made up of high fats and high carbohydrates. 

  • Processed meats are categorized as Group 1, meaning they are carcinogenic 
  • Red meats are categorized as Group 2A, meaning they are most likely to be carcinogenic 

Growth hormones in red and processed meats may be responsible for their carcinogenic effects. It is recommended that individuals limit the intake of red meats to 12-18 oz each day, and processed meats should be completely avoided. Many components of our diet may help prevent CRC: dietary fiber intake, for example, is inversely related to CRC development. Vitamins and minerals also play an important role in CRC prevention. 

  • Vitamins E and C have been shown to have a direct tumor suppressing effect on CRC 
  • Vitamin D has been shown to reduce the risk of developing CRC 
  • Calcium and selenium have also been shown to have an inverse effect on CRC

However, more research is needed to fully understand the role that fiber, vitamins, calcium, and selenium play in CRC development. 

There has also been significant interest in the role of gut microbiota (the bacteria in our gut) on CRC development. Research findings so far indicate that the microbiome and microbial metabolite health is pivotal to the prevention of several diseases such as CRC. The Mediterranean diet has positive effects on protecting individuals against CRC. Thus, nutritional therapies that are based on epigenetically active nutrients are likely to represent a good research direction.

In summary, dietary factors have a strong influence on CRC development. Consuming whole grains, dietary fiber, and dairy products can reduce the risk of CRC. Evidence also points to a role for vitamins in preventing CRC development. Ultimately, it is important to remember that future dietary recommendations will need to consider each person individually—looking at their cultural identities, risk factors, and the interaction between nutrients and the microbiota.

 

Abigail Parker is a Colorectal Cancer Prevention Intern with the Colon Cancer Foundation.

Slow-transit constipation (STC) is reported to occur in 15-30% of people in the U.S. The most widely accepted definition of STC is two or fewer bowel movements per week or straining at stool more than 25% of the time. Research continues to point to STC as a risk factor for colorectal cancer (CRC).

A study published in 2020 that looked at 2,165 patients (median age 54 years), found that the cumulative probability of CRC was 0.2% 5 years after STC diagnosis and 0.4% 10 years after STC diagnosis. This was not significantly different (p=0.575) than among those without STC diagnosis. However, this may be due to the small number of patients (5) who were diagnosed with CRC.

Although the authors of the 2020 study did not find a significant difference among those with and without STC diagnosis, it is well established that STC increases CRC risk. Gurérin et al. in their 2014 study of over 100,000 patients identified a statistically significant risk of CRC among those with STC:

  • 56% higher for CRC
  • 260% higher for benign neoplasm
  • 256% higher for benign neoplasm in colon
  • 262% higher for anal and rectal polyps

Current management options for STC range from dietary counseling, pharmacological therapy, and surgery. 

While the etiology of STC remains unclear, there is increasing evidence that it is caused by an imbalance in the gut microbiome. Zhang et al. in their 2021 review published in Gastroenterology Report found that gut microbiota may play a major role in modulating colonic motility, secretion, and absorption. However, there is still much research needed to understand how the gut microbiome modulates movement of fecal matter through the small intestine and colon.

Conversations about the role of the gut microbiome in CRC development were a part of the Early-Age Onset Colorectal Cancer Summit held by the Colon Cancer Foundation in May 2022.

 

Gargi Patel is a Colon Cancer Prevention Intern with the Colon Cancer Foundation.

 

A large cohort study that evaluated Swedish family inpatient and outpatient cancer registries found that those who had diabetes had an increased risk of colorectal cancer (CRC)—the magnitude of risk was similar to having a family history of CRC.

The study had a long timeline and follow-up was conducted between 1964-2015. The 12,614,256 individuals included in the study were born after 1931; 559,375 of them had diabetes and 162,226 had CRC. The authors queried the risk of developing CRC among those who had diabetes and found that:

  • 9-fold greater risk of CRC before 50 years among those diagnosed with diabetes before 50 years (range, 1.6-2.3)
  • 9-fold higher risk of CRC before age 50 years among those diagnosed with diabetes before 50 years who also had a family history of CRC (range, 4.1-12)
  • Lifetime risk of CRC before age 50 years among diabetic patients (0.4%) was similar to those with just a family history of CRC (0.5%). It was double that of the average population (0.2%).

This study confirms the positive association between early-onset diabetes and early-onset CRC and makes a case for earlier CRC screening among young adults with diabetes.

Results from the South Australian Young Onset (SAYO) CRC study identified a similar correlation between personal and family history of diabetes and CRC risk. The study cohort included 50 unrelated young adults up to age 55 years diagnosed with CRC (23-54 years), and 253 controls without CRC (18-54 years). Personal and family history of diabetes was documented in this entire population. The study found:

  • 24% of CRC patients also suffered from type II diabetes compared with 5% of the control group
  • 51% of young adults with CRC had at least one first-degree relative with type II diabetes
  • All patients with a personal history of type II diabetes also had first-degree relatives with type II diabetes
  • 44% of CRC patients under 45 years and 60% of CRC patients 45-54 years had a first-degree relative with type II diabetes

These findings create a very strong case for raising awareness among young adults with diabetes of their increased risk of early-onset CRC, especially if there is a family history of diabetes, so they can initiate CRC screening earlier than the USPSTF recommendation of 50 years.

You can help significantly decrease your chances of colorectal cancer through proactive action related to your diet.

Maintaining a Healthy Weight Helps Prevent Colon Cancer

One of the best things you can do is to get yourself to a healthy weight and maintain it within a designated range. By maintaining a healthy weight you won’t just be proactively protecting yourself from colon cancer, you’ll also be making an investment in your overall health.

What to Eat to Beat Colon Cancer and Help Prevent it

Some of the best foods to be eating to lower your chances of contracting colon cancer include, chicken, fish, fruits, and whole grains.

Foods that you should avoid eating in excess include red meats and anything that is rich in refined sugars.

The Link Between Obesity and Colon Cancer

A strong link has been identified between obesity and colon cancer. Diet choices have a profound impact on how susceptible you are to contracting colon cancer.

It’s important to remember that making healthy choices with what you eat and how much affects much more than your susceptibility to contracting colon cancer. Your diet affects your overall health. It’s also important to remember that portion size is just as important as the food that you choose to eat. You can eat red meat without increasing your chance of getting colon cancer if you do it in moderation.

Someone who enjoys a steak every couple of weeks or so for dinner with a salad is not going to have a particularly high risk of getting colon cancer. Conversely, someone who eats steak, pork, sausage, and bacon in large quantities every single day or even every other day, will greatly increase their chances of having colon cancer.

Eating red meats in small amounts and in limited frequency is perfectly fine. No one needs to be panicking about eating a steak every now and again. No matter what you eat, your portion size is vital. Larger portion sizes are unhealthy and will put weight on fast.

You shouldn’t commit to a healthy diet just to decrease your chances of contracting colon cancer, you should want to eat healthy to feel better about yourself and increase your overall health. If you exercise and maintain a healthy diet, you won’t just be limiting your chances of getting colon cancer. You will feel better, and eliminate your susceptibility to countless other health problems.

How Does a Poor Diet Increase Your Chances of Contracting Colon Cancer?

Some of you might be wondering exactly how a poor diet increases your chances of contracting colon cancer. Obviously foods that are rich in fats aren’t good for you, but why does such delicious food have to make you more susceptible to such a horrible disease?

Studies have shown that when mice were fed a diet consisting of foods that were high in fats, they exhibited aggressive cell growth of stem-like cells that encourage mutation. This aggressive cell growth is typically coupled with the development of cancerous tumors along the intestine.

The unfortunate mice who were tested offer us invaluable insights into the factors that affect one’s chances of developing colon cancer. Their sacrifice, while trivial compared to the totality of scientific inquiry, is significant and it can save lives, human lives.

Further Recommendations

With so much information out there on the internet, it can be difficult to distinguish genuinely useful information from inaccurate drivel. For example, fiber supplements and antioxidant vitamins do not reduce one’s chances of having colon cancer, nor does it affect polyps.

Calcium, on the other hand, does have an effect on polyps and helps reduce polyp recurrence. Another thing that can help you is regular exercise. If you’re going to make the effort to maintain a healthy diet, you should double down and add exercise to the mix.

By exercising, eating healthy, and consuming the recommended amount of calcium, you can reduce your chances of contracting colon cancer significantly. Although these lifestyle changes can give you much better odds, it’s still imperative that you schedule regular screenings. If you aren’t being screened for colon cancer, you can still contract if and all of your efforts will be for naught, especially if it isn’t detected early on, hence the importance of regular screenings.