- Colorectal cancer is the third most common cancer in the United States.
- The risk of developing colorectal cancer it increases with being overweight or obese, smoking, and a diet rich in red or processed meats.
- Including plenty of whole grains, fresh fruits, and vegetables in your diet can reduce this risk, existing research has shown.
- A large study has now found that, in men, a diet rich in healthy plant-based foods is associated with a lower risk of colorectal cancer.
Colorectal cancer, also known as bowel, colon, or rectal cancer, is the third most commonly diagnosed and the second deadliest cancer in the United States.
Most people diagnosed with colorectal cancer are over the age of 50, although it can affect younger people as well.
In recent years, cases in older people have begun to decline, but the incidence among younger people is increasing. However, these changes may be due to more effective cancer detection.
The risk of colorectal cancer increases with age. Other risk factors that people cannot influence are a family history of colorectal cancer, inflammatory bowel diseases, such as Crohn’s disease — and certain genetic syndromes.
However, there are many lifestyle factors that also influence a person’s risk of colorectal cancer. Factors that may increase risk include:
- a diet low in fiber, fruits and vegetables
- lack of physical activity
- a high-fat diet and red or processed meats
- overweight and obesity
- tobacco use and excessive alcohol consumption.
various studies have investigated the relationship between diet and colorectal cancer and have found that the typical Western diet high in fat, red meat, and processed meat increases risk.
Reducing these foods and increasing foods high in dietary fiber is associated with reduced risk.
Plant-based foods tend to be high in dietary fiber, but only raw.
Now, a study appearing in BMC Medicine has found that a diet rich in healthy plant-based foods (whole grains, fresh fruits, and vegetables) is associated with a lower risk of colorectal cancer in men.
Unhealthy plant-based foods (refined grains, fruit juices, and added sugars) had no beneficial effect on cancer risk.
“This US study adds to much existing evidence on the benefits of eating a balanced diet rich in fruits, vegetables and fiber for both men and women.”
– Beth Vincent, health information manager, UK Cancer Research (CRUK)
The study group included 79,952 men and 93,475 women who were followed for an average of 19.2 years. All participants were from Hawaii or the Los Angeles area and were between the ages of 45 and 75 at the time of enrollment. The group included African American, Japanese American, Native Hawaiian, Latino, and white volunteers.
At the beginning of the study, the researchers assessed the participants’ habitual diet with a self-report questionnaire.
Participants had to report how often and how much they ate of more than 180 different foods and drinks. They chose from four serving size options and frequencies ranging from never to four times a day.
From the responses, the researchers calculated daily energy and nutrient intake, then calculated three plant-based diet indices: overall (PDI), healthy (hPDI), and unhealthy (uPDI).
The researchers defined whole grains, fruits, vegetables, vegetable oils, nuts, legumes, tea and coffee as healthy plant-based foods. The least healthy plant-based foods included refined grains, fruit juices, potatoes, and added sugars.
To achieve a high hPDI score, participants had to have a high intake of healthy plant-based foods and a low intake of less healthy plant-based foods.
Overall, plant-based diets, particularly healthy plant-based diets, were associated with a reduced risk of colorectal cancer in men, but not in women. Unhealthy plant-based diets did not appear to reduce risk.
For healthy plant-based diets, the association was stronger in Japanese American, Native Hawaiian, and white men than in other groups.
The researchers suggest that “the benefits of plant-based diets may vary by gender, race and ethnicity, and the anatomical subsite of tumor.”
The study had a large sample size, long follow-up time, and racial and ethnic diversity in the study population. However, the authors acknowledge some limitations of the study, including possible selection bias in who responded to the questionnaires and the negative scoring of all foods of animal origin.
Several other studies have shown that some animal-based foods may actually be beneficial. Two reviews have found that both fish Y dairy products may reduce the risk of colorectal cancer.
Beth Vincent argued that the study’s findings should be viewed with a grain of salt:
“Research tried to compare ‘healthy plant foods’ and ‘unhealthy plant foods’ and found a link to bowel cancer in men. But due to the design of the study, the authors themselves acknowledge that we cannot read too much into their results. The study relied on people remembering what they had eaten up to a year ago. It also assumed that the participants’ diets stayed the same for many years and that all meats and animal products were unhealthy, which is not the case.”
This study adds to the growing evidence that diet and lifestyle play a key role in cancer risk.
Vincent agreed, giving the following advice: “Eating a well-balanced diet can help maintain a healthy weight, which reduces the risk of cancer. Not smoking, cutting back on alcohol, and staying safe in the sun are other important ways to reduce cancer risk.”
A study suggests that up to 35% of cancers are related to diet. Y Diet can affect a lot the risk of colorectal cancers.
the American Cancer Society recommends that to reduce the risk of colorectal cancer, a person should include plenty of vegetables, fruits, and whole grains, and limit the amount of meat eaten.
Prof Jihye Kimfrom Kyung Hee University, who is one of the authors of the study, says that:
“We speculate that antioxidants found in foods such as fruits, vegetables, and whole grains might help reduce the risk of colorectal cancer by suppressing chronic inflammation, which can lead to cancer. Since men tend to have a higher risk of colorectal cancer than women, we propose that this could help explain why eating greater amounts of healthy plant-based foods was associated with a reduced risk of colorectal cancer in men, but not in the women”.
The authors’ conclusion that “improving the quality of plant foods and reducing the consumption of animal foods may help prevent colorectal cancer” may be a bit optimistic, but their study certainly adds to the evidence that a healthy diet may help reduce the overall risk of cancer.
