Nutritionist holding a Clean Eating Menu Plan

The digestive system is comprised of the gastrointestinal tract and the biliary system. It functions to digest and absorb the nutrients from the food we eat by way of the GI tract, which starts with the mouth and ends at the anus. The biliary system consists of the liver, gallbladder, pancreas and bile ducts, delivering bile and/or enzymes to aid in digestion.

Gastrointestinal (GI) Cancers: Risk Factors

Cancers that affect the tissues and organs of the digestive system are referred to as gastrointestinal (GI) cancers and can be related to several factors. Some risk factors are out of our control such as age, family history, gender or a genetic condition. Other risk factors may be due to circumstances within our control such as smoking, physical activity levels, diet, alcohol consumption and fruit and vegetable intake.

It is important to note, however, that individuals with risk factors for GI cancers, or any cancer, are not guaranteed to develop cancer. There are modifiable factors that could increase the risk of developing a certain cancer which is why it is important to take control of those within our power.

According to the National Health Institute, colorectal cancer is currently the 4th leading cancer diagnosis in the United States, with rates higher in men than women. The incidence is highest for individuals between 65 and 74 years of age. Overall, incidence rates have been decreasing, on average, by 1.8% every year between 2010 to 2019. Pancreatic cancer is the next most common gastrointestinal cancer ranked as the 10th leading cancer diagnosis overall with the median age at diagnosis being 70 years. Cancer of the pancreas is also slightly more common in men than women. The 17th leading cancer diagnosis, accounting for 1.1% of all new cancer diagnosis in US, is esophageal. Again, this type of cancer is more common in men and is associated with older age. This incidence rates for esophageal cancer have been falling by about 1% every year between 2010-2019.

Modifiable Risk Factors and Their Impact

Modifiable risk factors are considered those that are within the control of an individual and typically include diet and lifestyle habits. Given the rates presented above it is important to consider the modifiable risk factors associated with these statistics to guide one’s day-to-day choices. Several risk factors apply to multiple cancer sites. For example, there is strong evidence indicating an increased risk for developing cancers of the esophagus, pancreas, colon and rectum in individuals who smoke tobacco, those with heavy alcohol use and obese individuals (BMI >30).

Dietary Factors in GI Cancer Risk

The relationship between obesity and increased GI cancer risk is based on the concept that excess body weight might cause an individual to have increased insulin levels in the blood which in turn might encourage the growth of cancer. There is also a potential association between the pro-inflammatory state of obesity contributing to cancer growth. The goal to maintain a healthy weight or promote weight loss to reduce excess body weight is suggested to help reduce the risk of several GI cancers.

There is also some evidence to suggest that consuming red and processed meats may increase the risk of developing pancreatic or colorectal cancer. Heavy alcohol use is quantified as greater than 3 drinks per day. Partaking in heavy alcohol use or consuming foods preserved by salting on a regular basis are two dietary risk factors with strong evidence to support potential increased for the development of gastric cancer. Limited evidence also identified low fruit intake and intake of processed meats as additional risk factors in the case of gastric cancer. The breakdown of alcohol results in the potent carcinogen, acetaldehyde. The higher the volume and frequency of intake, the greater the risk.

Positive Lifestyle Habits for Cancer Prevention

Looking at the reverse side, factors that may decrease cancer risk for an individual, include a diet rich in whole grains, engaging in regular physical activity, moderate consumption of dairy and consumption of foods containing fiber. Specifically, the evidence is considered strong for reducing the risk of colorectal cancer with the aforementioned habits. Additional limited evidence is suggestive for reducing esophageal cancer risk by including vegetables in the diet and regular physical activity.

It is not uncommon to want to know how to prevent chronic illness, or at least decrease risk, and cancer is no exception. The American Institute for Cancer Research (AICR), in collaboration with the World Cancer Research Fund International, utilizes an ongoing program to analyze and evaluate data related to cancer risk and create actionable steps toward prevention. There are three impactful areas with particular focus based on supportive research: weight, alcohol consumption and physical activity. AICR developed a 10-step approach to cancer prevention with these three areas in mind in addition to several others. It includes achieving and maintaining a weight within the healthy BMI range through healthful dietary changes and being physically active or increasing activity levels.

Additional steps to cancer prevention include consuming a diet that is: rich in whole grains, fruits, vegetables and beans, limit the intake of processed foods and meats and limit food and beverages with added sugars, reduce alcohol intake, and do not rely on supplement intake for cancer prevention.

Physical activity is a recurring theme among cancer prevention recommendations. The suggested level of physical activity incorporates a generally active lifestyle on a daily basis in addition to incorporating 150 minutes of moderate intensity activity per week. There is strong evidence that this level of exercise can be cancer protective for not only colon, but also breast and endometrial cancers.

Balancing Nutrition: Whole Foods vs. Supplements

Overall, it is important to focus efforts on consuming a variety of whole food to limit the need for dietary supplements. Supplementing one or more nutrients may be indicated in the event the diet is lacking. However, if you can incorporate a variety of nutrient-dense foods most of the time then you are likely to consume a balanced diet without the need for supplements. There are so many supplements on the market that do not have adequate research to support the benefits as well as any contraindications that may be present. Moderation truly is key to maintaining a healthy lifestyle. It is not necessary to cut out whole food groups or include high intakes of one nutrient. The most successful eating pattern will balance nutrient-dense foods from all food groups with regular physical activity.

1. SEER Cancer Stat Facts: National Cancer Institute. Bethesda, MD,

– Melissa Stump, MS, RDN

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