Navigating Nutritional Challenges of Colorectal Cancer Patients During Treatment

As much as a healthy diet is important to battle cancer, it is just as essential that the body can absorb the nutrients properly to benefit from them. In the case of colorectal cancer patients, it is more challenging because the colon’s natural function of digestion and nutrient absorption is affected by cancer and its treatments.

Colorectal cancer, the third most common malignancy in males and second in females in the United States, is usually treated by removing part of the colon during surgery, leaving patients with nutritional needs different from those with other types of cancer. Another type of treatment called chemotherapy has side effects like loss of appetite, nausea, vomiting, and bowel problems, which also present nutritional challenges.

Because of these, malnutrition and dehydration incidences are also more common in colorectal cancer patients than in those with other types of cancer. Since proper nutrition during treatment aids patients in maintaining their weight, muscle mass, and energy levels, they experience difficulty tolerating treatments and preparing for survivorship. Thus, in general, staying hydrated and eating foods rich in proteins, vitamins, antioxidants, and electrolytes are important.

The patients’ varying situations determine their specific nutritional needs during colorectal cancer treatment. For example, those with pre-existing conditions like obesity or heart disease have different nutritional requirements than those in relatively good health before beginning the treatment. Moreover, the specific side effects they experience may also be managed through proper nutrition.

The American Cancer Society recommends a mix of healthy food sources of proteins, fats, carbohydrates, vitamins, and electrolytes to fight off challenges during colorectal cancer treatment. Below are their functions and examples of food that colorectal cancer patients can consume.

  • Proteins are important for growth, body tissue repair, and keeping the immune system healthy after surgery, chemotherapy, or radiation treatment. The Cancer Treatment Centers of America typically recommend 1.13 to 1.41 grams of protein per 1 kilogram of body weight for healthy persons who are not very active.

Good sources of lean meat are eggs, fish, and poultry. Avoid red meat and processed meats. Plant-based protein sources like legumes, nuts, and beans are also ideal for cancer patients.


  • Fats and oils are a rich source of energy for the body. They also help insulate body tissues and transport vitamins A, D, E, and K.

Sources of healthy fats are fish oil, avocados, nuts, seeds, and olive oil. Red meats and other sources of saturated fats like fast food, butter, and cheese must be avoided. Intake of fats must not be over 25% of a person’s calorie source.

  • Carbohydrates serve as the body’s major source of energy, fueling physical activities and organ functions.

Complex carbohydrates found in fruits, vegetables, and whole grains like oatmeal, whole-wheat bread, barley, and beans are recommended over simple carbohydrates found in table sugar, syrup, and refined flour. Complex carbohydrates are healthy sources of fiber and phytonutrients while excessive sugar intake may lead to high blood glucose levels and unhealthy weight gain.

Other carbohydrate-rich foods such as sweet potatoes and beetroots have the additional benefit of being good sources of antioxidants.

While fibers help clean wastes in the colon, colorectal cancer patients who have just undergone chemotherapy or other treatments that cause severe diarrhea are generally advised to stay away from high-fiber food like raw fruits and vegetables, and whole grains. Sources of low-fiber carbohydrates and proteins, such as white rice and pasta are a better option.

  • Vitamins are micronutrients that play an essential role in the body’s ability to recover from colorectal cancer treatments. Vitamin D, for example, has been associated with poor treatment results and decreased survivorship in some studies. Vitamins A, C, and B complex are also crucial.

Experts recommend obtaining them from natural sources or food, but food supplements also work.

  • Electrolytes are essential minerals that help maintain the right balance of fluids in the body. Examples of these are calcium, potassium, sodium, and magnesium. Patients experiencing diarrhea, vomiting, and excessive sweating as side effects of treatments lose fluids, so monitoring their electrolyte intake is important.

Good sources of electrolytes include green leafy vegetables, bananas, watermelon, avocados, potatoes, almonds, and beans.

In addition to proper nutrition, adequate water intake is also crucial during and after colorectal cancer treatments. Lack of water or dehydration causes problems like headaches, fatigue, constipation, and low blood pressure. One way to know if the patient is well-hydrated is by looking at his urine output—less frequent urination or urine that possesses a strong odor and color are signs that he is not getting enough fluids.

Healthy cancer patients are advised to take eight glasses of water per day. Low-sugar electrolytes, in replacement for water, may also be taken occasionally. More fluid intake is recommended for those experiencing diarrhea or sweating after a colostomy procedure.

Regardless of the patient’s treatment method, it’s important that the care team monitors their nutritional status and weight. The patient should also report any weight loss, vomiting, diarrhea, dizziness, or other conditions that affect his appetite and ability to eat.

To overcome nutritional challenges during colorectal cancer treatment more effectively, working with a registered dietitian who has board certification in oncology nutrition is recommended by the Cancer Support Community. A dietitian calculates the patient’s caloric requirements and desings appropriate meal plans to satisfy these. Moreover, if the dietitian has experience handling cancer patients, it may also help prepare the patient for upcoming treatments. That way, the patient can avoid having nutritional deficiencies during treatment and rather recover more quickly.

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