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Diet During Cancer Treatment

Patients with cancer are often malnourished, which may decrease the effectiveness of cancer treatments and increase side effects.

There are no evidence-based recommendations for diet therapy during cancer treatment. Because of the poor appetite and severe weight loss in many cancer patients, they are often encouraged to increase food intake by any means possible. This may be a mistake. Diets high in fat, sugar, and animal protein may, over the long run, increase cancer growth, impair the immune system, foster inflammation, interfere with effective treatment, and worsen survival. These issues await further research.

The following dietary adjustments may be helpful to address common side effects of cancer treatment:

Nausea and vomiting: The American Cancer Society and National Cancer Institute suggest the following strategies to control the nausea and vomiting associated with chemotherapy:

  • Eating small, frequent meals
  • Using powdered or liquid meal replacements
  • Drinking only small amounts of liquids with meals
  • Avoiding strong odors
  • Avoiding sweet, fried, or fatty foods
  • Using soft, cool, and/or frozen foods
  • Keeping healthy snacks available
  • Not lying flat for at least two hours after a meal
  • Not eating for a few hours before treatment if chemotherapy causes nausea
  • Eating before bedtime
  • Having wine or beer with meals to stimulate appetite (assuming physician approval)
  • Exercising, as tolerated

However, controlled clinical trials are needed to assess the effectiveness of these recommendations.

  • Radiation enteritis: Radiation enteritis refers to irritation and injury of the intestines that occurs as a complication of high-dose radiation therapy. Symptoms include nausea, vomiting, abdominal cramping, and watery diarrhea. According to the National Cancer Institute, a diet that is lactose-free, low in fat, and low in fiber can be effective. However, evidence supporting this approach is minimal and requires confirmation in controlled trials.
  • Mucositis and stomatitis: These are irritations of the mouth and tongue that occur due to chemotherapy. Use of ice chips for 30 minutes before chemotherapy prevents or reduces symptoms in most patients. Further, supplementation with the amino acid glutamine decreases mucositis and significantly reduces pain and the need for pain medications.
  • Loss of taste: The loss of the sense of taste often occurs in patients undergoing chemotherapy and radiation therapy for cancer. It occurs in up to 70 percent of chemotherapy-treated patients, and may contribute to lack of appetite and malnutrition. Treatment with zinc sulfate (45 milligrams/day) reduces the likelihood of this problem and speeds recovery of taste in patients with head and neck cancers.

In addition to the above considerations, some evidence supports the use of the following interventions:

  • Selenium supplements: In women receiving chemotherapy for ovarian cancer, selenium supplementation (200 µg/d) significantly increased white blood cell count, decreased hair loss, and improved abdominal pain, weakness, malaise, and loss of appetite. Short-term treatment with high doses of selenium (4000 µg/d) reduces the risk of kidney failure and bone marrow disease in patients being treated with cisplatin chemotherapy. Further clinical trials are needed to establish the benefit and safety of selenium supplementation.
  • Specialized meal replacement formulas: Formulas containing arginine, glutamine, omega-3 fatty acids, and RNA appeared to be effective in patients who received surgery for stomach, head, and neck cancers. However, further study is needed to determine whether these formulas are more effective than standard formulas.
  • Behavioral interventions: Published studies support the effectiveness of behavioral interventions to prevent chemotherapy-related nausea and vomiting. Such interventions include hypnosis, guided imagery, and relaxation therapy, among others.