Malnutrition in cancer patients

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science

This page was updated on April 29, 2022.

Good nutrition is easy to overlook, but it’s an important aspect of cancer treatment. Getting enough of the right nutrients keeps your body stronger and helps you feel better during this time. Both cancer itself and cancer treatments may cause side effects that contribute to malnutrition.

Learn how to:

  • Prioritize sufficient nutrient intake
  • Equip your body to fight cancer and other infections
  • Prevent and manage malnutrition

During treatment, you’ll require even more nutrients and energy than normal, which may be a tall order when you don’t feel like eating. Still, there are steps you may take to stay nourished and resilient. A dietitian, as part of your cancer care team, may help guide you.

What is malnutrition?

Malnutrition occurs when your body isn’t receiving the energy it needs and, as a result, you may experience significant problems such as weight loss and muscle weakness. With malnutrition, the body doesn’t get enough calories and nutrients, such as vitamins and minerals, carbohydrates, proteins and fats. It might be that you’re having a hard time consuming the nutrients, or that your body isn’t fully absorbing the nutrients you're eating.

Your body’s needs will be different from someone else’s, and the risk for malnutrition depends on many factors. Regardless of the cause, combating malnutrition is extremely important: It leads to one in five cancer-related deaths, according to the National Cancer Institute.

Causes and risk factors for malnutrition in cancer patients

Studies estimate that anywhere from 30 percent to up to 85 percent of cancer patients experience malnutrition, so it’s important to prevent and be on the lookout for malnutrition symptoms during treatment.

These factors may lead to malnutrition:

  • Side effects of cancer. Cancerous tumors compete with your body for resources, altering your metabolism and contributing to starvation and loss of lean body mass. Side effects from cancer may cause anorexia (a loss of appetite or the desire to eat) and cachexia (a condition causing weight loss and weakness). Both conditions are common contributing factors to weight loss and other symptoms of malnutrition in cancer patients.
  • Location of the cancer. Cancers located in the head, neckesophagus, stomach, intestines, pancreas or liver make it difficult for many patients to consume enough nutrients due to blockages, malabsorption, difficulty swallowing and digestive issues.
  • Treatments. Patients undergoing immunotherapy, chemotherapy, radiation therapy or hormone therapy may experience side effects that interfere with eating and digestion, often requiring dietary changes. Common side effects of these treatments include an altered sense of taste and smell, nausea, oral and digestive tract ulcers, vomiting, loss of appetite and constipation. Also, surgery increases the body’s need for nutrients for proper healing and recovery. Stem cell transplants increase the body’s risk of infection, so more nutrients are required.

Signs and symptoms of malnutrition

Poor nutrition may impede your progress in cancer treatments, rendering them less effective or difficult to endure because your body has an even harder time with the physical side effects. A serious condition that makes recovery more challenging, malnutrition is tougher to treat as time goes on, so it’s important to catch it early. These are the key signs of malnutrition:

  • Loss of appetite. Cancer and treatments may drastically affect the desire to eat. Be aware of changes in appetite that last longer than a few days.
  • Weight loss. The loss of body weight, particularly fat and muscle loss, is an indication of malnutrition. If you’re losing more than 2 pounds of body weight each week, reach out to your cancer care team.
  • Low BMI. A body mass index of 18.5 or lower indicates possible malnutrition.
  • Weakness and fatigue: Without sufficient nutrients, you become weak or easily drained. This is a serious consequence that may impede recovery.

Preventing malnutrition

Your appetite may diminish during cancer treatment, but a balanced diet is vital. If you focus on healthy eating, you’ll feel better and preserve more of your strength and energy. Your body needs a variety of nutrients, including protein, carbohydrates, fats and micronutrients, to remain robust during treatment.

  • Protein. Fish, poultry, lean red meat, soy, dairy, nuts, seeds and legumes are all great sources of protein, a macronutrient necessary for growth, repair and increased immunity. Without sufficient protein, your body begins to break down muscle to use as fuel, making it harder to recover from illness and increasing infection risk.
  • Fat. You may avoid indulging in fatty foods in ordinary circumstances, but your body needs more fats when undergoing cancer treatment. Aim to incorporate plenty of healthy fats such as avocado, olive oil, nuts and seeds to boost your energy. Avoid saturated and trans fats as much as possible, as they’ve been linked to heart disease.
  • Carbohydrates. They’re considered the body’s main source of energy, but not all carbohydrates are created equal. Avoid overly processed, refined carbohydrates that have been stripped of vital nutrients. Instead, focus on whole fruits, vegetables and grains that contain plenty of fiber. Good options include sweet potatoes, oats, beans, brown rice, fresh fruits and veggies.
  • Water. To stay hydrated, drink eight, 8-ounce glasses of water each day, plus more when losing fluids from vomiting or diarrhea.

You may have to adjust your diet, consuming foods that are higher in fat and calories than you’d typically eat just to maintain your weight. Try to eat whatever you can—eating smaller, more frequent meals if that’s easier. Be sure to consult with a dietitian to create the best plan for your needs.

Managing and treating malnutrition

If you’re experiencing symptoms of malnutrition, speak with your care team. Managing malnutrition helps you maintain your body weight, recover from taxing surgery or treatments, and elevate your overall quality of life.

  • Maintaining your weight. Before, during and after cancer treatment, your body needs extra calories to maintain your weight and help you heal and recover. To keep up with your body’s demands, you may need to eat even when you’re not hungry. If full meals are difficult, try snacking often instead, emphasizing higher-calorie, nutrient-rich foods. Your tastes may have changed, so don’t be afraid to try new foods, being mindful of new intolerances.
  • Managing eating problems. From appetite changes to complications from treatment side effects, getting enough calories may become a challenge. Here are tips to help you ease some of the difficulties:
    • Decreased appetite. Try eating more frequently, using meal replacement shakes and supplements high in protein. If you’re really struggling to get anything down, your doctor may prescribe an appetite stimulant.
    • Nausea and vomiting. Stick with bland, easy-to-digest foods. Use peppermint or ginger to soothe nausea and aid digestion. Drink plenty of water, and take anti-nausea medications as recommended by your care team.
    • Mouth sores, sore throat, dry mouth and difficulty swallowing. Stick with soothing foods such as milkshakes, broth, pudding or scrambled eggs. Suck on ice chips to avoid dehydration, and avoid citrus and spicy foods. For dry mouth, use lozenges and sip liquids throughout the day.
    • Constipation. Prune or black cherry juice, plenty of water, fiber-rich foods and probiotic supplements are great ways to combat constipation. Sprinkle activity into your day whenever possible. Check with your doctor before using laxatives or stool softeners.
    • Diarrhea. Drink room-temperature liquids, eat small meals throughout the day, and avoid spicy, greasy or overly seasoned foods. Try binding foods such as bananas, crackers and potatoes.
  • Support when you can’t eat normally. If you’re unable to consume the calories and nutrients your body needs orally, ask your care team about nutrition support interventions. A feeding tube is inserted directly into the stomach for nutrition (enteral nutrition) or nutrients are infused directly into the bloodstream (parenteral nutrition). Ensuring the appropriate intake of protein, carbohydrates, fats, vitamins and minerals is of utmost importance in mitigating the harmful effects of malnutrition. Whatever it takes, strive to keep your body well-fed and strong.

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