Radiation therapy uses high-energy beams, such as X-rays or protons, to damage and kill cancer cells. Although precisely aimed, this treatment can cause collateral damage to healthy, rapidly dividing cells near the treatment area, placing significant stress on the body. Nutrition is a primary component of successful treatment and recovery, as maintaining strength and minimizing treatment interruptions are directly tied to dietary choices. A well-planned diet provides the resources the body needs to repair itself and maintain the energy required to endure the full course of therapy.
Nutritional Goals During Radiation Therapy
The primary objective of nutrition during radiation therapy is to maintain body weight and preserve lean muscle mass. Unintentional weight loss, particularly the wasting of muscle tissue known as cachexia, can weaken the immune system and negatively impact treatment effectiveness and recovery time. Experts often recommend a calorie intake ranging from 25 to 35 calories per kilogram of body weight to support the body’s increased energy demands.
A secondary goal is supporting the function of the immune system. The body’s ability to fight off infection and manage inflammation is directly linked to an adequate supply of vitamins, minerals, and proteins. Ensuring sufficient energy reserves helps the body tolerate the full course of treatment without needing dose reductions or unplanned breaks, facilitating the rapid repair of healthy tissues.
Essential Macronutrients for Healing and Tissue Repair
Protein is the most important macronutrient during radiation therapy because it is the fundamental material for cell repair and immune support. Radiation breaks down tissue, requiring a high-quality protein supply to rebuild healthy cells and produce antibodies. Good sources include lean meats, poultry, fish, eggs, dairy products like Greek yogurt, and plant-based options such as tofu, soy, and legumes. Experts suggest a protein intake ranging from 1.2 to 2 grams per kilogram of body weight per day to counteract muscle loss.
Complex carbohydrates serve as the body’s primary and most readily available source of energy, needed to combat the fatigue often associated with treatment. Choosing unprocessed sources like whole grains, oats, brown rice, and starchy vegetables provides sustained energy along with fiber, vitamins, and minerals. Unlike simple sugars, these complex sources help maintain steady blood sugar levels, preventing energy crashes that can worsen fatigue.
Healthy fats provide a dense source of calories, useful for patients with poor appetite who need to maximize nutrient intake in small volumes. Fats are also necessary for the absorption of fat-soluble vitamins (A, D, E, K) and contain compounds like omega-3 fatty acids that may help lower inflammation. Incorporate unsaturated fats from sources like avocados, nuts, seeds, nut butters, and olive oil to meet increased caloric needs and support cell function.
Dietary Strategies for Managing Common Side Effects
Nausea and Vomiting
Managing nausea often involves eating small, frequent meals throughout the day to prevent the stomach from becoming too full. Bland, easy-to-digest foods are better tolerated, such as dry toast, plain crackers, rice, or clear liquids like broth and gelatin. Avoid foods that are fried, fatty, overly spicy, or very sweet, as these can exacerbate stomach upset.
Taking anti-nausea medication as prescribed, rather than waiting for symptoms to start, is a proactive measure that can significantly improve food intake. Sipping on fluids between meals instead of with them can prevent the stomach from feeling overdistended. Some patients find relief by incorporating ginger or peppermint into their diet, through tea or candies, as these ingredients have soothing properties.
Loss of Appetite and Fatigue
Patients experiencing a loss of appetite should focus on making every bite count by choosing high-calorie, nutrient-dense foods. Fortified shakes and smoothies made with protein powder, whole milk or non-dairy alternatives, fruit, and nut butter are excellent options for maximizing nutrition in a liquid form. It is beneficial to eat during peak energy times, such as when appetite is strongest, and not wait until feeling hungry to consume calories.
Combatting fatigue involves consistent energy intake and adequate hydration. Having liquid nutritional supplements available for times when solid food is unappealing ensures a continuous supply of calories and protein. Small, nutrient-rich snacks carried throughout the day, such as hard-boiled eggs, yogurt, or cheese, can prevent long gaps between meals that lead to energy crashes.
Dysphagia (Difficulty Swallowing/Sore Throat)
Radiation to the head and neck area can cause painful swallowing (dysphagia) or a sore throat, necessitating a shift to a soft and moist diet. Foods that are pureed, blended, or naturally soft, such as mashed potatoes, scrambled eggs, well-cooked cereals, and soft fruits like bananas, are easier to manage. Moistening solid foods with gravies, sauces, broth, or yogurt can help them slide down more easily.
It is important to avoid foods with rough or abrasive textures, which can irritate a sensitive mouth and throat:
- Crusty breads.
- Raw vegetables.
- Chips.
- Crackers.
Highly acidic foods, including citrus fruits and juices, tomatoes, and vinegar-based products, should also be limited or avoided, as they can sting and inflame mouth sores. Using lukewarm or cool foods instead of very hot ones can provide comfort when swallowing is painful.
Diarrhea and Constipation
Radiation to the pelvis or abdomen can irritate the bowel, leading to either diarrhea or constipation, requiring different dietary adjustments. For diarrhea, the focus is on hydration with clear liquids and electrolyte drinks, while limiting foods that stimulate the bowel. This includes temporarily reducing high-fiber foods, especially insoluble fiber found in raw vegetables and whole grains, and potentially avoiding high-lactose dairy products if they cause irritation.
If constipation is the issue, increasing fluid intake is the first step, along with gradually adding sources of soluble fiber, such as oatmeal, bananas, and applesauce. Maintaining a regular, gentle level of physical activity, such as walking, can also stimulate the digestive system. Patients should consult their care team before making drastic changes to fiber intake, as the best strategy depends heavily on the specific symptoms and treatment location.
Foods and Supplements to Limit or Avoid
Certain foods and beverages can exacerbate common side effects or interfere with the effectiveness of the treatment itself. Highly acidic, spicy, or abrasive foods should be strictly limited, particularly if the radiation site includes the mouth, throat, or gastrointestinal tract, to prevent irritation and pain:
- Citrus.
- Tomatoes.
- Hot peppers.
- Hard pretzels.
Because radiation and cancer can compromise the immune system, the risk of foodborne illness is elevated. It is necessary to avoid unpasteurized dairy products and raw or undercooked foods, including sushi, raw shellfish, and unpeeled fruits and vegetables that have not been thoroughly washed. Alcohol and excessive caffeine should also be limited, as they can contribute to dehydration and may worsen dry mouth or diarrhea.
Patients should be cautious about taking high-dose antioxidant supplements, such as Vitamin C or Vitamin E, unless explicitly approved by their oncologist. These supplements could potentially protect cancer cells from the oxidative damage the radiation is designed to inflict, making the treatment less effective. Patients must consult with their oncology team or a registered dietitian before making any significant dietary changes or introducing new supplements.