Diet and Nutrition During Cancer Treatment: A Practical Guide

Why Nutrition Matters During Treatment

Cancer and its treatments place extra demand on the body. Surgery, chemotherapy, immunotherapy, targeted therapy, and radiation can affect appetite, digestion, immunity, and muscle mass. Adequate protein and calories help preserve strength, support wound healing, and reduce treatment interruptions caused by weakness or severe weight loss.

Malnutrition is more common than many families realise. Some patients lose weight quickly; others gain weight from steroids or reduced activity. Both situations need attention. The right plan depends on cancer type, treatment schedule, co-existing illnesses such as diabetes or kidney disease, and individual side effects.

A registered dietitian familiar with oncology, working with your oncologist, is often the best partner for personalised advice. General tips help, but one diet does not fit every patient.

Build Balanced Plates with Enough Protein

During active treatment, many patients need more protein than usual to maintain muscle. Good sources include dals, beans, paneer, curd, eggs, fish, chicken, soy products, nuts, and seeds—chosen according to tolerance and medical advice.

Combine protein with easily digestible carbohydrates such as rice, roti, oats, fruits, and potatoes, plus colourful vegetables when the gut is settling. Healthy fats from ghee in moderation, olive oil, nuts, or avocado can help when appetite is low and calorie needs are high.

Small, frequent meals often work better than three large ones. If solid food is difficult, smoothies, soups, khichdi, porridge, and oral nutrition supplements recommended by your care team can bridge the gap.

• Aim for a protein source at most meals and snacks
• Prefer cooked, soft foods if mouth sores or nausea are present
• Include fruits and vegetables when tolerated for vitamins and fibre
• Use oral supplements only as advised by your doctor or dietitian

Managing Nausea, Taste Changes, and Poor Appetite

Nausea remains one of the most common chemotherapy-related complaints. Anti-nausea medicines prescribed by your oncologist should be taken as directed—not only after vomiting starts. Bland foods such as toast, bananas, rice, applesauce, curd, and clear soups are often easier on treatment days.

Taste changes can make favourite foods suddenly unpleasant. Cold or room-temperature foods may be better tolerated than strong-smelling hot meals. Tart flavours like lemon (if mouth sores are absent), mint, or mild spices can help some patients. Good oral hygiene also improves taste and reduces infection risk.

When appetite is poor, focus on nutrient-dense bites rather than forcing large portions. Sip fluids between meals instead of during them if early fullness is a problem. Report ongoing vomiting, inability to keep fluids down, or rapid weight loss promptly—these may need medical support, IV hydration, or temporary feeding assistance.

Foods and Habits to Be Cautious About

There is no strong evidence that cutting out all sugar cures cancer. Completely eliminating carbohydrates can leave patients weak and underfed. That said, limiting sugary drinks and ultra-processed snacks is sensible for overall health and blood sugar control, especially if steroids are part of treatment.

Food safety matters when immunity is low. Wash produce well, cook meats and eggs thoroughly, avoid unpasteurised dairy, and be careful with street food or leftovers that have sat out. Your team may give stricter guidance during periods of very low white blood cell counts.

Alcohol can interact with medicines, worsen mouth irritation, and stress the liver. Tobacco should be stopped entirely. Herbal products, high-dose vitamins, and “immune boosters” sold online can interfere with chemotherapy or immunotherapy—always ask before starting any supplement.

Hydration and Side-Effect-Specific Tips

Staying hydrated supports kidney function, helps manage some treatment side effects, and reduces constipation risk. Water, oral rehydration solutions, coconut water, clear soups, and diluted juices are common options unless your doctor has fluid restrictions.

For diarrhoea, soft binding foods and electrolyte replacement may help, while high-fibre or very spicy meals are often paused temporarily. For constipation—common with pain medicines—fibre, fluids, and prescribed stool softeners are used carefully under guidance.

Mouth sores call for soft, non-acidic, lukewarm foods and gentle oral care. Difficulty swallowing needs urgent review before diet experiments. Each side effect has a tailored approach; tell your oncology team early rather than struggling silently.

Special Situations: Diabetes, Vegetarian Diets, and Caregivers

Patients with diabetes need coordinated plans so cancer nutrition and glucose control both stay on track. Steroids can raise blood sugar; meal timing and medicines may need adjustment with your endocrinologist and oncologist.

Vegetarian and vegan diets can work well during treatment when protein intake is planned carefully using dals, dairy or fortified alternatives, soy, nuts, and grains. The issue is not vegetarian food itself—it is inadequate calories or protein when appetite falls.

Caregivers play a major role. Preparing small appealing meals, keeping snacks available, tracking weight weekly, and noting what the patient can tolerate helps the medical team intervene sooner. Emotional mealtime pressure (“finish everything”) often backfires; gentle encouragement works better.

Practical Takeaways for Patients in India

Familiar Indian home foods—khichdi, dal-rice, curd rice, soft rotis, boiled vegetables, buttermilk, eggs, and lightly spiced soups—are often excellent during treatment. You do not need expensive imported “superfoods.” Consistency and hygiene matter more than exotic ingredients.

During festival seasons or family gatherings, plan ahead: eat smaller portions of richer foods, stay hydrated, and avoid experimental detoxes or fasting trends unless cleared by your oncologist. Fasting can be unsafe for many patients on active therapy.

If you are under my care at Marengo Asia Hospitals, Gurugram, discuss nutrition concerns at clinic visits. We can involve dietetic support, adjust anti-nausea plans, and address weight changes before they affect treatment tolerance.

Remember: the best cancer diet is one you can actually eat, that maintains your strength, and that fits your treatment and medical conditions.