The Importance of Diet During Cancer Treatment

Nutrition plays a pivotal role in any cancer treatment, a process that continues to place significant demands on the human body. Consuming the right types of foods prior to, during, and after treatment can help patients derive the greatest benefit from treatment, including feeling better and stronger.¹

Unfortunately, maintaining a healthy diet during cancer treatment can be difficult. Many of the side effects of treatment, such as nausea, vomiting, poor appetite or mouth sores, can deter patients from eating regularly. Many experience weight loss or loss of appetite so strong that they can technically be declared anorexic – an unfortunate reality that only emphasises the importance of good nutrition.²

The Importance of Diet During Cancer Treatment - Pancare

How Cancer Treatment Affects Diet

Treating cancer can sometimes be an aggressive process. Though treatments are constantly evolving, the three most common methods of treating cancer include:³

  • Chemotherapy – medications are administered to help cure or control cancer.
  • Surgery – the cancer is removed during the course of an operation.
  • Radiotherapy (Radiation) – treatment using X-rays and gamma rays to help cure or control cancer.

Because most cancer therapies involve damaging normal, otherwise healthy cells, while simultaneously killing cancer cells, patients may experience any number of side effects that affect the ability to eat or maintain a healthy appetite. They may include:⁴

  • Feeling sick (nausea)
  • Loss of appetite
  • Feeling fatigued
  • Having a dry mouth
  • Having a sore mouth
  • Having a sore throat or trouble swallowing
  • Constipation or diarrhoea
  • Changes or loss of taste or smell

It’s important to note that these side effects can vary from person to person, and typically depend on what part of the body is treated, the duration of treatment and the amount of treatment administered. Though most side effects are temporary, it is not uncommon for patients to need assistance controlling and managing them in order to maintain optimal nutrition.

How Nutrition Benefits Patients During Cancer Treatment

There are several nutrients essential to helping the body maintain the strength it needs in the fight against cancer – fat, protein, carbohydrates, water, vitamins and minerals.⁵ Like side effects, the needs for each vary from person to person, and may vary depending on the course of treatment.

For example, cancer patients typically require more protein than usual during treatment. Protein not only aids the immune system during treatment, it also helps to repair body tissue without breaking down muscle for fuel.⁵ Working together with your cancer care team can help better identify nutrition goals, and plan strategic ways to help you meet them during treatment.

Though there’s no evidence to concretely prove that eating certain foods can prevent or cure cancer, there are healthy habits that are recommended, both prior to and after diagnosis.⁶ The goal should be eating a wide variety of foods that cover the full spectrum of nutrients. In fact, studies indicate that maintaining a healthy diet during the course of cancer therapies may help you:⁷

  • Feel better
  • Better tolerate any treatment-related side effects
  • Have a lower risk of infection
  • Keep up your energy and strength
  • Maintain a healthy weight
  • Maintain your body’s nutrients
  • Heal and recover faster

A registered dietitian (RD) can be a valuable resource during treatment, and can work with your cancer care team to set goals on the path to recovery. It is also important to ensure that any and all medical professionals consulted are qualified in their respective fields.

Avoiding Misleading Information and Treatment Options

Though there has been a wealth of research regarding the positive effects of nutrition during cancer therapies, there have not been any concrete discoveries to suggest that specific foods or diets can completely prevent, treat, or cure any cancer.

However in recent years, there have been a number of diets or programmes claiming to cure or prevent cancer, causing a rising number of individuals to take to the internet to seek out treatment options. According to industry experts, such “miracle” therapies are often marketed in misleading ways, or are touted as complementary and alternative medicines (CAM), leading to some skewed perceptions regarding nutrition and wellness during cancer treatment.⁸

Before considering any complementary treatment, such as the help of a RD or other dietary specialist, it is important to consider your diagnosis and needs. Many diets marketed as CAM therapy recommend the removal of entire food groups, which could prove detrimental to cancer patients’ health during the course of treatment.⁹

Any questions or concerns regarding diet or nutrition-based therapies, or any CAM treatments, should be directed towards your primary care provider, who can recommend additional action or provide supplementary information regarding your diagnosis.

Where Can I Find Current, Reliable Information?

If you are looking for additional information regarding diet during cancer treatment, or if you are seeking information regarding complementary options during the course of your treatment, the most up-to-date information can be acquired from your local Cancer Council.

Cancer Council Helpline 13 11 20

Mon – Fri 9am – 5pm


This article is intended for information purposes only. Dietary therapies are meant to complement any regular or routine treatment options, and should be discussed with your cancer care team. Pancare also recommends consulting with your physician regarding any dietary complications, or if you are experiencing difficulties with appetite or weight loss.

Further Reading – References & Resources