Medically reviewed by John A. Flores M.D., M.S October 30, 2023| Written by Godfrey Makonere Wesutsa

Cancer Diet: Foods To Eat and Avoid

The cancer treatment process can take a relatively long period depending on factors such as the type of cancer you have and stage of development. In this case, effective treatment of cancer requires a change in both social and physical lifestyles. According to Cancer Research UK the chemotherapy used in the treatment of cancer may take between a period of three to six months. Treatment can take even more or less, depending on the type of cancer.

A diet change is one of the adjustments that cancer patients must make to enhance the treatment process. Although food is not the only cause of cancer problem, a change of lifestyle can influence the acquisition of vital minerals required for helping the body to restore itself. There are some foods that you must add to your diet and some that you must eliminate, which can affect the healing and treatment process.

Foods to Eat : Plant-Based Foods

Plant-based food products such as vegetables, nuts, seeds, and beans are effective food for the patient during cancer treatment. Plant protein can be successfully substituted for animal protein like beef and milk.  Turning to vegan diets helps to increase diverse nutrients, including proteins, vitamins, and fats. For instance, plants such as legumes are rich in Vitamin B, C, and calcium. Vegan diets are high in fiber, which has diverse benefits such as enhancing metabolism.

Eating more plant-based foods adds more phytochemicals, fiber, vitamins, and minerals to the body, which is required to boost the body's overall wellness. These phytochemicals enable the body to fight cancer replication, building the immune system and counter inflammation. When taking cancer treatments such as chemotherapy, you require a strong immune system to help restore destroyed body cells. Plant-based foods are vital in promoting such.

It is essential to understand that eating plant-based food products depends on the ability of the patient to chew and swallow foods. For instance, a patient with difficulty swallowing or constipation problems may require the food to be sliced into smaller pieces.

Use of Food Supplements

Cancer treatment requires an adequate supply of body minerals and nutrients into the body system to help enhance immunity and promote the overall metabolism process. Based on this understanding, you can include supplements in your diet to help boost the level of nutrients in your body. Supplements are highly recommended, especially if you are experiencing diarrhea or vomiting when taking the standard food products. One of the most common minerals that dietary supplements include vitamins D and E, which help the body to reduce fatigue, enhance bone strength, and boost overall immunity.

However, always understand that engaging a medical practitioner or consulting an expert is vital before adding any food supplement to your diet. Additionally, you should not overuse food supplements because they can make you gradually replace foods with supplements with the thoughts of enhancing the healing process, which may not necessarily be true.


Food products you can include in your diet include those rich in vitamins, which dietitians highly recommend because they help with antioxidation. Blackberries have anthocyanins, which help with lowering the risk of colon cancer. Berries can help protect and prevent the development of some cancerous cells,and may also enhance healing.

Cruciferous vegetables

The progress of some cancers, such as breast and colon cancer, is very robust. To reduce their impact, you must consume Cruciferous vegetables such as kale, broccoli, and cauliflower, which are rich in minerals. Manganese and vitamin K are among the vital nutrients found in such vegetables and are significant in inhibiting the progress of some cancerous cells.

Research conducted on Cruciferous vegetables indicates that they also have sulforaphane that has been found to inhibit cancer growth, especially colon cancer cells. Other research on the same elucidates that a combination of sulforaphane with genistein, a significant compound found in soybeans, can inhibit breast cancer tumor development and size. In addition, Sulforaphane has been linked to inhibiting histone deacetylase, a common enzyme that stimulates cancer development.

Research indicates that you should eat 3-5 servings of cruciferous vegetables every week. In this case, it may have cancer-preventive effects and inhibit its growth or spread in the body. 


Findings from The American Institutes for Cancer Research indicate that all nuts considerably inhibit the development of cancerous cells. One of the nuts that has received extensive study is walnuts, which have been shown to have a significant impact in countering the development of cancer. Walnuts contain Pedunculagin, which is metabolized into urolithin compounds. This compound is known to bind the estrogen receptor and can help prevent breast cancer. To validate the research, a 2019 finding on females with breast cancer consumed walnuts two weeks between the week of biopsy and surgery indicated suppression of cancerous tissues.


Legumes are crop species that are known for their protein nutrients. These crops include beans, peas, groundnuts, and lentils, among many others. However, these crops also contain high fiber content, which significantly lowers the risk for many types of cancer, like breast cancer. Multiple study reviews indicate that you are at a lower risk of getting cancer if your intake of legumes, such as beans, is high. In this case, people who consume a lot of proteins are at a lower risk of developing  cancer than those who do not.

Healthy protein and fats

Protein plays a significant role in the body besides helping people with cancer. This part of the protein nutrient includes milk products, eggs, fish, and meat. Therefore, eating a lot of proteins is essential in providing calcium, potassium, and vitamins. Protein helps repair tissues affected during chemotherapy and ensures that one is strong despite the disease in your body. 

Fish types, like salmon, mackerel, and anchovies, are vast in nutrients, omega-3 fatty acids, vitamin B, and potassium. Research indicates people who consume fish from freshwater have up to 53% lower risk for some cancer types compared to those in low freshwater fish.

Foods to Avoid: Processed Food

Meat is among the familiar sources of protein for many people. However, a good percentage of people consume processed meat. In this case, processed meat is a product preserved using salting, smoking, or other methods. They include bacon and hot dogs, among many others. Preserved meat is dangerous because it contains preservatives like nitrites that increase your chances of getting cancer. In most cases, preserved meat is heated at high temperatures, thus producing cancer-causing components. In addition, sodium is another chemical component mostly present in preserved meat; therefore, eating it poses a danger to your health, especially stomach cancer.


During the cancer treatment process, you should strongly avoid the use of alcohol because of its negative impact on the immune system. Alcohol is also linked to various cancers, including breast, liver, and colon-rectal cancer. It would be best if you avoided alcohol because it can interfere with the benefits of chemotherapy during the treatment process. Alcohol leads to side effects such as mouth sores, dehydration, and nausea, hence increasing the risk of additional development of cancerous cells.

The interaction of medications provided during the chemotherapy and alcohol can lead to adverse side effects such as vomiting and dizziness and inhibit the drug's ability to take effect on the body. When mixed with the drugs used in the treatment, such as Ultram or Tramadol, alcohol can magnify the side effects, affecting the drug's functionality and leading to other challenges such as blood pressure and heart problems. You should avoid the use of alcohol during the treatment process because of the magnitude of side effects caused by it.

Sugar-sweetened Beverages

Many people drink sugary drinks without understanding their effects on the body. According to the National Instituties of Health research, sugary beverages like soda and fruit juice cause weight gain. As you know, obesity and being overweight contribute to many health problems, including cancer. Drinking many sugary drinks increases calories, making it challenging to maintain a balanced body weight. When you consume more calories than your body can burn, there are increased chances of obesity or overweight in the long run.


Like cancer manifestation, treatment can take long, depending on the type of cancer and treatment method. Diet is among the factors determining the prevention and management of the condition during treatment. Oncologists and dieticians recommend that you consume a balanced diet with a critical emphasis on plant-based food, like fruits, legumes, and vegetables. However, other food product like milk and fatty fish also have some compound that helps you stay healthy and are essential during treatment. Nevertheless, other foods like processed meat and alcohol, among others, are to be eliminated if you want to stay healthy or overcome treatment.