Some people find they are unable to eat well due to side effects from their cancer or cancer treatment. If you have lost weight without trying or have difficulty eating please see our resources or ask to speak to a registered dietitian at your cancer centre.

If you do not have difficulty eating it is recommended that you follow a balanced diet throughout your cancer journey including after diagnosis, during treatment and after treatment. This can help to reduce your risk of cancer, cancer recurrence and other diseases. The World Cancer Research Fund and the American Institute for Cancer Research recommends that you:

• Focus your diet on plant foods such as whole grains, vegetables, fruits and pulses (legumes). Aim to fill at least two-thirds of your plate with plant foods.
• Limit 'fast foods' and other processed foods high in fat, starches or sugars.
• Limit red meat (beef, pork, lamb, and goat) to less than 500g (18oz) per week and avoid processed meats.
• Limit sugar-sweetened beverages.
• Limit alcohol consumption.
• Do not use supplements for cancer prevention.
• Maintain a healthy weight.
• Be physically active.

Sugar does not directly cause cancer or cause cancer to grow faster. Glucose, a simple sugar, found in most carbohydrate foods (including added sugar, grains, cereals, beans, fruits, vegetables, and dairy) is the main energy source for all cells, including cancer cells. Just like healthy cells, cancer cells need a blood supply, oxygen and energy to grow. Limiting all sources of carbohydrate will not starve cancer cells and may negatively affect your healthy cells. Your body needs energy and may use your muscle and fat tissue for energy, which is not recommended.

Many healthy foods such as whole grains, cereals, beans, fruits, naturally contain sugar along with vitamins, minerals, fibre and phytonutrients. Eat a variety of foods and limit table sugar (white or brown), soft drinks, sweet baked goods (cookies, cakes) and processed foods that contain large amounts of added sugar.

For more information, see the "Sugar and Cancer" (PDF) handout. You can read more about the sugar-cancer connection on the American Institute for Cancer Research website. The Academy of Nutrition and Dietetics also addresses the question "does sugar feed cancer" (PDF).

We don't yet know if either a true ketogenic or modified ketogenic diet helps people with cancer. Currently, no major health organization, including BC Cancer, recommends the ketogenic diet for cancer patients. A true ketogenic diet is a very high fat, low carbohydrate diet. This diet can be high in foods such as red and processed meats, as well as saturated fats. It can also be low in some nutrients the body needs along with most healthy plant foods. A modified ketogenic diet has less extreme carbohydrate restrictions. If you are interested in trying a ketogenic diet it is recommended that you seek individual nutrition advice from a registered dietitian with experience in ketogenic diet.

A diet rich in vegetables, fruits, whole grains and legumes is recommended for most cancer patients. For more details please see the common question "What do I eat after a cancer diagnosis?".

Visit the American Institute for Cancer Research (AICR) blog if you are interested in reading more about ketogenic diet and cancer.

‎Supporters of an alkaline diet claim that cancer growth can be slowed or stopped by following a diet that makes the body more alkaline. The acid-alkaline level in the body is very tightly controlled. Eating more alkaline foods will not make your blood more alkaline, but it can change your urine alkalinity. Extra acidic or alkaline substances don't build up in the blood because they are removed in the urine to keep the blood within a narrow and slightly alkaline range. Choose foods for their nutritional content and taste and not how they claim to change the acid or alkaline level in your body.

Visit the American Institute for Cancer Research (AICR) blog if you are interested in reading more about alkaline diet and cancer.

Pesticides used in farming have the potential to build up in the body, which has caused concern for the risk of developing cancer. Current evidence suggests there may be a possible association between pesticides and some cancers. There is evidence both for and against a link between pesticides and the risk of developing cancer and more research is needed. To reduce your risk of pesticide exposure, buy foods that are locally grown, in season and be sure to peel and wash vegetables and fruits well.

Buying organic food is an individual choice based on personal values, availability and cost. Overall, it is believed that the potential risks associated with pesticides are not as great as the nutritional value of plant foods and their role in cancer prevention and promoting good health. Therefore whether you choose organic or not it is important to eat a diet rich in fruits and vegetables and obtain the recommended servings each day.

Having cancer does not mean you need to take supplements. It is best to get your vitamins and mineral from food sources if you can. Large doses of vitamins and minerals have not been shown to boost the immune system in well-nourished people or be beneficial for other reasons, and could cause harm. A once a day multivitamin and mineral supplement may be needed if you are not able to eat a variety of foods or if your diet has changed. If you have questions about taking single nutrient supplements (ex. Calcium, Iron, vitamin D) talk to your health care team.

Can I take supplements during cancer treatment?

It is not recommended to take large amounts of antioxidants, including Vitamin A, C, E and selenium, in supplement forms during cancer treatment. Many (but not all) chemotherapy drugs and radiation work by causing oxidative stress to kill cancer cells. Taking antioxidant supplements can counteract this. The amount found in foods, such as fruits and vegetables, and a once-a-day multivitamin and mineral supplement is safe during cancer treatment. If you decide to take large doses of antioxidants, or other vitamins or minerals during treatment, speak to your health care team.

Are herbal products safe?

Herbal products or Natural Health Products include vitamin/minerals, herbs and other products that come in many forms such as teas, powders, tablets and liquid extracts. They are often thought to be safe because they are labelled as "natural". This is not necessarily true. Even though plants are natural, they are not always safe and their effect is not always known. Many of these products can increase risk of drug interactions, cause less cancer cells to be destroyed by treatment and affect test results. If you would like to use herbal products during your cancer treatment, please discuss the safest way to do this with your health care team.

Growth hormones are not approved for use in Canada in chickens or pigs or added to their feed. However, hormones may be used in beef cattle. One of the growth hormones used is a form of estrogen that occurs naturally in animals and humans. Any residues of these hormones in meat are very small when compared to the amount of estrogen a woman produces daily. Residues are thought to be stored in fat – you can lower your intake of these residues by choosing leaner cuts of meat, trimming visible fat or choosing other protein foods from Canada’s Food Guide.

Yes, red meat in moderation can be part of a healthy diet.  Red meat includes beef, pork, goat, and lamb. These foods provide many nutrients including iron, protein, vitamin B12, and zinc. See the "The Importance of Eating Protein" (PDF) handout during treatment and recovery for more about this nutrient.

It is recommended to limit red meat in your diet to 500 grams (18 ounces) cooked or less per week. Eating processed meat and too much red meat can increase the risk of colorectal cancer.

Processed meat may also increase the risk for cancer of the stomach, nasopharynx, esophagus, lung and pancreas.

Processed meat is often made from red meat, but poultry, or other meats that have been commercially preserved by smoking, curing, or with additives like nitrates are also considered processed meat. Examples of processed meats include ham, bacon, sausage, salami, hot dogs, pepperoni, many deli meats, and bologna. Products that are preserved with naturally-occurring nitrites such as celery extract are still considered processed meats and may also increase risk of cancer.

If you choose to eat processed meat, eat it in small amounts and less often, like ham at a holiday dinner or a hot dog at a hockey game.

The Canadian Cancer Society has more information about red and processed meat and cancer prevention on their website.

Receiving cancer treatment does not necessarily mean you need to avoid any foods. Foods to include and avoid during cancer treatment is different for each person. It is based on your type of cancer, the treatment you are receiving, and any symptoms or side effects you have that may be making it hard to meet your nutrition needs.

In general, cancer treatments can lower your immune system's ability to protect itself from infection. At this time, it is important to practice good food safety guidelines. Most importantly, wash hands often with warm soapy water before and after preparing foods and before eating. Make sure that food is well-cooked and that you avoid raw and undercooked eggs, meat, fish, poultry and seafood. This will decrease your exposure to bacteria that could cause food borne illness. Read more about food safety for people with weakened immune system.

It is also recommended that you limit your intake of red meat, avoid processed meats, limit salty foods, and limit alcohol to two drinks per day for men and one drink per day for women. See common question "Is it ok to eat red meat?" for more information about red meat and processed meats.

To learn more about what to eat after a cancer diagnosis:

• Click on "Recipes" tab to find suggested websites and cookbooks.

You may have heard about particular foods such as plant-based foods (fruits, vegetables, whole-grains and legumes) as “foods that fight cancer”. This is largely based on evidence for diet recommendations to prevent cancer. The research on foods to prevent cancer growth and recurrence is less clear.

If your weight is stable, within a healthy range and you don’t have any problems with eating, it is suggested you follow Canada’s Food Guide.

If you are underweight, have unintentional weight loss and/or have problems eating enough, you may need to choose foods that are higher in calories and protein. Depending on symptoms from your cancer or its treatment you may need to eat softer foods or foods lower in fibre.

Ask your health care team about your individual nutritional needs.

A healthy eating pattern includes plenty of plant-based foods including vegetables and fruits, whole grain foods and plant-based protein foods. Vegetarian diets include all these foods. Vegan diets exclude all animal foods including meat, poultry, fish, dairy and eggs. Some people include dairy and eggs in their vegetarian diet. A well-planned vegan or vegetarian diet can meet your nutrient needs and provide enough protein. Use your plate as a guide: Fill half your plate with vegetables and fruits, one quarter with whole grains and one quarter with protein foods. Plant-based protein foods include beans, lentils, split peas, soy foods (tofu, soy beverage, tempeh), nuts, and seeds. Eating a variety of different foods each day will help you meet your nutrition needs. See Canada's Food Guide for more information on a balanced diet.

It may take extra planning to get enough omega-3 fats, calcium, vitamin D, iron, zinc and vitamin B12 if you are eating a vegetarian diet. You can read more about these nutrients and find out how to make sure you are getting enough at HealthLink BC. For more information see the vegetarian and vegan diet information available from UnlockFood.ca. For individual advice call 8-1-1 to speak to a registered dietitian at HealthLink BC.

If you are having problems eating or problems with your bowels after a diagnosis, during treatment or after treatment it may be more challenging to plan a vegetarian diet. Contact a registered dietitian for food choices that meet your needs.