The truth is, eating well can be a challenge when you have cancer. And everyone is affected differently. Some people find their eating habits change only slightly, while others find that eating well is really hard. Many people are somewhere in-between.

How your eating is affected will depend on the type of cancer you have and the treatments you receive. But the goal for everyone is the same – to eat as well as you can to be as healthy as you can during and after treatment.

During treatment, how you respond to food can change from day to day. On some days you may have a good appetite. On others, you may feel you just can’t eat much or can’t resist an unhealthy craving. All of these responses are normal.

Once you’ve finished treatment and the side effects have eased off, your interest in food will probably return. It’s a gradual process – changes rarely happen overnight. Try to be patient if you don’t get back to your usual eating habits as quickly as you’d like. Your body needs a lot of time to recover.

Why eating well is important

A healthy diet gives your body the nutrition it needs during and after cancer treatment. There are many benefits to this.

In the short term, eating well can:

give you energy

help you feel better

keep your body strong

help you cope with side effects

Over the long term, eating well can:

help you heal and recover after treatment

lower your risk of heart disease, type 2 diabetes and osteoporosis (weakening of the bones)

lower your risk of some types of cancer

Eating well can also help you feel like you have some control over your own health. And we now know that people with cancer who are well nourished and able to maintain a healthy body weight live longer than people who have lost a lot of weight.

What is eating well?

In general, eating well means eating a variety of healthy foods like vegetables and fruit, whole grains and protein. Canada’s Food Guide is a good place to start.

Because everyone’s nutritional needs are different, you may want help from your healthcare team. A registered dietitian can help you find ways to eat well and maintain a healthy body weight throughout your cancer experience. A dietitian can also help you if you’re following a special diet (like vegan, vegetarian or gluten-free) or if you need to limit or avoid some foods because of a health condition such as diabetes, heart disease, food allergies or celiac disease.

Your dietitian can help you make sure that you get the right amount of calories, protein and fluids that you need to eat well.

During treatment, you may need more calories (energy) than usual so that you don’t lose weight. Good sources of calories include whole fat dairy products like milk, yogurt and cheese, and healthy fats like olive oil, avocados, nuts and nut butters.

Some people may have to be careful with the amount of calories during and after treatment to make sure they don’t gain too much weight.

Protein is good for your health in many ways. It helps your body grow cells, heal tissue and maintain a healthy immune system. And it can help you avoid infection and recover more quickly. The key is to know where to find it. Good sources of protein include fish, poultry, lean red meat, eggs, nuts and nut butters, dried beans, peas and lentils, dairy products and soy foods.

Fluids

As you focus on eating well, it’s easy to forget about fluids. Yet every cell in your body needs water. If there are days when you can’t eat solids, it’s even more important to drink plenty of liquids. They can provide much-needed calories and keep you from becoming dehydrated.

Do your best to drink plenty of water and other fluids each day. When it’s hot outside or you’re active, you’ll need to drink even more. You’ll also need to drink more if you have a fever, are vomiting or have diarrhea. Your dietitian can give you specific guidelines on how much is right for you.

Is it OK to drink alcohol?

Before you choose to drink alcohol during your cancer treatment, talk to your healthcare team.

Alcohol can interfere with some cancer treatments and medicines. It can make side effects like a sore mouth and throat worse. And we now know that drinking any type of alcohol increases your risk of developing some types of cancer.

Should you take a vitamin and mineral supplement?

The best way to get vitamins or minerals is to eat a well-balanced diet. If you do that, you usually get what you need to stay healthy.

Taking a regular-strength multivitamin and mineral supplement for your age group every day is often OK, but check with your healthcare team just to be sure.

There is no evidence that taking more than the recommended amounts of vitamins and minerals or that taking large amounts (megadoses) of any vitamin or mineral will improve your health or help to prevent or cure cancer.

In fact, taking too much of some types of vitamins or minerals can be harmful to your health – and it may even make cancer treatment less effective.

Is there a magic food that boosts your immune system?

Many people wonder whether eating specific foods will boost their immune system and help them fight cancer. No single diet, food or supplement can boost your immune system. The best thing you can do for your immune system is to follow an overall healthy lifestyle, which includes eating a balanced, healthy diet with a variety of foods.

Can a diet cure cancer?

There is no scientific evidence that any specific food or diet (for example, the alkaline diet, a macrobiotic diet or the Gerson therapy diet) can cure cancer. Because these diets often restrict food choices (like meat, milk, eggs and even vegetables and fruit), they may not provide enough calories, protein, vitamins and minerals. This can lead to weight loss and poor nutrition.

If you’re considering an unconventional or alternative diet, talk to your healthcare team.