A healthy diet, including adding fruits, can help cancer patients.

What’s the best diet for cancer patients going through treatment?

When you have cancer, a good diet plays a critical role in your survivor journey.

Your body needs energy to fight the disease. Chemotherapy, radiation and other cancer treatments take a toll on your body, too. As a result, you may lose weight – and in this case, that’s not a good thing.

“When you have tissue damage, whether it’s from the cancer or the treatment, your body works hard to restore itself. It uses the nutrients from your food, particularly protein, for this. If you’re not eating enough, your body will use up energy and protein. Then you will notice you feel more tired and your muscles start to feel weaker. This can put you at risk for malnutrition,” said Katrina Sommer, clinical dietitian for OSF HealthCare.

“Since you use up a lot of calories and protein during treatment, you need to eat to support this.”

What makes for a good cancer diet?

The best diet for you will depend on a number of factors. Those include the location of the cancer you’re fighting, your treatments and the side effects you experience.

But certain elements of a good diet are constant.

“Fruits, vegetables, beans, nuts, seeds and meats such as poultry and fish – along with drinking plenty of water – are ideal. These are foods that research has shown to promote and support good health,” Katrina said. “Try to avoid sugary beverages and processed foods, which can be high in added sugar and fat. The less we mess with food, the better. The more whole foods you eat, the better nutrition you get.”

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During cancer treatment, you should focus on maintaining your weight, staying hydrated and managing your symptoms.

The side effects of your treatment can have an impact on that.

“You may need to change what and how you eat based on the side effects you experience. There are different strategies and ways to manage symptoms with nutrition. A dietitian can counsel and teach you these during treatment so you can optimize what you are eating and drinking to meet your nutrition needs,” Katrina said.

Chemotherapy side effects can make you nauseous and cause loss of, or change in, appetite – or even make foods taste different. Some foods you once loved might make you feel sick.

Radiation therapy, especially to the head, neck and center of the chest, can cause pain and difficulty chewing and swallowing solid foods.

“Try a smoothie made with fruit, Greek yogurt and milk. A smoothie is easy to swallow and can have the nutrients of a balanced meal,” Katrina said. “Eating smaller, more frequent meals is easier on your digestive tract than eating a big meal and can also help you manage your symptoms.

“Protein is especially important during any cancer treatment. Have some protein every time you eat, even if it’s something small. Eggs are great because they’re inexpensive, but peanut butter is also easy to add to a snack. Eat more plant proteins, like nuts, seeds and lentils.”

Some cancer treatments can cause weight gain. It is important to still focus on eating well to help to manage your weight gain during treatment.

Are there foods that fight cancer?

Fruits, vegetables, legumes, nuts, seeds and whole grains are essentially all foods that fight cancer naturally. Research shows links between eating plenty of plant-based foods and lower cancer rates.

Nutritionist with patient

Plants produce chemicals – called phytochemicals – that have many benefits. They are anti-inflammatory, can protect cells from damage and disrupt cancer from developing.

There are other theories as to why people who eat more plant-based foods tend to get cancer less often, too.

Fiber, which is higher in plant foods, may help prevent cancer. Several studies have shown higher fiber diets are linked to lower risk of breast cancer and colorectal cancer.

Of course, the link between a plant-based diet and a lower risk for cancer could also be due to weight. People who eat mostly plant-based foods tend to consume fewer calories and are less likely to be overweight, which is a risk factor for several types of cancer.

The vegan diet and cancer

The vegan diet entails cutting out all food that is the product of animals. This means no meat, fish, eggs or dairy. Vegans use plant-based foods to replace the protein, some B-vitamins, and calcium in their diet that others get from animal-sourced foods.

The vegan diet, as well as the vegetarian diet, is made up almost solely of cancer fighting foods. When done properly, the diet is high in fiber and comes with all the benefits discussed above regarding eating plant-based foods. Some processed vegan foods can be high in sodium and added sugar, however.

Do alkaline foods help with cancer?

There is a theory that eating alkaline foods, which are high in pH, can help you fight or prevent cancer. The idea goes that cancer cells thrive in an acidic environment (low pH level), and if you consume enough alkaline foods, you can raise the pH level of your blood to make it less acidic, creating a hostile environment for cancer to grow.

However, there is a major problem with that theory. Your body’s pH level is highly regulated by your body, and you cannot change your blood’s pH level by eating foods high in alkalines or drinking alkaline water.

You simply could never eat enough food to move the needle one way or another on your blood’s pH level.

Foods for cancer patients to avoid

The goal of a cancer patient’s diet is to help your body be as fit and healthy as possible as it fights off cancer and deals with the side effects of treatment.  Avoid foods with little or no nutritional value, as well as anything that makes you nauseous or is hard to chew, swallow or digest.

You may need to avoid spicy and high-fat, fried foods and adjust the consistency of foods if chewing or swallowing is a problem. The overall goal through treatment is to maintain your weight and keep your strength.

Know and abide by your regular diet restrictions. If you have diabetes, stay mindful of your blood sugar, especially since certain cancer treatments can affect this. If you have heart issues, watch your sodium intake.

Read the food labels to know what is in your food and if it fits with your nutrition plan.

Is it true that sugar feeds cancer?

“You hear that sugar feeds cancer, which sounds really simple, but there is more to it,” Katrina said. “Eating a cookie does not necessarily mean the sugar from the cookie goes directly to cancer cells. All of our cells use sugar for fuel and we cannot choose which cells get this fuel. If someone is feeling lousy with side effects from treatment, making it difficult to eat, their healthy cells still need fuel. If you tell them they can’t have anything with sugar, this will limit the amount of tolerable, appealing foods making it even harder to maintain your strength, energy and weight.”

“So, if someone wants to eat a bowl of oatmeal, but not without brown sugar, then eat it with brown sugar. Try not to be too restrictive with food, especially during treatment.”

Eating natural foods doesn’t have to be expensive

Eating a plant-based diet does not necessarily mean all those foods need to be organic. Studies have shown there is no significant difference in nutrients between organic and conventional produce.

“Eating organic foods is good, if you can afford it. Keep in mind they can have a shorter shelf life and can be more expensive than conventionally grown,” Katrina said. “It is really up to you to decide which you prefer to eat, and what works in your budget. Whether you choose organic or conventional produce, you will still get all the nutrition benefits from these foods.”

What you eat makes a difference in how you feel. If you want to make changes to your diet to move more toward plant-based eating, set small goals. As you work toward them, you will move closer to achieving the big goal.

“During treatment, your goal is to eat to support your body through the treatment. After treatment, you can focus on how eating will look for you moving forward,” Katrina said.

When you make positive changes to help with your treatment, you create opportunities to establish good habits for the future.

“If you were eating a lot of meat and very little plant-based foods before treatment, then you can decide if you want to go back to your old eating habits or make changes,” Katrina said. “Even small diet changes, such as adding vegetables to your meals, can make a difference in your health.

“You don’t need to have a perfect diet, but it is important to pay attention what food you are eating because it matters.”

Last Updated: October 31, 2022

About Author: Kirk Wessler

After being a writer for OSF HealthCare for three years, Kirk Wessler retired in January 2022. A Peoria native and graduate of Bradley University, Kirk's experience included working for newspapers in Missouri, Texas and the Peoria Journal Star.

Kirk and his wife, Mary Frances, have five sons, four daughters-in-law and nine grandchildren. Kirk plans to spend his retirement on the golf course, mastering the guitar and traveling.

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Categories: Cancer