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Foods to Avoid During Prostate Radiation [& What to Include]

If you’re looking for nutrition tips while undergoing radiation therapy for prostate cancer, you are in the right place.

You’re likely wondering: What foods should I avoid during radiation? What can you eat during radiation for prostate cancer? Does food intake even matter?

As a Registered Dietitian, I’m here to break down the scientific recommendations regarding foods to avoid during prostate radiation. Plus, foods to include to optimize treatment.

Let’s dive in!

Radiation Options for Prostate Cancer

First, there are a handful of radiation options for prostate cancer. You and your oncologist will decide on the best treatment for you. 

Each treatment route will have different goals and side effects. Therefore, some nutrition tips will vary.


  • External Beam Radiation
    • 3 Dimensional Conformal Radiation therapy
    • Intensity Regulated Modulated Radiation Therapy
    • Stereotactic Body Radiation Therapy (AKA CyberKnife) 
    • Proton Beam Radiation Therapy
    • Image Guided Radiation Therapy
  • Brachytherapy (internal radiation)
    • Permanent Radiation
    • Temporary Radiation 
  • Radiopharmecuticals
    • Drugs that contain radioactive chemicals
      • Target prostate-specific membrane antigen

To read more about these therapies check out, The American Cancer Society.

How Radiation Works

Radiation uses high energy particles or waves to damage cellular DNA. It targets a specific area.

Radiation can kill or slow the growth of cancer cells. Cancer cells cannot repair themselves. So, exposing these cells to radiation kills them.

On the other hand, healthy cells in the body have repair mechanisms. Radiation can kill cancer and healthy cells. But, healthy cells have the ability to repair themselves. Therefore, radiation is not damaging healthy cells while killing cancer cells.

The timeframe of different forms of radiation varies. 

External Beam Radiation

In external beam radiation therapy (EBRT), beams of radiation are aimed at the prostate gland using a machine. 

Newer machines can pinpoint the tumor and direct radiation in that spot. This is typically a higher dose of radiation.


With brachytherapy, small radioactive pellets are placed directly on the prostate. These are placed in an operating room. 

Brachytherapy can be combined with EBRT, at different points in time.


Radiopharmaceuticals are drugs that are injected into the body. The serum finds and kills the cancer cells with radiation. Interestingly, these drugs can reach cancer anywhere in the body.

Side Effects of Radiation for Prostate Cancer

Everyone experiences different side effects post radiation treatment.

Common side effects of radiation include:

  • Diarrhea
  • Rectal Pain
  • Urinary Incontinence
  • Fatigue
  • Nausea
  • Erection Problems
  • Lymphedema 
  • Dry Mouth
  • Mouth Sores
  • Constipation
  • Loss of Appetite

Radiation therapy may also compromise your immune system.

The Role of Nutrition

Once you start radiation, it may be hard to follow your usual diet plan. 

Eating well while you’re being treated for cancer can impact your overall treatment.

Proper nutrition can help you:

  • Heal and recover faster
  • Provide energy
  • Prevent weight loss
  • Help tolerate treatment side effects
  • Feel better
  • Lower risk of infection

Head over to the Prostate Cancer Nutrition Blog Page to learn more about nutrition’s impact on treatment and recovery.

Diet During Prostate Radiation

Overall, most foods are ok to include while undergoing radiation for prostate cancer. Everyone will have a diverse journey and experience different symptoms (if any). 

Some foods are best to be eliminated from your routine. On the other hand, some diet adjustments are recommended based on symptoms. Additionally, there are some recommended foods to include during prostate radiation.

Foods to Avoid During Prostate Radiation

Let’s begin with a few foods to avoid during prostate radiation. 

These are overall recommended adjustments. Speak with your doctor or dietitian for a most personalized approach.


Number one, alcohol. In general, alcohol does not provide many benefits. Drinking too much alcohol can harm your health. 

Alcohol can affect the brain, heart, liver, and pancreas. Heavy consumption has been associated with cancer.

If you’re experiencing decreased appetite, alcohol will likely fill you. This will leave you with a full stomach without receiving any nutrients. Your body needs nutrients during radiation and life. This habit can even lead to malnutrition.

Malnutrition can lead to treatment complications, hospital visits, and decreased quality of life.

In some cases, alcohol can alter the effect of medications. 

However, there is no strict regulation on alcohol intake while undergoing prostate radiation. One study determined moderate alcohol consumption to be safe in prostate cancer patients.

I’d recommend limiting intake and avoiding heavy drinking.  


Supplements are generally not recommended while undergoing cancer treatment. These include vitamins in capsule, powder, tablet, and gummy forms. 

There are even mixed reviews on using multivitamins during treatment.

Yes, vitamins and minerals are necessary in our bodies. However, we can get adequate amounts from food. Too much of one vitamin can cause toxicity and lead to harmful effects.


  • Vitamins/Multivitamin
  • Minerals
  • Fish Oil/Omega 3 Fatty Acid
  • Herbs in altered form

Plus, antioxidant supplementation may reduce the effectiveness of radiation.


  • Vitamin C
  • Beta Carotene or Vitamin A
  • Selenium
  • Vitamin E 
  • Zinc

Additionally, avoid herb supplements. Most of these pills are not regulated by the FDA. 

Herb Supplements:

  • Turmeric
  • Ashwagandha
  • Echinacea

It is worth noting, there is a correlation between vitamin E supplementation and prostate cancer risk. 

Speak with your doctor to determine if you require repleting of any vitamin. 

On the flip side, use of probiotic supplementation may reduce diarrhea and rectal volume. Speak with your oncologist to determine if probiotic supplementation is best for you. 

Above all else, there have been no adverse effects of eating foods specifically high in antioxidants, omega 3s, and vitamins or minerals. Use of foods rich in omega 3 fatty acids and antioxidants have shown beneficial outcomes on cancer treatment side effects.

Gassy Food

For prostate cancer patients, it is recommended to limit gassy foods prior to treatment. Large amounts of gas in the bowel can affect the area being treated.  

Limiting these foods is also recommended during and after treatment. Given the location of the prostate to the rectum, inflammation of the rectum is common in prostate radiation. Limiting gassy foods during this time may decrease symptoms.

Long term, these foods can be apart of an overall healthy diet.

Gassy Foods: 

  • Carbonated Drinks
  • Energy Drinks
  • Beans
  • Chickpeas
  • Lentils
  • Broccoli
  • Cauliflower
  • Cabbage 
  • Brussels Sprouts

Foods with High Risk of Food Borne Illness

Radiation can compromise your immune system. Some foods are best avoided to reduce the risk of food borne illness. 

Raw and uncooked foods can hold bacteria leading to food poisoning. During treatment, your immune support is not as strong as it was, so eating these foods can lead to illness.


  • Raw Fish
  • Raw Egg
  • Raw or Undercooked Meat
  • Unpasteurized Dairy
  • Unwashed Fruits and Vegetables
  • Unpasteurized Fruit Juice and Cider

Sugar Substitutes

Sugar substitutes can include sugar alcohols and noncaloric sweeteners. For some, sugar substitutes can cause gas, bloating, abdominal discomfort, and diarrhea (1). Therefore, it is recommended to avoid during prostate radiation.

When choosing foods, check the ingredient list for foods with the below listed sugar alternatives.

Sugar Substitutes as Ingredients:

  • Aspartame
  • Sorbitol
  • Saccharin
  • Xylitol
  • Sucralose

These types of sugars are found in diet foods and drinks.


  • Diet Soda/Juice
  • Sugar Free Candy and Gum
  • Sugar Free Desserts
  • Splenda, Sweet N Low, Equal, Stevia

Check out overall Foods to Avoid for Prostate Health for additional info.

Foods to Eat During Prostate Radiation Treatment

We can’t discuss foods to avoid without touching on foods to eat during prostate radiation treatment.

Again, most foods are fine to include during treatment. Some foods provide extra nutrition that’s necessary during this time.


Hydration is an essential component during radiation treatment. In general, our bodies need water to hydrate tissues and cells so they can function properly. 

On top of that, water helps flush out toxins which can help reduce unwanted side effects.

Some of Water’s Role:

  • Gets Rid of Waste
  • Maintains Body Temperature
  • Protects Joint and Tissues
  • Maintains Blood Pressure
  • Carries Nutrients and Oxygen

Inadequate water intake can lead to dehydration. In general, cancer patients are at risk of dehydration.

Dehydration Can Lead To:

  • Dizziness
  • Lightheadedness
  • Dry Skin
  • Confusion
  • Dry Mouth
  • Headache 
  • Low Blood Pressure
  • Severe Complications

Additionally, drinking a consistent amount of water prior to treatment is essential. This is to keep your bladder size consistent during all treatments. 

It’s necessary to drink water daily to assure your tissues are hydrated. This way, when you need to fill your bladder for treatment, the water goes directly to your bladder and does not need to stop to rehydrate parts of your body.

One study recommends 300-400ml of water prior to all treatments.

Finally, many radiation side effects (such as diarrhea and vomiting) can lead to dehydration. It’s especially important to ensure adequate fluid intake during this time.

Immune Boosters

Due to the above mentioned compromised immune system, risk of infection is increased while undergoing prostate radiation. Luckily, some foods can aid in lowering risk of infection by enhancing the immune system. 

Adequate vitamins and nutrients can help fight infection during treatments. Be sure to include fruits and vegetables regularly. 

Probiotics, antioxidants, and omega 3 fatty acids have been shown to improve immune functions. On top of that, selenium, vitamin C, zinc, and vitamin E can promote a stronger immune system (2)

As stated above, these should not be taken in supplement form. However, it is a good idea to focus on foods high in these nutrients.

Unfortunately, some foods rich in these vitamins may not be recommended during prostate radiation due to their gassy effects.

To emphasize, obtaining these vitamins in pill form is not recommended. It’s possible to consume proper amounts with food.

Include as tolerated:

  • Probiotic rich foods (yogurt, kefir, sauerkraut) 
  • Berries
  • Herbs and Spices
  • Ginger
  • Green Tea
  • Cooked Tuna
  • Cooked Salmon
  • Kiwi
  • Tomatoes
  • Avocado 
  • Oranges
  • Cooked Eggs
  • Walnuts
  • Garlic and Onion (as tolerated)

Download your Free Copy of The Essential Guide to Grocery Shopping for Prostate Health.

Prostate Radiation Side Effect Nutrition Tips

Everyone experiences different side effects during radiation. Nutrition interventions can help alleviate symptoms. Each man can determine their own foods to avoid for prostate radiation.

Gastrointestinal Issues

Gastrointestinal issues can be common in radiation therapy. As stated above, the close proximity of the prostate and GI system can lead to GI related issues.

Relationship Between Prostate Radiation and Bowel Function

Prostate radiation can cause bowel dysfunction. In some cases, the lining of the bowel may become inflamed.

Undergoing prostate radiation may cause damage to the rectum due to the close proximity between the prostate and these organs.

But what does this mean? This means that patients may experience trouble passing stools or even the inability to control their bowels. Additionally, those undergoing radiation therapy may experience diarrhea, constipation, or abdominal discomfort.

“Avoiding foods that might irritate the gastrointestinal tract is important, but complete elimination of fibrous, bulky foods can lead to constipation and straining, which in turn can exacerbate rectal bleeding.”Hopkins Medicine

Some foods are easier to digest than others. So, if you’re experiencing general bowel problems consider including easy to digest foods.


  • White Bread/Toast
  • Boiled or Baked Poultry
  • White Rice 
  • Potatoes/Sweet Potatoes
  • Bananas


  • Fried Food
  • Cruciferous Vegetables
  • Spicy Food
  • Popcorn


 If you’re experiencing diarrhea, avoiding and including some foods can help.

Radiation treatment can cause inflamed intestines leading to diarrhea. Some foods aggravate the GI system more than others. Avoiding foods high in fat, fiber, lactose, and sugar may help. 

Plus, eating small, frequent meals has been shown to improve diarrhea. 


  • Foods high in sugar
  • Caffeine
  • Soda
  • Spicy Food
  • High Fiber Grains (whole wheat bread/cereals) 
  • Cream
  • Ice Cream
  • Dried Fruit
  • Raw Fruits and Vegetables (aside from bananas and melon)
  • Corn
  • Brussels Sprouts
  • Sugar Alcohol


  • White Rice/Bread
  • Banana
  • Potatoes without skin
  • Eggs
  • Crackers
  • Applesauce
  • Water
  • Rehydration Beverages
  • Yogurt with Live Active Cultures


Likewise, avoiding and including some foods can aid in constipation. Slow increase of fiber is key. 

Choose a handful of options on the “Include” list within the next few weeks. Too much fiber at once can cause discomfort. 

The foods on the avoid list are technically ok to consume. However, they can be easily substituted for a higher fiber option.


  • White Rice
  • Potatoes
  • Fruit Juice
  • White Flour


  • Water (aim for at least 64oz daily) 
  • Beans
  • Brown Rice
  • Barley
  • Oats
  • Quinoa
  • Whole Grain Bread/Cereal
  • Fruits and Vegetables

Additionally, walking and other physical activity can help relieve constipation. Check with your provider prior to participating in physical activity.

Bowel Function

For some, a goal may be to limit bowel movements during treatment.

A clinical trial showed that adherence to a low FODMAP diet led to less rectal gas and rectal volume. Low FOPMAP diets have been successful in managing Irritable Bowel Syndrome (IBS) symptoms. It is not meant to be a long term diet plan. 

IBS symptoms are similar to prostate radiation symptoms: bloating, abdominal pain, and change in bowel habits. 

What is Low FODMAP?

The full acronym stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. The idea is to swap out high FODMAP foods with low FODMAP foods. 

A few High FODMAP Foods:

  • Garlic
  • Onions
  • Artichokes
  • High Fructose Corn Syrup
  • Apple Juice
  • Legumes
  • Cow’s Milk
  • Wheat 
  • Dried Fruit
  • Mango
  • Watermelon

Low FODMAP Foods: 

  • Carrots
  • Cucumber 
  • Lettuce 
  • Potato
  • Cantelope
  • Strawberries
  • Peanuts
  • Eggs
  • Oats
  • Tofu
  • Almond Milk

Learn more about the FODMAP diet at Monash University.

Abdominal Discomfort or Gas

If you are experiencing abdominal discomfort, it may be worth limiting intake of some foods. 

Some foods can worsen abdominal pain and gas. Most of the below listed foods are also noted in foods to avoid during prostate radiation. The high fiber/gassy foods can contribute to abdominal pain. 

Constipation can cause gas. Slowly increasing fiber intake can help alleviate constipation (see above).  

Overall, it’s recommended to limit high fiber foods when experiencing abdominal pain. A low fiber diet reduces the frequency and volume of stools. 


  • Beans/Legumes
  • Cruciferous Vegetables
  • Sugar Substitutes
  • Dried Fruit
  • Seeds
  • Red/fatty Meats
  • Cream
  • Fried Food
  • Acidic Food
  • Gum and Hard Candy
  • Beer


  • Water
  • White Bread and Flour
  • Cooked Eggs
  • Tofu
  • Melon
  • Canned Fruits in 100% Fruit Juice

Loss of Appetite

Loss of appetite is a common symptom of cancer treatment. 

Weight loss may sound great for some, but significant weight loss during radiation can be dangerous. 

Maintaining a healthy weight and assuring adequate nutrition during therapy is essential for best outcomes. Additionally, maintaining weight is important for proper dosage of radiation.

If you’re struggling to consume adequate calories during radiation treatment, your best bet is to focus on energy dense foods. 

When it comes to energy and nutrient dense foods, you will be able to eat smaller portions and still get nutrition. 

On the flip side, the food to limit would be less energy dense foods. These foods will fill you up without providing much nutrition. 

It may be beneficial to eat small meals 6-8 times a day as tolerated. Additionally, remind yourself to eat. You do not need to wait until you’re hungry. 

You may have heard of the foods on the avoid list as “empty calories.” While we’re working toward adequate nutrition with loss of appetite, it’s important to increase nutrient dense foods to ensure proper nutrition with smaller volume. 

If you are only able to tolerate certain foods, then of course eat those. I’d recommend working with an oncology dietitian to find personalized ways to increase energy intake. 

Make every bite count! 


  • Potato Chips and other Chips
  • Low Fat Dairy (milk, yogurt, ice cream, cheese) 
  • Soda
  • Alcohol


  • Oral Nutrition Supplements (Ensure, Boost
  • Nut Butter 
  • Nuts
  • Seeds
  • Full Fat Dairy 
  • Protein Powder or Shakes (Premier Protein, Orgain)
  • Avocado
  • Eggs
  • Smoothies
  • Extra Virgin Olive Oil 
  • Milkshakes

Overall, try and add more to the foods you’re currently tolerating. 

Example: if you eat oatmeal in the morning, add berries, nuts, or nut butter. 

If you’re having a decreased appetite because of nausea, consider these Ginger Chews to help relieve nausea.

Mouth Sores

When it comes to prostate radiation, mouth sores are the most typical in those using radiopharmaceuticals. 

As you can expect, mouth sores can cause pain and make it difficult to eat and drink. If you are experiencing mouth sores, consider these tips and foods to avoid during prostate cancer radiation.


  • Citrus Food
    • Oranges and Orange Juice
    • Lemons and Lemonade
    • Grapefruit
    • Limes
    • Clementines 
  • Spicy Food
    • Spicy Salsa
    • Jalapenos
    • Hot Peppers 
    • Cayenne Pepper
    • Chili Powder
    • Some Curry
    • Red Pepper Flakes
  • Salty Food
    • Prepackaged Snacks
    • Fried Food
    • Many Take Out Options
    • French Fries
    • Canned or Frozen Foods
    • Smoked Meat
  • Alcohol and Carbonated Drinks

While experiencing mouth sores, some foods seem intolerable. Try including easy to swallow foods and drinks. 


  • Ice Cream 
  • Smoothies
  • Milkshakes 
  • Pudding
  • Yogurt
  • Applesauce
  • Jello
  • Protein Drinks
  • Mashed Potatoes
  • Softened or Puree Foods with Gravy 

Bonus Tip: Rinse your mouth with 1 quart of water mixed with ¾ teaspoon salt, 1 teaspoon baking soda throughout the day to help with pain. 


Nutrition interventions can help optimize your prostate radiation treatment plan. Food can be helpful during this time by providing proper nutrients.

Prostate radiation may come with some unwanted side effects. Luckily, some food and nutrition tricks can help alleviate symptoms.

There are some foods to avoid during prostate radiation. Likewise, there are foods recommended to include during prostate radiation for added benefits.

Don’t forget to sign up for your Free Copy of my Essential Guide to Grocery Shopping for Prostate Health!

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Additional References

  1. Yadav P, et al. Sugar Substitutes and Health, IOSR Journal of Dental and Medical Sciences. 13(8):68-7. DOI: 10.9790/0853-13836875
  2. Tirpathi M, Kotwaliwale N. Functional foods that boost the immune system and fight infections. Octa Journal of Biosciences. Vol 8(1): 14-16.

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