Top 5 Diet and Cancer Myths

By Shayne Robinson, RD, CSO, CDN and Jackie Topol, MS, RD, CSO, CDN

RefrigeratorWe know that there is a great deal of conflicting information about nutrition that patients may receive from various sources. As Registered Dietitians who are board certified in oncology nutrition, we are here to clear up some of the confusion. Here are some of the most common nutrition myths we hear from patients:

Myth # 1 – Sugar feeds cancer.

Within the body, all carbohydrates break down to sugar which both healthy and cancer cells use for fuel. Research shows that the body responds to a high sugar intake by making more insulin and related growth factors, which influence cancer cell growth. However insulin levels also depend on genetic factors, physical activity, BMI (body mass index), metabolic syndrome (a group of medical conditions linked to insulin resistance) and the type of sugar you eat. Therefore just avoiding sugar is not the right plan for everybody. It’s important to maintain healthy blood sugar and insulin levels during cancer treatment and in general. In prostate cancer, hormonal therapy is associated with weight gain and the way the body processes sugar, so it’s important to be mindful of this when making dietary choices. Ongoing research is looking to target some of these pathways.

The key question to ask is “How much and what type of carbohydrates should I eat?” A Registered Dietitian who is specially certified in oncology nutrition (RD, CSO) can help you design a well-balanced eating plan that best fits your needs.


Myth #2 – I need to avoid raw fruits and vegetables.

Raw fruits and vegetables that have been washed can be eaten while you are receiving chemotherapy and/or radiation. If you have a very low neutrophil count (known as “neutropenia”) or a recent bone marrow transplant, your doctor or dietitian may recommend a low microbial diet. On the low microbial diet, you can eat most raw vegetables and most raw fruits that have a smooth skin or a thick peel. The fruits and vegetables we advise not consuming on the low microbial diet are the ones you cannot wash thoroughly or those that may have mold such as raw mushrooms, sprouts, strawberries, blueberries, raspberries, grapes, peaches, and plums. In the current era of treatment for genitourinary cancers, most targeted therapies do not suppress the immune system or require a low microbial diet. Not all cancer patients will have to follow these guidelines since they are specifically for leukemia and bone marrow transplant patients. If you are not sure whether you should be following a low microbial diet or how long you should follow it for, we encourage you to speak to your doctor or dietitian. Additionally, there are certain oral treatments for kidney cancer that are linked with gastrointestinal side effects such as diarrhea. There are ways to include fruits and vegetables in the diet while taking these factors into account. There are many health benefits that go hand-in-hand with eating fruits and vegetables, so make sure to include them in your diet! If you are concerned that you may not be meeting your nutritional needs, you can make an appointment with one of our dietitians who can help.

Reference: and NewYork-Presbyterian’s “Guidelines for the Low Microbial Diet”

Myth # 3 –  Certain foods will increase my white blood cell count.

Chemotherapy drugs, radiation therapy, and cancers of the blood and bone marrow can damage bone marrow and lower white blood cell counts. These cells recover with time.  Blood counts are low because the bone marrow isn’t working properly, not because the body lacks the nutrients to make blood cells.

No specific foods or nutrients increase production of white blood cells, but if you have low blood counts it is very important that you eat well because a well-nourished person recovers quicker from treatment than a malnourished person. Specific foods or nutrients won’t speed up the recovery of your bone marrow, but you do want to eat well so that when your bone marrow recovers all the nutrients that are the building blocks for cells are available for your body to make the white blood cells. A Registered Dietitian specially certified in oncology nutrition (RD CSO) can help you ensure you are eating well and in turn optimize your white blood counts.


Myth # 4 – Cancer survivors must eat only organic produce.

Organically grown produce have lower pesticide residues and synthetic (man-made) food additives, but following an organic diet does not guarantee a healthy diet. In fact, avoiding conventionally grown produce may eliminate some healthy food options. In a study looking at 50 years of scientific articles about the nutrient content of organic and conventionally grown foods, the researchers concluded that organic and conventionally grown foods are not significantly different in their nutrient content. There have not been any direct studies on humans to show that organically grown produce can prevent cancer or other diseases any more effectively than conventionally grown foods.

What does this mean in terms of your grocery list? If you go into the market to buy a fresh organic apple, and they only have conventionally grown produce, don’t walk out with a bag of processed organic chips or cookies… A conventionally grown apple is a better choice than organic processed foods.

References:  (from the Environmental Working Group)

Myth # 5 – I need to avoid soy foods.

It is safe to eat soy! Research has shown that moderate consumption is safe for women with a history of breast cancer, including women previously diagnosed with estrogen receptor positive breast cancer, and that soy consumption may even decrease the likelihood of breast cancer recurrence. Confusion about soy arises from the term “phytoestrogens.” Some soy nutrients have a chemical structure that look a bit like the estrogen found in a woman’s body. This is where the term phytoestrogen originated. However, phytoestrogens are not the same thing as female estrogens. Soy foods do not contain estrogen. Men with prostate cancer who are taking hormonal therapies also commonly inquire about the impact of eating soy, but again, soy is okay to eat. If you consume soy products, we recommend choosing whole soy foods such as such as soymilk, tofu, tempeh, edamame, soy nuts, and miso. You can have up to two servings per day.  One serving would be 1 cup of soymilk; ½ cup of tofu, tempeh, or edamame; ¼ cup of soy nuts; or 1 tablespoon of miso paste. It is best to get soy directly from foods sources; we do not recommend taking a soy isoflavones supplement.


Nothing replaces the individualized counseling you will receive from working with an RD on a one-on-one basis. We’re here to help you.

shayne Robinson_head shot 2Shayne Robinson RD, CSO, CDN is an oncology dietitian at New York-Presbyterian.  To make an appointment, call the Outpatient Nutrition Practice at (212) 746-0838 (physician referral required). 

Jackie Topol RD_Headshot_jgt9003
Jackie Topol, MS, RD, CSO, CDN is an integrative dietitian at
Integrative Health at NYP – Weill Cornell Medicine, located at 211 East 80th Street. To make an appointment, please call: 646-962-8690.

When Food and Cancer Meds Don’t Mix

Food_Meds_CancerWhat you eat and drink can affect the way your cancer medication works. It is important to have a well-balanced diet and to make sure you are getting enough nutrients, while simultaneously avoiding foods that could alter treatment or damage your body.

After oral medications are ingested, the drugs are broken down and absorbed by the body. This process begins in the digestive system. Sometimes, certain drinks, foods, and medications don’t mix. That’s because levels of certain enzymes in our gut (which are responsible for breaking down large substances into smaller substances) change during the digestive process. These changes can increase or reduce the level of the medication that gets absorbed by the body, making some meds weaker and others stronger. This is problematic because doctors intentionally prescribe a specific dosage based on your type and stage of cancer, as well as other factors such as your height and weight.

Additionally, there are several negative “food-drug interactions” that are well established. For example, grapefruit interferes with the action of some cancer medications since it affects the way enzymes work. Grapefruit has the ability to increase absorption of the drug into the bloodstream, which can be very dangerous. By amplifying the effect of a drug, the medicine is no longer working in the way it was intended and there is increased risk for unexpected side effects and liver damage. This can be very harmful to the body and make the treatment side effects more difficult.  

When in doubt, check the label or package insert of your medication. More than likely, there will be certain foods that your medicines should not be mixed with and directions on how the meds should be taken. For example, the time of day and whether they should be taken with water or food, on an empty or full stomach, etc. These directions are there for a reason, but don’t hesitate to ask your doctor or pharmacist if you are uncertain about these instructions or specific restrictions.

Sometimes, cancer patients turn to vitamins and supplements after learning of a cancer diagnosis. Whether the goal is to seek out alternative medicine, strengthen the immune system, or lessen the treatment side effects, it’s important to always speak with your physician before taking anything. However, there is no conclusive data showing that supplementation benefits cancer patients, so it is not recommended that vitamins and supplements be used. They can interfere with treatment and cause discomfort.

Our team includes dietitians who specialize in cancer care and can provide you with additional information about what to eat and what to avoid in order to reduce side effects and potential negative drug interactions.

Read more about supplement usage with cancer treatment from our oncology dietitian, Shayne Robinson, RD, CSO, CDN, who recently wrote a great piece on the topic for the Weill Cornell Medicine Lymphoma Program’s blog.

Navigating Dinner When the Food Tastes Worse Than the Plate

By Shayne Robinson, R.D., C.S.O, C.D.N

Food photo_Cancer Taste ChangesSweet, salty, savory and sour are words we often use to describe different flavors in the foods we eat, but cancer and its treatments can turn your sense of taste upside down. It is normal to experience taste changes as a result of cancer and cancer treatment. Some people report a bitter or metallic taste in their mouth, while others find that their overall sense of taste has diminished.

How foods taste and smell can change from day to day, and these changes may affect your appetite. To find foods that are appealing, try experimenting with new foods or cuisines, marinades and spices. It can even help to try new ways of preparing the foods you typically eat. Good oral care is also important.

Here are some tips to help combat common cancer-related taste changes:

Loss of Taste

  • Choose foods with strong and/or tart flavors, such as citrus fruits, vinegar and pickled foods. Marinate meats, chicken and fish to infuse flavor. Try strong flavored greens such as arugula or mizuna greens. Caution: avoid acidic foods if you have a sore mouth or throat.
  • Zinc deficiency can decrease your sense of taste. Discuss testing your zinc level and/or supplementing zinc with your health care provider.

Unpleasant Salty, Bitter, Acidic or Metallic Tastes

  • Add a sweet flavor to foods such as topping salad with fruit. Try topping meats, chicken and fish with a fruit chutney.
  • Use plastic utensils or chopsticks if metal forks and spoons taste unpleasant.
  • Add lemon juice, cucumber slices, cranberries or other flavorings to water.
  • Suck on slices of Granny Smith Apples or frozen chunks of pineapple.

Meat Tastes Strange

  • Choose other protein-rich foods (such as poultry, fish, eggs, dairy products, beans, tofu or soy milk) instead of meat.
  • Marinate and cook meats, poultry and fish in sweet juices, soy sauce, acidic dressings or wine.

Overwhelming Food Odors

  • Choose foods that are served cold, such as sandwiches, crackers and cheese, yogurt and fruit, or cold cereal and milk. Foods served hot often have stronger odors.
  • Carry a handkerchief dabbed with oil that has a pleasant odor such as mint or lavender.
  • Eat in cool, well-ventilated rooms that don’t have any food or cooking odors.
  • Drink oral supplements in a covered cup and with a straw to reduce the odor of the supplement.

Oral Care Tips

  • To keep your mouth clean and healthy, rinse and brush your teeth after meals and before bed (or every four hours during the day).
  • Before eating, rinse your mouth with a solution of 1 quart water, ¾ teaspoon salt, and 1 teaspoon baking soda. This rinse can help keep your mouth clean and improve your sense of taste.

While taste changes can be common during cancer treatment, eating well during treatment can decrease side effects. Good nutrition will help you maintain your weight, your strength, and maximize your quality of life.

If you are struggling with taste changes or any treatment side effects that affect your ability to eat, consult with a Registered Dietitian (RD). Nothing replaces the individualized counseling you will receive from working with an RD on a one-on-one basis. To see a dietitian at the NewYork-Presbyterian Outpatient Nutrition Practice call (212) 746-0838 (physician referral required).