Sugar and Cancer: Wilmot Registered Dietitians Weigh In on What You Should Know

Aug. 15, 2018

Sugar. It’s a topic that often comes up when discussing diet, particularly for those concerned about cancer. Some may wonder about the impact of eliminating sugar when it comes to cancer risk, but unfortunately, it’s not a simple answer because healthy cells need sugar to make energy. Wilmot’s registered dietitians, Sue Czap and Melissa Zahn, help explain the relationship between sugar and cancer.


Can sugar cause cancer?sugar slipping through fingers

In a word, no.  We cannot point to a specific nutrient or food, like sugar, and say definitively that it causes cancer. A healthy eating pattern based on whole, plant-based foods is recommended to reduce the risk of developing cancer. Research also does show that being overweight and having excess body fat can contribute to cancer risk. Being overweight occurs when you eat too many calories and/or exercise too little.  For most people, these extra calories come in the form of high sugar foods such as sweets, soda and other sweetened drinks.  Eating these types of foods also causes inflammation in the body, which can contribute to cancer risk as well as other conditions.   

Because of the relationship between excess weight and body fat and potential cancer cell growth, we recommend a healthy lifestyle, which includes maintaining a healthy weight, eating a balanced diet from all food groups, and getting adequate physical activity, among other behaviors.


As a cancer patient, if I just stopped eating all sugar, would my cancer go away?

Research does not support eliminating sugar from your diet to make cancer go away.

Let’s define “sugar” and talk about where sugar comes from in our diets. Sugar is a type of carbohydrate. In the body, carbohydrates are digested into smaller molecules of sugar, including glucose. All cells in our body need glucose to make energy. 

Sugar is not just in candy or ice cream. It’s also in many healthy foods such as fruits, whole wheat breads and brown rice, sweet potato, corn, beets, peas, beans, artichokes, squash, quinoa, oatmeal, etc. These foods are examples of “good” or “high-quality” carbs and contain many nutrients that are necessary to keep your body functioning properly.

It is not practical or advisable to stop eating all sugar because healthy cells need it to survive. Even without dietary sugar, the body will make sugar from other sources, such as the body’s stored muscle and fat. 


Should I make changes to my diet while receiving treatment for cancer?

Nutrition recommendations are very individualized based on how you tolerate treatment. For example, if you’re having unintentional weight loss, your diet needs to be less restrictive to ensure adequate calorie and protein intake. This may include sugar in the form of juices, ice cream, puddings or premade nutrition supplements. The priority is for you to maintain your body weight, strength and energy levels to avoid treatment interruption. 

After your treatment is over, and any side effects have diminished, then you can return to your usual diet, or even begin a healthy diet for the first time! Your registered dietitian can help you through treatment and get you on the right track to a healthy diet.


How can I reduce the amount of added sugar I eat, and is it ok to have naturally occurring sugar?

Focus on whole foods. Instead of drinking soda or sweet tea, make your own fruit-infused water. Eat whole fruit rather than drink the juice. You’ll get more nutrition and fiber from the fruit than you will from the juice. Replace refined grains, like white bread and rice, with whole grain options, such as whole wheat bread or brown rice.  

Don’t worry too much about foods that naturally contain sugar, like whole fruits and vegetables, whole grains and dairy. Instead, minimize the added sugar present in your diet. That means limiting things like cookies, pies, cakes, and sweetened beverages such as soda pop, juice, or sweetened teas/coffees.


What’s the bottom line?

Maintain a healthy lifestyle, by:

  1. Eating a whole foods, plant-based diet with vegetables, fruits, whole grains and lean protein and limiting processed foods and added sugars.
  2. Getting physical activity. Aim for at least 150 minutes of moderate intensity exercise per week.
  3. Maintaining a healthy body weight.


All of these factors work together to reduce the risk of some cancers or cancer recurrence. If you would like individualized guidance, tell your oncology team you’d like to meet with a registered dietitian.