Myth vs. Truth: Sugar and Cancer

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By Margaret Martin, RD, MS, LDN, Licensed Dietitian and Nutritionist; Certified Diabetes Educator, PearlPoint Cancer Support


You shouldn’t eat sugar at all if you have cancer. False!

You CAN have small amounts of sugar, even after a cancer diagnosis. Sugar does NOT cause cancer. The myth that sugar causes cancer gives sugar a bad name.

There are many flavors and foods a person with cancer may not be able to swallow or digest. Weight loss and malnutrition is a concern for many cancer patients. Too many food restrictions—such as completely eliminating foods with sugar—may keep cancer patients from eating enough or cause unnecessary stress. It takes lots of time, energy, and resources to limit all sugar in a menu. Aim for a healthy amount of sugar intake daily—less than 10 percent of your calories.

When might some moderation in sugar intake be suggested? Let’s look at when you might keep an eye on your sugar intake.

  • Diabetes, pre-diabetes, insulin resistance or elevated blood glucose readings: If your blood sugar (blood glucose or A1C) lab readings are creeping up, or if you have been diagnosed with diabetes, insulin resistance, or pre-diabetes, you may be advised to eat the same amount of carbohydrates every day. Sugar is one type of carbohydrate. Most types of carbohydrates affect your blood sugar in similar ways—so it is no longer suggested that you eliminate sugar from your meals and snacks. It is recommended to balance your physical activity, health, medications, and carbohydrate intake to maintain the blood sugar range you and your doctor select. The adult brain needs a minimum of 120 grams of carbohydrate daily for proper cognitive function or mental alertness. So, don’t cut yourself short by trying to avoid sugars or overzealously limiting carbohydrates.
  • Concentrated sugar choices frequently replacing healthier foods: If you see a pattern of often eating sweet breakfast foods, desserts, and sweet drinks in place of foods with more nutrition, then you need to swap some foods. Instead of doughnuts for breakfast 5 days per week, reach for whole grain cereal and fruit or a low-fat breakfast sandwich. There is nothing wrong with an occasional dessert or sweet treat. If these occasional treats become a 2-3 times a day habit, you may need to rethink your intake of sweets.
  • Unwanted weight gain during cancer treatment: Are you seeing the number on the scale steadily rising? Are your clothes getting a little too tight? Are you grabbing sweets instead of healthier options? You may want to start a healthier food habit or two. A piece of fruit about the size of a baseball carries about 60 calories. A snack cake, however, may have 120 calories, twice the calories of fruit. Over time those snack cakes may start to add inches to your waist. Sugar has only limited nutrients and carries a lot of calories (4 calories per gram). So instead of a snack cake, grab nature’s original fast food, a piece of fruit or sliced veggies. Instead of frequently using added sugar or beverages with lots of simple sugars, reach for a piece of fruit. Add extra fruit or carrots to your smoothie instead of honey or table sugar. Swap out sweets for tangy or tart flavors at a meal to challenge your taste buds. Finally, try a natural sugar substitute like stevia.

If you are worried about your sugar intake, ask your oncology healthcare team what is healthy for you!

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