Sugar: Does it cause cancer?

Does sugar feed cancer? Not exactly. There is no current evidence that shows a direct link between sugar intake and cancer growth! But, here’s what we do know:

  • A diet high in simple or added sugar increases our risk for diabetes, which is linked to an increased risk for cancer
  • Excess body weight can also increase our risk for cancer, and over-consumption of sugary foods can lead to weight gain
  • Sugar (glucose) comes from all types of carbohydrate foods.

There are two types:

  • Added, or simple sugars, which we may add to foods or drinks to sweeten them, and are often found in processed foods. These types of sugars break down quickly with digestion, raising blood glucose levels rapidly. Rapidly rising blood glucose means an increased need for our body to produce insulin. There has been some research that shows there may be a connection between cancer growth and high insulin levels.
  • Natural occurring sugars, usually called complex carbohydrates. These are often found in minimally processed foods like milk, fruits, vegetables, beans, and whole grains. This type of sugar breaks down slower because it’s “complex,” causing a slow rise in blood glucose levels. These foods also contain cancer-fighting chemicals called phytochemicals, as well as other vitamins and minerals that keep our bodies functioning.

Yes, it is often best to choose foods and drinks with naturally occurring sugars instead of those with added sugars, but if you are having difficulty with getting adequate calories, or are losing weight without trying, you are at risk for malnutrition.

If you do not eat or drink enough to provide your body with adequate energy, your body will find a way to make glucose, typically utilizing your muscle first, then sometimes fat stores, causing weight loss. People who are malnourished, often have a more difficult time completing cancer treatment, or recovering from cancer treatment, so it’s best to focus on adequate intake during treatment to prevent malnutrition, even if that means consuming foods or beverages that have added or simple sugars sometimes.

Once you are feeling better, the best thing you can do to prevent cancer from coming back is to eat a diet high in plant-based foods, such as fruits, vegetables, and whole grains; stay physically active; and maintain a healthy weight to prevent increased risk of other health problems.


  • Oncology Nutrition DPG, “Sugar and Cancer”, July 2014
  •, “Does Sugar Feed Cancer?”, August 2016