Sugar and Cancer: Is There a Connection?

 

The facts about sugar and cancer can be confusing. They often are presented in a way that is misleading and anxiety-producing for people with cancer. However, if you learn a bit about the science behind the connections between what we eat and cancer risk, you can make wise nutrition choices for better health.

The concept that sugar feeds cancer is not useful. Sugar feeds every cell in our bodies. Our bodies need glucose, or simple sugar, for energy. Even if you cut every bit of sugar out of your diet, your body will make sugar from other sources, such as protein and fat.

So cancer cells need sugar to grow, just like healthy cells. It helps to remember that there is nothing particular about sugar that “feeds” cancer cells any more than sugar feeds all cells in our body.

Do I need to be concerned about sugar?

Even though sugar doesn’t exactly “feed” cancer cells, it is a good idea to limit the amount of simple sugar you eat. This is because when you eat a lot of sugar, your body produces a lot of insulin.

Insulin is a natural substance made by the body. Insulin can tell cells to grow. In simple terms, insulin can “rev up” cell growth. For healthy cells, this is a good thing. This is because the cells in your body grow, divide, die, and are replaced as part of the natural process of living. However, cancer cells can be encouraged to grow more, too, when our bodies produce too much insulin. So while some insulin in the body is normal, excess insulin may encourage cancer cells to grow more, which is not a good thing (1-6). 

This is the downside of insulin: Our bodies need it to function, but it’s unhealthy if we make too much of it.

In summary, sugar does not “feed” cancer cells. However, a lot of sugar can cause our bodies to produce too much insulin, and this is not good for health.

Should I avoid all sugar?

You don’t have to avoid every bit of sugar in your diet. Nor should you avoid all carbohydrates. In fact, the best sources for healthy, complex carbohydrates such as vegetables, fruit, whole grains, and legumes (beans), are the very foods that appear to fight cancer best (7-17). So if you do not need to avoid all sugar and other carbohydrates, what is the answer?

There are three other things in the diet that can help reduce the amount of insulin produced by the body when you eat sugar and carbohydrates. These are protein, fat, and fiber. When eaten along with even the simplest sugars, these three items help the body to make less insulin in response to simple sugar.

If you eat sugar with some protein, some fat, or some fiber, your body won’t produce as much insulin. Eating this other food helps your body process sugar more slowly, and this means that your body does not overproduce insulin. In short, protein, fat, and fiber help your body process sugar in a more healthful way.

Putting the Information to Work for You

For an example of how this works, think about fruit and fruit juice. The amount of insulin your body makes after you eat a piece of fruit is much lower than the amount of insulin produced when you drink fruit juice. Whole fruit contains fiber and that fiber helps balance out the sugar in fruit.

For another example, think about eating specific foods together to get a healthier snack or meal. Instead of having two pieces of fruit as a snack, try having one piece of fruit and a small handful of nuts. The nuts contain protein, fat, and fiber. These three things help your body keep insulin in balance.

The Bottom Line

The most important point is that sugar itself is not bad. However, too much sugar, without enough protein, fat, and fiber to balance it out, can cause our bodies to make too much insulin. It is not the sugar, but rather the insulin that may be a problem for spurring cancer cell growth (18-33). To prevent this, you should limit the simple sugar in your diet. There is no need to follow a stringent diet and swear off every single dessert. The key is moderation. Use the following tips to help yourself find a healthy balance with your food choices:

  • Stick with naturally occurring sugar, such as the sugar that is found in fruit. This is a much healthier option than processed sugar that is found in candy, cake, desserts, pie, and baked goods.
  • Avoid concentrated sources of sugar, such as soda and fruit drinks. It is OK to have 100 percent fruit juice in moderation. Stick to a 6-ounce serving. But avoid fruit drinks that don’t contain any real fruit juice.
  • Limit your “treats,” such as dessert, to just a couple of times each week. Have a modest serving size.
  • Focus on whole, healthy, unprocessed food, including vegetables, fruit, whole grains, legumes (beans, lentils, and peas), nuts, and seeds.

When you understand the science behind the headlines, you can relax and focus on eating a healthy, well-balanced diet that you can enjoy and that will put you on the road to wellness.

References

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This content was last reviewed August 15, 2010 by Dr. Reshma L. Mahtani.
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