You might have heard that sugar causes cancer or makes it grow faster. In some ways, this makes sense. Every cell in your body uses blood sugar (glucose) for energy. But cancer cells use about 200 times more than normal cells. Tumors that start in the thin, flat (squamous) cells in your lungs gobble up even more glucose. They need huge amounts of sugar to fuel their growth.
The sugar your cells need comes from your diet. And not just from gooey desserts or giant white chocolate mochas. Sugar is also found in:
- Fruit (fructose)
- Vegetables (glucose)
- Dairy products (lactose)
- Carbs like bread, pasta, and rice
What would happen if you cut out these foods? Would that slow cancer or stop it from forming in the first place?
So far, there’s not much proof that a low-sugar or low-carb diet lowers your chance of cancer. One exception is cancer of the esophagus, the tube that runs from your throat to your stomach. A recent study suggests that sugar and sweetened drinks may raise the chances of this cancer by 70% or more.
Is It Obesity?
Many experts, including the American Cancer Society and National Cancer Institute, don’t think sugar causes cancer. They say the real problem is obesity.
Fat cells release inflammatory proteins called adipokines. They can damage DNA and eventually cause tumors. The more fat cells you have, the more of these proteins you’re likely to have.
Being overweight or obese puts you at risk for at least 13 types of cancer, including breast, liver and colon cancer.
Other cancer experts say sugar itself can drive cancer. One such expert is noted cancer researcher Lewis Cantley, PhD, director of the Meyer Cancer Center at Weill Cornell Medicine in New York.
Cantley thinks some cancers may start with high levels of insulin, the hormone that controls the amount of sugar in your blood. He says his research shows that “having high levels of insulin is likely to drive cancer. And what drives insulin levels is sugar.”
He doesn’t eat any sugar himself because he believes the link between sugar and cancer is clear.
What Should I Eat?
Even if you don’t think sugar can cause cancer, it’s still a good idea to eat less sugar. Research says you should shoot for 6 teaspoons a day if you’re a woman and 9 if you’re a man. Yet most people in the U.S. eat about 22. That’s 130 pounds of sugar each year.
Cantley says that means many Americans have high insulin levels all the time and a higher risk of cancer.
Peiying Yang, PhD, a cancer researcher and associate professor at M.D. Anderson Cancer Center in Houston, agrees.
“I would be surprised if reducing sugar consumption wouldn’t help reduce cancer risk,” she says. “It makes sense to limit added sugar, including high-fructose corn syrup in soft drinks, sweetened teas, sports drinks, and processed foods, along with candy, cookies, ice cream, and sweetened breakfast cereal.”
She’s often asked whether it’s OK to eat fruit, since many fruits are high in fructose.
“It’s fine to eat fruit as part of a normal diet,” Yang explains, “but there should be less fruit than vegetables. If the recommended serving is five fruits and vegetables a day, at least three servings should come from vegetables.”
What to Watch For
It can be tough to track down all the sugar you eat. It’s hidden in things you’d never expect, like soups, salad dressings, peanut butter, yogurt, ketchup, instant oatmeal, nut milks, and hot dogs.
And often, it’s not even called sugar (sucrose) on the label.
There are more than 60 names for added sugar. Some, like maltose, dextrose and glucose, end in “ose.” Also watch for:
- Fruit nectar
- Corn, rice, and maple syrups
They may sound healthier than sucrose. But to your cells, they’re all just sugar.