Fact Check: Does Sugar Cause Cancer?

Our relationship with sugar can be a tough one. We know that it’s not good to have too much of it. But we also know our bodies and our brains crave it. And let’s be real ... it’s delicious.

So, when you hear that sugar causes cancer or feeds cancer cells, you can’t help but feel torn as you stare longingly at the bakery case.

But is it true? Does eating sugar cause cancer?

Oncology dietitian Michela Palma, RD, LD, explains the connection.

The relationship between sugar and cancer

Sugar doesn’t directly cause cancer. At least not in the way that smoking or sun exposure does.

In the United States, the National Toxicology Program (NTP) publishes lists of known and possible carcinogens (substances that cause cancer). Sugar doesn’t make the cut.

That’s the quick answer.

The full answer is more complex.

“It’s not that sugar causes cancer, it’s that excess sugar leads to excess calories. This can lead to excessive weight gain and metabolic syndrome — and that can increase cancer risk,” Palma explains.

In other words, eating sugar doesn’t give you cancer. But a high-sugar diet can set off a chain reaction that raises your risk.

Foods that are high in added sugar include sweet treats and sugar-sweetened beverages. Additional risk comes from eating an excess amount of simple carbohydrates, which also includes refined grains.

Let’s look at it step by step.

1. You eat sugar. Added sugar (also referred to as glucose) comes from carbohydrate-containing foods. These are all foods except for protein and fats.
2. Your body uses a certain amount of that sugar to help keep your systems running. It’s your cells’ preferred food source to power your body.
3. If you have more sugar in your system than your body can use, it gets stored away as fat cells. If you continue to eat more sugar than your body needs, you’ll continue to add fat cells.
4. Excess body fat leads to health concerns like obesity, diabetes, inflammation and insulin resistance.
5. Those conditions can raise your risk for a number of cancers, including breast, colon, upper stomach and pancreatic cancer.

So, no, it’s not as simple as eat-sugar/get-cancer.

It’s more like eat-too-much-added-sugar/get-excess-calories/raise-your-risk-for-chronic-conditions-that-raise-your-risk-for-cancer.

Does sugar feed cancer?

Even if sugar doesn’t necessarily cause cancer, does it help cancer grow and spread?

Yes and no.

“Yes, cancer cells feed on sugar, but so does every other cell in your body,” Palma clarifies. “In fact, cancer cells will also feed off of protein and fat as well. So, if you cut out sugar to ‘starve the cancer,’ you can also deprive the rest of your body of the nutrients it needs. You can’t starve the cancer without starving your healthy cells, too.”

Now, we’re not talking about your body needing sugar bombs like candy or double chocolate chip cookies. Refined, added sugars aren’t what your body needs.

But the complex carbohydrates you get from foods like fruit and whole grains? Your body uses the nutrients in those foods — sugar included — to keep you going. And when you have cancer — particularly if you’re undergoing treatments like radiation, chemotherapy or immunotherapy — you don’t want to deprive your body of much-needed fuel.

“A lot of people who undergo cancer treatment are at risk for malnutrition,” Palma points out. “It’s very important to nourish your body and fuel yourself well to keep your immune system strong and tolerate the treatment.”

Tips for healthy sugar intake

Even if sugar doesn’t immediately lead to cancer, it’s still important to be mindful of how much you’re eating. Keeping your intake at a healthy level can help you avoid a host of health concerns, cancer included.

Palma offers these tips to follow a sugar-smart diet.

• Know your limits. The Dietary Guidelines for Americans recommend limiting adding sugars to no more than 10% of your total calories per day. That’s 50 grams of added sugar for people following a 2,000-calorie-per-day diet.
• Ballpark it. If counting grams is too much, start by cutting back the number of times you eat processed sweets. Ideally, it should be fewer than three per week. “It’s not all-or-nothing,” Palma says. “Nothing is off the table. It’s about how often you’re having sugar, not whether you can have it at all.”
• Consider your beverages. Sweet drinks are probably the first place to start if you’re cutting back on sugar. Limit your intake of soda, sweetened tea, juices and sugary coffee concoctions.
• Mind your refined grains. Whole grains contain fiber, so they help your body to absorb sugars more slowly. Opt for whole-grain breads and brown rice, rather than white bread and white rice. And experiment with other grains like quinoa, oats and buckwheat.
• Don’t fear fruit. Whole fruits come with fiber, vitamins and minerals that your body needs. And that sweet, sweet taste can be just the thing you need if you’re trying to stay away from less-natural desserts. Cut back on added sugar, but not the natural kinds.
• Try the “plate method.” Not sure what exactly a balanced diet entails? Your plate should look like this: half non-starchy vegetables, a quarter lean protein and a quarter starchy carbs (ideally whole grains).

Bottom line

Sugar doesn’t exactly give you cancer. But a diet full of refined sugars isn’t doing you or your cancer risk any favors.

If you’re concerned about how your diet and sugar intake are affecting your health and your risk for cancer and other conditions, talk with a healthcare provider. They can help you find the sweet spot between too much sugar and just enough to keep your body healthy and your sweet tooth satisfied.