- Health risk
Sugar and cancer: Is there a link?
- Sugar is the modern-day diet villain, but does it cause cancer?
- Does sugar feed cancer cells making them grow more aggressively?
- How does the sugar we consume through food and drink affect our health, and what can be done about this?
These are just a few questions we try to answer as we take a long hard look at sugar and its relationship with cancer. We hope to bust some myths and share what researchers are studying in the hope of finding new ways to treat people with cancer.
- Does sugar cause cancer?
Sugar feeds every cell in your body, but does sugar cause cancer or even help it to grow and spread? It’s true that sugar feeds every cell in our body, even cancer cell. Research shows that eating sugar doesn’t necessarily lead to cancer, but what sugar does to your waistline can lead to cancer.
- Does sugar cause cancer cells to grow more aggressively?
Taking in too many sugar calories may result in weight gain, and being overweight or obese puts you at a higher risk for cancer and other diseases. It is likely that overfilled fat cells, possibly occurring from chronic excessive sugar consumption and high insulin levels, produce cancer promoting hormones. Insulin production itself is triggered by sugar consumption and is a known growth hormone.
- What is sugar, and why do our bodies need it?
Sugar is the generic name for sweet-tasting, soluble carbohydrates many of which are found in food. Simple sugars include glucose (also known as dextrose), fructose, and galactose. Compound sugars or double sugars are molecules composed of two joined simple sugars, and common examples are sucrose, lactose, and maltose.
“Table sugar” is extracted from sugarcane or sugar beets and then granulated. It’s a compound sugar composed of glucose and fructose and, in the body, is hydrolyzed, or broken down, into these two components.
When you search for sugar and cancer on the internet, you will find many warnings that sugar is the “white death” that feeds cancer cells. The idea that sugar is responsible for kick-starting or fueling a cancer’s growth is an over-simplification of some very complicated biology.
Glucose is a basic fuel that can power every single one of our cells, but is not an essential nutritional nutrient because your body can make all of the sugar it needs without you eating any granulated sugar.
Sugar and cancer?
Cancer cells usually grow very rapidly and multiply at a high rate which takes a lot of energy. This means they need a lot of glucose as fuel. Cancer cells also need other nutrients such as amino acids and fats.
Here’s where the concept that sugar fuels cancer was born: if cancer cells need a lot of glucose, then cutting sugar out of our diet must help to stop cancer cells from growing and multiplying and could even stop it from developing in the first place. Unfortunately, all our healthy cells need glucose too, and there’s no way of telling our bodies to let healthy cells have the glucose they need while keeping it away from the cancer cells.
Although there’s no evidence that cutting carbohydrates from our diet will help treat cancer, important research has shown that understanding the abnormal ways that cancer cells make energy could lead to new treatments.
A scientist in the 1940s named Otto Warburg noticed that cancer cells use a different chemical process from normal cells to turn glucose into energy. While healthy cells use a series of chemical reactions in small cellular ‘batteries’ called mitochondria, cancer cells bypass their ‘batteries’ to generate energy more rapidly to meet demand. This discovery was named the Warburg Effect.
This shortcut for making energy might be a weakness for some cancers giving researchers an advantage for developing new treatments because:
- First, it opens up the potential for developing drugs that shut down cancer cells’ energy-making processes without stop healthy cells’ energy making. Researchers are currently testing drugs that work in this way.
- Second, the abnormal processes in cancer cells can also leave them less able to adapt when faced with a lack of other nutrients like amino acids. These potential vulnerabilities could lead to new treatments also.
As these approaches are still experimental, we don’t know yet if treatments that starve cancer cells are safe or if they work.
Why worry about sugar then?
If cutting out sugar doesn’t help treat cancer, why then do we encourage people to cut down on sugary foods in our diet advice?
There is an indirect link between cancer risk and sugar. Eating more than recommended amounts of sugar over time can cause you to gain weight, and robust scientific evidence shows that being overweight or obese increases the risk of 13 different types of cancer. In fact, obesity is the single biggest preventable cause of cancer after smoking, which we’ve written about many times before.
So, should you avoid sugar?
“Your body’s cells use sugar to keep your vital organs functioning,” says Erma Levy, a research dietitian in Behavioral Science. “But too much daily sugar can cause weight gain, and unhealthy weight gain and a lack of exercise can increase your cancer risks.”
So, how much sugar is safe to eat? Women should have no more than six teaspoons per day (25 grams), and men should have no more than nine teaspoons per day (36 grams), says the American Heart Association. This equals to about 100 calories for women and 150 for men.
The biggest source of added sugar in the American diet is sugar-sweetened beverages. Other obvious sources include cakes, cookies, pies and ice cream. Some foods, such as pasta sauce, salad dressings, and canned vegetables, have hidden sugars, so it is very important to read food labels.
Your first clue that a product is high in sugar is if the word “sugar” is listed as the first ingredient. Some sugary foods don’t include “sugar” on the ingredient list. It is often disguised under different names, so if you don’t see “sugar” then look for these words:
- fructose (sugar from fruits)
- lactose (sugar from milk)
- sucrose (made from fructose and glucose)
- maltose (sugar made from grain)
- glucose (simple sugar)
- dextrose (form of glucose)
There are ways to moderate your sugar intake without avoiding it altogether:
- Rein in your sweet tooth: When eaten in small amounts, sugar can fit into a balanced diet.
- Opt for natural sugars: Natural sugars, like molasses, agave nectar, honey and maple syrup, are packed with antioxidants that protect your body from cancer.
- Avoid artificial sweeteners: Some studies done with laboratory animals have found links between artificial sweeteners and cancer.
So, what is the future for the sugar-cancer link?
On the one hand, sugar itself doesn’t cause cancer, but there’s no way (at the moment) of specifically starving cancer cells of glucose without harming healthy cells too. On the other hand, the amount of added sugar people are consuming is alarming because it’s promoting weight gain. Being overweight or obese increases the risk of at least 13 types of cancer. Although throwing sugar out won’t stop cancer in its tracks, we can all reduce our risk of getting cancer by making healthy choices, and lowering the amount of added sugar in our diets is a good way to help maintain a healthy body weight.
Since sugar is not an essential nutrient, at the very least one should avoid consumption of all refined sugars which have essentially no nutritional value.
- MD Anderson Cancer Centre (2019): Does sugar cause cancer? Retrieved from
- Web MD: Cancer and Sugar: Is There a Link? Retrieved from
- Cancer Research UK (2017): Sugar and cancer – what you need to know. Retrieved from
- Wikipedia : Sugar. Retrieved from