The Not-So-Sweet Link between Sugar and Cancer

Is there a link between sugar and cancer? The answer may surprise you.

Sugar consumption and cancer incidence rates are both on the rise. While the death rate from cancer has declined steadily over the past 25 years, the incidence of cancer other than lung cancer and stomach cancer has risen at a rate of about 1.2 percent each year since 1950. The Centers for Disease Control and Prevention (CDC) expects the number of new cancer cases to have gone up about 24 percent in men and 21 percent in women between 2010 and 2020.

Sugar consumption among adults in the United States has increased by more than 30 percent in the past thirty years. The average American consumes more than 16 teaspoons of sugar each day, according to The Sugar Association.

Because the rise in cancer rates seems to coincide with the rise in sugar consumption, many researchers are now investigating the potential link between eating sugar and the development and spread of cancer. The first step in determining how sugar can affect cancer is to understand how cancer cells use sugar.

Cancer Cells Use Sugar Differently

Every cell in the human body breaks down blood sugar, also known as glucose, for energy. Cancer cells also use glucose for energy. The big difference, though, is that cancer cells break down sugar 200 times faster than do normal cells. This change in cellular metabolism of sugar is one of the hallmarks of cancer.

We get glucose from carbohydrates in food, such as vegetables, fruits, whole grains and low-fat dairy sources. Many of us also get glucose from the added sugars in soda, sweetened tea and coffee, sugary snacks, and junk food.

The Indirect Connection between Sugar and Cancer

Researchers have not yet confirmed a direct connection between sugar and cancer, but overconsumption of sugar can lead to obesity, and there is a strong link between obesity and cancer.

Sugar is high in calories, so eating large quantities of sugar can contribute to weight gain and obesity. Health professionals characterize obesity as a having an unhealthy amount of fat or an unhealthy distribution of fat in the body. Healthcare professionals use body mass index (BMI) and other measurements that reflect the distribution of body fat to measure obesity.

Research provides consistent evidence that shows an association between higher amounts of body fat and the development of a number of cancers. The National Cancer Institute says that overweight and obese women are two to about four times as likely to develop endometrial cancer as are their normal-weight counterparts. People who are overweight or obese are about twice as likely to develop specific types of cancer of the esophagus, upper part of the stomach, liver, or kidneys. Being overweight or obese can also increase the risk of pancreatic cancer, colorectal cancer, gallbladder cancer, breast cancer, ovarian cancer, thyroid cancer, the type of brain tumor known as meningioma, and multiple myeloma that forms in certain white blood cells.

Researchers are still working to understand exactly how being overweight or obese leads to cancer, but they have suggested some mechanisms. Obesity often causes low-level inflammation, which can damage DNA in ways that leads to cancer. Fat tissue produces estrogen that, at excessive levels, increases the risks of breast, endometrial, ovarian, and some other cancers. Obese people frequently have high levels of insulin and insulin-like growth factor-1 (IGF-1), which can promote the development of colon, prostate, kidney, and endometrial cancers.

Furthermore, fat cells may produce hormones that stimulate or inhibit the growth of cells. Fat cells may also have direct and indirect effects on other regulators of cell growth in the human body.

Study in Lab Mice Suggest Possible Direct Connection between Sugar and Breast Cancer

In a 2016 study, researchers fed starch to young mice in the control group and fed sugars to young mice in the test group. The amounts of sugars consumed by the mice was comparable to that found in a typical Western diet, which usually features high intakes of refined sugars, red meat and saturated fat with low intakes of fresh fruits, vegetables and whole grains.

By the age of 6 months, 30 percent of the mice that ate starch had breast cancer tumors, while 50 to 58 percent of the mice that consumed sugars had those tumors. The results of the study suggest that high sugar intake has a significant effect on the development and spread of breast cancer. The authors of this study suggest inflammation may be the mechanism by which sugar influences the development of cancer.

It is important to note that there are different types of sugar, and that some types of sugar may have a closer link to cancer than do others. Cancer Treatment Centers of America notes that the natural sugar in fruits provide essential nutrients that keep the body healthy and prevent diseases, such as cancer. Refined sugar, which is highly processed to make table sugar and high-fructose corn syrup, has no nutritional value. These refined sugars do have plenty of calories, which can lead to weight gain and even obesity. Obesity is associated with several cancers, including breast, prostate, uterine, colorectal and pancreatic cancer.