Soda being poured into a glass.

Sugar-sweetened beverages, such as soda and sports drinks, are the leading source of sugar in the American diet, with about 60 percent of kids and teens and half of adults consuming at least one a day.

These drinks have long been associated with an increased risk of obesity, type 2 diabetes, high blood pressure, and death from heart disease. New research published in the British Medical Journal provides compelling evidence that these beverages, along with 100 percent fruit juice (which contains natural sugars), may raise the risk of cancer.

For years groups including the American Cancer Society (ACS) have urged people to cut down on beverages with added sugars as well as fruit juice “because the evidence strongly linked them to excess weight, which is a big risk factor for cancer,” says Colleen Doyle, M.S., R.D., managing director, nutrition and physical activity, at the ACS. “But what makes this study unique is it’s the first one of its kind to suggest a direct link—that it’s sugar itself, whether it’s added or from natural sources like fruit juice, that is the problem.”

What the Study Found

The researchers had over 101,000 healthy French adults complete 24-hour dietary questionnaires every six months while following them for up to nine years. They calculated each participant’s daily consumption of sugary drinks, defined as sugar-sweetened beverages and 100 percent fruit juices. In their analysis, the researchers controlled for obesity and weight gain so they could examine the effect of sugary drinks separate from weight.  

More on Sweeteners and Your Health

This was an observational study, which means researchers couldn’t prove a definitive cause and effect, but it found that compared with drinking no sugary beverages, every 3.4 ounce serving was associated with an 18 percent increased risk of overall cancer and a 22 percent increased risk of breast cancer. The researchers didn’t find a link between diet drinks and cancer.

There are several reasons why sugary drinks may increase cancer risk. One theory is that they may trigger inflammation, which causes cell damage, explains the lead study author, Mathilde Touvier, Ph.D., a nutritional epidemiologist with the Sorbonne Paris Cité Center of Research in Epidemiology and Statistics Research. High blood sugar (glucose) levels are a cancer risk factor (especially for breast cancer), and sugary drink consumption raises blood sugar. The drinks may also affect the microbiome—the bacteria that populate the gut—which in turn may have an impact on cancer risk, too, adds David Katz, M.D., M.P.H., director of the Yale University Prevention Research Center. 

Sipping Wisely

While the occasional soda or glass of juice is fine as a treat, your best bet is to get most of your fluid intake from low-calorie options such as water, unsweetened tea and coffee, and low-fat or fat free milk, advises Alice Bender, M.S., R.D.N., senior director for nutrition programs at the American Institute for Cancer Research. Here, four tips for healthy hydration:

Spice up your water. Plain old water is the best way to quench your thirst because it’s both sugar- and calorie-free, says Bender. But if you get bored drinking it straight up, there are ways to make it more palatable. If you prefer a carbonated beverage, opt for sparkling water (just make sure you choose an unsweetened option). Or drop some frozen fruit like berries, cherries, or peaches into your water. (The flavor will intensify as the fruits thaw.) You can also freeze herbs and/or fruit in ice cubes, or add herbs like mint or lavender for a more satisfying flavor.

Be cautious with diet drinks. Although this study didn’t find a link between artificially sweetened diet beverages and cancer, Touvier still urges caution. “Most people in our study didn’t drink them, so we didn’t have enough evidence to say definitively that they don’t have an impact,” she explains, adding that other research has linked them to increased risk of diseases such as type 2 diabetes and stroke.

Drink unsweetened coffee or tea. Despite some concerns that coffee beans contain the carcinogen acrylamide, both java and tea are rich in antioxidants that may have cancer protective effects, stresses Bender. And two studies published in the Annals of Internal Medicine in 2017 found a link between coffee consumption and a ower risk of dying from many common diseases, including cancer. But skip the sugar and sprinkle cinnamon or cocoa on top of your coffee instead.

Go easy on fruit juices and sports drinks. Unless you’re exercising outdoors for more than an hour, you’re unlikely to need sports drinks, says Doyle. And if you (or your kids) are a juiceaholic, cut down. Doyle recommends less than 4 ounces of 100 percent juice a day. You can start by mixing juice with water, then gradually decreasing the amount as you get used to the flavor so that your taste buds adjust to less sugary beverages.