Cancer and Food: Facts and Fiction

Soy Products

“I’m being treated for cancer. Is this food healthy? Should I avoid it?”

These are questions often asked of Candice Schreiber, RD, CSO, LD, a clinical nutritionist at The Ohio State University Comprehensive Cancer Center – James Cancer Hospital and Solove Research Institute (OSUCCC – James).

“We get asked a lot about soy, sugar and coconut water,” she says.

So with the help of Schreiber and the results of extensive research, let’s take a look at several of the “healthy or not healthy” questions on the minds of many cancer patients.


“This is the question we get asked the most, as a lot of cancer patients think, and are often told, that they’re not supposed to eat soy,” Schreiber says. “Studies [involving mice] did not translate to humans, and new and larger studies have created a body of evidence that shows it’s not only safe to eat soy, but that there are possible health benefits from soy for patients with breast or prostate cancer.”

Sugar and artificial sweeteners

When it comes to sugar, the delivery method makes all the difference, according to Schreiber.

“Sugar is healthy when it comes from natural sources such as fruits and vegetables. Along with the sugar, you’re taking in vitamins, minerals, fiber and phytochemicals. The problem comes when you take in too much sugar from cake and cookies and from highly-processed foods with added sugar.”

While swapping sugar for calorie-free alternatives may appeal to patients, Schreiber suggests that they think about the big picture before making the switch to artificial sweeteners.

“They’re considered safe [when it comes to cancer], but research shows they can have other negative health effects. They can create an insulin response and trick the brain into thinking it’s getting sugar, and then when it realizes it’s not sugar, you crave it and this can lead to weight gain.”

Coconut, aloe vera and alkaline waters

While not harmful—though consumers should be aware that aloe vera water can have a laxative effect—rumored detoxifying benefits of these trendy waters aren’t backed up by scientific research, Schreiber says, though they may provide some advantages via addition by subtraction.

“If you replace soda with unsweetened coconut water, that’s an improvement. But in general, drink plain water and lots of it.”

Regarding alkaline water, which is marketed as promoting a bodily state that’s hostile to cancer cells, Schreiber doesn’t mince words.

“This isn’t true—there’s no good science behind this claim. The body, your liver and kidneys maintain a constant pH balance, and alkaline water won’t change this.”


While extensive research has been conducted on the impact of dairy products on cancer risk, the results are mixed.

For example, some studies have linked dairy products with an increased risk for prostate and ovarian cancers, while other studies have shown that milk reduces the risk of colorectal cancer. Another large study showed no proven association between total dairy intake and cancer mortality risk, according to Schreiber, though an increase in whole milk consumption did result in a rise in prostate cancer mortality risk.

“Overall, research does not show a clear link between the consumption of dairy products and cancer,” Shreiber says.


Before, during or after cancer treatment—and for those without cancer—Schreibers advice is simple: less meat, especially red meat, is healthier.

“Your diet should be plant-heavy and light on the meat—less than 18 ounces a week of red meat (which is linked to increased colorectal cancer risk) including beef, pork and lamb.”

Bottom line

“You shouldn’t believe everything you read online or see in a commercial about the benefits of a product. In the end, it’s simple: eat a diet filled with fruits, vegetables, whole grains and beans. They’re so good for you and may prevent a wide range of diseases,” Schreiber says.