Eating healthfully is an important part of cancer treatment, but if you’re a prostate patient undergoing proton therapy it can be a challenge.
That’s because doctors order patients to adhere to a “low residue” diet restricting them from eating foods high in fiber. The purpose of the diet is to keep the digestive system flowing smoothly and reduce gas and bloating that could result in displacement of the markers that help guide the protons to their tumor target.
“These foods are in and out pretty quick. Long-term this is not something that would be considered healthy,” says Casey Coffey, nutritionist at Provision Center for Proton Therapy, to a group of prostate cancer patients who come to hear her advice each Tuesday morning. “This is a short-term ‘necessary evil’ for the wonderful treatment that you’re having.”
Although the diet is not ideal, it’s not as restrictive as many people think, she says, and it’s important for patients to incorporate the guidelines of a healthy diet as much as possible.
The bottom line of the low residue is this: consume less than 10-15 grams of fiber a day.
“You can still make some ok choices,” Coffey says.
Keeping most proteins in the diet is acceptable (as long as it’s tender and unprocessed), including every category of meat and dairy as well as nut butters that are smooth, not crunchy.
“Beware of steak, chewy bacon and sausage,” she says.
Although whole grains are out, patients can keep quick oatmeal in their diets, and Coffey recommends sourdough bread as a way of lowering the rush of sugar into the bloodstream when eating the required refined carbs.
Most vegetables are still on the menu with modifications including potatoes with no skins, cucumbers with no skins or seeds—English cucumbers are seedless, FYI—and tomatoes, seeds removed. Try Romas, she says. Also, if a vegetable can be cooked, it should be—and well. Although more limited, patients also can have some fruit, including a banana per day, melons, apricots, nectarines, papayas, peaches and plums.
Decaffeinated coffee is a hard pill to swallow for many patients—caffeine stimulates the bowel and bladder, potentially causing spasms during treatment. And fats are permitted, but Coffey recommends limiting them—using an oil spray, for example, when cooking or frying.
However, the guidelines aren’t exhaustive, because the effect of certain foods can vary person to person.
“If you eat something and it’s causing a problem, you might just have to leave it out, even if it’s on the list,” she says.