Cancer Patients: Should You Juice?

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If antioxidants are good for us, then we should take a lot of them in food and supplements, right? Not so fast, says Lesley Klein, a clinical oncology dietitian, and the clinical nutrition manager for Sylvester Comprehensive Cancer Center.

“Antioxidants, like we get from fruits and vegetables are good for us, but we shouldn’t go overboard with them.”

Her preference? Get your nutrition from what you eat. Supplements may contain much higher levels of antioxidants than our bodies can handle, she says. She typically gives her patients a range of types of nutrients they should shoot for, like grams of protein or antioxidants like beta-carotene.

Juicers of the world, take note. You can get too much of a good thing.

While some people associate 100 percent fruit juices with a healthy diet, they sometimes contain as much sugar as a soda. That can lead to weight increase, which has been linked to 12 different types of cancer, according to the American Institute for Cancer Research (AICR).

Eat the whole fruit, Klein says. The whole fruit provides fiber and other nutrients not found in just the juice, but even then, go easy. “A diet that is heavier in vegetables is better for us than one heavier in fruit, again because of the simple sugars. A balanced diet is always better than too much of one type of food. I use the rainbow as an analogy to encourage eating a variety of different colors of plant-based foods.”

One dietary cause of inflammation is sugar. Since starchy vegetables and fruits can be high in sugar, Klein tells people to lean toward a plant-based diet. The majority of carbohydrates should come from non-starchy vegetables and small amounts of fruit. “The inflammation from sugar can increase the number of free radicals in our bloodstream. Those free radicals can cause mutation in normal cells, which in turn can produce cancer cells. That’s why we want to have a healthy vegetable-based diet to produce antioxidants to control those free radicals. It may not be realistic to encourage people to become vegetarians, but you can more easily follow AICR’s guidelines for the New American Plate. Two-thirds of your plate should be covered in plant food, and one-third, covered in animal protein.”

What about during cancer treatment?

The balance of antioxidants and free radicals (atoms that attack cells) in our system changes, depending on the situation. When you are healthy, you should try to follow a diet that keeps the number of free radicals lower.

During cancer treatment, it’s a different story. Free radicals produced during cancer treatment can help chase down and disable cancer cells, so you don’t want to overdo the antioxidants at that time. “If you are being treated for breast cancer, too high a level of antioxidants can actually interfere with the effectiveness of radiation or chemotherapy.”

If chewing and eating solid foods is a problem, Klein says pureeing your food (blending) is an option. This can help to add more servings of vegetables and fruits to an already-healthy diet, but don’t juice.

Talk to a registered dietitian about how to meet all of your calorie and protein needs, and stay safe if you have swallowing difficulties. Avoid overdoing the antioxidants during treatment. Klein says that once treatment is complete, or for prevention, juicing is ok in moderation.

Experts at the American Cancer Society, the World Health Organization, and the US Department of Agriculture agree: following a low-fat, plant-based diet can lower your cancer risk and improve the survival rates for people with breast, colon, prostate cancers, even melanomas. So when it comes to both cancer prevention and the effectiveness of cancer treatment, Klein says to seek out a cancer dietitian for the best approach to nutrition.


Mary Jo Blackwood, RN, MPH, is a contributing writer for UMiami Health News. She is a two-time breast cancer thriver, and freelance medical writer
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