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Breast Cancer Health Center

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Eating Right During Cancer Treatment

Cancer treatment can sap your appetite, but that's when getting adequate nutrition is more important than ever. Here's how to meet your needs.
WebMD Feature
Reviewed by Louise Chang, MD

When you're being treated for cancer, it's more important than ever to eat a healthy diet and get good nutrition -- but it can also be more difficult than ever. Your body is working overtime to fight the cancer, while it's also doing extra duty to repair healthy cells that may have been damaged as a side effect of treatments like chemotherapy and radiation. At the same time, many cancer treatments -- especially chemotherapy -- come with side effects that drain your strength and sap your appetite. So how can you make sure you're getting all the essential nutrients, vitamins, and minerals you need?

You might assume the answer lies in power doses of vitamin supplements. After all, if you're having trouble keeping food down, wouldn't it be easier to get nutrients from a simple capsule? Not necessarily. "If you want to supplement the nutrition you get from your regular diet, we recommend taking just one multivitamin per day from a reputable manufacturer," says Gary Deng, MD, assistant attending and assistant member in the Integrative Medicine Service at Memorial Sloan-Kettering Cancer Center in New York.

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"We suggest that patients avoid high-dose multivitamins, because there is some concern that some of these, especially those with high-dose antioxidants, may interfere with treatment. As long as there remains controversy about this, we think it's prudent not to take high-dose multivitamins."

Plus, it's almost impossible to get "too much" of any given vitamin through food alone, while loading up on some vitamins in pill form can cause problems, like dangerous buildup in the liver. If a certain amount of a nutrient is good for you, twice or three times as much is not necessarily better.

Certain kinds of herbal supplements, like St. John's wort, can also interact badly with some types of cancer treatment. "Some complex herbal extracts may contain substances that can change drug metabolism, interfering with the way in which your body metabolizes chemotherapy," warns Deng. Talk to your doctor before taking any type of herbal product or supplement during cancer treatment.

Get Vitamins In Food, Not Capsules

Instead, say experts, focus on what you need most now: calories. When you're being treated for cancer, taking in enough calories to maintain your strength and keep your body going trumps pretty much everything else. "For many people undergoing chemotherapy, we're happy to tell them to eat whatever they like to eat. If it appeals to you and you can keep it down, then eat it," says Deng. "If you ask someone to eat too strict a diet, often they end up not eating enough."

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