Cancer Nutrition Myths We Hear All the Time, And What Science Actually Says

Jan 20

When you or someone you love receives a cancer diagnosis, it's natural to want to do everything possible to help. And in Maine, where we're known for our independence and resourcefulness, that often means turning to the internet, talking to neighbors, or reaching out to family members who "heard about this thing that worked."

At the Christine B. Foundation, we hear from patients across Maine every single week with questions about nutrition. Should I cut out sugar completely? What about that alkaline water my cousin mentioned? Can I just juice everything?

You're not wrong for wondering. These questions come from a place of love and a desire for control during a time when so much feels uncertain. But we also know that misinformation can lead to unnecessary stress, wasted money, or even harm.

So let's walk through some of the most common cancer nutrition myths we hear, and what the science actually says.

Myth #1: "Sugar Feeds Cancer"

This is probably the single most common question we get from patients in Bangor, Portland, and everywhere in between.

The logic seems to make sense: cancer cells grow quickly, they use glucose for energy, so cutting out sugar should starve them, right?

Here's what science tells us: Yes, cancer cells do use glucose (sugar) for energy. But here's the thing, so does every other cell in your body. Your brain, your muscles, your healthy cells all depend on glucose to function. And even if you completely eliminated sugar from your diet, your body is remarkably clever. It can produce its own glucose from protein and fat through a process called gluconeogenesis.

There's no quality scientific evidence showing that eating sugar makes cancer grow faster, or that eliminating sugar slows cancer growth.

That said, we're not giving you a free pass to live on cookies and soda. Excessive sugar intake is linked to weight gain and obesity, which are risk factors for several types of cancer. The goal isn't to fear sugar, it's to enjoy it in moderation while focusing on nutrient-dense foods that support your overall health.

The bottom line: You don't need to cut out your grandchild's birthday cake. Focus on balance, not elimination.

Myth #2: "An Alkaline Diet Can Cure Cancer"

Maybe you've seen the social media posts: "Cancer can't survive in an alkaline environment!" The idea is that eating mostly "alkaline" foods (like leafy greens and certain fruits) while avoiding "acidic" foods (like meat and dairy) will change your body's pH and prevent or cure cancer.

Here's the reality: Your body is incredibly good at regulating its own pH. Your blood pH stays between 7.35 and 7.45 regardless of what you eat, your kidneys and lungs work around the clock to keep it that way. The foods you eat can change the pH of your urine, but not your blood or tissues where cancer grows.

According to the American Institute for Cancer Research, there is no scientific literature establishing that an alkaline diet prevents or cures cancer.

Here's the nuance: Many foods promoted in alkaline diets, fruits, vegetables, legumes, are genuinely good for you. They're packed with fiber, vitamins, and antioxidants. But they're beneficial because of their nutrients, not because they change your body's pH.

The bottom line: Eat your veggies because they're nutritious, not because they're "alkaline."

Myth #3: "Juicing Is Better Than Eating Whole Foods"

We get it. When you're going through treatment, sometimes eating feels impossible. Nausea, mouth sores, fatigue, solid food can be the last thing you want. Juicing seems like a logical solution: all those nutrients in an easy-to-drink form.

And for some patients, juice can be a helpful way to get calories and vitamins when eating is difficult. We're not anti-juice.

But here's where the myth goes too far: Some people believe that juicing alone can cure cancer, or that a juice "cleanse" will detox your body and eliminate cancer cells.

There is no scientific evidence that juicing cures or prevents cancer. And here's what you lose when you juice: fiber. That pulp you're throwing away contains most of the fiber, which helps regulate blood sugar, supports gut health, and keeps you feeling full.

For patients undergoing chemotherapy, raw juice diets can actually be risky. Unpasteurized juices may contain bacteria that a compromised immune system can't fight off.

The bottom line: Juice can supplement your diet, but it shouldn't replace whole foods, especially protein, which your body desperately needs during treatment.

Myth #4: "Supplements Can Replace Food"

Walk into any health food store, and you'll find shelves of supplements promising everything from immune support to tumor reduction. It's tempting to think you can pop a few pills and cover all your nutritional bases.

Here's what the research shows: There is no evidence that multivitamins or supplements lower cancer risk beyond what a balanced, healthy diet provides. And some supplements can actually interfere with cancer treatment.

Take turmeric, for example. It's often touted as a cancer-fighting superfood. While curcumin (the active compound in turmeric) does have anti-inflammatory properties, studies haven't established how much your body can actually absorb. More concerning: turmeric can interfere with certain chemotherapy drugs by affecting how your liver processes medications.

This doesn't mean all supplements are bad. Some patients genuinely need vitamin D, B12, or iron supplementation based on their bloodwork. But these decisions should be made with your oncology team, not based on what worked for someone on YouTube.

The bottom line: Supplements aren't a shortcut. Real food contains thousands of compounds that work together in ways a pill simply can't replicate.

The Bigger Myth: "One Food Can Cure Cancer"

Whether it's turmeric, green tea, acai berries, or apple cider vinegar, we've heard them all presented as miracle cures.

The truth is this: No single food prevents or cures cancer. The term "superfood" is a marketing label, not a scientific category.

Cancer prevention and management come from your overall dietary pattern, not from any one ingredient. The strongest evidence points to eating a variety of whole grains, fruits, vegetables, and legumes while limiting processed meats, excessive red meat, and alcohol.

What Actually Helps During Cancer Treatment

So if these myths aren't the answer, what is?

At the Christine B. Foundation, we work with Maine patients every day to provide medically-tailored nutrition that support their actual nutritional needs during treatment. Here's what the evidence supports:

Adequate protein to maintain muscle mass and support healing
Enough calories to prevent malnutrition (yes, this sometimes means eating things you'd normally limit)
Variety to ensure you're getting a range of vitamins, minerals, and phytonutrients
Foods you can actually eat based on your symptoms and side effects
Guidance from registered dietitians who specialize in oncology nutrition

If you're facing cancer in rural Maine and struggling with nutrition access, you're not alone. We've supported over 1,500 patients across our state, and we're here for you too.

You're Not Wrong for Asking

Let's be clear: questioning what you eat during cancer isn't foolish. It's human. You want agency. You want to help.

The best thing you can do is stay curious, but stay grounded in evidence. Talk to your oncology team before making major dietary changes. And remember that nutrition is just one piece of your care: an important piece, but not something you should stress over to the point of exhaustion.

We're here to help. Whether you need access to nutritious meals, guidance on eating during treatment, or just someone who understands what Maine families face, reach out to us at the Christine B. Foundation.

You don't have to figure this out alone.