Cancer nutrition myths: Separating fact from fiction

August 30, 2021 Providence Nutrition Team

In this article:

  • Cooking with Teflon® or using a microwave oven won’t give you cancer.

  • Cutting out sugar won’t starve your cancer cells and make them disappear.

  • Superfood is a marketing term and not necessarily a food that contains magical, cancer-fighting properties.


Whether it’s a widespread rumor you found during an online search on “Dr. Google” or an article you read on Facebook, myths about nutrition and cancer are everywhere you look.

Last month we talked to Rémy Leigh Peters, RDN, CNSC, about eating to combat cancer and the Providence Thrivorship program. Peters is a registered dietitian at the Providence Disney Family Cancer Center (DFCC). She understands the role nutrition plays in comprehensive, holistic cancer care and is passionate about helping others adjust heir menus to improve their health. This month Peters shares her insights into some of the most common cancer nutrition myths and offers tips to help separate fact from fiction.

Myth: Cooking with non-stick Teflon® pans causes cancer.

Teflon® is the brand name for a group of chemicals used in commercial applications since the 1940s to create a friction-free surface on a wide range of products, including cookware.

The concern over Teflon centers around a chemical called perfluorooctanoic acid (PFOA). PFOA stays in the environment and the human body for a long time. Some studies have shown a tentative link between PFOA consumption and increased cancer risk, but many were based on research done on animals using large amounts of PFOA and not relevant to humans. And even more importantly, PFOA has not been used to manufacture Teflon-branded products since 2013.

According to the American Cancer Society, “While PFOA was used in the past in the US in making Teflon, it is not present (or is present in extremely small amounts) in Teflon-coated products.”  

“I like to refer people with concerns or questions directly to the US Environmental Protection Agency," says Peters.

Myth: Radiation from cooking with a microwave increases your cancer risk.

Radiation exists on a spectrum that ranges from low frequencies, such as those from power lines, to high frequencies like those in gamma rays and X-rays. Microwave ovens use a form of low-frequency radiation called radiofrequency radiation to make microwaves that cause the water in your food to vibrate and generate heat. The process does not contaminate your food or make it radioactive.

Microwave ovens are regulated by the Food and Drug Administration (FDA) to ensure they meet safety standards. They are designed to prevent leakage and must have two independent locks and a monitoring system that controls the oven's use if its door is open.

The container or plate you use when microwaving food may have a more significant impact on your health than the appliance itself.

The container or plate you use when microwaving food may have a more significant impact on your health than the appliance itself. Plastic dishware that contains bisphenol-A (BPA) could leach the potentially carcinogenic compound into your lunch if you use it in the microwave. Be sure to use only microwave-safe plastic, glass or ceramic containers to safeguard your health.

Numerous studies have determined there is insufficient evidence to link cancer with microwave use.

Myth: Sugar feeds cancer cells

In its most basic form, sugar is made up of a single molecule called glucose. All cells, including cancer cells, use glucose for energy. Glucose comes from foods with carbohydrates, including healthy choices like fruits, vegetables and whole grains. But it's also contained in refined carbohydrates like white bread and pasta, sweetened beverages and “junk” food with large amounts of added sugar.

The idea that you can quit eating sugar and somehow starve your cancer cells just isn't accurate.

The idea that you can quit eating sugar and somehow starve your cancer cells just isn't accurate. “It’s never that simple,” says Peters. Your body can't determine which cells get glucose and which cells go without. And if you don't eat enough carbs, your body will use other sources, like fat and protein, to make the glucose it needs to function. This can lead to muscle loss, malnutrition and unintentional weight loss and affect your health overall.

According to the National Institutes of Health (NIH), there are no scientific studies that show that eating sugar makes cancer grow or that eliminating it from your diet will make cancer disappear. However, cancer risk may be related to how your body responds to sugar. If you eat sugar rich foods there may be greater spike in blood sugars. These surges result in an increased release of insulin-like growth factor (IGF), which has been shown to boost cancer cell growth.

Of course, if you habitually eat large amounts of sugar and gain an excessive amount of weight, the resulting inflammation and obesity could put you at greater risk for several types of cancer.

While it is not necessary to completely avoid sugar, reducing added sugars is important for overall health. The American Heart Association recommends women should have no more than six teaspoons of sugar per day (25 grams) and men should have no more than nine teaspoons of sugar per day (37 grams).

Peters suggests these healthful nutrition strategies:

  • Opt for whole grains like whole-wheat bread, pasta, brown rice, or quinoa over refined grains like white bread, pasta and rice.
  • Balance your plate. Make 50 percent of your plate high fiber vegetables and fruit. Twenty-five percent of your plate should be protein-rich foods and the other 25 percent should be whole-grain carbohydrates or starchy vegetables such as peas, corn or potatoes.
  • Include a lean protein source with every meal and snack like skinless poultry, fish, eggs, low-fat dairy, tofu, beans, nuts or seeds.
  • Consume a diet rich in vegetables and fruit rich in vitamins, minerals, fiber, and immune-supporting phytonutrients. Choose whole fruit over fruit juices and dried fruit.
  • Stay well hydrated. Choose mostly water.  Limit or avoid sugary beverages such as juice and soda.

Myth: Breast cancer survivors should avoid eating soy.

Soybeans are a type of legume that can be eaten on their own, like edamame, or used to make foods such as soy milk, tofu, tempeh and miso. Soy flour and protein can also be added to a wide range of foods, including bread, energy bars and breakfast cereal.

Soy contains plant compounds called isoflavones, which are part of a group of phytoestrogens or plant estrogens. Isoflavones have some qualities that are similar to those found in estrogen hormones. Since some studies have linked estrogen to breast cancer, people with estrogen-receptor-positive breast cancer may be concerned that soy is unsafe. That worry may not be necessary, says Peters.

The majority of current studies show that whole soy foods do not increase your risk of cancer, according to the Susan G. Komen® organization.

Studies done with animals may not produce the same results as research conducted with people since animals and people process soy differently. The majority of current studies show that whole soy foods do not increase your risk of cancer, according to the Susan G. Komen® organization. In many cases, they can even provide protection against even hormone positive cancer types.

Myth: Don’t consume food or beverages that contain artificial sweeteners.

Artificial sweeteners are also called sugar substitutes. They are man-made substances used to replace sucrose or table sugar. There are a wide variety of sweeteners available, including saccharin, aspartame and sucralose. Each has different components and are used in various products such as Splenda®, Equal® and NutraSweet®. Artificial sweeteners are regulated by the FDA.

Misunderstandings and myths about artificial sweeteners are common. Many stem from early studies that showed cyclamates and saccharin could potentially cause cancer in laboratory animals. However, more recent studies of FDA-approved sweeteners have not demonstrated a clear link between cancer and artificial sweeteners, according to the NIH.

“Do sweeteners cause cancer? The short answer is no. There’s nothing conclusive that says this is a cancer-causing substance,” says Peters. “However, I usually try to steer people away from artificial sweeteners because they can affect your metabolism and cause long-term issues with how your body processes real sugar. I always tell people, ‘You’re sweet enough,’” she says with a laugh.

Myth: Superfoods have unique properties that prevent cancer.

So-called superfoods have been making headlines as a way to stop cancer before it starts, but are the claims of healing and prevention accurate? The word superfood is “primarily a marketing term” associated with nutrient-packed, impressively beneficial foods, says Peters. Although many foods provide numerous health benefits, no one food has been shown to prevent cancer, according to the American Institute for Cancer Research.

It may not prevent cancer, but eating a diet filled with vegetables, fruits, beans, whole grains and lean protein promotes good health in general.

It may not prevent cancer, but eating a diet filled with vegetables, fruits, beans, whole grains and lean protein promotes good health in general and helps deter many chronic conditions such as heart disease or diabetes.

“When it comes to superfoods, there is never going to be just one. The key is always going to be variety, variety, variety,” says Peters. “There’s never going to be one berry that changes your world. When you look at your plate, focus on color, and identify a good source of protein,” says Peters.

Fact or fiction?

Knowing the facts when it comes to nutrition and cancer care can be confusing as you try to identify the misinformation and myths from what’s really true. Peters offers tips to identify good sources of information and separate the facts from fiction:

  • Consider the source carefully. Look for information provided by reputable organizations that use established scientific evidence to back up their claims.
  • If you’re doing online research, check the letters in the URL and look for sites that use .gov, .edu and .org.
  • Check the date of the research or studies and ensure they contain current information.
  • Credible sources provide credible information. Look for organizations that share information from qualified nutrition experts and medical professionals.


Find a doctor

The cancer care team at Providence continues to drive leading-edge research and pioneer new treatments that are focused on caring for our cancer patients like family until the fight is won. If you need to access an oncologist or specialist, you can use our provider directory.

In Southern California, the Providence Roy and Patricia Disney Family Cancer Center offers cancer patients and their loved ones a medical home of every stage of diagnosis, treatment and survivorship in one building. To learn more about this program and integrative and nutritional counseling, call Integrative Medicine at 818-748-4701, or email

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About the Author

We are all about food! The Providence Nutrition Team loves to talk about and share our expertise on how to help you find the right diet, food types and maintenance tactics to help you live life to the fullest...while also enjoying the best foods that mother nature has to offer.

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