What to Know About 3 Common Misconceptions Around Food and Cancer Risk

April 25, 2023
Jyoti Patel, MD, FASCO

Eating is profoundly personal. Our diets reflect our cultural identities, pay homage to our ancestors, help us connect with each other, and serve to give us both physical and emotional nourishment. In any way you look at it, nutrition is an important part of our lives.

There is often a heightened awareness of nutrition in relation to cancer prevention, treatment, and recovery. For many people with cancer, food is one of the few things that they can be in control of during treatment.

We know that following a healthy diet and maintaining a healthy weight are important to reducing cancer risk. But these measures can also help people with cancer to better tolerate treatments, such as radiation therapy, chemotherapy, hormone therapy, immunotherapy, and/or surgery. These procedures and medications can impact appetite and energy, putting people with cancer at risk of malnutrition or fatigue. This can interfere with the goal of keeping your weight constant during cancer.

Despite some popular advice, there is not 1 single food that you can consume or avoid that will reduce your cancer risk or get rid of existing cancer. It’s important to focus instead on eating a balanced diet that includes adequate protein, healthy fats, whole grains, and vitamins and minerals.

Because of all of the information, or misinformation, that exists around cancer diets, my patients often ask me about nutrition claims they have read or heard about. Here are some of the common myths around cancer and food that all people should understand the truth about.

Myth #1: It’s important to “starve” cancer cells by eliminating sugar.

Truth: Sugar feeds all cells in the body, including cancer cells. Even when you don’t consume sugars or carbohydrates, your body will break down fat and protein to make sure that your body will function. So, eliminating sugar from your diet is not only challenging, but eliminating it from your body is just not possible. However, limiting sugar is important to preventing excessive weight gain which does, in fact, increase cancer risk. Focus on avoiding added sugars and choose complex carbohydrates from whole food sources instead.

Myth #2: “Superfoods” can cure cancer.

Truth: Although eating a healthful diet full of fruits and vegetables, whole grains, and complex carbohydrates may reduce your cancer risk, loading up on just 1 or 2 “superfoods” isn’t going to protect you from the disease. Sometimes, people refer to foods like blueberries, broccoli, raspberries, and other fruits, vegetables, or spices like turmeric as “superfoods.” It’s true that a healthy, balanced diet can help reduce the risk of cancer, but it is unlikely that any single food will make much of a difference on its own.

Myth #3: Stay away from soy products.

Truth: Eating soy products does not affect cancer risk, including breast cancer. Soy products, like tofu and soy milk, contain isoflavones. Isoflavones can imitate the action of estrogen but have much, much milder effects. Research has shown that neither soy products nor isoflavones impact cancer risk.

While food plays an important role in preventing some cancers, the therapeutic value of food in treating existing cancer is less clear. It is, however, true that a person with cancer or who is recovering from cancer needs good nutrition in order to better cope with the disease and treatment.

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