​​By Alaa El Danab, MScA, RD, Revised by Karmen More, Registered Dietitian

Working in the field of oncology is both rewarding and challenging, especially when social media takes a strong stance towards a particular diet trend. It can be difficult to tell the difference between fact and fiction. Not only can false information lead to anxiety and distress, but it can also make eating real food less enjoyable. As a practitioner, I make it my duty to de-bunk such myths to ensure that patients are meeting their requirements, while still enjoying their meals.

Below are the top cancer-related nutrition myths. ​

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​​​ Sugar and cancer growth

Sugar and cancer growth is something that I often get questions about. Sugar is a carbohydrate, and it is present in fruits, vegetables, grains, and milk products. Sugar is used by our bodies for energy. Cancer cells require energy to grow and this energy comes from the food that we eat. The foods that we eat exist in complex compounds. This means that simply avoiding sugar will not change the growth of your cancer. Active treatment for cancer is not easy on the body. It is important to ensure that your diet is complete with nutrients such as carbohydrates, protein, fats, fibre, vitamins, and minerals to help you get the most nutrition out of meals and snack times.

​​​ Soy and breast cancer

The topic of soy and breast cancer is very popular. Research has shown that high levels of the hormone estrogen increases the risk of breast cancer. The confusion and fear surrounding soy comes from the fact that soy contains "phytoestrogens" or "dietary estrogens". Phytoestrogens are compounds naturally found in plants and in many foods such as soy. Phytoestrogen looks similar to estrogen found in the female body. But when ingested, phytoestrogens affect your body in a much weaker way than estrogen.

In fact, research shows that consumption of soy is safe for women with breast cancer. More research is needed, but some studies suggest that breast cancer survivors that ate a moderate amount of had a lower risk of cancer recurrence than those who avoided soy. It is important to note that most of the research has been conducted in soy-containing foods. For this reason, soy supplements should be avoided until more research data is available. Overall, if you choose a diet that includes soy, a moderate amount of soy is safe to enjoy.

What is a moderate amount of soy?

The American Institute of Cancer Research (AICR) defines a moderate amount of soy as "1-2 standard servings daily of whole soy foods such as tofu, soy milk, edamame, and soy nuts."

An example of 1 serving

  • 1 cup soy milk
  • 1/3 cup (or about 3 ounces) of tofu, tempeh, or soy meats
  • 1/2 cup cooked soy beans
  • 1/4 cup (or 1 ounce)​ soy nuts

​​​ Cleansing and detoxes

A very common question I get asked is, "What diet should I follow to help cleanse my body from cancer?" Unfortunately, the answer may be disappointing for some. There is no evidence to suggest that a detox or cleanse helps get rid of harmful substances or cancer cells from our body. Some diet cleanses have been shown to be restrictive and harmful, impacting a person's ability to meet their daily requirements.

Keep in mind that our bodies have natural processes in place to remove harmful substances via the liver and kidney.

​​​ Are organic foods better for you?

The answer is simply: "No". There is no evidence to suggest that eating organic food reduces cancer risk.

Organic foods are produced without man-made pesticides and fertilizer, unlike conventional foods (non-organic). Farmers producing organic foods use natural pesticides that are approved and regulated by the federal government under the Organic Products Regulations. But it is unclear if organic foods have less pesticide residue than non-organic foods.

There is no evidence to suggest that organic foods are more or less nutritious than conventional foods. Both organic and non-organic foods contain the same amounts of vitamins and minerals. Organic foods tend to cost more due to the production process. Whether or not you would like to purchase organic foods comes down to personal preference.

​​​ Where can I go for good nutrition information?

These are just some of the many myths that are circulating the web. If you have any questions/concerns, ask your health care team to refer you to a Registered Dietitian. Registered dietitians at the Princess Margaret specialize in nutrition and cancer and can work with you to create a healthy eating plan that is right for you.

The internet can also be a great resource if you know where to go. Search reputable websites including cancer agencies, hospital websites, and government agencies:


Last reviewed: 9/28/2023
Last modified: 9/29/2023 12:52 PM
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