At the N.C. Cancer Hospital, patients tell us that they receive well-meaning but often conflicting advice from friends, family, acquaintances and internet sites about nutrition during cancer treatment and beyond. When combined with the side-effects of cancer treatment, this advice can provoke a great deal of anxiety at an already stressful time.
That’s why our oncology nutritionist, Aimee Shea, sat down with us to discuss some of the common questions patients have about cancer and nutrition.
Your questions, our experts: An interview with oncology dietitian Aimee Shea, MPH, RD, CSO, LDN
Q: I have heard that sugar feeds cancer. If I have a cancer diagnosis, should I cut all sugars out of my diet?
Aimee: There’s a lot of confusion out there about the connection between sugar and cancer. The idea that sugar feeds cancer is really not useful because sugar feeds ALL of our cells. Our bodies need glucose, or sugar, for energy. Even if you cut every bit of sugar out of your diet, your body will make sugar from other sources, like protein.
The real problem with a lot of simple sugar is that it causes the body to produce insulin, which can tell cells to grow. For healthy cells, this is a good thing. For cancer cells, this is not a good thing. In general, keeping insulin in balance is very important for your health.
If you have a cancer diagnosis, the recommendations are to follow a plant-based diet. . Here are some tips that we often share with people trying to improve their nutrition:
- In general, eat a healthy diet that includes a wide variety of foods. It’s best to avoid foods that are very high in refined sugar and thus don’t have a lot of nutritional value, for example, sodas or sweetened beverages, cakes, cookies, candy, etc.
- Choose complex carbohydrates like vegetables, fruits, whole grains, and legumes (beans) instead of simple carbohydrates like candy, soda, or baked goods. Coincidentally, these complex carbohydrates are the very foods that contain cancer-fighting nutrients!
- Combine foods to balance out your insulin response. In general, combining carbohydrates with protein, fat or fiber can help slow down the body’s insulin response. So, instead of having two pieces of fruit, combine a piece of fruit with a handful of nuts (nuts contain protein, fat and fiber). Or, instead of choosing fruit juice, choose whole fruit (it contains fiber which helps slow down the release of sugar into the bloodstream.)
Q: I have heard that having an “acid environment” in the body can encourage cancer cells to grow and that I should avoid acidic foods.
Aimee: This is a common idea that comes from a misunderstanding about the connection between cancer and acid in the body. It’s true that cancer cells can create acid – but extra acid in the body does not cause cancer.
Your body is a finely-tuned machine that really doesn’t allow big swings in its acid-base balance. The good news is that the same foods that fight cancer in other ways also help make the body less acidic. These include plant-based foods such as vegetables, fruits and legumes. You don’t have to be a vegetarian, but everyone can benefit from eating more plants. A general rule is to try to have two-thirds or more of your plate covered by plant foods (vegetables, fruit, whole grains and beans) and one- third or less covered by animal foods (meat, chicken, fish, dairy, eggs).
Q: Are soy foods dangerous for women with breast cancer?
Aimee: This is a great question that creates a lot of anxiety for individuals who have been diagnosed with breast or other hormone related cancers. It is also one of the misunderstood concepts relating to healthy nutrition for women with a history of breast cancer.
Research studies do not support the idea that soy foods produce estrogen and therefore should be avoided. This idea comes from the fact that these foods do contain a group of nutrients known as phytoestrogens (plant estrogens). While these nutrients look chemically similar to human estrogen, they are not the same as naturally occurring human estrogens.
Researchers have noted that women who consume soy food as part of a normal diet, such as Japanese women living in Japan, have much lower breast cancer rates than women who do not eat soy foods regularly. However, remember that there are many other lifestyle factors that may also contribute to breast cancer rates among Japanese women!
The consensus in the oncology nutrition world is that 2-3 servings of whole soy foods per day are fine. Whole foods include edamame, tofu, tempeh, miso, and soy milk. As with many other foods, highly-processed soy-based foods, such as soy protein powder or processed soy patties, are likely not as beneficial as whole foods and shouldn’t be your primary source of soy
Q: Should I switch to organic foods? What about the high cost of eating organic?
Aimee: Many people feel that pesticides in the food they eat may have played a role in their cancer, which leads them to ask about organic foods. Some research tells us that organic fruit and vegetables generally are higher in vitamins, minerals, antioxidants and other healthy nutrients when compared with conventionally-grown foods. Choosing organic foods can also decrease our exposure to pesticides.
The reality is that organic foods can be more expensive. However, by making smart choices when buying organic, you can balance your health and your budget.
The Environmental Working Group recommends that you buy organic for the following group of fruits and vegetables – often called “The Dirty Dozen”:
- Sweet Bell Peppers
- Grapes (imported)
At the same time, they found that certain foods are generally grown using many fewer pesticides, making it less beneficial to buy organic. The “Clean Fifteen” includes:
- Sweet Corn (Frozen)
- Sweet Peas (Frozen)
- Kiwi Fruit
You have to do your own personal cost-benefit analysis, but these recommendations can help you make smart choices about when to buy organic.
Q: Where can I find reliable information about diet and cancer on the internet?
This is a great question! While the internet can be a wonderful source of information, there is also a lot of mis-information out there that is not supported by science. Two web sites that I find helpful are:
American Institute for Cancer Research http://aicr.org/ — click on the “Diet” link for lots of good resources
Caring for Cancer http://caring4cancer.org/ – click on “Eating Well” to enter the nutrition section
Editor’s note: For more of Aimee’s web recommendations, see our nutrition web page at http://unclineberger.org/patient/programs/conn-nutrition.asp