Nutrition: Fighting Cancer With Food with Sally Scroggs

Last Editorial Review: 10/23/2003

WebMD Live Events Transcript

The opinions expressed in this transcript are those of the health professional and have not been reviewed by a WebMD physician. If you have questions about your health, you should consult your personal physician. This event is meant for informational purposes only.

Moderator: Welcome to WebMD University: "Stories of Survivors: Your Breast Cancer Guide." Joining us now is dietitian and health educator Sally Scroggs, MS, RD, LD. Before we get to our member questions, can you tell us about the nutrition work you do at the M.D. Anderson Cancer Center?

Scroggs: Specifically I work in the Cancer Prevention Clinic. And a cancer prevention clinic is unique in a cancer facility. I see general population and I also see patients that are at high risk for cancer or perceived high risk. The cancer prevention clinic is also where the genetic counselors see patients, and they may send patients to talk to me. The undiagnosed breast clinic is associated with the Cancer Prevention Clinic, so I will see patients that will come through there. These patients may receive a breast cancer diagnosis. The majority of the patients do not. And I am able to review their risks and give them guidance in reducing the risk of breast cancer.

Also, some patients that come through our clinic are survivors; these are some of my most favorite patients. Their goals are reducing their risk or recurrence or reducing their risk of another type of cancer. So basically I see general population, patients at risk for cancer, and survivors.

Member: Cancer feeds on sugar, but does cutting sugar out of the diet help fight cancer?

Scroggs: Sugar is a carbohydrate. Carbohydrates are supplied in our diet from fruits, vegetables, whole-grain starches, beans, and dairy products. They provide us our source of energy. And these complex carbohydrates also provide nutrients and phytochemicals. Most health authorities recommend no more than 10% of our total calories come from sugar or refined carbs, as these foods are typically empty calories. An example: soda pop has sugar and empty calories vs. a piece of fruit which has sugar, complex carbohydrates, nutrients, and phytochemicals. When the body takes in these foods, the whole body will utilize these sources of nutrients as well as the cancer. So reducing sugar to 10% of the calories can be beneficial because you will introduce nutrients, antioxidants, and phytochemicals that can reduce the risk of cancer as well other diseases including heart disease and complications from obesity.

Member: There are so many different myths. Someone told me online that the myth about sugar feeding cancer is not true.

Scroggs: Well I hope that I just answered that but I need to clarify. Sugar is a carbohydrate. It's a source of fuel or energy. Your whole body system needs carbohydrates as well as all cells, including cancer cells. A healthy, balanced diets includes the majority of the calories coming from carbohydrates, therefore you can't cut out carbs 100%. That would only leave you with fats, protein, and alcohol. So one certainly can make healthier choices by reducing simple carbohydrates to 10% or less of total calories.

Member: It's important to me to make sure I'm getting the right nutrients as I am recuperating from surgery. What should I focus on?

Scroggs: Surgery creates stress in the body. You have to heal, you have to recover, and you want to reduce your risk of infection. A balanced diet will do this. Protein is especially important. This can come from meats and dairies, but it can also come from a plant-based diet with beans providing protein in combination with grains so you can receive all the essential amino acids for tissue repair. In addition, the other foods in a balanced diet provide the energy source, nutrients, and ability to make enzymes to help with protein utilization.

A second concern after surgery is typically blood loss and low iron stores. Again, beans, dark green vegetables, dried fruits (raisins, apricots, prunes) are good sources of iron. A more available iron source would be from animal meats -- beef, chicken, or fish, for example. The body is pretty amazing in that when iron stores are low it will better absorb iron introduced from foods and the best bang for the buck would be red meats. But poultry and fish are also good sources. For better absorption, make sure ascorbic acid (vitamin C) is available. So, for example, having orange juice with a meal or strawberries for dessert will enhance iron absorption.

Member: Is it true that certain vitamins, like E, can interfere with chemo and radiation?

Scroggs: Someone has done their research! Radiation treatment works on an oxidative process as well as a proposed mechanism for some chemotherapy agents. Adriamycin, which is a chemotherapy agent often used with breast cancer treatment, is in that category where it is proposed, not proved, that it works on an oxidative process. An oxidative process is where free radicals are introduced that increase cell death, and a cascade of these free radicals can promote cell death, which is what your goal is for chemotherapy treatment or radiation treatment, to kill the cancer cells.

Now I'm going give two sides to this: One side says don't overdo antioxidants. An example would be the vitamin E that was referred to, plus vitamin C, vitamin A, and selenium are all nutrients with antioxidant properties. Taking large amounts, mega-antioxidant supplements, may stop the cascade of cell deaths because antioxidants help reduce the free-radical activity. They help stabilize the cells.

On the other side, there is some research going on looking at the role of antioxidants with some cancer treatments at some specific cancer sites, in mostly test-tube and animal studies and very small numbers of human studies, looking at having an antioxidant with a treatment, hoping to show fewer toxic side effects. Some of the research indicates that less of the chemotherapy treatment needs to be given because it makes the treatment more effective, so you can use less of the chemotherapy drug.

These studies are not conclusive. They seem to be very specific. It's going take a lot of research in this new science to see which antioxidants are best for which chemotherapy treatments for which cancer diagnosis. When these studies get to a phase II clinical trial the subjects in the studies will be monitored for adverse effects, tolerance, organ function, etc.

So that's very different from someone buying over-the-counter supplements, where mega-doses can be purchased. For example, I have had patients who are taking an antioxidant supplement, a mega-dose multivitamin supplement, an immune-system booster, and a stress-relief supplement, which added up can be above the upper limits recently establish by the National Academy of Science. And the upper limit can be defined as an amount taken over time that can result in adverse effects. So there could be side effects like taking a drug because you're taking such high amounts and there can be nutrient interaction.

The American Cancer Society recently published an article, Nutrition During and After Cancer Treatments, and they recommend staying below the upper limit. And this gives a very broad range with the dietary reference intake including an RDA (recommended dietary allowance) and then a broad range to an upper limit. An example would be selenium, a potent antioxidant mineral. The RDA is 55 mcg and the upper limit is 400 mcg. So as long as your food intake and supplements don't exceed the upper limits, then you're in a safe range. However, you would need to discuss this with your oncologist, regarding supplements to take with treatment or not to take with treatment. After treatment, it's a different story.

Member: So where does that leave me right now, as to how to introduce antioxidants to my diet?

Scroggs: A healthy balanced diet is loaded with antioxidants. I analyze patients' intakes and, for example, vitamin C, just from the diet, may be as high as 400% above the RDA. This would still put you well below the upper limit of 2000 mg for vitamin C. I appreciate that it can be a challenge to eat or consume all the foods you know you need when receiving treatment.

Member: Would a low-carb diet be appropriate?

Scroggs: Research for cancer prevention indicates that we can reduce the risk of cancer by 30-40% with feasible dietary means. The American Institute for Cancer Research estimates that 33-50% of breast cancers are preventable by diet. In their guidelines for reducing risk, they recommend five or more servings of fruits and vegetables a day and more than seven portions of cereals or beans, starchy foods. To do this, you would have more of a plant-based diet that would provide 50% or more of your calories coming from carbs.

Research is being done on why this seems protective. Is this because plant-based diets are nutrient dense? It's where those great antioxidants come from. It's where the phytochemicals come from (phyto is the Greek word for plant). The phytochemicals show promise in disease reduction from initiation, promotion, and progression as well as reducing risk from heart disease. A plant-based diet has more fiber, so this may play a role. A plant-based diet is lower in fat and this may play a role.

The National Cancer Institute estimates that by simply getting the five a day, three vegetables, two fruits, one can reduce their risk of cancer by 20%. So the research supports a plant-based diet, which contributes carbohydrates to your total caloric intake. As I said earlier, if you are eliminating carbs and still needing to maintain calories then you have fats, protein, and alcohol left. And the cancer-fighting properties are coming from a plant-based diet that provides the nutrients, antioxidants, and phytochemicals. Again simple carbs, as discussed earlier, provide only empty calories.

Member: Does it matter if those "five a day" are fresh, frozen, or canned?

Scroggs: Excellent question. Research has been done on nutrients available in fresh produce vs. frozen vs. canned, and the results were interesting in that they were pretty much equal. Some speculation is that the reason is frozen and canned produce are picked at their peak of ripeness and preserved. Fresh produce may be picked before it's ripe, can sit in a truck, be shipped cross country, and sit on the produce counter with less nutrients and/or losing nutrients. What's important is that you eat your fruits and vegetables. If fresh produce is available, that's a choice. But if it's not always convenient with limited shopping time or accessibility. Have frozen on hand as well as canned.

Member: That is good to know because living in northern Wisconsin, there is a very short growing season for fresh produce.

Scroggs: The important thing is to get the fruits and vegetables in.

Member: How important are omega-3 fatty acids for someone concerned about recurrence?

Scroggs: This is a tough question because the research is not yet definite, but I can tell by the question that you've done your research. Omega-3, in a couple of studies, has shown reduced risk with prevention. But there are other studies that show there's a conflict in results where it doesn't show protection or it's neutral. So what do you do? Omega-3 is being looked at also for benefit for the immune system and it's already known that it reduces risk for heart disease. Therefore, a healthy choice would be to introduce omega-3 sources into your diet. Some examples:

  • Substituting cold-water fish for red meats.
  • Walnuts can be a decent source.
  • Sesame seeds that can be toasted and thrown on a salad can be a good source.
  • Flaxseed is also a good source of omega-3 and the flaxseed oil can be used in salad dressing.

Member: What is your opinion concerning soy intake and ER+ [estrogen-receptor positive] breast cancer?

Scroggs: My opinion is that this is the most dreaded question. You know as a healthcare provider, I am in this to help people. I get this question almost daily and the reason I dislike it is because there is no clear-cut answer. I'll do my best. Soy and the phytoestrogen genistein have been researched extensively the past 12 or so years and look very promising in prevention. The problem with an estrogen-receptor positive diagnosis is that we truly don't know if it's working as an estrogen or an anti-estrogen in your body. This is a decision that you will have to make on your own and I will try and give you some guidance. The concern comes from studies showing increased mammary tumor growth with estrogen supplementation. These are not human studies, these are mammary cell lines (breast cell lines) and in rodent studies. We don't know how taking a whole food, such as tofu or soybeans, introduced into a whole body system functions.

So what do you do? Soy has been shown to reduce risk of heart disease. There may be a role in bone protection. It's a great plant source for protein, includes all essential amino acids, has no cholesterol, is low in saturated fats, and it has other phytochemicals that have cancer-fighting properties. But with an estrogen-receptor positive diagnosis you know there's a tumor that feeds on estrogen. So we're hesitant to put something similar to estrogen, a phytoestrogen, into that picture. Will it feed the tumor? There is a proposed mechanism that it works similar to tamoxifen and blocks the receptor sites, therefore, yielding a protective factor. Some guesses, and these are guesses, are that it possibly won't hurt to have somewhere between two to five servings per week. But no one knows; it's a tough question and there's no clear answer at this time. I would refer you back to your oncologist to help with direction and guidance.

Another point might be to understand that there are phytoestrogens in other foods. Genistein is in other foods. It's in other beans, not just soybeans. It's in other plants, including apples and dates. So there's no way to 100% eliminate it from your diet. And there are other phytoestrogens in foods as well; it's just that soy has a more concentrated amount, relatively speaking.

There's also recent info looking at soy and it's protection in the Asian diet, for example, as being available through the lifecycle. With prevention and reducing risk, there is some thought that it's more appropriate to have the soy products in the diet, perhaps when breast buds are forming. And that may be where the protection comes from. We don't know if there is protection with adding soy later in life, in our 30s, 40s, or 50s, for breast cancer, specifically. But again, for prevention, there is evidence that it reduces the risk of heart disease and has a number of other positive aspects that I previously mentioned. I know I didn't answer the question; I did give a recommendation. I'm sorry there is no answer. Stay tuned!

Moderator: Thanks for joining us, members, and thanks to Sally Scroggs for being our guest.

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