Nutrition, Supplements and Cancer Treatment

Cancer breeds questions. At the U-M Comprehensive Cancer Center, we face tough questions every day – in our clinics, our laboratories, our classrooms and our community – and we know we’re only as good as our latest answer. In this installment of “Frequently Asked Questions,” two experts, Kathryn Haraminac, R.D. (pictured to the left), the Cancer Center’s adult nutrition counselor (KH), and Mark Moyad, M.P.H. (pictured to the right), the Phil F. Jenkins Director of Complementary and Alternative Medicine for the Michigan Urology Center (MM), tackle the subject of nutrition and nutritional supplements and their impact on cancer treatment.

There’s so much talk about supplements…what general advice would you give to cancer patients who are considering using supplements?

MM: I’m a steadfast supporter of supplements. But I always tell patients that benefiting from supplements requires doing their homework.
The supplement industry is virtually unregulated. The exception is the Dietary Supplement and Health Education Act (DSHEA) of 1994. While the DSHEA does place some limits on labeling and advertising, it provides little consumer protection. Unlike the rigorous government oversight required to bring a new pharmaceutical to market, the DSHEA statute contains no provision to guarantee that a supplement does what it is marketed to do. You can put virtually any thing in a bottle and market it as a supplement.

KH: It’s the classic case of “buyer beware.” Without government oversight, you, the patient, need to become your own “expert” and advocate – researching the available data and determining from the information available whether it’s indicated for your specific situation.

What advice do you give patients to help them become smart consumers of supplements?

MM: We’ve developed a list of supplement “commandments”– here are a few:

Look for the catch – if it isn’t there, there’s nothing there. If a dietary supplement doesn’t come with the risk of a side effect, it either hasn’t been tested or it does nothing at all.

Pay attention to the placebo effect. In some studies, significant progress is seen in study participants who receive a sugar pill or “placebo” instead of the supplement. This shows just how real the mind-body connection is. In order to
signal a promising result, a supplement’s test results should always “beat the placebo effect.”

And a final word of caution: To be safe, always stop taking all supplements prior to surgery or radiation therapy. Many thin the blood and can interact with anesthesia – just as you would stop taking aspirin prior to surgery, stop supplements during that period too.

What are the common misconceptions patients have regarding supplements?

MM: People tend to take a supplement thinking “it might help, and it won’t hurt.” That’s a dangerous assumption. The media tends to focus on the positive “sound bites” surrounding a supplement, but only rarely publishes the negative results, or specifics on dosage, side effects or drug interactions.

KH: A related mistake is people thinking that if a little is good, a lot is better. It’s important to remember that even natural substances can be toxic in large doses. And if more than one supplement is being taken, the compounding effects, positive or negative, should be considered as well.

MM: Another is to listen to advice that says “everyone should take this.” A recent instance is selenium, which may slow the progression of certain cancers, including colon, lung and prostate. Taken at face value, every cancer patient would begin to take selenium. But upon closer investigation, success in the limited clinical trials was seen only in those patients with a low baseline of selenium in their bodies to begin with – not in the general population. Again, a little homework makes a big difference.

What resources are available to patients to do that homework?

MM: Our own resources, including the Patient Education Resource Center (PERC) are a great place to start. With the assistance of trained volunteers, patients can access the latest data from published sources and reliable web sites.

KH: Reliable is the key word there. Since so many supplement marketers make fantastic claims on the web, finding credible research studies can be really challenging. One site we recommend is a database created by Memorial Sloan Kettering called Information Resource: About Herbs, Botanicals and Other Products. (www.mskcc.org/mskcc/html/11570.cfm). 135 of the most popular supplements and herbal remedies are reviewed there, including some pertinent clinical studies and background on claims, drug interactions and side effects.

MM: Once you’ve done your research, the next step is to bring what you’ve learned to the attention of your doctor. If you can determine that a supplement is shown useful for your given situation, your doctor should be open to having you try it.

Let’s touch on two of the many hot topics in cancer nutrition – antioxidants and soy.

KH: The proposed function of antioxidants is the protection of cells from injury caused by substances called free radicals, which are gen- generated by the byproducts of the oxygen our bodies need and use every day. Free radicals can make cells weaker and flaky and not function as well as they should – much like another form of oxidation – rusting metal. Anti-oxidants protect cells from injury by free radicals.

Phytochemicals – a fancy word for plant chemicals –are theorized to act as anti-oxidants. Brightly colored fruits and vegetables are good sources of antioxidants and phytochemicals, as well as nuts and whole grains.

MM: Soy provides nature’s best source of plant-based estrogens. Numerous studies point to soy’s potential for countering hot flashes in breast and prostate cancer patients and for possibly protecting against some cancers. Plant estrogens have also been shown to help lower blood cholesterol levels, so they’re heart-healthy too. In general, a heart healthy diet is a good starting point for most cancer patients. But, with both traditional soy products and flaxseed, there is some controversy breast cancer patients should consider. Some theorize that they could promote the growth of breast tumors because they contain plant estrogens. Since there is no definitive data, I suggest these patients talk with their doctors before deciding whether or not to include them.

KH: At the Cancer Center, we suggest that patients eating soy obtain it from whole sources, like soy milk, tofu, or tempeh, and that these be eaten moderately among a wide variety of foods consumed. The evidence to date shows no harmful effects for breast cancer patients from eating soy, but neither is there sufficient data to promote soy to assure survival.

The benefits of both antioxidants and plant estrogens highlight why, whenever possible, we encourage moving toward a plant-based diet. International studies reveal that populations with diets richer in fruits, vegetables, whole grains, legumes and whole soy have a lower incidence of many cancers.

In general, do you recommend that cancer patients take a multi-vitamin supplement?

MM: Yes. In many cases multi-vitamin supplements can be
helpful in countering nutritional deficits. The benefits of multivitamins have been well-documented. But remember, as with any supplement, consult with your doctor before taking any multivitamin. Some may contain too many ingredients, or mega-doses of certain compounds such as vitamin A that could impact bone mineral density and possibly increase the risk of a future fracture.

KH: I agree. We frequently suggest a multivitamin/mineral supplement to help reach recommended daily levels of critical elements. But we always caution patients that no amount of supplementation can fully compensate for a poor diet. Foods are just too complex to be contained in a daily multivitamin supplement.

What other issues do you encounter when counseling cancer patients on their diets?

KH: We see many cancer patients who have too little variety in their diets. Many do eat fruits and vegetables regularly, but on closer examination we learn that they choose from a limited list – like a banana every day as their fruit. By encouraging them to venture beyond their established favorites, they’ll take in a variety of essential plant compounds. So rather than eating only iceberg lettuce, adding a darker green lettuce like spinach can provide an additional anti-oxidant “punch.”

So, what’s the last word in supplements?

MM: I see a promising future as research into supplements becomes more widespread and accepted. Supplements are clearly impacting medicine. For example, vitamin E is now a medically accepted therapy to slow the progression of Alzheimer’s disease in patients exhibiting symptoms. I think we’ll soon see similar advances leading to more widespread use of supplements in cancer treatment.

And your parting advice about nutrition?

KH: Make every bite and every sip count. When making food choices, ask yourself whether there are ways to get more out of what you’re eating, and make the choices that make your diet as varied as possible. People usually assume that nutrition counseling is about eliminating “bad foods” – but it’s really about identifying and adding foods that are consistently missing from your diet. The foods that have been shown to have the largest positive impact on health are the ones that are lacking in the average diet.

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