ARLINGTON, Va. - Many dietary supplements may have potential benefits in cancer treatment, but relatively little attention has been paid to how much of these substances should be taken and how they interact. As doctors and patients work to define how alternative therapies fit in with conventional cancer care, the body of evidence derived from scientific research is mounting.
Currently, the appropriate dose of many phytochemical compounds -- molecules that are derived from plants -- can only be guessed at, based on laboratory and animal testing, said John C. Boik, a board-certified acupuncturist and practitioner of Oriental medicine in Boulder, Colo., who conducts research on natural compounds for M.D. Anderson Cancer Center.
An estimated 10 to 60 percent of cancer patients use some form of alternative medicine as part of their treatment. Herbal remedies and dietary supplements are readily available, but there is little incentive for pharmaceutical companies that market these products to conduct the scientific research needed to establish safety and effectiveness. In fact, many compounds are ignored entirely by manufacturers because there is no way to make money on them, Boik said here Friday at Comprehensive Cancer Care 2000, a national conference on integrating complementary and alternative therapies. Patents cannot be obtained for natural substances, he added.
Some plant compounds may turn out to be much less toxic than chemotherapy drugs. However, this means that they are less effective at killing cancer cells and that to derive the most benefit from them, the active ingredients must be used at high concentrations. This could, in turn, raise the risk of adverse effects, according to Boik.
Taking a lesson from traditional Chinese medicine, Boik's research has focused on the benefits of combining a dozen or more compounds to obtain a synergistic effect, in which the whole is greater than the sum of its parts. With this approach, greater anti-tumor activity can be achieved at much lower concentrations. In one laboratory experiment, the concentration of a single compound needed to kill cancer cells was four times higher than the concentration of 12 compounds combined, Boik said. His research has examined dozens of natural compounds, such as anthocyanidine, astragulus, butcher's broom, and the fish oils EPA and DHA.
On the other hand, lower doses of plant compounds, perhaps even at the levels available from diet alone, may be sufficient to help prevent cancer, Leo Galland, M.D., director of the Foundation for Integrated Medicine, said at the conference.
How to support the body's own detoxifying defenses
The body has a balanced two-step chemical mechanism for dealing with potential carcinogens, and this mechanism is influenced by both genetic and lifestyle factors, including diet, Galland explained. When this balance is disrupted, free radicals, a by-product of the first, potentially dangerous step, can get out of control, causing DNA damage that can lead to cancer, he said. Smoking, consumption of charbroiled meats and high intake of alcohol and vegetable oils can allow this to happen.
On the other hand, it is thought that eating a vegan diet (no meat, dairy or eggs) helps keep this risky chemical phase in check, as can compounds found in grapefruits, the spice turmeric, chili peppers (capsicum), cloves and onions.
The second, defensive phase of detoxification can be compromised by nutritional deficiencies, exposure to toxins, alcohol and insufficient intake of protein. In fact, insufficient intake of protein can lead to low levels of glutathione, one of the key antioxidants that neutralize the free radical products of the first phase.
On the other hand, cabbage, broccoli, cauliflower, brussels sprouts and other cruciferous vegetables are thought to have a positive effect, as do garlic oil, rosemary, soy, citrus peels, dill seeds, caraway oil, curcumin, SAM-e and milk thistle.
