Vitamin Supplements While Undergoing Cancer Treatment |
Purpose:Studies have shown that a diet rich in fresh fruits and vegetables reduces the risk of many diseases, including some types of cancer. Many people take vitamin supplements to obtain the protective effects similar to those provided by a healthy diet. What is still hotly debated within the medical community is whether vitamins are beneficial to patients undergoing cancer treatment. Proponents of supplementary vitamins often recommend combining vitamins A, C, and E. They claim that these vitamins improve general well being, strengthen the immune system and may delay the development and progression of serious disease. Opponents claim that vitamins, especially antioxidants, can reduce the effectiveness of many chemotherapy drugs and that not enough is known to advocate vitamin use for patients undergoing treatment. What Has Been Proven?The majority of studies done to this date have examined the role of vitamin supplements in the prevention of various types of cancer. Researchers who have looked at the interaction of vitamins with chemotherapy have not been able to agree on whether the vitamins are beneficial or harmful. Much of the debate focuses around the antioxidant properties of some vitamins. Antioxidants are a normal part of the human diet and protect against cell damage by guarding normal, healthy cells from reactive oxygen species, also known as ROS. Antioxidants act like vacuum cleaners within the body, removing reactive oxygen species. Some researchers are concerned because many of the chemotherapy drugs need the reactive oxygen species to effectively fight tumors. If patients undergoing treatment take supplements that further raise the amount of antioxidants in their body, there may be fewer ROS left for the chemotherapy drugs to use. In a sense the antioxidants are eating up a key ingredient, the ROS, needed to make the recipe of cancer treatment within the body. Some researchers believe that in the long run vitamin supplements may reduce the efficacy of chemotherapy treatment, even though they may help patients have less immediate symptoms during treatment. Much of this debate is theory and predictions based on what is known about antioxidants and chemotherapeutic drugs. To date, no definitive human studies have demonstrated the long-term effects, one way or the other, of combining oral antioxidants and chemotherapy drugs. The proponents of supplementary vitamins believe that research shows that vitamins enhance treatment and patient survival. They point out that certain antioxidants are used currently in combination with chemotherapy to reduce the harmful side effects. An example of this would be the antioxidant mesna (Mesnex). Mesnex does not travel around the body acting as a vacuum cleaner, but instead goes straight to the kidneys. In the kidney pathway Mesnex reacts with toxic substances produced from drugs such as cyclophosphamide and ifosfamide. Mesnex does not affect the efficacy of these drugs but does help reduce harmful side effects. Proponents also argue that vitamins A, C, and E exhibit a role in tumor regression and inhibition of tumor growth. Multivitamins and Megadose vitamins:Because more research is still needed to make any final recommendations regarding vitamin supplements, different physicians will advocate different vitamins. Most agree that there does not appear to be harm in taking a multivitamin once a day. Most also agree that there too little known to endorse megadose vitamins and these should not be taken by patients. Possible Side Effects:Vitamin toxicity is a condition in which a person develops symptoms as side effects from taking massive doses of vitamins. Vitamins vary in the amounts that are required to cause toxicity and in the specific symptoms that result. Megadoses of vitamins for healthy individuals are mostly harmless. But in the cases of a few of the vitamins--specifically vitamin D, vitamin A, and vitamin B6-- megadoses can be harmful or fatal. Special Considerations/Contraindications:Research has shown that eating a healthy diet, low in fat, high in fiber, with plenty of fruits and vegetables, may help to lower cancer risk. It should be emphasized that maintaining a healthy diet during and after cancer treatment is very important. While vitamin supplements remain a topic of debate for patients undergoing cancer treatment, a healthy diet should be maintained. As with all complementary therapies, individuals considering a therapy should talk to their doctor to avoid harmful interactions with current medications and treatments. Written 4/00 |
