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| enhance the activity of various carcinogens. Other studies also indicate a link between alterations of the intracellular metabolism of cobalamin (B 12) and the increased growth of melanoma. There is a strong association between folate deficiency and cervical dysplasia, cervical and uterine cancers, cancers of the gastrointestinal tract, squamous cancers of the respiratory tract, and bone marrow cancers. 32 A recent study carried out at the Harvard Medical School has shown that long-term use of multivitamins may substantially reduce the risk of colon cancer. The study points to folio acid as the nutrient responsible for this benefit.33 |
| The onset of folate deficiency in tumor cells is accompanied by changes in the adhesive properties of the cells. Growth of murine melanoma cells in a lowfolate medium for longer than two-and-a-half days resulted in tumor cells that adhered more rapidly and in higher percentages to plastic dishes coated with laminin or fibronectin. Because folate deficiency affects several important characteristics of tumor cells, inadequate levels of this vitamin may contribute to the progression of malignancies. Studies in mice indicate that folate-deficient B 16 melanoma cells produce more metastases than folate-replete control cells.34 |
| It is increasingly apparent that methylation, the process of methyl metabolism, plays a central role in chemical carcinogenesis. Methyl groups are supplied in the diet (eggs and any green vegetables) principally by methionine and choline, and normal methyl metabolism requires, in addition, the nutrients folate and B 12. Deficiencies of choline, methionine, B 12, or folate are of widely varying importance in humans, with folate deficiency being by far the most important. Vitamin B 12 is found in seaweed, some seafood, and meat, and is therefore difficult to get in a vegetarian diet. Subclinical or borderline definiency of these nutrients is now thought to be a risk factor for cancer as well as heart disease. Testing for elevated levels of homocysteine in the blood is an effective way to evaluate methylation efficiency, as well as to determine the need for folio acid and/or vitamin B 12 supplementation. |
| Methotrexate, a standard chemotherapuetic agent used to treat various cancers, interferes with the activation of folate, therefore disrupting DNA replication for cancer and other cells. While it is generally accepted that folate supplementation must be avoided while a patient is on this drug, 1 mg of folate can reduce the side effects of methotrexate without interfering with its therapeutic effect. Methotrexate also negatively affects the metabolism of |
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