Margaret A.WinkerMDIndividualAuthorPhil B.FontanarosaMD, Senior EditorIndividualAuthor
To the Editor.—The otherwise excellent article by Dr Rimm et al1 on the epidemiology of CHD among women left out a major confounding variable—decreased food vitamin B12absorption with increasing age2- 5 —and thereby drew the erroneous conclusion that intake of folate and vitamin B6above the current recommended dietary allowance may be important in the primary prevention of CHD among women. Coronary heart disease among women is primarily a postmenopausal event. Much more important is intake of a daily supplement of vitamin B12without added vitamin C and iron (which destroy much of the vitamin B12when the 3 dissolve together in the stomach).2,3 Extra folic acid suppresses the appearance of megaloblastic anemia, allowing neuropsychiatric damage from vitamin B12deficiency to progress to irreversibility,2,5 and hyperhomocysteinemia from vitamin B12deficiency to eventually override the added folate.5 Incidentally, low serum folate levels in vitamin B12deficiency are due to enterocyte megaloblastosis,5 and low red blood cell folate levels in vitamin B12deficiency occur because vitamin B12is necessary for folate transport into, and retention by, erythrocytes.
Herbert V. Relationship of Dietary Folate and Vitamin B6With Coronary Heart Disease in Women. JAMA. 1998;280(5):417-419. doi:10-1001/pubs.JAMA-ISSN-0098-7484-280-5-jbk0805