Homocyst(e)ine and Cardiovascular Disease: A Critical Review of the Epidemiologic Evidence

  1. John W. Eikelboom, MBBS, FRACP;
  2. Eva Lonn, MD, FRCPC;
  3. Jacques Genest, Jr., MD, FRCPC;
  4. Graeme Hankey, MBBS, MD, FRCP, FRCP(Edin), FRACP; and
  5. Salim Yusuf, MBBS, DPhil, FRCPC
  1. From McMaster University, Hamilton, Ontario, Canada; Clinical Research Institute of Montreal, Montreal, Quebec, Canada; and Royal Perth Hospital, Perth, Western Australia.

    Abstract

    Purpose: To review epidemiologic studies on the association between homocyst(e)ine level and risk for cardiovascular disease and the potential benefits of homocysteine-decreasing therapies.

    Data Sources: Computerized and manual searches of the literature on total homocysteine levels and cardiovascular disease.

    Study Selection: Prospective studies and major retrospective epidemiologic studies evaluating the association between homocyst(e)ine levels and cardiovascular disease and the association between blood levels or dietary intake of folate, vitamin B6, and vitamin B12 and cardiovascular disease.

    Data Extraction: Relevant data on patient population, plasma homocyst(e)ine levels, duration of follow-up, and main results were extracted from studies that met the inclusion criteria.

    Data Synthesis: The designs and results of studies included in this review are summarized. A formal meta-analysis was not performed because the studies were heterogeneous in method and design.

    Conclusions: Results of epidemiologic studies suggest that moderately elevated plasma or serum homocyst(e)ine levels are prevalent in the general population and are associated with an increased risk for cardiovascular disease, independent of classic cardiovascular risk factors. Simple, inexpensive, nontoxic therapy with folic acid, vitamin B6, and vitamin B12 reduces plasma homocyst(e)ine levels. Although the association between homocyst(e)ine levels and cardiovascular disease is generally strong and biologically plausible, the data from the prospective studies are less consistent. In addition, epidemiologic observations of an association between hyperhomocyst(e)inemia and cardiovascular risk do not prove the existence of a causal relation. Therefore, the effectiveness of folate, vitamin B6, and vitamin B12 in reducing cardiovascular morbidity and mortality requires rigorous testing in randomized clinical trials. Several such trials are under way; their results may greatly affect cardiovascular morbidity and mortality, given the simplicity and low cost of vitamin therapy.

    Article and Author Information

    • Grant Support: Dr. Eikelboom is the recipient of a Medical Research Fellowship from the Haematology Society of Australia and the University of Western Australia. Dr. Yusuf is the recipient of a Medical Research Council of Canada Career Scientist Award and holds a Heart and Stroke Foundation of Ontario research chair.

    • Requests for Reprints: Eva Lonn, MD, Preventive Cardiology and Therapeutics Program, McMaster University, HGH, McMaster Clinic, 237 Barton Street East, Hamilton, Ontario L8L 2X2, Canada.

    • Current Author Addresses: Drs. Eikelboom, Lonn, and Yusuf: Preventive Cardiology and Therapeutics Program, McMaster University, HGH, McMaster Clinic, 237 Barton Street East, Hamilton, Ontario L8L 2X2, Canada.

    • Dr. Genest: Clinical Research Institute of Montreal, 110 avenue des Pins ouest, Montreal, Quebec H2W 1R7, Canada.

    • Dr. Hankey: Department of Neurology, Royal Perth Hospital, Wellington Street, Perth 6001, Australia.

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    1. Ann Intern Med September 7, 1999 vol. 131 no. 5 363-375
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