Charles Patrick Davis, MD, PhD
Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.
William C. Shiel Jr., MD, FACP, FACR
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
In this Article
- What is homocysteine?
- Can elevated homocysteine levels be genetic?
- How common is hyperhomocysteinemia?
- How can homocysteine levels be lowered?
- Does a lowering homocysteine level prevent heart attacks and strokes?
- Who should undergo testing for homocysteine blood levels?
How common is hyperhomocysteinemia?
Mild elevation in homosysteine levels (hyperhomocysteinemia) are common, and seen in about 5% to 12% of the general population. In specific populations such as, alcoholics (due to poor vitamin intake) or patients with chronic kidney disease, this may be more common. The severe genetic form, homocystinuria, is rare (0.02%).
How can homocysteine levels be lowered?
The consumption of folic acid supplements or cereals that are fortified with folic acid, and to a lesser extent vitamins B6 and B12, can lower blood homocysteine levels. These supplements may even be beneficial in people with mild genetic hyperhomocysteinemia to lower their homocysteine levels. However, it is noteworthy that so far there is no compelling data to support the treatment of hyperhomocysteinemia for prevention of heart disease or treatment of known heart disease or blood clots. Homocysteine levels are not routinely measured in indivduals with heart disease (atherosclerosis) or other diseases.
Does a lowering homocysteine level prevent heart attacks and strokes?
Currently, there is no direct proof that taking folic acid and B vitamins to lower homocysteine levels prevents heart attacks and strokes. However, in a large population study involving women, those who had the highest consumption of folic acid (usually in the form of multivitamins) had fewer heart attacks than those who consumed the least amount of folic acid. In this study, the association between dietary intake of folate and vitamin B6 and risk of heart disease was more noticeable than between dietary intake of vitamin B12 and heart disease, which was minimal.
Many other observational studies have been performed to assess the effect of folate and the other B vitamins on heart disease. Most of these studies have concluded that oral intake of folate has been associated to lower risk of heart disease, possibly because due to lowering of homocysteine levels. The relation between oral intake of vitamin B12 and B6 and heart disease was not as obvious in many of these studies. In one study, it was concluded that even in people with elevated homocysteine levels due to genetic reasons, oral intake of folate and possibly the other B vitamins was related to lower incidence of heart disease.
Most of these data, however, are obtained from observational studies rather than purely controlled scientific data. Therefore, it is important to mention that despite these studies suggesting an association between the intake of these vitamins and the lower incidence of heart disease, in general, there is no compelling clinical evidence to treat hyperhomocysteinemia other than homocystinuria (the severe genetic form) in regards to heart disease, stroke, or blood clots. As stated previously, homocysteine levels are not routinely measured in individuals with these problems.
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