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Medical Author:

Siamak T. Nabili, MD, MPH

Siamak T. Nabili, MD, MPH

Dr. Nabili received his undergraduate degree from the University of California, San Diego (UCSD), majoring in chemistry and biochemistry. He then completed his graduate degree at the University of California, Los Angeles (UCLA). His graduate training included a specialized fellowship in public health where his research focused on environmental health and health-care delivery and management.

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Medical Editor:

William C. Shiel Jr., MD, FACP, FACR

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.

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In this Article

• What is homocysteine?
• Why is it important to monitor homocysteine levels?
• What are the possible symptoms or features of elevated homocysteine levels?
• What is considered a high level for homocysteine?
• What causes elevated homocysteine levels?
• Can elevated homocysteine levels be genetic?
• Can nutritional problems cause elevated homocysteine levels?
• How common is hyperhomocysteinemia?
• How can homocysteine levels be lowered?
• How many vitamins should I take to lower my homocysteine level?
• Does lowering homocysteine levels prevent heart attacks and strokes?
• What should I do to prevent heart attacks and strokes?
• Who should undergo testing for homocysteine blood levels?
• Patient Comments: Homocysteine - Cause
• Homocysteine Index

Can nutritional problems cause elevated homocysteine levels?

The other more common (5%-7% of the population) and less severe type of elevated homocysteine level may be caused by nutritional deficiencies in folate, vitamin B6 and vitamin B12, chronic (long-term) kidney disease, and cigarette smoking.

As mentioned above, these vitamins are essential in the breakdown of homocysteine. In some studies, lower levels of these vitamins, especially folate, have been demonstrated in people with elevated homocysteine levels. On the other hand, other studies have suggested that adequate intake of folate, Vitamin B6, and Vitamin B12 have resulted in lowering of the homocysteine level. ⁽³⁾

How common is hyperhomocysteinemia?

Mild hyperhomocysteinemia levels are seen in about 5%-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.

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. There are many studies underway to determine whether there may be any benefit to treat high levels of homocysteine in patients with known heart disease or blood clots. Further recommendations may be available when these studies are completed. ⁽⁴⁾