Homocysteine is an amino acid produced when the body metabolizes methionine, which is found in protein-rich foods. Normally, vitamins help break down homocysteine, keeping its levels in the blood low. When this process is inefficient, its concentration can rise, a condition known as hyperhomocysteinemia. While part of a normal biochemical cycle, elevated levels of homocysteine can become a health concern.
Causes of Elevated Homocysteine
The most common cause of high homocysteine relates to nutritional status. The body requires adequate amounts of three B vitamins—B12, B6, and folate (B9)—to properly metabolize homocysteine. A deficiency in any of these vitamins can disrupt this process and lead to its accumulation in the blood. Folate deficiency is the most common nutritional reason for elevated homocysteine in many populations.
Genetic factors also affect how the body processes homocysteine. A common genetic variation, an MTHFR gene mutation, can impair an enzyme that processes folate. This makes it more difficult for the body to convert homocysteine back into methionine, leading to higher levels, particularly when folate intake is low. While rare genetic disorders cause severely high levels, the MTHFR variation is a more common contributor to mild or moderate elevation.
Beyond diet and genetics, certain medical conditions and lifestyle choices contribute to increased homocysteine. Reduced kidney function can impair the clearance of homocysteine from the blood. Other contributing factors include:
- Hypothyroidism
- Psoriasis
- Smoking
- Excessive alcohol consumption
- Excessive coffee consumption
Associated Health Risks
Elevated homocysteine is a risk factor for several health problems, particularly those affecting the cardiovascular system. High levels can damage the inner lining of arteries (the endothelium). This damage promotes inflammation and accelerates atherosclerosis, a condition where plaque builds up inside the arteries. The resulting hardening and narrowing of arteries increases the risk of blood clots, heart attacks, and strokes.
High homocysteine also impacts neurological health, with research linking it to an increased risk of cognitive decline, dementia, and Alzheimer’s disease. By damaging blood vessels in the brain, homocysteine may reduce blood flow and contribute to neuronal damage. Studies have found that individuals with levels above 14 micromoles per liter (µmol/L) had double the risk of developing Alzheimer’s compared to those with lower levels.
Other health concerns are associated with hyperhomocysteinemia, including a higher incidence of bone fractures, potentially due to interference with collagen. In pregnant women, elevated levels may be linked to complications such as preeclampsia. Having high homocysteine indicates an increased risk, not a certainty of developing these conditions.
Testing and Interpreting Levels
Homocysteine is measured with a simple blood test. To ensure an accurate reading, you may be asked to fast for 8 to 12 hours before the test. You should also inform your doctor of any medications or supplements you are taking, especially B vitamins, as they can affect the results.
Results are reported in micromoles per liter (µmol/L), and while ranges can vary between labs, a normal level is less than 15 µmol/L. Mild or moderate elevation is 15-30 µmol/L. An intermediate elevation is 30-100 µmol/L, and a severe elevation is any level above 100 µmol/L.
Interpreting these numbers requires a conversation with your healthcare provider. Elevated levels can suggest a B vitamin deficiency or an underlying condition. Your provider will consider the results alongside your overall health, family history, and other risk factors to determine the significance and necessary next steps.
Management and Reduction Strategies
Addressing high homocysteine often begins with dietary adjustments to increase B vitamin intake. Foods rich in folate (B9) include leafy green vegetables, legumes, and citrus fruits. Good sources of vitamin B6 include chickpeas, salmon, and poultry. Vitamin B12 is primarily available in animal products such as meat, fish, eggs, and dairy. Consciously incorporating these foods into your daily meals can help support the body’s natural homocysteine metabolism.
If dietary changes are not enough, or for those with significant deficiencies or an MTHFR mutation, supplementation may be recommended. B-complex supplements with folate, B6, and B12 can lower homocysteine levels. For some, a specific form of folate called methylfolate may be more effective. Any supplementation plan must be guided by a healthcare provider to ensure appropriate dosages and monitor effectiveness.
Lifestyle modifications also help manage homocysteine. Quitting smoking and reducing excessive alcohol consumption are beneficial, as both habits can deplete B vitamins. Regular physical activity and stress management can also help by reducing inflammation, which is linked to elevated homocysteine. These strategies, combined with diet and supplementation, offer a comprehensive approach.