High homocysteine can be a marker of vitamin deficiency. It has been linked to many health problems including heart disease, dementia, and Alzheimer’s. However, studies have shown that lowering homocysteine with vitamin supplements doesn’t necessarily produce desired health benefits and may even be harmful. This post explains homocysteine, reviews the factors that influence its levels, including diet, lifestyle, and genetics (i.e. MTHFR mutation), and discusses the best ways to optimize your levels in ways that are actually conducive to better health.

What is Homocysteine?

Homocysteine is a sulfur-containing amino acid that the body produces from another amino acid, called methionine. Foods that are high in methionine include meat, egg whites, and seafood.

Homocysteine is usually found in very small amounts in your body. That’s because your body converts it efficiently into other products with the aid of B vitamins. Higher homocysteine levels can indicate a deficiency of these vitamins [1].

Apart from vitamin deficiency, higher homocysteine levels have been linked to heart disease, cognitive dysfunction, and dementia.

The Breakdown of Homocysteine

Homocysteine is converted into less toxic and more useful amino acids via two biochemical pathways, i.e. remethylation or transsulfuration:

• Remethylation – A methyl group from 5-MTHF, a breakdown product of dietary folate, or betaine is added to homocysteine to convert it back to methionine. Vitamin B12 is needed in this process, as are the enzymes methionine synthase MTHFR [2, 3].
• Transsulfuration – Homocysteine is converted to cystathionine by cystathionine β-synthase. Vitamin B6 is needed for this conversion [2, 3]. Cystathionine can then be converted into cysteine and subsequently glutathione (a very powerful antioxidant) [4].

When homocysteine can not be converted to other compounds, it builds up in the body and may cause damage. B vitamins play a very important role in this balance.

Homocysteine Blood Test

A doctor may order a homocysteine test to:

• Find out if there is vitamin B12, folate, or vitamin B6 deficiency
• Check for heart disease in people at high risk
• Help diagnose homocystinuria, a rare genetic disorder

Homocysteine is not a commonly used test. It’s relatively expensive and rarely covered by insurance. Ranges and results may slightly vary from lab to lab, due to differences in equipment, techniques, and chemicals used.

A high-protein meal can significantly increase homocysteine levels. Therefore, fasting throughout the night before