homocysteine

noun

ho·​mo·​cys·​te·​ine ˌhō-mō-ˈsi-stə-ˌēn  ˌhä- 

: an amino acid C₄H₉NO₂S that is produced in animal metabolism by the demethylation of methionine and that appears to be associated with an increased risk of cardiovascular disease when occurring at high levels in the blood

Examples of homocysteine in a Sentence

Recent Examples on the Web

Betaine helps lower levels of homocysteine, another amino acid used by your body to make proteins. —Lindsey Desoto, Health, 10 June 2025

Lower Homocysteine Levels in the Body Vitamin B12 plays a role in reducing the amount of homocysteine in the blood by breaking it down. —Melissa Nieves, Verywell Health, 13 May 2025

An increase in homocysteine has been found to increase the risk of heart disease.17 Supplementing with creatine in the short term may positively affect the heart. —Emmanuella Ogbonna, Health, 8 May 2025

There were perturbations in levels of omega-6 fatty acid, homocysteine, total protein, bilirubin and a host of other things. —Bruce Y. Lee, Forbes.com, 27 Apr. 2025

For the study, researchers in Australia took blood samples from 172 middle-aged adults and checked their levels of magnesium, homocysteine, folate, and vitamin B12. —Nick Blackmer, Verywell Health, 11 Apr. 2025

There isn’t clear evidence, for example, that taking B vitamins to lower homocysteine levels actually reduces risk for heart problems. —IEEE Spectrum, 28 May 2015

Since high levels of homocysteine are linked to heart disease, methylated vitamins support cardiovascular health. —Allison Futterman, Discover Magazine, 7 Jan. 2025

According to the researchers, the toxic combination of low magnesium and high levels of homocysteine can increase the likelihood of contracting gastrointestinal disease, several cancers, diabetes, and Alzheimer's and Parkinson's diseases. —Killian Baarlaer, The Courier-Journal, 19 Dec. 2024

Word History

Etymology

International Scientific Vocabulary hom- + cysteine

First Known Use

1932, in the meaning defined above

Medical Definition

homocysteine

noun

ho·​mo·​cys·​te·​ine ˌhō-mō-ˈsis-tə-ˌēn  ˌhäm-ō- 

: an amino acid C₄H₉NO₂S that is produced in animal metabolism by the demethylation of methionine and forms a complex with serine that breaks up to produce cysteine and homoserine and that appears to be associated with an increased risk of cardiovascular disease when occurring at high levels in the blood