What is homocysteine?

Rootine TeamNov 11, 2021

What is Homocysteine?

You’ve probably heard about homocysteine and how some vitamins, including vitamin B 12, folate, and vitamin B 6 help regulate homocysteine levels – but how does it work and why are elevated homocysteine levels bad?

Homocysteine is an amino acid that is formed during the metabolism of methionine to cysteine [1]. Homocysteine is metabolized when regenerating methionine via a vitamin B 12- and folate-dependent pathway or when converting homocysteine into cysteine, also by a vitamin B-dependent pathway.

These biochemical processes are thus dependent on vitamin levels and vitamin deficiency in vitamin B 12, folic acid, and vitamin B 6 may lead to hyperhomocysteinemia, which is the term used to describe elevated homocysteine levels in the blood. Other factors that may lead to high levels of homocysteine include poor diet, smoking, alcohol and coffee intake, and thyroid function [2].


Hyperhomocysteinemia may also be caused by genetic defects of the enzymes involved in the metabolism of homocysteine, particularly a common variant on the MTHFR gene. Normal MTHFR function is key to maintaining normal levels of bioactive folate and methionine and prevents accumulation of homocysteine [3].

Hyperhomocysteinemia is a risk factor for cardiovascular disease, cognitive decline, stroke, and osteoporosis. Some people with hyperhomocysteinemia may not have any symptoms, but others can experience fatigue, numbness or tingling, weight loss, cognitive decline, osteoporosis, or dementia [4].

Homocysteine and food

Studies show that some foods high in animal protein, such as chicken, red meats, milk, and dairy products, are associated with hyperhomocysteinemia [5]. In comparison, a diet rich in plant-protein foods such as cereals, legumes, and soybean products was found to protect against high levels of homocysteine.


Maintaining a low homocysteine level is an important part of achieving optimal health. Rootine uses your DNA, blood status, and lifestyle habits to consider all your unique qualities and create a personalized micronutrient formula tailored precisely to your goals and help you perform at your best every day. Get started on your Rootine journey with a free lifestyle quiz.

These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease. Always consult with your healthcare provider before starting any supplement program.

[1] Kumar, A, Palfrey, HA, Pathak, R, Kadowitz, Gettys, TW, Murthy SN. The metabolism and significance of homocysteine in nutrition and health. Nutrition & Metabolism. 2017; 14:78. https://doi.org/10.1186/s12986-017-0233-z

[2] Hart, G. Methylation and Homocysteine. Food for the Brain Foundation. Available at: https://foodforthebrain.org/for-health-professionals/methylation-and-homocysteine/

[3] Brustolin, S, Giugliani R, Félix, TM. Genetics of homocysteine metabolism and associated disorders. Brazilian journal of medicine and biological research. 43(1):1-7. doi:10.1590/s0100-879x2009007500021

[4] Son P, Lewis L. Hyperhomocysteinemia. [Updated 2021 May 12]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK554408/

[5] Xiao Y, Zhang Y, Wang M, Li X, Xia M, Ling W. Dietary protein and plasma total homocysteine, cysteine concentrations in coronary angiographic subjects. Nutr J. 2013 Nov 7;12(1):144. doi: 10.1186/1475-2891-12-144. PMID: 24195518; PMCID: PMC4176105.

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