Homocysteine is a naturally occurring amino acid that is produced as a byproduct of methylation and metabolism of methionine. This means that even though methionine comes from the diet (mostly from foods such as fish, meat, nuts, and seeds) homocysteine does not come from the diet; your body makes it. These amino acids will continue to be recycled, as long as the body has the proper nutrients and enzymes for the process to continue.

When does hyperhomocysteinemia become dangerous?

Circulating homocysteine at normal levels is not a problem, as long as your body has plenty of B vitamins, specifically folate, to help process it. Diets high in meat are associated with higher homocysteine levels. And, if you’re not consuming enough B vitamins, or you have another biochemical hold-up in the metabolism of homocysteine, levels can build up in your blood plasma causing a condition called hyperhomocysteinemia. 

High homocysteine levels in the blood can damage the lining of the arteries and put you at greater risk for heart disease. High levels of homocysteine can also cause blood to clot when it’s not supposed to. When blood clots inside of your blood vessel it is called a thrombus. When a thrombus travels through the bloodstream to the lungs, it can cause pulmonary embolism, if the clot travels to the brain, it can cause a stroke, and if the clot travels to the heart, it can cause a heart attack. There is a growing body of scientific evidence to show that high levels of homocysteine in the plasma is not only a risk factor for many diseases but also a predictor of potential non-cardiovascular health problems such as Alzheimer’s.

What causes homocysteine to elevate?

Most people with high homocysteine levels are simply not getting enough B vitamins from their diet. These B vitamins include folate (folic acid/B9), B6, B12, and B2. If this is the case, homocysteine levels should return to a healthy range as soon as these vitamins are replaced. Certain common medications can deplete some of these vitamins, especially folate and B12, leading to an increased possibility of deficiency.Other causes of high homocysteine could be hypothyroidism, kidney disease, psoriasis, a side effect of medication, or a genetic condition. One such condition is the MTHFR mutation.

MTHFR is a gene that provides instructions to make an enzyme called methylenetetrahydrofolate reductase. It has been estimated that up to 60% of Americans carry an inherited mutation in the MTHFR gene. Methylenetetrahydrofolate reductase is a necessary factor for a chemical reaction breaking down folate to its active form, L-methylfolate (5-MTHF). So if your genes don’t allow you to make this enzyme efficiently, you will not get the benefits of dietary folate. While many people with mutations in this gene will live a normal life without experiencing symptoms, some individuals experience a drop in enzyme efficiency by 30-70%, depending on the variant of the mutation. If this is the case, folate cannot be converted to L-methylfolate, and unconverted folate and homocysteine levels build up in the blood without consistent conversion.

This genetic mutation is also associated with negative changes in mood, energy level, and sense of well-being. If you are experiencing these symptoms, you may consider genetic testing.

What can I do about high homocysteine?

First and foremost, if you suspect you may have high homocysteine levels, have your blood tested by a physician. You do not need to prepare for the blood test in any way, but there is really no reliable way to diagnose this condition at home. Your doctor can also test you for the MTHFR gene mutation.

If you do not have the MTHFR mutation, but your homocysteine levels are just slightly high, your doctor may recommend a watch and wait period, while you make sure you are consuming a healthy, nutritious diet and supplementing as needed. The nutrients that help to reduce homocysteine levels are folate, B12, B6 and B2, zinc, and trimethylglycine (TMG). Your doctor also may have some specific supplementation recommendations based on your blood work, but the good news is, often homocysteine levels can be balanced through nutritional changes.

If you do have a genetic mutation in your MTHFR gene, there are nutritional options for you too. L-methylfolate, the activated form of folate needed to break down homocysteine, can be taken as a supplement, and MethylPro is an excellent option. L-methylfolate supports a number of methylation processes in the body, not only related to the cardiovascular system, but also fertility, detoxification, estrogen metabolism, mood support and production of neurotransmitters, and nerve health. As the body of knowledge has grown linking these methylation processes to varied areas of human biology such as heart health, so has awareness of the potential benefits of methylfolate.


Clarke, Robert, et al. “Effects of lowering homocysteine levels with B vitamins on cardiovascular disease, cancer, and cause-specific mortality: meta-analysis of 8 randomized trials involving 37 485 individuals.” Archives of internal medicine 170.18 (2010): 1622-1631.

Cotlarciuc, Ioana, et al. “Effect of genetic variants associated with plasma homocysteine levels on stroke risk.” Stroke 45.7 (2014): 1920-1924.

Moll, Stephan, and Elizabeth A. Varga. “Homocysteine and MTHFR mutations.” Circulation 132.1 (2015): e6-e9.

Rodionov, Roman N., and Steven R. Lentz. “The homocysteine paradox.” (2008): 1031-1033.

Zhang, Weili, et al. “High plasma homocysteine levels contribute to the risk of stroke recurrence and all-cause mortality in a large prospective stroke population.” Clinical science 118.3 (2009): 187-194.