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Understanding BHMT, Homocysteine, and What Your Genotype Means for Health

Homocysteine is a sulfur-containing amino acid produced during normal metabolism. At typical levels it is harmless, but when homocysteine rises it has been linked to higher risk for cardiovascular disease, stroke, and some cognitive concerns. The BHMT gene encodes an enzyme that helps lower homocysteine by converting it back into the essential amino acid methionine. This reaction uses a nutrient called betaine as a cofactor.

Genetic variations in BHMT can change how efficiently this enzyme works. Depending on your genotype at rs3733890, you may have normal enzyme function or a reduced ability to clear homocysteine through the BHMT pathway. Regardless of genotype, lifestyle, diet, and other genes also influence homocysteine levels.

How to read this report

  • Find your genotype result for rs3733890 (AA, AG, or GG).
  • Open the matching section below for a clear interpretation of what that genotype means.
  • Review the practical diet, supplement, lifestyle, and testing recommendations to support healthy homocysteine metabolism.

Genetic interpretation

Two effect alleles (AA) — reduced BHMT function

If your genotype is AA at rs3733890, you carry two copies of the effect allele. This pattern is associated with reduced BHMT enzyme efficiency. When BHMT activity is lower, the conversion of homocysteine to methionine using betaine can be less effective, which may make higher homocysteine levels more likely.

What this can mean for you:

  • Increased risk, over time, of elevated homocysteine compared with people who have normal BHMT function.
  • Potentially higher long-term risk for cardiovascular disease, stroke, and age-related cognitive decline when homocysteine is chronically elevated.
  • Greater potential benefit from focused nutritional and lifestyle support to maintain normal homocysteine.
One effect allele (AG) — mildly reduced BHMT function

If your genotype is AG, you carry one copy of the effect allele. This is associated with a mild reduction in BHMT enzyme efficiency. The BHMT pathway may work slightly less well than optimal, which can modestly influence homocysteine control.

What this can mean for you:

  • Your risk of elevated homocysteine is slightly increased compared with people with two non-effect alleles, but the effect is generally mild.
  • Diet, B vitamin status, and lifestyle have a strong influence and can usually keep homocysteine in a healthy range.
  • Simple, consistent dietary and lifestyle strategies are likely the most effective way to support normal levels.
Zero effect alleles (GG) — typical BHMT function

If your genotype is GG, you carry two copies of the non-effect allele. This is the common pattern and is associated with normal BHMT enzyme function. Your BHMT pathway is expected to convert homocysteine to methionine efficiently when betaine and other nutrients are available.

What this can mean for you:

  • Typical genetic capacity to manage homocysteine through the BHMT route.
  • Maintaining adequate intake of B vitamins and betaine, plus healthy lifestyle choices, remains important to keep homocysteine in a healthy range.

Diet recommendations to support homocysteine metabolism

Diet has a major impact on homocysteine. Focus on foods that supply folate, vitamin B6, vitamin B12, and betaine. These nutrients support both BHMT and the complementary remethylation pathways that keep homocysteine in balance.

  • Folate-rich foods: dark leafy greens (spinach, kale), asparagus, Brussels sprouts, lentils, beans, and fortified whole grains.
  • Vitamin B6 sources: poultry, fish, potatoes, chickpeas, bananas, and fortified cereals.
  • Vitamin B12 sources: shellfish, fish, beef, eggs, dairy, and fortified plant foods. People who follow a vegan or vegetarian diet may need to pay special attention to B12 intake.
  • Betaine-rich foods: beets, spinach, wheat bran, quinoa, and seafood. Beets and spinach are particularly useful sources of dietary betaine.
  • Protein balance: include moderate lean protein and plant proteins to support methylation reactions without excess methionine from very high-protein diets.
  • Limit alcohol and processed foods: excess alcohol can impair B vitamin status and raise homocysteine.

Supplement considerations

Supplements can be helpful when diet alone does not provide enough B vitamins or betaine. Always discuss supplements with your healthcare provider before starting them.

  • B-complex containing folate, vitamin B6, and vitamin B12: a balanced B-complex supports multiple pathways that clear homocysteine.
  • Folate options: methylfolate may be preferred for people with MTHFR issues, but discuss with your clinician.
  • Betaine (trimethylglycine, TMG): can support the BHMT reaction directly. Use under medical guidance, especially if you have liver disease or other medical conditions.
  • Multivitamin: a well-formulated multivitamin can help correct mild nutritional gaps.
  • Testing-based supplementation: consider supplements tailored to blood test results rather than routine high-dose use without monitoring.

Lifestyle habits that support healthy homocysteine

  • Regular physical activity: aim for a mix of aerobic exercise and strength training most days of the week to support cardiovascular and metabolic health.
  • Healthy weight: maintaining a healthy weight helps overall metabolic balance and reduces cardiovascular risk.
  • Quit smoking: smoking is associated with higher homocysteine and increased cardiovascular risk.
  • Limit alcohol: excessive alcohol impairs B vitamin absorption and can elevate homocysteine.
  • Stress management and sleep: chronic stress and poor sleep can affect inflammation and metabolic control. Aim for restorative sleep and stress reduction practices like mindfulness or gentle movement.

When to check your homocysteine and other tests to consider

  • Plasma homocysteine: the direct test to measure current levels and track response to interventions.
  • Vitamin panels: measure folate, B12, and sometimes vitamin B6 to identify deficiencies that raise homocysteine.
  • Lipid and cardiovascular risk testing: if homocysteine is elevated, review overall cardiovascular risk with your clinician.
  • Liver and kidney function: these organs influence homocysteine clearance and the safety of some supplements.

Putting it all together

Your BHMT rs3733890 genotype gives one piece of information about your genetic capacity to manage homocysteine. If you carry one or two effect alleles, you may benefit more than average from focused dietary intake of folate, B6, B12, and betaine, along with healthy lifestyle habits and targeted supplementation when indicated. If you have the non-effect genotype, your BHMT pathway is expected to function typically, but the same healthy strategies still help maintain optimal homocysteine and cardiovascular health.

PlexusDx does not provide medical advice. This information is educational and about genetic predispositions only. Always consult your healthcare provider before making changes to your diet, starting supplements, or altering medications. Your clinician can help interpret genetic results alongside blood tests, family history, and your overall health to create a personalized plan.