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Understanding Arsenic Detoxification and Your AS3MT Gene

Arsenic detoxification is the body’s way of converting toxic arsenic into forms that are easier to eliminate. The AS3MT gene makes an enzyme that adds methyl groups to arsenic, a chemical change that helps the kidneys remove it in urine. Variations in AS3MT can change how well this process works. If methylation is less efficient, arsenic may stay in the body longer after exposure, which can raise the risk of health effects such as skin lesions.

This article explains what different genotypes at rs11191439 in AS3MT mean, practical steps to reduce arsenic exposure, and dietary, supplement, and lifestyle approaches that support methylation and overall detoxification. PlexusDx does not provide medical advice. Always consult your healthcare provider before making changes to diet, supplements, or medical testing.

How arsenic exposure typically happens

  • Contaminated well water or municipal sources in some regions
  • Rice and rice-based products, which can concentrate arsenic
  • Occupational or environmental exposure to industrial pollutants

General precautions for everyone

  • Test private well water for arsenic and use filtration if needed
  • Rinse and drain rice before cooking and diversify grains (quinoa, barley, millet)
  • Limit consumption of rice-based infant foods and formulas if possible
  • Avoid known industrial sources of arsenic and tobacco smoke
Two effect alleles (CC) — higher potential impact on arsenic methylation

If your genotype is CC at rs11191439, you carry two copies of the effect allele. This pattern is associated with reduced efficiency of the AS3MT enzyme. That can mean slower conversion of arsenic to its excretable forms, which may lead to higher internal arsenic levels during exposure. People with this genotype may have an increased risk of arsenic-related skin lesions when exposed to contaminated water or certain foods.

Recommended actions

  • Test private well water for arsenic annually and consider point-of-use or whole-house filters certified to remove inorganic arsenic.
  • Rinse rice thoroughly, use a high water-to-rice cooking ratio and drain excess water to lower arsenic content.
  • Diversify your grain intake to reduce cumulative arsenic exposure from rice.
  • Consider checking urine arsenic with speciation (inorganic vs organic forms) through your healthcare provider if you suspect exposure.
  • Follow dietary and supplement recommendations below to support methylation pathways.
One effect allele (CT) — moderate potential impact

If your genotype is CT, you carry one copy of the effect allele. This genotype may be associated with a modest reduction in AS3MT enzyme effectiveness compared to non-carriers. Your body’s arsenic methylation still works, but it may be slightly slower, making steps to limit exposure and support methylation especially useful.

Recommended actions

  • Take practical exposure-reduction steps: test well water, rinse rice, and diversify grains.
  • Monitor dietary intake of nutrients that support methylation and consider discussing targeted testing with your clinician.
  • Maintain regular screening if you live in an area with known arsenic contamination or work with potential exposures.
No effect alleles (TT) — typical risk

If your genotype is TT, you carry two copies of the non-effect allele associated with standard AS3MT function. Your enzyme activity is expected to support normal arsenic methylation and elimination. Even with typical genetic risk, limiting exposure and supporting methylation are still recommended to protect long-term health.

Recommended actions

  • Continue exposure-limiting strategies: test well water, rinse rice, and choose a variety of grains.
  • Follow general dietary and lifestyle recommendations to keep methylation and overall detoxification functioning well.

Dietary nutrients that support methylation and arsenic detoxification

Methylation is the biochemical process that adds methyl groups to arsenic and many other molecules. A diet that provides key methyl donors and cofactors helps this process work efficiently.

  • Folate: Found in leafy greens, beans, asparagus, and fortified foods. Consider methylfolate if you have known MTHFR issues, under provider guidance.
  • Vitamin B12: Found in animal products and fortified foods. Vegetarians and older adults may need supplementation after testing.
  • Vitamin B6: Present in poultry, fish, chickpeas, and bananas; supports one-carbon metabolism.
  • Methionine: An essential amino acid in eggs, meat, fish, nuts, and seeds; provides methyl groups.
  • Choline: Found in eggs, liver, and soy products; an additional methyl donor that supports liver function.

Supplement considerations

  • Multivitamin with B-complex can help meet baseline needs for folate, B12, and B6.
  • Methylfolate (5-MTHF) and methylcobalamin (B12) are forms that may be better absorbed for methylation support; consult your provider before starting.
  • Omega-3 fatty acids support overall cellular health and inflammation control.
  • Do not begin supplements specifically to “detox” without consulting your healthcare provider, especially if you are pregnant, nursing, or taking medications.

Lifestyle habits that help reduce risk

  • Avoid tobacco and limit alcohol, both of which can impair detox pathways.
  • Stay well hydrated to support kidney clearance of water-soluble metabolites.
  • Regular physical activity supports circulation and metabolic health.
  • Maintain a healthy weight and manage chronic conditions such as diabetes which can increase susceptibility to toxic exposures.
  • Reduce exposure to other environmental pollutants that burden detox systems, including lead and mercury.

Testing and monitoring

  • Private well owners should test for inorganic arsenic and retest after treatment systems are installed.
  • Clinicians can order urine arsenic with speciation to distinguish inorganic arsenic and its methylated metabolites from less harmful organic forms commonly found in seafood.
  • Blood tests for arsenic are less commonly used for routine exposure assessment because arsenic is rapidly cleared from blood; urine speciation provides more useful exposure information.

When to talk with your healthcare provider

  • If you test positive for elevated arsenic in water or have a urine test showing elevated inorganic arsenic or methylation impairment
  • If you have symptoms potentially related to arsenic exposure, such as skin changes or unexplained gastrointestinal or neurologic signs
  • Before starting targeted supplements like methylfolate or B12, especially if you have medical conditions or take prescription medications

PlexusDx provides educational insights about genetic predispositions and actionable steps to reduce exposure and support health. PlexusDx does not provide medical advice. Always consult your healthcare provider to interpret test results, decide on diagnostic testing, and choose personalized medical or supplement plans.