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GSTP1 and Pregnancy: Understanding How Your Genes Affect Mercury Detoxification

Pregnancy is a time when the body’s ability to clear environmental toxins matters more than ever. The GSTP1 gene makes an enzyme that helps the body neutralize and remove toxic compounds, including mercury. Variations in GSTP1 can change how well this detoxification pathway works and may influence how maternal mercury exposure affects fetal brain development. This article explains what GSTP1 variations mean for pregnancy, offers practical diet and lifestyle suggestions, and provides tests and supplement options to discuss with your healthcare provider.

How GSTP1 Affects Mercury Detoxification

GSTP1 encodes an enzyme in the glutathione S-transferase family. These enzymes help attach glutathione to toxins to make them easier to excrete. Some genetic variants reduce GSTP1 activity, which can slow mercury elimination. During pregnancy, higher maternal mercury levels have been linked with differences in child neurodevelopment in studies that considered GSTP1 genotype. That means if your GSTP1 function is reduced, limiting mercury exposure is especially important.

Practical Recommendations for Pregnancy

  • Limit high-mercury fish: Avoid tuna (especially bigeye and albacore), swordfish, king mackerel, shark, and similar species.
  • Choose low-mercury seafood: Prefer salmon, sardines, trout, shrimp, tilapia and other low-mercury options for omega-3s and protein.
  • Diversify protein sources: Include plant proteins, poultry, eggs, and dairy to reduce reliance on larger predatory fish.
  • Focus on antioxidants: Eat a wide variety of fruits and vegetables rich in vitamin C, vitamin E, carotenoids, and polyphenols to support detox pathways.
  • Avoid other mercury sources: Minimize exposure from contaminated occupational environments, certain traditional remedies, and broken fluorescent bulbs. Discuss dental amalgams with your provider if relevant.
  • Discuss testing with your clinician: Blood or hair mercury testing can clarify exposure and guide monitoring during pregnancy.

Supplements and Support to Discuss With Your Provider

Some nutrients support detoxification and antioxidant defenses. These may be helpful when used under medical supervision:

  • Vitamin C to support antioxidant capacity and regeneration of other antioxidants.
  • Selenium, which binds mercury and supports antioxidant enzymes. Selenium balance is important because both low and excessive intake have risks.
  • N-acetylcysteine (NAC) to boost glutathione production, a key molecule for detoxification.
  • Standard prenatal vitamin with folate, iron, iodine, and vitamin D to support overall pregnancy health.

Always consult your healthcare provider before starting any supplement during pregnancy. PlexusDx does not provide medical advice. The information here is educational and should be reviewed with your clinician.

Lifestyle and Monitoring

  • Minimize cigarette smoke exposure. Tobacco smoke contains toxins that can increase oxidative stress and lower detox capacity.
  • Maintain a balanced, nutrient-dense diet that supports liver function and glutathione synthesis: adequate protein, sulfur-rich foods like garlic and onions, cruciferous vegetables, and colorful fruits and vegetables.
  • Stay hydrated and avoid excessive alcohol use before and during pregnancy.
  • If your home or workplace involves potential mercury exposure, request environmental assessment and mitigation steps.
  • Consider periodic mercury testing in pregnancy if fish consumption is frequent or if there are known exposure risks. Discuss the best test type and frequency with your healthcare provider.

Genetic Interpretation

Two effect alleles (GG for rs1695)

You carry two copies of the effect allele, which is associated with reduced GSTP1 enzyme function. This reduction can impair mercury detoxification. During pregnancy, this genotype is linked to a higher sensitivity to mercury exposure: higher maternal mercury intake from fish has been associated with lower mental development scores in children when maternal GSTP1 function is reduced.

Recommendations for GG genotype:

  • Strictly avoid high-mercury fish such as tuna (especially large or albacore), swordfish, king mackerel and shark.
  • Choose low-mercury seafood like wild or farmed salmon, sardines, trout, shrimp and anchovies for omega-3 intake.
  • Emphasize antioxidant-rich fruits and vegetables daily to support detox pathways.
  • Discuss targeted testing with your provider: maternal blood or hair mercury levels during pregnancy can inform risk and monitoring.
  • Talk with your clinician before taking supplements. Vitamin C, selenium, and N-acetylcysteine may aid detoxification but must be used under medical supervision in pregnancy.
  • Reduce other environmental sources of mercury and avoid unnecessary exposure.
One effect allele (AG for rs1695)

You carry one copy of the effect allele, which is associated with moderately reduced GSTP1 function. This may slow mercury elimination compared to the non-effect genotype. Studies suggest that pregnant women with one effect allele who consume high-mercury fish might have children with lower mental development scores compared to those with lower exposure.

Recommendations for AG genotype:

  • Limit or avoid high-mercury fish such as tuna (large species), swordfish, king mackerel and shark.
  • Prefer low-mercury seafood choices like salmon, sardines, trout, shrimp and small fish varieties to obtain beneficial omega-3s.
  • Include a wide range of antioxidant-rich fruits and vegetables to support detoxification.
  • Consider periodic mercury testing if your diet includes regular fish consumption or if there are other possible exposures.
  • Discuss supplements with your healthcare provider. Vitamin C, selenium, and N-acetylcysteine are options to consider under clinical guidance.
No effect alleles (AA for rs1695)

You carry two copies of the non-effect allele, which is associated with typical GSTP1 enzyme function. Your genetic profile suggests normal capacity to detoxify and clear mercury and other environmental toxins. This does not eliminate the need to follow general pregnancy nutrition guidance, but it indicates you are not at increased genetic risk for impaired mercury detoxification based on this variant.

Recommendations for AA genotype:

  • Follow standard pregnancy fish consumption guidelines: choose low-mercury seafood and limit high-mercury species.
  • Maintain a balanced, nutrient-rich diet with plenty of fruits and vegetables to support overall maternal and fetal health.
  • Routine prenatal testing and monitoring as recommended by your healthcare provider.
  • Discuss supplements per usual prenatal care, including standard prenatal vitamins.

Questions to Ask Your Healthcare Provider

  • Should I test my blood or hair for mercury now or during pregnancy?
  • Which fish are safe for me to eat and how often?
  • Are vitamin C, selenium, or N-acetylcysteine appropriate for me during pregnancy?
  • Do I have any other environmental exposures to be concerned about?
  • Would referral to a maternal-fetal medicine specialist or a clinical geneticist be helpful?

PlexusDx does not provide medical advice. This information is educational only. Discuss your genetic results, diet, supplement choices, and testing options with your healthcare provider to create a personalized plan for a healthy pregnancy.