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FADS1 and Omega-3s During Pregnancy and Breastfeeding

Pregnancy and breastfeeding are times when your nutrition has a direct effect on fetal and infant brain and eye development. The FADS1 gene helps produce an enzyme that converts plant-based omega-3 fats into the long-chain omega-3s DHA and EPA. These long-chain omega-3s are especially important for the developing brain and retina. Some people have genetic variants that reduce FADS1 enzyme activity, which can make it harder to get enough DHA and EPA from plant sources alone. Knowing your FADS1 genotype can help you plan dietary, supplement, and testing strategies to support a healthy pregnancy and lactation period.

Why DHA and EPA Matter

  • DHA supports fetal brain structure and function and contributes to visual development.
  • EPA plays roles in inflammation regulation and may support maternal mood and cardiovascular health.
  • During pregnancy and breastfeeding, maternal supply of DHA and EPA is the main source for the baby.
  • If conversion from plant omega-3 precursors is impaired, dietary or supplemental preformed DHA and EPA become more important.

Practical Guidance

  • Prioritize direct sources of DHA and EPA if your conversion is reduced: low-mercury fatty fish and algae-based omega-3 supplements are reliable options.
  • Aim for about 600 mg combined DHA and EPA daily during pregnancy and lactation unless your healthcare provider advises differently.
  • If you prefer plant-based diets, choose algae-based DHA supplements to ensure preformed DHA without fish.
  • Continue to include plant sources of ALA, such as flaxseed, chia seeds, walnuts, and canola oil, but do not rely on them alone if conversion may be limited.
  • Limit high-mercury fish (shark, swordfish, king mackerel, tilefish) and focus on low-mercury choices like salmon, sardines, trout, herring, and anchovies.

Diet, Supplements, Lifestyle, and Testing Recommendations

  • Diet: 2 to 3 servings per week of low-mercury, oily fish (salmon, sardines, trout). Include ALA-rich plant foods daily for overall omega-3 intake.
  • Supplements: Consider algae-based or fish oil supplements providing at least 600 mg combined DHA and EPA per day during pregnancy and breastfeeding. If using prenatal supplements that include DHA, check the dose and supplement additional DHA if needed.
  • Lifestyle: Maintain a balanced intake of omega-6 fats to avoid excessive imbalance; avoid smoking and excessive alcohol; manage stress and ensure adequate sleep to support maternal and infant health.
  • Blood tests: Discuss measuring plasma or red blood cell DHA/EPA levels with your healthcare provider if you are concerned about adequacy or have dietary restrictions.
  • Other considerations: If you have known absorption issues, take supplements with a meal containing fat to improve absorption. If you follow a strict vegan diet, algae-based DHA provides a direct, plant-friendly source.
2 effect alleles (TT) — Reduced FADS1 activity

If you have the TT genotype for rs174546, you carry two copies of the effect allele. This genotype is associated with significantly reduced FADS1 enzyme activity, which means your body is much less efficient at converting plant-based omega-3s into the long-chain forms DHA and EPA.

Implications during pregnancy and breastfeeding

  • Greater risk of low DHA and EPA if relying only on ALA-rich plant sources.
  • Because DHA is important for fetal brain and eye development, prioritizing preformed DHA and EPA is important throughout pregnancy and lactation.

Recommended actions

  • Consume 2 to 3 servings per week of low-mercury fatty fish (salmon, sardines, trout), or
  • Take an algae-based or fish oil supplement providing at least 600 mg combined DHA and EPA daily during pregnancy and breastfeeding. If your prenatal contains less DHA, consider an additional supplement to reach the target dose.
  • Include plant omega-3 sources (flax, chia, walnuts) as complementary but not sole sources.
  • Discuss testing of red blood cell or plasma DHA/EPA levels with your healthcare provider to confirm adequacy.
1 effect allele (CT) — Reduced FADS1 activity

If you have the CT genotype for rs174546, you carry one copy of the effect allele. This genotype is associated with reduced FADS1 enzyme activity, so your conversion of plant-based ALA into DHA and EPA is less efficient than average.

Implications during pregnancy and breastfeeding

  • You may be more likely to have lower DHA and EPA if you rely only on plant sources when needs are higher during pregnancy and lactation.

Recommended actions

  • Prefer direct sources of DHA and EPA: 2 to 3 servings weekly of low-mercury fatty fish, or
  • Consider an algae-based or fish oil supplement providing at least 600 mg combined DHA and EPA daily while pregnant and breastfeeding.
  • Continue plant-based ALA sources as part of an overall healthy diet.
  • Ask your healthcare provider about testing DHA/EPA levels if you have dietary limitations or want to confirm status.
0 effect alleles (CC) — Typical FADS1 activity

If you have the CC genotype for rs174546, you carry two copies of the non-effect allele. This genotype is associated with typical FADS1 enzyme activity, meaning your body converts plant-derived ALA to DHA and EPA efficiently.

Implications during pregnancy and breastfeeding

  • You can make effective use of both plant-based ALA and preformed DHA/EPA from food or supplements.
  • Standard omega-3 recommendations for pregnancy and lactation typically apply.

Recommended actions

  • Follow general guidance: aim for 2 to 3 servings weekly of low-mercury oily fish, or use supplements if needed to achieve recommended DHA/EPA intakes.
  • Include plant ALA sources daily for overall omega-3 balance and variety.
  • If you are vegan or avoid fish, consider algae-based DHA supplements to ensure adequate preformed DHA.
  • Speak with your healthcare provider about testing only if you have special dietary concerns or symptoms suggesting deficiency.

When to Talk with Your Healthcare Provider

  • Before starting any new supplement during pregnancy and breastfeeding.
  • If you have dietary restrictions such as vegetarian or vegan diets that limit direct DHA/EPA intake.
  • If you have known malabsorption conditions or chronic illnesses that might affect nutrient status.
  • If you would like laboratory testing to confirm DHA/EPA levels or to tailor dosing.

PlexusDx provides educational genetic information to help you understand how your genes may influence nutrient needs and health. This information is not medical advice. Always consult your healthcare provider before making changes to your diet, supplements, or medical care. Your healthcare provider can integrate your genetic information with your medical history, current health status, and lab results to develop a personalized plan.