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Last reviewed: May 12, 2026 Last updated: May 12, 2026

Written by: Jay Hastings , CEO of PlexusDx

Jay Hastings is the CEO of PlexusDx, a precision health company focused on genetic testing, blood biomarker insights, and personalized wellness recommendations. He has more than 20 years of experience across healthcare innovation, genomics, laboratory operations, healthcare investing, and strategic finance. His work has included scaling healthcare startups, leading CLIA lab integrations, and helping expand consumer access to precision health tools.

Medically reviewed by: Jayden Lee, PharmD, EMBA

Jayden Lee, PharmD, EMBA, is the PlexusDx Medical Science Liaison with a PharmD and MBA specializing in pharmacogenomics and clinical product development, with a proven ability to bridge the gap between genomic research and practical patient outcomes. Dr. Lee has more than 10 years of professional experience in clinical pharmacy, academia, and research.

Selenium and the SEPP1 Gene: What Your Results Mean for Health and Nutrition

Selenium is a trace mineral that plays an important role in immune function, thyroid hormone regulation, antioxidant defense, and DNA synthesis. SEPP1 is the gene that encodes Selenoprotein P, a primary carrier that moves selenium from the liver to other tissues. Variations in SEPP1 can change how efficiently selenium is transported in the body and may influence circulating selenium levels. Below is a clear explanation of what different genotypes at rs7579 mean and practical, consumer-friendly recommendations to support healthy selenium status.

How SEPP1 and Selenoprotein P Work

Selenoprotein P carries selenium in the blood to organs and tissues that need it, including the brain, thyroid, and immune cells. When SEPP1 function is reduced, tissues may receive less selenium even if dietary intake is unchanged. That can affect the activity of selenoproteins involved in antioxidant protection and thyroid hormone metabolism. Genetics is only one factor that affects selenium status. Diet, soil selenium levels where food was grown, age, health conditions, and medications also matter.

Genetic Interpretation

2 effect alleles (TT) — Two copies of the effect allele

If you have the TT genotype at rs7579 you carry two copies of the effect allele. This variation is associated with lower serum selenium levels. Your SEPP1 gene may produce or utilize Selenoprotein P less efficiently, which can lead to lower circulating selenium compared with other genotypes. This is a genetic predisposition and does not automatically mean you have a selenium deficiency.

Practical points:

  • Focus on selenium rich foods: Brazil nuts in moderation, seafood, lean meats, eggs, and selenium containing vegetables.
  • Consider periodic monitoring of serum selenium or selenoprotein P if you have symptoms suggestive of deficiency or other risk factors.
  • If you choose supplements, use them cautiously and under guidance from your healthcare provider to avoid excessive intake.
1 effect allele (CT) — One copy of the effect allele

With the CT genotype at rs7579 you carry one copy of the effect allele. This genotype is associated with likely lower serum selenium levels, reflecting a moderate influence on how efficiently Selenoprotein P transports selenium from the liver to other tissues.

Practical points:

  • Prioritize selenium rich foods such as Brazil nuts (small portion), seafood, lean meats, eggs, and dairy products.
  • Follow the recommended daily allowance of about 55 micrograms for most adults through diet. Your individual needs may differ.
  • Talk with your healthcare provider before starting supplements because excess selenium can cause toxicity.
0 effect alleles (CC) — No effect alleles

If you have the CC genotype at rs7579 you carry two copies of the non effect allele. This genotype is associated with typical selenium transport and metabolism. Your SEPP1 gene is likely producing Selenoprotein P at levels that support normal selenium delivery to tissues.

Practical points:

  • You are not predisposed to lower selenium levels because of this genetic factor, but diet and environment still affect selenium status.
  • Maintain a balanced diet that includes selenium rich foods to meet the recommended daily allowance of about 55 micrograms for most adults.
  • Consider periodic assessment only if you have medical reasons to check selenium or selenoprotein levels.

Diet Recommendations

  • Eat a variety of selenium rich foods: Brazil nuts, seafood like tuna, shrimp, and salmon, lean meats, poultry, eggs, and dairy.
  • Consume Brazil nuts in moderation. One to three Brazil nuts several times a week is often sufficient to raise selenium intake without exceeding safe limits.
  • Include plant foods that may contain selenium depending on soil: certain grains, beans, and vegetables. Soil selenium varies by region so animal and seafood sources are more reliable for consistent intake.
  • Balance selenium sources with overall diet quality. A varied whole foods diet supports absorption and overall nutrient status.

Supplement Recommendations and Safety

  • Supplements can correct low intake but should be used cautiously only when indicated by diet assessment or testing.
  • Avoid high dose supplements unless prescribed by a healthcare provider. Chronic excess selenium can cause symptoms such as gastrointestinal upset, hair or nail changes, and neurologic effects.
  • If considering a supplement, use a form and dose recommended by your provider. Typical multivitamins contain safe, moderate amounts while targeted selenium supplements should be supervised clinically.

Lifestyle and Monitoring

  • Consider a blood test for serum selenium or selenoprotein P if you have symptoms that could relate to low selenium, are on restrictive diets, or have health conditions that affect absorption.
  • Review medication and supplement lists with your healthcare provider. Some medications and interactions can change selenium status.
  • Keep a food log for a few weeks to estimate selenium intake if you are uncertain about diet quality. Discuss findings with your provider or a registered dietitian.
  • If you have thyroid disease, autoimmune conditions, or are pregnant, discuss selenium status with your clinician because requirements and benefits of supplementation can differ.

When to Talk with Your Healthcare Provider

  • If you have symptoms such as unusual fatigue, hair loss, brittle nails, or new thyroid symptoms.
  • If you are considering taking a selenium supplement or are already taking one and want to check dose safety.
  • If you follow a restrictive diet, have malabsorption issues, or have chronic health conditions that could affect nutrient levels.

PlexusDx provides genetic information to help you understand potential predispositions related to nutrient transport and metabolism. This information is educational and not medical advice. Always consult your healthcare provider before making changes to supplements, medications, or major dietary patterns. Your provider can interpret genetic results in the context of your full medical history, lab tests, and current health concerns.

If this genetic variant is present in your PlexusDx results, the following tests and reports are commonly used to explore it further:

🧬 Genetic Tests:

🧪 Blood Tests:

📄 Genetic Report:

Frequently Asked Questions About Selenium and SEPP1 rs7579

What does the SEPP1 rs7579 variant mean for my selenium levels?

SEPP1 encodes Selenoprotein P, the main carrier that transports selenium from the liver to tissues like the brain, thyroid, and immune cells. If your rs7579 genotype includes effect alleles (TT or CT), it’s associated with likely lower serum selenium levels because selenium transport may be less efficient. This creates a genetic predisposition but does not automatically mean you are selenium deficient.

How should I change my diet if I have the TT or CT rs7579 genotype?

If you have TT (two effect alleles) or CT (one effect allele), focus on selenium-rich foods to help support healthier selenium status. Common options include Brazil nuts (in moderation), seafood (tuna, shrimp, salmon), lean meats, eggs, and selenium-containing dairy/plant foods depending on local soil selenium. Brazil nuts are often enough at about 1–3 nuts several times per week to raise intake without going too high.

Do I need selenium supplements if I have a SEPP1 rs7579 effect allele?

Not necessarily. Supplements should be used cautiously and typically only when suggested by diet assessment or lab testing, because too much selenium can be toxic. If you’re considering supplements—or you already take one—talk with your healthcare provider about dose safety. If symptoms could relate to low selenium (like unusual fatigue, hair loss, or brittle nails) or you have risk factors (restrictive diet, malabsorption, thyroid disease, pregnancy), ask about checking serum selenium or selenoprotein P.

What tests can help me learn more about Selenium and SEPP1 rs7579?

The Optimal Diet and Weight Loss Genetic Test delivers over 295 genetic insights related to nutrition response, body composition, metabolism, and fitness. The Diet and Nutrition Genetic Report translates your results into personalized, actionable guidance. Your healthcare provider can also recommend targeted blood tests based on your specific pathway results and health history to complement your genetic insights with current biomarker data.

Medical and Editorial Standards

Medical review process: This article was reviewed for medical accuracy, scientific clarity, evidence alignment, and appropriate discussion of genetics, medications, supplements, biomarkers, and health-related claims.

Sources and evidence: PlexusDx educational content is developed using peer-reviewed research, clinical literature, reputable medical references, and, where applicable, public health or regulatory guidance. References are included at the end of the article when scientific, medical, or health-related claims are discussed.

Commercial transparency: PlexusDx offers genetic testing, blood biomarker testing, personalized supplement recommendations, and related precision wellness services. Product mentions are intended to help readers understand available options and should not be interpreted as medical advice.

Important disclaimer: PlexusDx educational content is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about medications, supplements, genetic testing, lab testing, or health-related care.