HSA | FSA CARDS ARE NOW ACCEPTED

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.

Riboflavin (Vitamin B2) and FMO3: What Your Genes May Mean for Metabolism and Wellness

Riboflavin, also called Vitamin B2, plays a central role in energy production, healthy skin and eyes, nervous system function, and red blood cell formation. It also helps the body absorb iron and metabolize other B vitamins. One way Riboflavin supports health is by helping enzymes form the coenzymes they need to work. The FMO3 enzyme, produced by the FMO3 gene in the liver, depends on Riboflavin-containing coenzymes to break down certain nitrogen-containing compounds found in foods like eggs, fish, and legumes.

Variation in the FMO3 gene can affect how well this enzyme works. When FMO3 activity is reduced, compounds such as trimethylamine may accumulate and cause body odor or other metabolic differences. Knowing your genotype at rs1736557 can help you understand whether you might benefit from focusing on Riboflavin intake and lifestyle habits that support enzyme activity.

How Riboflavin Supports FMO3 Function

  • Riboflavin is a building block for coenzymes needed by many metabolic enzymes, including FMO3.
  • Adequate Riboflavin helps FMO3 convert nitrogen-containing food compounds into forms the body can eliminate.
  • Riboflavin deficiency may reduce coenzyme availability and lower enzyme efficiency.

Food Sources and Practical Tips

  • Riboflavin-rich foods: dairy products, eggs, lean meats, fish, mushrooms, almonds, and fortified cereals.
  • Storage tip: Riboflavin is sensitive to light. Store milk and other dairy in opaque containers to reduce nutrient loss.
  • Balanced diet: a varied diet that includes the foods above usually supplies adequate Riboflavin for most people.

Supplements and When to Consider Them

  • Riboflavin supplements and B-complex vitamins can help if dietary intake is low or absorption is a concern.
  • Discuss supplement type and dosage with your healthcare provider before starting, especially if you take medications or have medical conditions.
  • High-dose Riboflavin is generally well tolerated because excess is water soluble and excreted, but medical guidance is recommended.

Lifestyle Habits That Support Enzyme Function

  • Regular exercise helps overall metabolic health and can support liver enzyme function.
  • Adequate sleep and stress management support broad metabolic pathways and nutrient utilization.
  • Avoid excessive alcohol and smoking, which can impair nutrient status and liver function.

Genetic Interpretation: rs1736557 (FMO3)

2 effect alleles (AA) — decreased FMO3 enzyme activity

If your genotype is AA at rs1736557, you carry two copies of the effect allele and this is associated with decreased FMO3 enzyme activity. This can reduce the liver enzyme's efficiency in breaking down certain nitrogen-containing compounds from foods such as eggs, fish, and legumes. Ensuring adequate Riboflavin intake may help support what enzyme activity you do have.

Dietary recommendations

  • Include Riboflavin-rich foods daily: dairy products, eggs, lean meats, fish, mushrooms, and fortified cereals.
  • Add plant sources like almonds and fortified plant milks if you follow a vegetarian or vegan pattern.
  • Store milk and other dairy in opaque containers to limit Riboflavin loss from light exposure.

Supplement considerations

  • Consider a Riboflavin supplement or B-complex if dietary intake is insufficient or if you have increased needs.
  • Work with your healthcare provider to choose dose and form, and to check for interactions with medications.

Lifestyle and monitoring

  • Support overall liver and metabolic health with regular exercise, good sleep, and stress management.
  • If you notice persistent body odor changes, digestive issues, or other concerns, talk with your healthcare provider. They may recommend targeted testing or dietary adjustments.
1 effect allele (AG) — decreased FMO3 enzyme activity

If your genotype is AG at rs1736557, you carry one copy of the effect allele and this is associated with reduced FMO3 enzyme activity to some degree. You may not experience strong symptoms, but small reductions in enzyme efficiency can be supported through diet and lifestyle.

Dietary recommendations

  • Prioritize Riboflavin-containing foods: dairy, eggs, lean meats, fish, mushrooms, almonds, and fortified cereals.
  • For plant-forward diets, include fortified cereals and plant-based alternatives that offer Riboflavin.
  • Consider cooking methods that preserve nutrients and avoid prolonged exposure to light for dairy items.

Supplement considerations

  • Riboflavin or a B-complex supplement can be helpful when dietary intake is inconsistent.
  • Consult your healthcare provider before starting supplements to determine appropriate dosing for your situation.

Lifestyle and monitoring

  • Keep a balanced lifestyle with exercise, sleep, and reduced alcohol use to support metabolic health.
  • If you have concerns about odor or digestion related to certain foods, discuss them with a clinician who can evaluate and advise on testing or dietary modification.
0 effect alleles (GG) — typical FMO3 enzyme function

If your genotype is GG at rs1736557, you carry two copies of the non-effect allele and this is associated with typical FMO3 enzyme function. Your FMO3 enzyme generally breaks down nitrogen-containing food compounds effectively. Continuing to include Riboflavin-rich foods helps maintain normal enzyme activity and overall metabolic health.

Dietary recommendations

  • Maintain a varied diet with dairy, eggs, lean meats, fish, mushrooms, and fortified cereals to sustain Riboflavin levels.
  • Use opaque storage for light-sensitive foods like milk to conserve Riboflavin.

Supplement considerations

  • Most people with a balanced diet will not need Riboflavin supplements, but a B-complex can be used if diet is limited.
  • Consult with your healthcare provider if you consider supplements for other reasons.

Lifestyle and monitoring

  • Continue healthy habits: regular exercise, good sleep, and stress management support liver and metabolic health.
  • If you have symptoms such as strong body odor or digestive changes, reach out to your healthcare provider for evaluation.

When to Talk with a Healthcare Provider

  • If you are considering supplements, especially in higher doses.
  • If you have symptoms that could relate to altered metabolism of dietary compounds such as persistent unusual body odor or digestive complaints.
  • If you have chronic health conditions, take medications, or are pregnant or breastfeeding.

PlexusDx provides educational information about genetic predispositions and how genes may interact with diet and lifestyle. PlexusDx does not provide medical advice. Always consult your healthcare provider before making changes to your diet, starting supplements, or making medical decisions based on genetic information.

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 Riboflavin and FMO3 rs1736557

How does the FMO3 rs1736557 variant affect metabolism and wellness?

The FMO3 gene helps your liver break down certain nitrogen-containing compounds from foods such as eggs, fish, and legumes. Variation at rs1736557 is associated with decreased FMO3 enzyme activity in people who carry one or two effect alleles (AG or AA), which may lead to metabolic differences such as changes in body odor. Your genotype can help guide a riboflavin-focused approach to support the enzyme activity you have.

Can riboflavin (vitamin B2) support FMO3 enzyme function if I have the effect allele?

Yes. Riboflavin is used to form coenzymes needed by many metabolic enzymes, including FMO3. Adequate riboflavin intake supports FMO3’s ability to convert nitrogen-containing food compounds into forms the body can eliminate. If your rs1736557 results suggest decreased enzyme activity, ensuring riboflavin-rich foods—and considering a supplement if your intake is low—may help support optimal metabolism.

What diet and lifestyle steps are most helpful for rs1736557?

Focus on riboflavin-rich foods daily, including dairy products, eggs, lean meats, fish, mushrooms, almonds, and fortified cereals (and fortified plant milks/cereals if you follow a plant-forward pattern). Because riboflavin is sensitive to light, store milk and other dairy in opaque containers. Support overall metabolic and liver health with regular exercise, adequate sleep, stress management, and avoiding excessive alcohol and smoking; if you notice persistent unusual body odor or digestive changes, talk with a healthcare provider for targeted evaluation.

What tests can help me learn more about Riboflavin and FMO3 rs1736557?

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.