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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.