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

Riboflavin, also known as Vitamin B2, is a water soluble vitamin that helps your body convert food into energy, supports healthy skin and eyes, and contributes to nervous system and red blood cell health. It also plays an antioxidant role, helping protect cells from oxidative damage. One of riboflavin's key biochemical roles is forming the flavin coenzymes that many enzymes need to function properly, including the enzyme produced by the FMO3 gene.

The FMO3 enzyme, produced mainly in the liver, helps break down certain nitrogen containing compounds generated by gut bacteria and from the diet. One of these compounds is trimethylamine, which can produce a strong body odor when it is not fully processed. Variations in the FMO3 gene can change how well this enzyme works. Riboflavin supports FMO3 activity because it contributes to the enzyme's active components. Below are practical, evidence informed suggestions for diet, supplements, lifestyle, and testing tailored to different FMO3 genotypes.

How to use this information

  • These genetic results describe predispositions only. Genetics are one part of a larger picture that includes diet, gut microbiome, medications, liver and kidney health, and lifestyle.
  • PlexusDx does not provide medical advice. Always consult your healthcare provider before making changes to medications, supplements, or major dietary plans.

Dietary Recommendations

  • Prioritize riboflavin rich foods: dairy products, eggs, lean meats (beef, chicken), oily fish, green leafy vegetables, mushrooms, almonds, and fortified cereals.
  • Include a variety of protein sources to supply substrates for healthy liver metabolism and to support the gut microbiome balance.
  • Fiber rich vegetables, whole grains, and legumes feed beneficial gut bacteria and may reduce production of compounds that stress FMO3.
  • Limit excessive dietary precursors of trimethylamine such as high amounts of choline rich foods (for example, large servings of liver or certain supplements) if you notice odor issues. Discuss personalized limits with your clinician.

Supplement Considerations

  • Riboflavin supplements can help people who do not meet intake needs from food alone. Typical supplemental doses range from 1.3 mg daily for adults to higher therapeutic doses that your clinician may recommend in specific situations.
  • If you are considering higher dose riboflavin, discuss with your healthcare provider first to ensure there are no interactions with medicines or underlying conditions.
  • Multivitamins with B complex may be appropriate if diet is limited, but choose products from reputable manufacturers and follow label guidance or clinical advice.

Lifestyle and Other Practical Strategies

  • Maintain a balanced diet and steady meal patterns to support metabolic health and liver function.
  • Practice good gut health habits: regular physical activity, adequate fiber intake, hydration, and minimizing unnecessary antibiotics when possible.
  • Monitor medications and supplements that can affect liver enzymes or interact with nutrient absorption. Review these with your clinician or pharmacist.
  • If odor concerns arise, keep a symptom diary recording foods, supplements, bowel habits, and any products used. This can help identify triggers to discuss with your clinician.

When to Consider Lab Tests or Clinical Evaluation

  • If you experience persistent body odor or changes in breath or urine odor that are noticeable and unexplained, consult your healthcare provider for evaluation.
  • Blood tests for liver function, renal function, and vitamin B2 status may be useful in some cases. Your clinician can guide appropriate testing based on symptoms and medical history.
  • Referral to a metabolic specialist, hepatologist, or genetic counselor may be appropriate if symptoms are severe or if multiple metabolic issues are present.

Genetic Interpretation

2 effect alleles (GG) — decreased FMO3 function

You have the GG genotype at rs2266780, which is associated with decreased FMO3 enzyme function. Reduced FMO3 activity can make processing of trimethylamine and similar compounds less efficient. Riboflavin forms part of the flavin coenzymes that FMO3 requires to work. Maximizing riboflavin intake may help support whatever enzyme activity remains.

  • Diet: Emphasize riboflavin rich foods such as dairy, eggs, lean meats, mushrooms, leafy greens, and fortified cereals. Spread riboflavin sources across meals.
  • Supplements: Consider discussing riboflavin supplementation with your healthcare provider. They may suggest low or moderate daily doses to support enzyme cofactors.
  • Lifestyle: Support gut health with fiber, regular activity, and balanced meals. Track foods that might increase odor symptoms and review with a clinician.
  • Testing: If you notice persistent odor, seek medical evaluation. Blood tests for liver function and nutrient status may be helpful.
1 effect allele (AG) — slightly decreased FMO3 function

You have the AG genotype at rs2266780, which is associated with a slight decrease in FMO3 enzyme function. Your enzyme activity is likely close to typical but may be sensitive to low riboflavin status or other metabolic stressors. Ensuring adequate riboflavin intake helps the enzyme work efficiently.

  • Diet: Include riboflavin rich foods regularly: dairy, eggs, lean meats, fortified cereals, mushrooms, almonds, and leafy greens.
  • Supplements: If dietary intake is limited, a multivitamin with B2 or targeted riboflavin supplement can be considered after consulting your healthcare provider.
  • Lifestyle: Maintain a balanced diet and support gut and liver health. Avoid excessive consumption of dietary precursors of trimethylamine.
  • Testing: Routine symptoms typically do not require testing. If signs such as persistent body odor occur, consult a clinician for evaluation.
0 effect alleles (AA) — typical FMO3 function

You have the AA genotype at rs2266780, associated with typical FMO3 enzyme function. Your enzyme is expected to process dietary compounds like trimethylamine normally. Riboflavin still plays important roles in energy metabolism and antioxidant protection, so keep dietary intake adequate.

  • Diet: Maintain a varied diet with regular riboflavin sources: dairy, eggs, lean meats, mushrooms, fortified cereals, and leafy greens.
  • Supplements: Most people with typical function can meet needs through diet, but use a multivitamin if recommended by your clinician.
  • Lifestyle: General healthy habits support long term metabolic and liver health.
  • Testing: No routine additional testing required for FMO3 if you are symptom free.

Key Takeaways

  • Riboflavin is essential for FMO3 enzyme activity and broader metabolic health.
  • People with reduced FMO3 function may benefit from ensuring adequate riboflavin intake through food and, when appropriate, supplements under clinical guidance.
  • Maintain a balanced diet, support gut and liver health, and consult your healthcare provider if you notice persistent symptoms or before starting new supplements.

PlexusDx does not provide medical advice. This information is educational and describes genetic predispositions only. Always consult your healthcare provider, pharmacist, or a qualified clinician before changing medications, starting supplements, or making major diet or lifestyle changes.