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How FMO3 and Riboflavin Affect Body Odor and Health

Riboflavin, known as Vitamin B2, helps your body turn food into energy and supports healthy skin, eyes, and the nervous system. The FMO3 gene encodes an enzyme that converts trimethylamine (TMA) — a compound produced by gut bacteria after digesting certain foods — into an odorless molecule that the body can safely eliminate. Variants in the FMO3 gene can reduce this enzyme's function, allowing TMA to build up and sometimes cause a fishy body odor.

Riboflavin is important because it is a precursor to coenzymes needed for FMO3 activity. Ensuring adequate riboflavin intake through diet or supplements can help the enzyme work as well as possible. This article explains how different FMO3 genotypes relate to enzyme function and offers practical, approachable diet, supplement, and lifestyle suggestions to support TMA processing and overall well-being.

Quick overview

  • FMO3 enzyme is mainly active in the liver and clears TMA produced by gut bacteria.
  • Lower FMO3 activity can lead to TMA buildup and a fishy body odor in some people.
  • Riboflavin (Vitamin B2) supports FMO3 enzyme function and general cellular energy processes.
  • Diet, targeted supplements, and simple lifestyle adjustments can help manage symptoms and support enzyme function.

Genetic interpretations

2 effect alleles — TT for rs61753344 (decreased FMO3 function)

If your genotype is TT, you carry two copies of the effect allele. This is associated with reduced FMO3 enzyme activity. Reduced activity can allow trimethylamine to accumulate and produce a noticeable fishy odor in sweat, breath, or other body secretions.

Practical implications

  • Focus on maintaining steady riboflavin intake to support whatever FMO3 activity remains.
  • Be mindful of high TMA-precursor foods and consider moderating their intake if you notice body odor after eating them.
  • Good hygiene and targeted odor-control practices can help manage day-to-day symptoms.

Suggested actions

  • Diet: Emphasize riboflavin-rich foods — dairy, eggs, lean meats, fortified cereals, spinach. Reduce or moderate eggs, certain fish, and legumes if they trigger odor.
  • Supplements: Consider a riboflavin supplement if dietary intake is low. Typical over-the-counter options include B-complex formulas that supply riboflavin; discuss dosing with your healthcare provider.
  • Lifestyle: Maintain daily hygiene, launder clothing promptly, and consider odor-absorbing fabrics or topical deodorants. Work with your healthcare provider to rule out other causes if odor is persistent.
  • When to test: If body odor is new, severe, or affecting quality of life, consult your healthcare provider for medical evaluation and to discuss further testing or specialist referral.
1 effect allele — GT for rs61753344 (slightly decreased FMO3 function)

If your genotype is GT, you carry one copy of the effect allele. This is associated with a mild decrease in FMO3 enzyme function. Many people with this genotype have normal day-to-day TMA handling, but you may be slightly more sensitive to the amount of TMA produced after certain meals.

Practical implications

  • Optimizing riboflavin intake can help maximize FMO3 performance and reduce the chance of TMA buildup.
  • Moderating foods high in TMA precursors after learning how your body responds can be helpful.

Suggested actions

  • Diet: Include riboflavin-rich choices such as low-fat dairy, eggs in moderation, lean poultry, and fortified grains. Add leafy greens and a variety of vegetables to support overall gut and liver health.
  • Supplements: A low-dose riboflavin supplement or B-complex can be considered if dietary sources are inconsistent. Talk with your healthcare provider about the right dose.
  • Lifestyle: Monitor which foods trigger odor for you. Simple measures like good hygiene, showering after heavy sweating, and wearing breathable fabrics can help.
  • Monitoring: Keep a short food and symptom diary for a few weeks to identify patterns between meals and any transient odor changes.
0 effect alleles — GG for rs61753344 (typical FMO3 function)

If your genotype is GG, you carry two copies of the non-effect allele and are likely to have normal FMO3 enzyme function. Your body should convert TMA into an odorless form effectively, and you are unlikely to experience TMA-related body odor problems.

Practical implications

  • Continue a balanced diet that includes riboflavin-containing foods for overall health and energy metabolism.
  • No special restrictions are usually necessary, but if you notice odor after certain foods, simple adjustments can help.

Suggested actions

  • Diet: Maintain a varied diet with dairy, eggs, lean meats, fortified cereals, and vegetables to meet riboflavin needs.
  • Supplements: Not generally required for FMO3 support if diet is adequate. Use supplements only under healthcare provider guidance.
  • Lifestyle: Standard hygiene and balanced nutrition are sufficient in most cases. Address any new or persistent odor changes with your healthcare provider.

Dietary recommendations

  • Prioritize riboflavin-rich foods: milk, yogurt, cheese, eggs, lean beef, poultry, fortified cereals, almonds, and leafy greens such as spinach.
  • Moderate high TMA-precursor foods if you notice a link to odor: eggs, certain fish, large amounts of legumes, and some crassicae vegetables in sensitive individuals.
  • Support gut health: include fiber, fermented foods, and a diversity of plant foods to promote a balanced microbiome. A healthier gut microbiome can influence the amount and type of metabolites bacteria produce.
  • Hydration: drinking water supports normal kidney and liver function and helps the body eliminate waste products.

Supplement recommendations

  • Riboflavin (Vitamin B2): Consider supplementation if dietary intake is inconsistent. Many people take riboflavin as part of a B-complex for broader support.
  • Dosing: Typical supplemental doses vary. Discuss the right dose with your healthcare provider before starting any supplement.
  • Quality and interactions: Choose reputable brands and review potential interactions with other medications or conditions with your healthcare provider.

Lifestyle and hygiene tips

  • Shower regularly and use gentle cleansing products; focus on areas prone to sweating.
  • Launder clothing promptly and choose breathable fabrics like cotton to reduce odor retention.
  • Use topical antiperspirants or deodorants as needed; some formulations target odor-causing bacteria.
  • If odor is intermittent and linked to specific meals, timing change of meals or spacing problematic foods from social situations may help.

When to see a healthcare provider and tests to consider

  • Seek medical evaluation if you experience new, persistent, or severe body odor that affects daily life or has no clear cause. Other medical conditions can produce odors and should be ruled out.
  • Blood tests and clinical evaluation can assess liver and kidney function, nutritional status, and other causes of body odor.
  • Discuss genetic results and personalized strategies with your healthcare provider to create a safe plan that fits your needs.

Important disclaimer

PlexusDx provides educational information about genetic predispositions only. This content is not medical advice. Always consult your healthcare provider before starting or stopping supplements, making substantial dietary changes, or if you have concerns about symptoms such as persistent or severe body odor. Your healthcare provider can help interpret genetic findings in the context of your overall health and guide appropriate testing or treatment.