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How SLC25A32 and Riboflavin (Vitamin B2) Affect Energy and Exercise

Riboflavin, also called vitamin B2, is an essential nutrient that helps convert carbohydrates, proteins, and fats into usable energy. It supports cell growth, red blood cell production, and the activation and metabolism of other B vitamins. Within cells, a riboflavin-derived molecule called flavin adenine dinucleotide, or FAD, is a critical cofactor for enzymes that produce energy in mitochondria. The SLC25A32 gene encodes a mitochondrial transporter that moves FAD into mitochondria. Variants in SLC25A32 can reduce that transport, which in some people leads to low mitochondrial energy output and symptoms such as unusual fatigue or exercise intolerance.

Why this matters

  • Reduced FAD transport can limit mitochondrial enzyme activity and energy production, particularly during physical activity.
  • Symptoms may include muscle tiredness during exercise, prolonged recovery, and overall low stamina.
  • Importantly, these symptoms often respond to increased riboflavin intake because providing more substrate for FAD synthesis can help compensate for reduced transport.

Practical steps to support riboflavin function

Whether your genetic test shows an increased risk or not, riboflavin is essential for energy metabolism. The following diet, supplement, lifestyle, and monitoring suggestions can help support mitochondrial health and overall energy.

Diet

  • Focus on riboflavin-rich foods: dairy (milk, yogurt, cheese), eggs, lean meats (beef, pork, poultry), fatty fish (salmon, mackerel), fortified cereals and bread, almonds, and leafy green vegetables.
  • Include a variety of protein sources to supply amino acids needed for mitochondrial enzymes.
  • Pair carbohydrates and protein around workouts to improve performance and recovery.
  • Limit excessive alcohol, which can impair B vitamin status and mitochondrial function.

Supplements

  • Riboflavin supplements are available in multiple forms. Typical supplemental doses used for riboflavin-responsive exercise intolerance in reported cases have ranged from about 50 mg to 200 mg daily. Lower doses from a multivitamin (1.3 to 2 mg) are adequate for baseline needs in many people.
  • If you have symptoms such as exercise intolerance or unexplained fatigue, discuss higher-dose riboflavin with your healthcare provider to determine appropriateness and dose.
  • Riboflavin is water-soluble and excess is generally excreted in urine; urine may turn bright yellow with supplementation. Still, consult a clinician before starting high-dose supplements and review interactions with any medications you take.

Lifestyle

  • Gradual, consistent exercise helps boost mitochondrial capacity. If you notice exercise intolerance, pace increases in intensity and duration to avoid setbacks.
  • Prioritize sleep quality; sleep supports mitochondrial repair and energy regulation.
  • Reduce chronic stress through practices you find sustainable, such as walking, mindfulness, or yoga, because chronic stress can worsen fatigue.
  • Stay well hydrated and maintain balanced electrolytes during prolonged or intense activity.

When to check labs or seek evaluation

If you experience persistent or unexplained fatigue, exercise intolerance, muscle weakness, or other concerning symptoms, talk to your healthcare provider. They may consider basic tests and targeted evaluations to rule out common causes and to assess nutritional status.

  • Basic blood tests that are commonly reviewed include a complete blood count and metabolic panel.
  • Your clinician may consider tests of nutritional status or muscle metabolism when indicated. Discuss specific testing with your provider.

Genetic Interpretation: SLC25A32 (rs147014855)

The accordion below summarizes genotype-specific interpretations and practical recommendations for the rs147014855 variant in SLC25A32. Each entry describes what the genotype means for FAD transport and energy, typical symptoms to watch for, and suggested dietary, supplement, and lifestyle considerations. PlexusDx does not provide medical advice. Always consult your healthcare provider before starting supplements or making significant changes to your care.

2 effect alleles (TT) — Higher likelihood of riboflavin-responsive exercise intolerance

Interpretation

  • You carry two copies of the effect allele. This genotype is associated with reduced transport of FAD into mitochondria and a higher likelihood of exercise intolerance that has been reported to respond to riboflavin supplementation.
  • This may lead to unusual fatigue during or after physical activity, reduced exercise capacity, or prolonged recovery.

What to consider

  • Prioritize riboflavin-rich foods: dairy, eggs, lean meats, fish, fortified cereals, almonds, and leafy greens.
  • If dietary intake is insufficient or symptoms occur, discuss riboflavin supplementation with your healthcare provider. Clinical reports often use 50 mg to 200 mg daily for riboflavin-responsive exercise issues, but your provider will recommend an appropriate dose.
  • Maintain regular, gradually progressive exercise and give extra attention to rest, recovery, hydration, and sleep.
  • If symptoms persist despite dietary and lifestyle changes, ask your clinician about evaluation and targeted management. Labs and other assessments may help rule out alternative causes.
1 effect allele (CT) — Possible reduced FAD transport with milder impact

Interpretation

  • You carry one copy of the effect allele. This may modestly reduce mitochondrial FAD transport and could contribute to milder exercise intolerance in some people.
  • Carrying one effect allele does not guarantee symptoms, but it can make riboflavin status more important for optimal energy production.

What to consider

  • Emphasize riboflavin-rich foods as part of a balanced diet to support mitochondrial function.
  • If you notice unusual fatigue or problems with exercise, discuss riboflavin supplementation with your healthcare provider. Lower supplemental doses or dietary adjustments may be sufficient.
  • Use gradual training progressions, adequate sleep, and stress management to support energy metabolism.
0 effect alleles (CC) — Typical riboflavin transport

Interpretation

  • You carry two copies of the non-effect allele. This genotype is associated with normal SLC25A32 function and typical transport of FAD into mitochondria.
  • You are not genetically predisposed to riboflavin-related exercise intolerance, but riboflavin remains essential for energy metabolism and overall health.

What to consider

  • Maintain adequate riboflavin intake through diet: dairy, eggs, lean meats, fish, fortified cereals, almonds, and leafy greens.
  • If you have unexplained fatigue or exercise issues, discuss them with your healthcare provider to evaluate other causes.
  • Support mitochondrial health with balanced nutrition, regular activity, good sleep, and stress reduction.

Final notes and disclaimer

This information is intended to help you understand how a variant in SLC25A32 may relate to riboflavin handling and energy. PlexusDx does not provide medical advice. Genetic information is one piece of a larger health picture. Always consult your healthcare provider before starting supplements, changing your diet, or undertaking new treatments or testing. Your provider can interpret genetic results in the context of your symptoms, medical history, medications, and lab results to create a safe, personalized plan.