Vitamin B2

How strong is the research?

2 papers read.

Who was studied: The cited trial cannot be located, so who was in it is unknown.

No human intervention trial of riboflavin supplementation for chronic fatigue or chronic fatigue syndrome exists in the published literature. The sole human evidence is an observational study (Heap et al. We cannot stand behind this claim on the evidence we have, so it carries no rating.

How much to take

daily

50–100 mg

Urine may turn bright yellow (harmless). Take with food to enhance absorption.

Before you take it

• No Tolerable Upper Intake Level (UL) has been established by NIH/IOM for riboflavin; the Food and Nutrition Board did not set a UL because no adverse effects from high-dose supplementation (including 400 mg/day for ≥3 months) have been reported; excess riboflavin is either not absorbed or is renally excreted.
• NIH ODS states riboflavin is not known to have any clinically relevant interactions with medications; prior claims that tricyclic antidepressants inhibit conversion of riboflavin to its active coenzymes (FAD and FMN) are not confirmed by NIH ODS and the clinical significance of this interaction is uncertain.
• Doses at or above 400 mg/day commonly cause bright yellow-orange urine (riboflavinuria); this is harmless and is not a sign of toxicity, but users should be informed proactively.
• In pregnancy, inadequate riboflavin intake is associated with increased risk of preeclampsia; evidence on the benefit of supplementation in pregnancy is described by NIH ODS as 'mixed'.
• Chronic fatigue can be a symptom of serious reversible medical conditions (iron-deficiency anemia, hypothyroidism, sleep apnea, depression, celiac disease); presenting it as supplement-addressable without a verified evidence base may delay appropriate diagnostic evaluation.

When to take it

Best taken: morning

What we make of it

The trial cannot be found in any database.