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Vitamin B2

Supplement vitamin energygeneral nutrition
Aka: riboflavin
Brands seen in Singapore: NOW Foods, Life Extension, Natural Factors, Nature's Way, Thorne
Third-party tested: Thorne certifies other products with NSF Certified for Sport, but nothing for vitamin b2.Certification is granted per product, so check the tub you actually own. Not being listed is not the same as failing.
Not medical advice. Check with your doctor or pharmacist before you start, stop or change the timing of anything you take.
How to use
What it’s for
Energy production · fat, drug and steroid metabolism
When to take
No timing rule
Take with
Water · absorption tops out at about 27 mg per dose
Pros & cons
Pros
  • RDA is small — 1.3 mg men / 1.1 mg women
  • No UL — 400 mg/day for 3 months without reported harm
  • No known clinically relevant drug interactions
Cons
  • Most people (US data) already get the RDA from food
  • Fnb still urges caution with excessive amounts
  • SG caps B2 in health supplements at 40 mg/day
Sources
  1. NIH ODS — Riboflavin (Health Professional), updated May 11, 2022 — Introduction · read 2026-08-27
    what it says
    “Riboflavin (also known as vitamin B2) is one of the B vitamins, which are all water soluble … These coenzymes play major roles in energy production; cellular function, growth, and development; and metabolism of fats, drugs, and steroids”
  2. NIH ODS — Riboflavin (Health Professional), updated May 11, 2022 — Introduction (absorption) · read 2026-08-27
    what it says
    “The body absorbs little riboflavin from single doses beyond 27 mg and stores only small amounts of riboflavin in the liver, heart, and kidneys … either not absorbed or the small amount that is absorbed is excreted in urine”
  3. NIH ODS — Riboflavin (Health Professional), updated May 11, 2022 — Sources: food · read 2026-08-27
    what it says
    “About 95% of riboflavin in the form of FAD or FMN from food is bioavailable up to a maximum of about 27 mg of riboflavin per meal or dose”
  4. NIH ODS — Riboflavin (Health Professional), updated May 11, 2022 — Table 1 RDAs + DV note · read 2026-08-27
    what it says
    “Table 1: Recommended Dietary Allowances (RDAs) for Riboflavin … 19–50 years 1.3 mg 1.1 mg 1.4 mg 1.6 mg … 51+ years 1.3 mg 1.1 mg … The DV for riboflavin is 1.3 mg for adults and children age 4 years and older”
  5. NIH ODS — Riboflavin (Health Professional), updated May 11, 2022 — Dietary supplements · read 2026-08-27
    what it says
    “Multivitamin/mineral supplements with riboflavin commonly provide 1.3 mg riboflavin (100% of the DV) … In most supplements, riboflavin is in the free form, but some supplements have riboflavin 5'-phosphate”
  6. NIH ODS — Riboflavin (Health Professional), updated May 11, 2022 — Riboflavin intakes and status · read 2026-08-27
    what it says
    “Most people in the United States consume the recommended amounts of riboflavin … Riboflavin deficiency is extremely rare in the United States”
  7. NIH ODS — Riboflavin (Health Professional), updated May 11, 2022 — Groups at risk (athletes, pregnancy) · read 2026-08-27
    what it says
    “vegetarian athletes are at risk of riboflavin deficiency because of their increased need for this nutrient … Pregnant or lactating women who rarely consume meats or dairy products … are at risk of riboflavin deficiency”
  8. NIH ODS — Riboflavin (Health Professional), updated May 11, 2022 — Groups at risk (vegans, transporter deficiency) · read 2026-08-27
    what it says
    “Vegans and those who consume little milk in developed countries are also at risk of riboflavin inadequacy … Riboflavin transporter deficiency … is a rare neurological disorder … high-dose riboflavin supplementation can be a life-saving treatment in this population”
  9. NIH ODS — Riboflavin (Health Professional), updated May 11, 2022 — Riboflavin and health: migraine · read 2026-08-27
    what it says
    “Some, but not all, of the few small studies conducted to date have found evidence of a beneficial effect of riboflavin supplements on migraine headaches … 400 mg/day riboflavin … although the evidence supporting this recommendation is of low quality”
  10. NIH ODS — Riboflavin (Health Professional), updated May 11, 2022 — Health risks from excessive riboflavin · read 2026-08-27
    what it says
    “adverse effects from high riboflavin intakes … (400 mg/day for at least 3 months) have not been reported, the FNB did not establish ULs for riboflavin … the FNB urges people to be cautious about consuming excessive amounts of riboflavin”
  11. NIH ODS — Riboflavin (Health Professional), updated May 11, 2022 — Interactions with medications · read 2026-08-27
    what it says
    “Riboflavin is not known to have any clinically relevant interactions with medications”
  12. HSA Singapore — Health Supplements Guidelines GL-CHPB-3-001 Rev. No. 020 (January 2026), s4.8 general-adult limits, Table 4 Vitamins Limits + List of Health Claims rows 42, 53 + clause 4.11 · read 2026-08-27
    what it says
    “Table 4: Vitamins Limits … Vitamin B2 40mg … Vitamin B2 for patients with certain genetic or metabolic disorders … Help in energy metabolism in the body … Vitamin B2, B3, B5, B6, B12 … Maintain good health … All vitamins and minerals”
  13. HSA Singapore — Guidelines on Prohibited and Restricted Ingredients in Health Supplements and Traditional Medicines, GL-CHPB-1-012 Rev. 001 (October 2025), Annex A row 109 · read 2026-08-27
    what it says
    “109. Vitamin B2 Restricted use in HS and TM Maximum Daily Dose … should not provide more than 40mg … Cautionary Statement When for oral use by patients with certain genetic or metabolic disorders”
  14. FDA — Daily Value on the Nutrition and Supplement Facts Labels (Reference Guide: Daily Values for Nutrients), content current as of 03/05/2024 · read 2026-08-27
    what it says
    “Riboflavin 1.3mg … DVs are the recommended amounts of nutrients to consume or not to exceed each day”
  15. iHerb Singapore — Vitamin B2 Riboflavin category page (default order), first listings · read 2026-08-27
    what it says
    “1 - 19 of 19 results … NOW Foods, B-2, 100 mg … Life Extension, Homocysteine Resist … Natural Factors, BioCoenzymated™, B2, Riboflavin 5'-Phosphate, 50 mg … Nature's Way, Riboflavin Vitamin B2, 400 mg … Thorne, Riboflavin 5' Phosphate, 36.5 mg”
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Updated 2026-08-30. Every line above traces to a numbered source. Kozen-X is not a medical device and does not give medical advice. It lists what published sources have written down — nothing more. A pair not listed is unrecorded, not cleared. Before you start, stop or re-time anything, talk to your doctor or pharmacist.