FAO Nutrition Meetings Report Series 
    No. 46A WHO/FOOD ADD/70.36

    The content of this document is the result of the deliberations of the
    Joint FAO/WHO Expert Committee on Food Additives which met in Rome,
    27 May - 4 June 19691

    Food and Agriculture Organization of the United Nations

    World Health Organization

    1 Thirteenth report of the Joint FAO/WHO Expert Committee on Food
    Additives, FAO Nutrition Meetings Report Series, in press;
    Wld Hlth Org. techn.  Rep. Ser., in press.


    Biological Data

    Biochemical aspects

    Riboflavin is essential for all animals and many micro-organisms.
    Riboflavin-5-phosphate is the prosthetic group of flavoproteins
    involved in general cell metabolism as hydrogen acceptors. The
    recommended daily dietary allowance1 (U.S. Food and Nutrition Board,
    1968). The recommended therapeutic doses for treatment or prevention
    of riboflavin deficiency are:

                          1968 BP and 1963 BPC      1965 USP XVII

    Therapeutic dose      5-10 mg/day               10-15 mg/day
    Prophylactic dose     1-4 mg/day                    2 mg/day

    Crystalline riboflavine was recovered from the bladder and ureters of
    rats a few hours after i.v. injection of a saturated solution in
    saline. Nephrectomized rats accumulated injected riboflavin in the
    small intestine through excretion from the jejunal mucosa. The large
    intestine destroyed riboflavin (Selye, 1943). Normal man excretes
    unchanged riboflavin in faeces and urine (Axelrod et al., 1941).2
    Human deficiency is indicated by adult urinary excretion of less than
    10 g/6 hours (Harrison et al., 1962). The total amount absorbed by
    man never exceeds 15 - 20 mg per day.


    1 For man is about 1.5 mg/day (pregnant women 1.8 mg/day, lactating
    women 2.0 mg/day).

    2 The urinary recovery after oral administration to fasted normal
    humans decreased with higher doses, but administration immediately
    after breakfast resulted in a constant per cent of urinary recovery
    independent of dose (Levy & Jusko, 1966).

    Acute toxicity

    Compound              Animal    Route            LD50            Reference
                                               mg/kg body-weight

    Riboflavin            mouse     i.p.            > 340            Kuhn & Boulanger, 1936

                          rat       oral3         >10 000            Unna & Greslin, 1942
                                    s.c.            5 000            Unna & Greslin, 1942

                                    i.p.              560            Unna & Groslin, 1942
                          dog       oral          > 2 000            Unna & Greslin, 1942
    riboflavinate         rat       oral          >10 000            Unna & Greslin, 1942
                                    s.c.              790            Unna & Greslin, 1942
                                    i.p.              560            Unna & Greslin, 1942

    3 Oral > 10 000, Pellmont, 1962; i.v. 50 -100, Pellmont, 1962.
    The high oral LD50 in rats is probably due to poor absorption from
    the gastro-intestinal tract and the low solubility of riboflavin.
    Parenteral administration of 0.6 g/kg body-weight leads to renal
    obstruction of pelvis and collecting tubules crystals of riboflavin
    with death from renal failure and weight less. Toxicity is similar to
    pyridoxine or pantothenic acid (Unna & Greslin, 1942).

    Short-term studies

    Rat. 10 mg/day fed to male and female rats over 20 weeks after
    weaning in 3 successive generations produced no apparent adverse
    effect on growth and reproduction. No pathological changes were
    observed (Unna & Greslin, 1942).

    Dog. Four dogs fed 25 mg/kg body-weight/day for, 5 months showed no
    adverse effects or pathological changes (Unna & Greslin, 1942).


    Animals fed high doses of riboflavin show no toxic effects. There are
    numerous biochemical studies and a vast amount of clinical and
    nutritional data on riboflavin. It is reasonable to use this
    information for evaluation.


    Level causing no toxicological effect in the rat

    50 mg/kg body-weight per day.

    Estimate of acceptable daily intake for man

                                     mg/kg body-weight
    Unconditional acceptance                           
                                         0 - 0.5


    Axelrod, A. E., Spies, T. D. & Elvehjem, C. A. & Axelrod, V. (1941) 
    J. clin. Invest., 20, 229

    British Pharmaceutical Codex 1963

    British Pharmacopoeia 1968

    Emmerie, A. (1938) Acta. brev. neerl. Physiol.,  8, 116

    Food & Nutrition Board (1968) Publication 1694, National Academy of
    Science N.R.C., Washington, D.C.

    Harrison, T. R. (1962) Principles of Internal Medicine, 4th edn.,
    537, McGraw-Hill, N.Y., Toronto & London

    Khun, R. & Boulanger, P. (1936) Hoppe-Seylers Z. physiol. Chem.,241,

    Koschara, W. (1935) Hoppe-Seylers Z. physiol. Chem., 232, 101

    Levy, G. & Jusko, W. J. (1966) J. Pharm. Sci  55, 285

    Pellmont (1962) Handbuch der allgemeinen Pathologie Band 11, pp.
    984, Springer Verlag, Berlin

    Selye, H. (1943) J. Nutr., 25, 137

    United States Pharmacopoeia, seventeenth revision, 1965

    Unna, K. & Greslin, J. G. (1942) J. Pharmacol. exp. Ther.,  76, 75

    See Also:
       Toxicological Abbreviations
       Riboflavin (ICSC)
       RIBOFLAVIN (JECFA Evaluation)