Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (1998) / Chapter Skim
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5 Riboflavin
5 Riboflavin
Pages 87-122
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From page 87... ...
for riboflavin, including the erythrocyte glutathione reductase activity coefficient and urinary riboflavin excretion. The RDA for riboflavin for adults is 1.3 mg/day for men and 1.1 mg/day for women.
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From page 88... ...
At low intake levels most absorption of riboflavin is via an active or facilitated transport system. Although older studies in animals (Daniel et al., 1983; Meinen et al., 1977; Rivier, 1973)
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From page 89... ...
In healthy adults consuming well-balanced diets, riboflavin accounts for 60 to 70 percent of the excreted urinary flavins (McCormick, 1989~. Urinary excretion of riboflavin varies with intake, metabolic events, and age (McCormick, 1994~.
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From page 90... ...
SELECTION OF INDICATORS FOR ESTIMATING THE REQUIREMENT FOR RIBOFLAVIN Several indicators have been used to estimate the acloquacy of riboflavin status in humans (McCormick, 1994; McCormick and Greene, 1994~. Principal among them are erythrocyte glutathione recluctase; erythrocyte flavin concentration; and urinary excretion of the vitamin in fasting, random, or 24-hour specimens or by loaci tests.
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From page 91... ...
Erythrocyte F11avin Erythrocyte flavin has been used as an indicator of the cellular concentration of the vitamin in its coenzyme forms because these coenzymes comprise over 90 percent of flavin (Burch et al., 1948~. Because of the instability of the predominant FAD, which is rapidly hycirolyzeci enzymatically when cells rupture, erythrocyte flavins are deliberately hydrolyzed and measured either microbiologically or fluorometrically as riboflavin.
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From page 92... ...
Urinary Fltavin Urinary riboflavin has often been used in metabolic studies to estimate the riboflavin requirement. It can be measured by fluorometric HPLC methods (Chastain and McCormick, 1987; Roughhead and McCormick, 1991)
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From page 93... ...
A break point for increased urinary excretion of riboflavin occurred with or without the loaci when adult men received more than 1.1 mg/ciay of clieta~y riboflavin (see Figure 5-1~. Above this level, there is a sharp linear increase in the slope of urinary excretion for riboflavin intakes up to 2.5 mg/ciay (Sauberlich ~ , 800 700 600c~ O 500.
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From page 94... ...
suggested a reference value of 1.4 mg or more for the normal 4-hour urinary excretion of riboflavin after a 5-mg loaci. The change in slope of urinary excretion of riboflavin after a loaci test is an especially useful status assessment.
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From page 95... ...
inclicateci that the EGRAC method is preferred for the assessment of riboflavin status whereas the urinary excretion method is better for determining riboflavin requirements. Both EGRAC and urinary riboflavin respond more rapidly to clietary riboflavin intake than floes erythrocyte riboflavin (Bamji, 1969)
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Physical Activity Riboflavin status measurements seem to be affected by physical activity. Some studies have clemonstrateci a moderate rise in the erythrocyte glutathione reductase activity coefficient (EGRAC)
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From page 97... ...
. APPROACHES FOR DERIVING THE ESTIMATED AVERAGE REQUIREMENT Primary: Maintenance or Restoration of Riboflavin Status by Using Biochemical Indicators To derive the Estimated Average Requirement (EAR)
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From page 98... ...
98 DIETARY REFERENCE INTAKES TABLE 5-1 Metabolic Stuclies Provicling Eviclence Useci to Derive the Estimateci Average Requirement (EAR) for Riboflavin for Aclults Riboflavin Intake Baseline Number During Repletion Duration Riboflavin of or Maintenance Reference of Study Intake Subjects (mg/d)
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From page 99... ...
RIBOFLAVIN to 99 Intake pletion Urinary rance Excretion Erythrocyte EGRACa of Riboflavin Riboflavin Other NAC Abnormald NA 60% abnormale Normal Normal Normal Normal NA Abnormald 75% abnormal Abnormal 33% abnormal Normal Normal NA NA Abnormald NA NA Normal Normal Normal Normal Normal ,000 kcalg NA 45% abnormald NA NA ,000 kcal 17% abnormal ,000 keel Normal ,000 keel Normal }00 kcalg 50% abnormalh NA NA NA }00 kcal 20% abnormal }00 kcal 10% abnormal }00 kcalg 100 keel 100 kealt }00 kcal }00 kcalt 100 kealt 100 kealt 92% abnormal} NA 100% normal 100% normal 60% abnormal 73% abnormal 100% normal 100% normal NA Normalf Normal Normal Normal Normal Normal NA continued
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From page 100... ...
a EGRAC = Erythrocyte glutathione reductase activity coeff~cient. b During repletion, various amounts of supplements (1-15 mg/d orally)
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From page 101... ...
RIBOFLAVIN 101 Intake pletion Urinary lance Excretion Erythrocyte EGRACa of Riboflavin Riboflavin Other ,000 kcalg 43% abnormalk NA NA NA }00 kcal 43% abnormal 100 keel 100 % normal 100 keel 100 % normal Abnormall Abnormalm NA Normaln Abnormal Abnormal Normal Abnormal Abnormal Normal Abnormal Normal Normal Normal Normal Normal Normal Normal Normal NA Normald NA Normals NA Abnormald NA AbnormalP Normal Normal NA Abnormald NA AbnormalY Abnormal Normal Abnormal Normal Abnormal Normal Normal Normal Normal Normal Normal Normal Normal Normal NA NA Abnormalr 50% abnormal" Abnormal 30% abnormal 63% abnormal Normal Normals Normal Normal Normal c NA = not applicable. d Abnormal urinary excretion = < 266 nmol (100 1lg)
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From page 102... ...
The value selected for the EAR for riboflavin was the intake that was sufficient to maintain or restore acloquate status in half the inclivicluals in the groups stuclieci. Ancillary: Kinetic, Catabolic, and Clinical Reflections of Riboflavin Status Whole-body dynamics based on pharmacokinetic analysis were used to set limits for rates and amounts of riboflavin absorption and excretion and appeared to reflect the flux of major metabolites (Zempleni et al., 1996~.
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From page 103... ...
In this case, the AI reflects the observed mean riboflavin intake of infants feci principally with human milk. The riboflavin content of human milk used for calculations in this report is baseci on milk from healthy, well-nourisheci mothers who are not taking supplements.
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From page 104... ...
Only 9 percent of the mothers and 36 percent of the infants haci EGRAC values lower than 1.2, the standard for adequacy used in the study. The mean riboflavin concentration of the human milk the infants were consuming was 0.22 + 0.01 (stanciarci error)
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From page 105... ...
AI for Infants 0-6 months 0.3 mg/day of riboflavin ~0.04 mg/kg 7-12 months 0.4 mg/day of riboflavin ~0.04 mg/kg Children and Adolescents Ages ~ through IS Years Method Used to Estimate the Average Requirement Very limited data were found concerning the riboflavin requirements of children or adolescents. An older stucly of two normal 5-year-olci boys given different levels of intake and with urinary output measured microbiologically revealed that riboflavin at 0.53 ma/ 1,000 kcal was ample (Olc~ham et al., 1944)
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From page 106... ...
reported EGRAC values for a group of 431 students age ci 14 to 17 years. For an EGRAC cutoff value of 1.20, 4 percent of the white males exceecleci the cutoff compared with 20 percent of the black males, 11 percent of the white females, and 38 percent of the black females.
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From page 107... ...
Biochemical changes in riboflavin status occur well before the appearance of overt signs of deficiency. Such studies help to bracket the riboflavin requirement.
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From page 108... ...
cliets. Study results suggest that no distinctions in the riboflavin requirements of men and women other than those baseci on general size and energy expenditure can be made, nor is there any data to indicate that requirements for younger adults differ from those of older (over 70 years)
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From page 109... ...
A for Women 19-30 years 1.1 mg/day of riboflavin 31-50 years 1.1 mg/day of riboflavin 51-70 years 1.1 mg/day of riboflavin Adults Ages Older Than 70 Years Evidence Considered in Estimating the Average Requirement Few aciclitional studies estimating the riboflavin requirements have been conclucteci in the elderly. In healthy elderly women age ci 70 years or older, doubling the estimated riboflavin intake by means of a supplement containing 1.7 mg of riboflavin doubled the urinary riboflavin excretion in the supplemented group compared to the unsupplementeci group, from 4.36 to 9.06 Prolog (1.64 to 3.41 mg/g)
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From page 110... ...
A for Women > 70 years 1.3 mg/day of riboflavin 1.1 mg/day of riboflavin Pregnancy Evidence Considered in Estimating the Average Requirement Few studies provide information about the riboflavin requirements of pregnant women. Bamji (1976)
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From page 111... ...
This increaseci neeci is supported by the urinary excretion of less riboflavin cluring the progression of pregnancy and the more frequent appearance of clinical signs of ariboflavinosis in pregnant women on low intakes (less than 0.8 mg/ciay) than in their nonpregnant counterparts (Brzezinski et al., 1952; Jansen and Jansen, 1954~.
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From page 112... ...
Riboflavin EAR and RDA Summary, Lactation To the EAR of 0.9 mg/ciay of riboflavin for the nonpregnant and nonlactating woman, 0.4 mg/day is added, giving an EAR of 1.3 mg/day. EAR for Lactation 14-18 years 1.3 mg/day of riboflavin 19-30 years 1.3 mg/day of riboflavin 31-50 years 1.3 mg/day of riboflavin The RDA for riboflavin is set by assuming a coefficient of variation (CV)
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From page 113... ...
Similarly, a group of healthy residents of rural Georgia was found to have a mean ciaily intake of riboflavin of 2.1 mg (Roughead and McCormick, 1991~. For all life stage and gender groups, fewer than ~ percent of indivicluals have estimated intakes that are less than the Estimated Average Requirement (EAR)
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From page 114... ...
Mixed foods were not considered for this table. SOURCE: Unpublished data from the Food Surveys Research Group, Agricultural Research Service, U.S.
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From page 115... ...
No adverse effects were reported in humans after single oral closes of up to 60 mg of supplemental riboflavin and 11.6 mg of riboflavin given intravenously as a single bolos close (Zempleni et al., 1996~. This study is of limited use in setting a Tolerable Upper Intake Level (UL)
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Intake Assessment Although no UL can be set for riboflavin, an intake assessment is provicleci here for possible future use. Data from the Third National Health and Nutrition Examination Survey (see Appendix H)
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From page 117... ...
1969. Glutathione reductase activity in red blood cells and riboflavin nutritional status in humans.
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1984. Effects of aerobic exercise and weight loss on riboflavin requirements of moderately obese, marginally deficient young women.
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1950. Correlation of urinary excretion of riboflavin with dietary intake and symptoms of ariboflavinosis.
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1982. Factors affecting riboflavin requirements of oral contraceptive users and nonusers.
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1972. Application of the erythrocyte glutathione reductase assay in evaluating riboflavin nutritional status in a high school student population.
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1992. Riboflavin requirements and exercise adaptation in older women.
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