Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (1998) / Chapter Skim
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11 Biotin
11 Biotin
Pages 374-389
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From page 374... ...
There are no nationally representative estimates of the intake of biotin from food or from both food and supplements. There are not sufficient data on which to base a Tolerable Upper Intake Level (UL)
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From page 375... ...
Malonyl CoA then serves as a substrate for fatty acid elongation. The second biotin-clepenclent carboxylase, pyruvate carboxylase, catalyzes the carboxylation of pyruvate to form oxaloacetate, which serves as an intermediate in the tricarboxylic acid cycle.
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From page 376... ...
Intestinal Absorption and Microbial Synthesis A biotin carrier located in the intestinal brush border membrane transports biotin against a sodium ion concentration gradient and is structurally specific, temperature clepenclent, and electroneutral; at pharmacological concentrations, diffusion predominates (Mock, 1996~. Biotin is synthesized by intestinal microflora (Bonjour, 1991~.
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From page 377... ...
Two aciclitional minor metabolites, bisnorbiotin methyl ketone and biotin sulfone, were recently iclentifieci in human urine (Zempleni et al., 1997~. The urinary excretion and serum concentrations of biotin and its metabolites increase roughly in the same proportion in response to either intravenous or oral administration of large closes of biotin (Mock and Heirci, 1997; Zempleni et al., 1997)
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From page 378... ...
The urinary excretion of biotin clecreaseci dramatically with time in normal subjects on a raw egg white cliet, reaching markocily abnormal values in 9 of 10 subiects by clay 20. Bisnorbiotin excretion cleclineci in parallel, provici~ng evidence for regulated catabolism of biotin.
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From page 379... ...
Plasma Biotin A low plasma biotin concentration is not a sensitive indicator of inadequate biotin intake. Abnormally decreased plasma biotin was absent in half the subjects fed raw egg white (NI Mock et al., 1997)
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From page 380... ...
The AI reflects the observed mean biotin intake of infants feci principally with human milk. Ages O through 6 Months.
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From page 381... ...
If the reference hotly weight ratio methoci clescribeci in Chapter 2 to extrapolate up from the AI for biotin for infants ages O through 6 months is used, the AI for biotin for the older infants is 6 ~g/ciay after rouncling. Biotin Al Summary, Ages O through I 2 Months AI for Infants 0-6 months 5 1lg/day of biotin ~0.7 ~lg/kg 7-12 months 6 1lg/day of biotin ~0.7 ~lg/kg Children and Adolescents Ages ~ through I 8 Years Method Used to Set the Al Evidence concerning the biotin requirement is minimal and floes not justify the setting of an Estimated Average Requirement (EAR)
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From page 382... ...
Extrapolation from the AI for infants exclusively feci human milk would be expected to overestimate the requirement for adults because adults require biotin only for maintenance. The result of such an extrapolation using the formula adult (AIyoung infant)
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From page 383... ...
cletecteci increased 3-hyciroxyisovaleric acid in more than half of healthy pregnant women by the third trimester, and urinary excretion of biotin was clecreaseci in about 50 percent of the women stuclieci. It is not known whether these changes in values are normal for pregnant women or indicate low biotin intake relative to neeci.
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From page 384... ...
Department of Agriculture Continuing Survey of Food Intakes by Inclivicluals, the Third National Health and Nutrition Examination Survey (NHANES III) , and the Boston Nutritional Status Survey do not report biotin intake.
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From page 385... ...
These results are not consiclereci useful for deriving a Tolerable Upper Intake Level (UL) for human intakes because of the high closes used, mocle and vehicle of administration used (subcutaneous injection administration of 0.1 mol/L of NaOH, which would itself be toxic)
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From page 386... ...
1995. Biotin deficiency complicating long-term total parenteral nutrition in an adult patient.
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From page 387... ...
1981. Biotin-responsive in vivo carboxylase deficiency in two siblings with secretory diarrhea receiving total parenteral nutrition.
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From page 388... ...
1997. Increased urinary excretion of 3-hydroxyisovaleric acid and decreased urinary excretion of biotin are sensitive early indicators of decreased status in experimental biotin deficiency.
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From page 389... ...
1997. Identification of biotin sulfone, bisnorbiotin methyl ketone, and tetranorbiotin-l-sulfoxide in human urine.
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