Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (1998) / Chapter Skim
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4 Thiamin
4 Thiamin
Pages 58-86
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From page 58... ...
for thiamin combines erythrocyte transketolase activity, urinary thiamin excretion, and other findings. The RDA for adults is 1.2 mg/day for men and 1.1 mg/day for women.
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Total thiamin content of the adult human has been estimated to be approximately 30 ma, and the biological half-life of the vitamin is probably in the range of 9 to 18 days (Ariacy-Nejad et al., 1970~. C11inica11 Effects of Inadequate Intake Early stages of thiamin deficiency may be accompanied by nonspecific symptoms that may be overlooked or easily misinterpreted '- ' ' ' I' ' ~^^^'.
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. Urinary Thiamin Excretion The urinary excretion of thiamin is the indicator that has been used most widely in metabolic studies of thiamin requirements and TABLE 4-1 Reference Values for the Primary Measures of Thiamin Status Indicator Marginal Deficiency Deficiency Erythrocyte transketolase activitya 1.20-1.25 > 1.25 Erythrocyte thiamin (nmol/L)
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concluded that evaluation of thiamin status should consider other indicators along with erythrocyte transketolase activity. Factors other than thiamin status, such as genetic defects, may influence the enzyme activity and thus the test results.
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Baines and Davies (1988) provicleci evidence that, compared with erythrocyte transketolase activity, erythrocyte TPP is more stable in frozen erythrocytes, easier to stanciarclize, and less susceptible to factors that influence enzyme activity.
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Anderson and colleagues (1986) presented evidence that expressing the thiamin requirements in absolute terms is more useful for predicting biochemical thiamin status than expressing it in relation to energy intake, and ciata from inclivicluals presented by Henshaw and coworkers ~ 1970)
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. Thiamin concentration, erythrocyte transketolase activity, and urinary thiamin clecreaseci significantly over the 11-week experimental period, and oc-erythrocyte transketolase activity (or activation coefficient)
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(Wyatt et al., 1991~. Because total thiamin concentrations in whole blood and cerebrospinal fluid decrease in the first 12 to 18 months of life, agespecific norms should be used for determining thiamin status in infancy.
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for adults and adjusting for the expected variance to estimate a recommencleci intake, gives an AI of 0.3 mg of thiamin, a value higher than that obtained from the first method. Alternatively, the AI for thiamin for infants ages 7 through 12 months could be calculated by using the estimated thiamin content of 0.6 L of human milk, the average volume consumed by this age group (thiamin content equals 0.13 mg)
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From page 67... ...
. However, the indicators of thiamin status (erythrocyte transketolase, erythrocyte transketolase activity coefficient, and total erythrocyte thiamin concentration)
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From page 68... ...
These ciata suggest that the average thiamin requirement is less than 1.3 mg/ciay, especially considering the short period of repletion and the use of a generous cutoff point for urinary thiamin excretion, but they do not allow further refinement of the estimate. In a stucly of eight boys age ci 14 to 17 years, Dick and colleagues (1958)
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From page 69... ...
Data are not sufficient to indicate differing requirements for adults 19 through 30 versus 31 through 50 years of age. Thiamin EAR and RDA Summary, Ages ~ 9 through 50 Years Examination of the ciata in Table 4-2 indicates that the EAR for thiamin is at least 0.3 mg/1,000 kcal or 0.8 mg/ciay and that intakes greater than 1.0 mg are marginally acloquate for normal erythrocyte transketolase activity and generally adequate for urinary thiamin excretion.
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Elsom et al., 1942 9 women 28-120 d 0.8 mg/d 0.3 mg/d 0.7 mg/d NA NA NA NA NA NA 0.2 0.2 0.35 0.41 0.52 0.57 0.65 0.70 0.77 Foltz et al., 1944 4 men 1 mo NA 0.57 1 mo 095 9-12 mo 1.44 Horwitt et al., 1948 24 3 y 1 mg/d 0.2 0.4 4.0 Ziporin et al., 1965 8 men 30 d depletion Mean intake during 0.15 12 d repletion 9-d control period 0.58 =1.75 mg/d Kraut et al., 1966 4 men, 9-10 mo NA 2.0-2.5 2 women Reuter et al., 1967 6 obese women NA NA 0.7k Bamji, 1970 4 men, 2-3 wk depletion 0.1 mg/1,000 kcal 0.65 (mc 4 women 1 wk repletion (depletion level) 1.3 (mer 0.4 (won 0.8 (won Henshaw et al., 39 women 3 d NA 0.82° 1970 7 d 1.02 Sauberlich et al., 7 men 14 d > 0.6 mg/1,000 kcal 0.39 1979 11 d 0.56 11 d 0.84 13 d 1.08
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THIAMIN to hiamin 71 Thiamin Intake During Repletion Erythrocyte Urinary or Maintenance Transketolase Excretion of ~take (mg/d) Activity Thiamin Other 0.2 0.2 0.35 0.41 0.52 0.57 0.65 0.70 0.77 0.57 0.95 1.44 0.2 0.4 4.0 ce during '1 period /d }00 kcal n level)
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"Abnormal clinical symptoms = decreased appetite, decreased endurance, increased h Abnormal metabolism of carbohydrate and abnormal clinical signs (decreased deep reflexes, skin changes, decreased appetite, decreased blood pressure, dull vibratory sense, and edema)
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. I Normal erythrocyte transketolase activity (ETKA)
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No differences were found in erythrocyte transketolase activity or erythrocyte thiamin content. The investigators clici not report on relationships between thiamin intake and the indicators of status.
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When thiamin intake was increased, the older women's urinary thiamin excretion clici not increase as quickly as clici that of the younger women. The authors conclucleci that the thiamin requirement of elderly women is higher than that of young women and that the ratio of thiamin to energy must be higher, but the highest thiamin intake level tested, 0.81 mg/ciay, showoci a very wicle range of urinary thiamin excretion, especially after 6 clays at this intake.
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Regardless of the nutritional status of the mother, erythrocyte transketolase activity was higher in cord blood than in maternal blood (Tripathy, 1968~. Similarly, the free thiamin concentration was higher in cord blood (Slobody et al., 1949~.
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reported that approximately three times as much thiamin, as obtained from both supplements and cliet, was neecleci by 16 pregnant women to achieve the urinary excretion peak in the tenth lunar month as was neecleci by a group of nonpregnant women. Thiamin EAR and RDA Summary, Pregnancy For pregnancy the requirement is increased by about 30 percent baseci on increased growth in maternal and fetal compartments (approximately 20 percent)
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To estimate the average thiamin requirement of lactating women, an aciclitional 0.1 mg of thiamin is acicleci to the EAR (0.9 mg/ciay) for the nonpregnant, nonlactating woman to cover the energy cost of milk production.
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For all life stage and gentler groups except lactating females, fewer than ~ percent of the inclivicluals haci intakes that were lower than the Estimated Average Requirement (EAR)
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Food Group Men Women Foods Within the Group that Provide at Least 0.3 mg of Thiamine per Serving 0.3-0.6 mg > 0.6 mg Food groups providing at least 5% of total thiamin intake Bread and bread products 17.1 17.7 Mixed foods, main ingredient is grain 9.6 8.1 NAd NA Ready-to-eat cereals 9.3 11.8 Moderately Highly fortified fortified Mixed foodse 9.1 6.5 NA NA Pasta, rice, and cooked cereals 6.7 7.2 Egg noodles, Fortified spinach oatmeal noodles Processed meatsf 5.8 4.1 Pork sausage Pork 5.6 4.9 Pork and ham Thiamin from other food groups Finfish 0.9 1.5 Pompano, fresh tuna, catfish, and trout Soy-based 0.7 0.2 Soy milk Soy-based meat supplements and substitutes meal replacements Seeds 0.1 0.3 Sunflower seeds NOTE: Most of the grain products are enriched, whole grain, or fortified. a CSFII = Continuing Survey of Food Intakes by Individuals.
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TOLERABLE UPPER INTAKE LEVELS Hazard Identification Adverse Effects There are no reports available of adverse effects from consumption of excess thiamin by ingestion of food and supplements. Because the ciata are inacloquate for a quantitative risk assessment, no Tolerable Upper Intake Level (UL)
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To do this, close attention should be given to the identification of indicators on which to base thiamin requirements.
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1988. The evaluation of erythrocyte thiamin diphosphate as an indicator of thiamin status in man, and its comparison with erythrocyte transketolase activity measurements.
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1991. Thiamin status of incarcerated and nonincarcerated adolescent males: Dietary intake and thiamin pyrophosphate response.
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1994. Thiamin status of the elderly: Dietary intake and thiamin pyrophosphate response.
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1968. Erythrocyte transketolase activity and thiamine transfer across human placenta.
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