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Background Measures that better describe “healthy” and sustainable recovery during nutritional treatment of children with moderate acute malnutrition (MAM) are needed. Objectives We compared changes to body composition among children receiving 1 of 4 specialized nutritious food (SNFs) during treatment of MAM and by recovery and relapse outcomes. Methods The study was nested within a prospective, cluster-randomized, community-based, cost-effectiveness trial assessing 4 SNFs to treat children aged 6–59 mo with MAM [midupper arm circumference (MUAC) ≥11.5 cm and

Background Nutrition programs frequently approach wasting and stunting as 2 separate conditions with distinct causes and effects. Although several cross-sectional studies have identified an association between the 2 conditions, longitudinal studies are useful to quantify the risk of acute malnutrition based on the trajectory of linear growth. Objective We analyzed data from a longitudinal study to explore associations between linear growth and relapse to acute malnutrition in high-risk children during the year after recovery from moderate acute malnutrition (MAM). Methods This was a secondary data analysis from a cluster randomized trial involving 1487 Malawian children 6-62 mo old treated for MAM and enrolled upon recovery. Children were followed for 1 y, during which data were collected on anthropometric progress, symptoms of illness, and household food security. Multivariate fixed-effects logistic regression was used to identify associations between linear growth and relapse to acute malnutrition. Results Children who have recovered from MAM proved to be a high-risk population, with nearly half experiencing a decrease in height-for-age z score (HAZ) for 12 mo. Children whose HAZ was declining were more likely to relapse to MAM or SAM than were those whose linear growth rate maintained or increased their HAZ (P

The C677T polymorphism of the methylenetetrahydrofolate reductase (MTHFR) gene differs in frequency in various ethnic groups that have differing prevalence of age-related cognitive impairments. We used a series of neuro-psychological tests to examine the association of the MTHFR C677T polymorphism with cognition and depression and also to assess whether genotype modifies the association of folate and homocysteine with these outcomes. This study analyzed pooled cross-sectional data from 2 ethnically diverse cohorts of community-living adults: the Boston Puerto Rican Health Study (n = 939) and the Nutrition, Aging, and Memory in Elders study (n = 1017). Individuals in both cohorts underwent anthropometric and laboratory measurements and dietary and health assessments using validated questionnaires between the years 2003 and 2007. Cognitive outcomes included measures of global cognition [Mini-Mental Status Exam (MMSE)], depression (Center for Epidemiological Studies Depression Scale), and 3 factor scores for the domains of attention, executive function, and memory that were derived from a detailed set of neuropsychological tests. Low plasma vitamin B-12 concentrations were associated with poorer MMSE scores and higher depression scores, and low vitamin B-6 concentrations were associated with lower MMSE and worse attention and executive function in the multivariate analysis. In contrast, MTHFR genotype, folate, and homocysteine were not associated with cognition or depression in either ethnicity-pooled or stratified analysis. The current study did not find evidence of an association between the MTHFR C677T TT genotype and impaired cognition or depression in a population with adequate folate status and a high prevalence of cognitive impairment and depression.

Anemia and micronutrient deficiencies are common among Indian schoolchildren. We assessed the effectiveness of micronutrient fortification of meals cooked and fortified at school on anemia and micronutrient status of schoolchildren in Himalayan villages of India. In this placebo-controlled, cluster-randomized study, 499 schoolchildren (6-10 y) received either multiple micronutrients (treatment group) or placebo (control group) as part of school meals (6 d/wk) for 8 mo. Both groups were dewormed at the beginning of the study. The micronutrient premix provided 10 mg iron, 375 microg vitamin A, 4.2 mg zinc, 225 microg folic acid, and 1.35 microg vitamin B-12 for each child per day (approximately 75% recommended dietary allowance). Blood samples drawn before and after the intervention were analyzed for hemoglobin, ferritin, retinol, zinc, folate, and vitamin B-12. Baseline prevalence of anemia (37%), iron deficiency anemia (10%), low serum ferritin (24%), retinol (56%), zinc (74%), folate (68%), and vitamin B-12 (17%) did not differ between groups. Postintervention, fewer in the treatment group had lower serum retinol [odds ratio (OR) (95% CI): 0.57 (0.33-0.97)] and folate [OR (95% CI): 0.47 (0.26-0.84)] than the control group. The serum vitamin B-12 concentration decreased in both groups, but the magnitude of change was less in the treatment than in the control group (P < 0.05). Total body iron (TBI) increased in both groups; however, the change was greater in the treatment than in the control group (P < 0.05). Micronutrient fortification of school meals by trained school personnel was effective in improving vitamin A, folate, and TBI status while also reducing the magnitude of a decrease in vitamin B-12 status.

Poor folate status is associated with cognitive decline and dementia in older adults. Although impaired brain methylation activity and homocysteine toxicity are widely thought to account for this association, how folate deficiency impairs cognition is uncertain. To better define the role of folate deficiency in cognitive dysfunction, we fed rats folate-deficient diets (0 mg FA/kg diet) with or without supplemental L-methionine for 10 wk, followed by cognitive testing and tissue collection for hematological and biochemical analysis. Folate deficiency with normal methionine impaired spatial memory and learning; however, this impairment was prevented when the folate-deficient diet was supplemented with methionine. Under conditions of folate deficiency, brain membrane content of the methylated phospholipid phosphatidylcholine was significantly depleted, which was reversed with supplemental methionine. In contrast, neither elevated plasma homocysteine nor brain S-adenosylmethionine and S-adenosylhomocysteine concentrations predicted cognitive impairment and its prevention by methionine. The correspondence of cognitive outcomes to changes in brain membrane phosphatidylcholine content suggests that altered phosphatidylcholine and possibly choline metabolism might contribute to the manifestation of folate deficiency-related cognitive dysfunction.

We conducted a systematic review to evaluate the association between folate, vitamin B-6, vitamin B-12, and cognitive function in the elderly. Our search was conducted in Medline for English-language publications of human subjects from 1966 through November 2006; we supplemented these results with information from article reviews and domain experts. We included longitudinal cohort and case-control studies of B vitamins and analyses of cognitive tests or Alzheimer's disease. We evaluated the quality and heterogeneity of study outcomes and assessed 30 different cognitive function tests. Of 24 studies that met eligibility criteria, 16 were determined to be of fair quality. A majority of the studies reviewed 2 or more B vitamins. Considerable heterogeneity was found among B-vitamin-level thresholds, comparisons, and data analyses. Six of 10 folate studies reported a significant association between low baseline blood folate concentrations and subsequent poor test performance in the global cognitive domain, and 4 of 9 folate studies found associations between low blood folate concentrations and increased prevalence of Alzheimer's disease. Studies did not reveal an association of vitamin B-6 and vitamin B-12 blood concentrations with cognitive-test performance or Alzheimer's disease, nor was B-vitamin dietary intake associated with cognitive function. Higher plasma homocysteine concentrations were associated with poorer cognitive function. Although the majority of studies indicated that low blood folate concentrations predicted poorer cognitive function, data supporting this association were limited because of the heterogeneity in cognition-assessment methodology, and scarcity of good quality studies and standardized threshold levels for categorizing low B-vitamin status.

I suppose I should establish my bonafides for participation in this symposium. I did participate in 3 Interdepartmental Committee on Nutrition for National Defense (ICNND) surveys as far separated as one on the Blackfeet Indian Reservation (1) in Montana and 2 in Asia-Burma (2) and East Pakistan (3). In fact, the Blackfeet Reservation and Burma surveys were my training grounds for becoming the clinical chief for the East Pakistan survey and later the codirector. More importantly, in 1962, I followed Alan Forbes, who is much missed at this symposium, as the deputy to Arnie Schaefer at ICNND and NIH, and did have experience of an office in the Stone House on the NIH campus. There I participated in the transmutation of the ICNND to the Interdepartmental Committee on National Development and its alignment with the Office of International Research at the NIH and a repositioning within the Department of Health and Human Services. It was from this position that ICNND went on to organize some civilian surveys in the mid-1960s, including those in Central America and Panama (4), and it was from this position that the groundwork was laid for the application of ICNND techniques to the first U.S. domestic survey outside of an Indian reservation, culminating in the Ten State Nutrition Survey (5), which documented that there was hunger in America, as well as abroad.

The C677T variant of methylenetetrahydrofolate reductase (MTHFR), a key enzyme in the remethylation of homocysteine to methionine, is a frequent genetic cause of mild hyperhomocysteinemia among individuals with low folate status. However, little is known about the influence of subject characteristics, such as age and sex, on the relation between the C677T MTHFR polymorphism and fasting plasma total homocysteine (tHcy) concentrations. The aim of the present study was to explore the influence of age and gender, together with folate status, on the association between the C677T polymorphism and tHcy concentrations. The C677T genotype was determined for 1820 participants from the fifth examination of the Framingham Offspring Study. Mean age of the participants was 56 y (range 28-82 y). The allelic distribution was not different from the Hardy-Weinberg equilibrium, with a TT frequency comparable in men and women (14%). Geometric mean tHcy was 15% higher in men than in women (P < 0.001), and women had significantly higher plasma folate levels (P < 0.001). Geometric mean tHcy was significantly higher in TT participants (P = 0.001) than in participants with the CC and CT genotypes among those with plasma folate

Although the elevation of circulating total serum homocysteine (tHcy) concentration in a fasting state is associated with an increased risk of occlusive vascular disease in adults, the implications of elevated levels in children are not known. The goals of this study were to describe the distribution of tHcy among a representative sample of children and adolescents in the United States, and to test for differences in tHcy among sex, age and race-ethnicity categories. Using surplus sera from Phase 2 of the third National Health and Nutrition Examination Survey, we measured tHcy for a nationally representative sample of 942 boys and 1085 girls aged 4-19 y. The age-adjusted geometric mean tHcy concentrations were 6.2 and 5.8 micro mol/L in non-Hispanic Caucasian boys and girls, 6.4 and 6.1 micro mol/L in non-Hispanic African-American boys and girls, and 6.4 and 5.5 micro mol/L in Mexican American boys and girls, respectively. A significant interaction between age and sex (P < 0.01) reflected the divergence of tHcy concentrations at about age 10 y, with higher concentrations in boys than in girls throughout adolescence. These first data on homocysteine concentrations in a nationally representative sample of American youth suggest that sexual dimorphism of tHcy concentrations occurs earlier, at approximately 10 y of age, than previously reported on the basis of smaller nonrepresentative samples. Improved understanding of the determinants of levels during growth and development may provide important clues to the etiology of adult disease.

In 1996, the U.S. Food and Drug Administration issued a regulation requiring that all enriched cereal-grain products be fortified with folic acid by January 1998. An average increase in folic acid intake of 100 micro g/d was projected as a result of this fortification. The objective of the present study was to estimate the effect of this fortification on the intake of folic acid and total folate, and on the prevalence of individuals with inadequate folate intake and with high folic acid intake. We used data on food and nutrient intake from 1480 individuals who participated in the 5th and 6th examinations of the Framingham Offspring Cohort Study. Fortification was instituted during the 6th examination so that 931 participants were examined before its implementation (nonexposed) and 549 after implementation (exposed). Published data on total folate in enriched cereal-grain products were used to correct folate content in these foods to reflect fortification. Among nonsupplement users, folic acid intake increased by a mean of 190 [95% confidence interval (CI): 176, 204] micro g/d (P < 0.001) and total folate intake increased by a mean of 323 (95% CI: 296-350) micro g dietary folate equivalents (DFE)/d (P < 0.001) in the exposed participants. Similar increases were seen among supplement users exposed to fortification. The prevalence of exposed individuals with total folate intake below the estimated average requirement (320 micro g DFE/d) decreased from 48.6% (95% CI: 44.2-53.1%) before fortification to 7.0% (95% CI: 3.1-10.9%) after fortification in individuals who did not use folic acid supplements. This prevalence was approximately 1% or less for users of supplements both before and after fortification. Prevalence of individuals with folic acid intake above the upper tolerable intake level (1000 micro g folic acid/d) increased only among supplement users exposed to fortification (from 1.3 to 11.3%, P < 0.001). No changes in folic acid intake were observed over time in the nonexposed participants. By these estimations, folic acid fortification resulted in a mean increase in folic acid intake that was approximately twice as large as previously projected.

High circulating total homocysteine (tHcy) concentration, which is influenced by folate and vitamin B-12 status, is a suspected cause of cardiovascular events. This relation has been investigated in both case-control and prospective studies but has not been evaluated for different sex x age subgroups of the general U.S. population. We used data on adult (i.e., aged > or =40 y) male (n = 1097) and female (n = 1107) participants in the third National Health and Nutrition Examination Survey, excluding diabetics and those supplemented with estrogen, vitamins or minerals, to evaluate the association between serum tHcy concentration and self-report of heart attack or stroke. After adjustment for age, race-ethnicity, smoking, blood pressure, blood pressure medication, body mass index and serum concentrations of creatinine and cholesterol, past events were reported 2.4 (95% confidence interval 1.0-5.5) times as often by men with tHcy concentration of >12 micromol/L as by men with lower values. The odds ratio for women was 2.6 (95% confidence interval 1.1-6.6) after adjustment for the same factors plus menopausal status. A stronger relation in men aged < or =60 y compared with older men may help reconcile conflicting results of earlier studies.

We examined the relationship between intake of food group (and supplement) sources of folate and plasma folate and homocysteine concentrations among 885 elderly subjects in the Framingham Heart Study. Dietary data were collected by food-frequency questionnaire, and blood samples analyzed for folate and homocysteine concentrations. Top contributors to total folate intake were ranked. Mean folate intake, plasma folate and homocysteine concentrations were estimated for users vs. non-users of supplements, and key foods--those which both contribute to total folate intake and are known to be good sources of folate--and examined statistically with adjustment for age, gender and total energy intake. Plasma folate and homocysteine concentrations were also determined by quintile of intake frequency for breakfast cereals and for fruits and vegetables. Plasma folate was significantly greater and homocysteine lower in women than in men. Despite somewhat greater plasma folate concentrations with age, homocysteine was significantly higher in those over 80 y of age than in younger subjects. Major contributors to folate intake were cold breakfast cereals (13.3%), multivitamins (12.8%) and orange juice (12.4%). Users of supplements, breakfast cereals, or green leafy vegetables had significantly greater plasma folate and lower homocysteine levels than non-users. Plasma folate concentration was also greater in those who drank orange juice. We identified clear dose-response relationships for both plasma folate and homocysteine with increased quintile of breakfast cereal and of fruit and vegetable use. Frequent consumption of these foods is associated with higher folate and lower homocysteine concentrations.

Unlike mammalian tissues, certain intestinal microflora are capable of de novo synthesis of folate. To explore the availability of bacterially synthesized folate to the host organism, we used [3H] p-aminobenzoic acid (3H PABA) to label folate newly synthesized by the intestinal microflora. Labeled folates were isolated by affinity chromatography and identified by ion-pair HPLC. In this study [3H]PABA was injected into rat cecum to determine whether the [3H]folate synthesized by bacteria appeared in rat liver and other tissues. Rats were kept in sling suits to prevent coprophagy. Ion-pair chromatography of the purified liver folate demonstrated that bacterially derived [3H]folate was incorporated into all host liver-specific folate polyglutamates, mostly penta- and hexaglutamyl derivatives. Similar results were observed in kidney folates. These data provide direct evidence that some of the folate synthesized by the microflora in the rat large intestine is incorporated into the tissue folate of the host.

One of the important consequences of the infection–nutrition interaction is mediated by malabsorption associated with chronic inflammation in the intestine enteritis. Studies made possible after development of the peroral intestinal biopsy technique in the 1950s indicated the wide prevalence of enteropathy particularly in tropical developing countries with poor levels of sanitation. Some consider this so-called subclinical tropical malabsorption to be the base of an iceberg whose tip is tropical sprue a severe form of malabsorption leading to nutritional deficiency that had been reported in colonial expatriates in tropical countries for 200 y. Some of the first demonstrations of the prevalence of tropical enteritis in Asia were made in quest of the pathologic lesion of cholera and further examination of the water and electrolyte as well as nutrient malabsorption in cholera led serendipitously to the discovery of the oral rehydration solution for the treatment of diarrheal disease. (authors)

To describe serum methylmalonic acid (MMA) concentrations of elderly Americans and examine relationships between serum MMA and other factors, we used surplus serum samples collected from elderly (n = 1145) and young-adult (n = 1026) participants in Phase 2 of the third National Health and Nutrition Examination Survey (1991-1994). In approximately 20% of participants >/=65 y old, serum MMA was >370 nmol/L, the 90th percentile of the distribution of participants aged 30-39 y. Consistent with previous reports, we observed strong, independent positive associations between serum MMA concentration and serum concentrations of creatinine and homocysteine. After controlling for demographic factors and creatinine, geometric mean MMA concentration was lower in non-Hispanic blacks [223.6 nmol/L; 95% confidence interval (CI), 198.8-251.5] than non-Hispanic whites (265.1 nmol/L; 95% CI, 240.3-292.4). However, the prevalence of elevated levels did not vary with race/ethnicity. Serum MMA concentration bore a strong inverse relation to serum vitamin B-12 concentration. Nevertheless, elevated serum MMA concentrations affected approximately 15% of those with both normal serum creatinine concentrations and serum B-12 concentrations >148 pmol/L. We conclude that many elderly Americans demonstrate metabolic evidence of low B-12 status, that elevations occur frequently in the absence of traditional deficiency indicators and that levels vary with race/ethnicity and renal function.

In 1996 the Food and Drug Administration (FDA) issued a regulation to take effect in January 1998 that all enriched cereal grain products include 140 microg of folic acid/100 g. The present cross-sectional study was undertaken to assess the effect of this fortification on RBC folate concentrations in the Framingham Offspring Cohort. Among those who did not take B-vitamin supplements, we compared RBC folate in 561 individuals who were examined before implementation of the FDA mandatory folic acid fortification (not exposed) vs. 354 individuals who were examined after implementation of fortification (exposed). We calculated the prevalence of deficient (160 microg/L, 362.6 nmol/L) and acceptable (200 microg/L, 453.2 nmol/L) RBC folate concentrations in both groups. Those exposed to folic acid fortification had a mean RBC folate of 450.0 microg/L (1019.7 nmol/L), a value 38% higher than the mean RBC folate of 325.3 microg/L (737.1 nmol/L) in those who were not exposed to fortification (P0.001). The prevalence of individuals with deficient RBC folate was 4.9% in the group not exposed to fortification compared with 1.9% in the group exposed to fortification (P0.02), and the prevalence of individuals with acceptable RBC folate was 87.0% in the group not exposed to fortification compared with 96.1% in the group exposed to fortification (P0.001). Similar results were seen in individuals who used supplements containing B-vitamins. The results of this study showed that in this cohort, the introduction of folic acid fortification significantly improved folate nutritional status measured as RBC folate.

Methylenetetrahydrofolate reductase (MTHFR) catalyzes the synthesis of 5-methyltetrahydrofolic acid (5-CH(3)-H(4) folic acid), the methyl donor for the formation of methionine from homocysteine. A common C677T transition in the MTHFR gene results in a variant with a lower specific activity and a greater sensitivity to heat than the normal enzyme, as measured in vitro. This study was undertaken to determine the capacity of homozygotes for the MTHFR C677T transition to convert 5-formyltetrahydrofolic acid (5-HCO-H(4) folic acid) to 5-CH(3)-H(4) folic acid, a process that requires the action of MTHFR. Six subjects homozygous for the C677T transition (T/T) and 6 subjects with wild-type MTHFR (C/C) were given a 5-mg oral dose of (6R:,S:)-5-HCO-H(4) folic acid. Plasma and urine were analyzed for 5-CH(3)-H(4) folic acid concentrations using affinity/HPLC coupled with fluorescence or UV detection. The mean areas under the curves created by the rise and fall of plasma 5-CH(3)-H(4) folic acid after the oral dose did not differ between the two genotypes, 424.5 +/- 140.3 (T/T) vs. 424.1+/- 202.4 h.nmol/L (C/C). There also was no significant difference in the mean cumulative 7-h urinary excretion of 5-CH(3)-H(4) folic acid between the T/T (2.5 +/- 1.4 micromol) and C/C (1.9 +/- 1.0 micromol) genotypes. Under the conditions employed, the conversion of oral 5-HCO-H(4) folic acid to 5-CH(3)-H(4) folic acid is not impaired in persons with the T/T MTHFR genotype. Possible reasons for these findings are discussed.

Recent studies demonstrated associations between occlusive vascular disease and hyperhomocysteinemia of both genetic and nutritional origin. In the present study we analyzed plasma samples from the 20th biannual examination of the Framingham Heart Study cohort to determine distribution of plasma homocysteine concentrations with emphasis on relationships to B vitamins and prevalence of carotid artery stenosis. Results showed that homocysteine exhibited strong inverse association with plasma folate and weaker associations with plasma vitamin B-12 and pyridoxal-5'-phosphate (PLP). Homocysteine was also inversely associated with intakes of folate and vitamin B-6, but not vitamin B-12. Prevalence of high homocysteine (14 micromol/l) was 29.3% in this cohort, and inadequate plasma concentrations of one or more B vitamins appear to contribute to 67% of the cases of high homocysteine. Prevalence of stenosisor = 25% was 43% in men and 34% in women with an odds ratio of 2.0 for individuals in the highest homocysteine quartile (or = 14.4 micromol/l) compared with those in the lowest quartile (or = 9.1 micromol/l), after adjustment for sex, age, high density lipoprotein cholesterol, systolic blood pressure and cigarette smoking (Ptrend0.001). Plasma concentrations of folate and pyridoxal-5'-phosphate and folate intake were inversely associated with extracranial carotid stenosis after adjustment for age, sex and other risk factors.

In the half century since Dr. Hazel Stiebling of the USDA and her colleagues fashioned the first Recommended Dietary Allowances (RDA), the scientific insight underlying those allowances, including the work of Atwater, has resulted in an unprecedented stability of recommendations in the subsequent ten issues of the RDA. The same half-century has witnessed important newer developments in human nutrition relating diet and disease: the paradigmatic relationship being diet and heart disease. The quest for better recommendations to the public about diet and disease prevention has taken the form of national Dietary Guidelines and goals for the year 2000. Thus, nutrient recommendations in the RDAs have intersected with food and diet recommendations and the specific goals. Recommended Dietary Allowances have been called into focus once again. Definitions of optimal diets or health have been varied and imprecise. However desirable the goal may be to achieve vigorous health throughout the life cycle by appropriate diet and other lifestyle factors, we will not be able to avoid the critically based scientific method that formed the foundation for the sound nutritional recommendation of RDAs.

We examined the absorption of biotin using the in vivo intestinal loop technique. Jejunal segments from male rats were filled with solutions containing (/sup 3/H)biotin and (/sup 14/C)inulin in Krebs-Ringer phosphate buffer, pH 6.5. Absorption was determined on the basis of luminal tritium disappearance after correction for inulin recovery. At biotin concentrations of 0.1 and 5.0 microM, luminal biotin disappearance was linear for at least 10 min. At biotin concentrations ranging from 2.3 nM to 75 microM, 10-28% of the administered dose was absorbed in 10 min. The concentration dependence of luminal biotin disappearance is consistent with the presence of both saturable and nonsaturable (linear) components of biotin uptake, with estimated Km = 9.6 microM and Jmax = 75.2 pmol/(2.5 cm loop X min). The rate constant for nonsaturable uptake is 3.1 pmol/(2.5 cm loop X min X microM). We conclude that at biotin concentrations less than 5 microM, biotin absorption proceeds largely by the saturable process, whereas at concentrations above 25 microM, nonsaturable uptake predominates. Additional studies demonstrated significantly less biotin uptake in the ileum than in the jejunum, a finding in agreement with previous in vitro studies.

We used the in vivo intestinal loop approach, with short (10-min) and long (3-h) incubations, to examine biotin absorption in proximal jejunum, distal ileum, cecum and proximal colon. In short-term studies, luminal biotin disappearance from rat ileum was about half that observed in the jejunum, whereas absorption by proximal colon was about 12% of that in the jejunum. In 3-h closed-loop studies, the absorption of 1.0 microM biotin varied regionally. Biotin absorption was nearly complete in the small intestine after 3 h; however, only about 15% of the dose had been absorbed in the cecum and 27% in the proximal colon after 3 h. Independent of site of administration, the major fraction of absorbed biotin was recovered in the liver; measurable amounts of radioactive biotin were also present in kidney and plasma. The results support the potential nutritional significance for the rat of biotin synthesized by bacteria in the distal intestine, by demonstrating directly an absorptive capability of mammalian large bowel for this vitamin.

Flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), are two major coenzyme forms of dietary riboflavin. Yet little attention has been given to the release of the vitamin from its coenzyme forms during the absorptive process. Homogenates from rat intestine catalyze the hydrolases of these flavin coenzymes. To determine the location of FMN and FAD hydrolases, homogenates of intestinal mucosa were fractioned. FMN and FAD phosphatases were localized in brush border membranes. FAD pyrophosphatase activity was maximal at pH between 6.5 and 8.5 while FMN phosphatase has a pH optimum of 7.5 - 8.0. FAD pyrophosphatase is more stable to heat. The two enzymes separate on ion exchange chromatography of an isobutanol extract of intestinal brush border membrane fraction. Inhibition of 14C-riboflavin uptake by FMN and FAd in everted rings of rat intestine is directly related to the amount of conversion of these coenzymes to free riboflavin by intestinal enzymes. When FMN and FAD conversion to riboflavin is inhibited by EDTA, competition with 14C-riboflavin for transport was correspondingly decreased. These studies are best explained by a sequential process in which hydrolysis of FMN and FAD by enzymes of the intestinal brush border is followed by absorption of free riboflavin.