A study of folate absorption and metabolism in man utilizing carbon-14—labeled polyglutamates synthesized by the solid phase method

Butterworth, Charles E.; Baugh, Charles M.; Krumdieck, Carlos L.

doi:10.1172/jci106070

Cited by 128 publications

(58 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Although more than 85% of the dietary folates are present as conjugated pteroylpolyglutamates (3), scant attention has been paid to the assessment of the absorption of these folates in tropical sprue. The intestinal mucosa is a potent source of the -v-carboxypeptidase known as folate conjugase which is required for the cleavage of the y-peptide linkages present in conjugated folates (4,5).…”

Section: Introductionmentioning

confidence: 99%

“…In vivo studies in the dog and the human have shown that cleavage of pteroylpolyglutamates to pteroylmonoglutamate (simple folate) occurs during or soon after intestinal absorption (4)(5)(6). Thus, the malabsorption of conjugated folates may result from decreased mucosal hydrolysis, decreased intestinal transport of pteroylmonoglutamate, or a combination of these factors.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Jejunal Perfusion of Simple and Conjugated Folates in Tropical Sprue

Corcino¹,

Reisenauer²,

Halsted³

1976

J. Clin. Invest.

View full text Add to dashboard Cite

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Jejunal Perfusion of Simple and Conjugated Folates in Tropical Sprue

Corcino¹,

Reisenauer²,

Halsted³

1976

J. Clin. Invest.

View full text Add to dashboard Cite

“…The major portion of food folate is a polyglutamate [7,9,43,45]. The polyglutamates have to be broken down to monoglutamates by deconjugating enzymes of the intestinal mucosa before they are absorbed [3,6,8,29,43,44]. We have no data with regard to the efficiency of the absorption of food folate in newborns and have not been able to find any in the literature.…”

Section: Discussionmentioning

confidence: 93%

“…WHITEHEAD and COOPER [58] have shown that PGA is absorbed through the small intestine intact and methylation of folate occurs in the liver. BUTTERWORTH et al [8] have shown that no significant methylation of PGA occurs during the first 1-2 h after ingestion of PGA.…”

Section: Discussionmentioning

confidence: 99%

Folate Metabolism in Newborns and during Early Infancy: I. Absorption of Pteroylglutamic (Folic) Acid in Newborns

Shojania

Hornady

1970

Pediatr Res

View full text Add to dashboard Cite

ExtractFolic acid (PGA) absorption (40 ,«g/kg of body weight) was studied in normal newborns and adults using Lactobacillus casei and Streptococcus faecalis microbiological assays for folate determination. The PGA was given orally or intramuscularly to the subjects after either saturating their tissues with folate or without prior saturation of their tissues. Without prior saturation of the tissues the folic acid absorption curves in newborns were much lower than those found in adults (figs. 1 and 2). Saturation of the tissues of the newborns with folic acid, prior to administration of the oral test dose, raised the absorption curves of the folic acid, but these were still lower than those seen in adults (fig: 5). The folate curve of the newborns after an intramuscular test dose of PGA was also lower than that observed in adults (fig. 3); however, after saturating the tissues of the newborns with folic acid, the folate curve became comparable to that of the unsaturated adults ( fig. 4).After the oral test dose, newborns excreted a much smaller percentage of the administered dose in their urine than did the adults (table II). When the tissues in newborns were saturated with folic acid, however, the excretion of folate in the urine became comparable to that of unsaturated adults (table II) These data indicate that: 1) plasma clearance of folate in newborns is more rapid than that in adults and that large saturating doses of folic acid are needed to reduce this clearance rate; and 2) the folate absorption curve in the newborn is lower than in the adult. With the criteria set for adults, this could be interpreted as evidence of impaired folate absorption in newborns. The proper interpretation of the data indicates, however, that folate absorption by newborns is slower than seen in adults and that the net absorption is comparable to that of adults. SpeculationIn newborns, the absorption curve for orally administered folate is lower than in adults. Our study indicates that this is due to the slower absorption of folates and more rapid tissue uptake of folates by newborns. Further studies should be carried out to investigate the absorption of folate conjugates which are the main forms of folate found in food, to determine how much of the folate in food is available to newborns and small infants, and to evaluate the need for supplementary folate in small infants. SHOJANIA and HORNADY 413

show abstract

“…Folic acid or PGA is practically no present as such in nature where it exists only as traces in human tissues and foods, it represents the purified, stable form used in pharmaceutical preparations most of which is as Polyglutamates (PG) 15,[18][19][20][21] . Folic acid is a yellow, watersoluble crystalline powder that is sensitive to air, light and heat; this explains the losses observed during cooking 22 .…”

Section: Figurementioning

confidence: 99%

Folates: Key Nutrients to Remember

Freha

Mihoub

Henchiri

2017

AJPRHC

View full text Add to dashboard Cite

Folic acid or vitamin B9 or pteroylglutamic acid, is a relatively simple molecule with two characteristics; firstly, it must be reduced by 2 or 4 hydrogen atoms to be metabolically active which makes it sensitive to oxidation and must be protected by ascorbic acid, secondly it may include in addition to the constituent residues of the molecule, 1-7 glutamate residue at one of its ends. These polyglutamate forms that make up the largest share of food folate, must be deconjugated by a specific enzyme present in the intestinal lumen before being absorbed in the jejunum. It is in the methylated form after passing through the enterocyte it is transported in the blood, excreted in bile and reabsorbed. It must be demethylated to integrate folic cell cycle and methyl transfer, that allows the synthesis of methionine (only possible in the presence of vitamin B12), purine, serine and especially thymidylic acid, constitutive DNA. As a methyl donor that plays a fundamental role in cerebral and nervous metabolism. Folates are involved in cell division thus; any folic acid deficiency causes a slowdown in rapid multiplication systems which may lead to red blood cell disorders (macrocytic anemia), immunity, and neural tube defects, in addition to physiological disorders (cardiovascular, cancer ...). Folic acid supplementation appears to allow the correction of these disorders.

show abstract

A study of folate absorption and metabolism in man utilizing carbon-14—labeled polyglutamates synthesized by the solid phase method

Cited by 128 publications

References 27 publications

Jejunal Perfusion of Simple and Conjugated Folates in Tropical Sprue

Jejunal Perfusion of Simple and Conjugated Folates in Tropical Sprue

Folate Metabolism in Newborns and during Early Infancy: I. Absorption of Pteroylglutamic (Folic) Acid in Newborns

Folates: Key Nutrients to Remember

Contact Info

Product

Resources

About