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Title: Effect of folic acid on zinc absorption

Abstract

The effect of folic acid on zinc uptake was studied in the human and in the rat. The serum zinc response to a 25 mg oral dose or zinc was measured with and without a 10 mg dose of folic acid. Serum zinc levels were measured prior to the oral dose of zinc and at hourly intervals up to 4 hours after the dose. When zinc was given along, the increases in serum zinc from baseline at hours 1, 2, 3 and 4 were 92, 118, 92 and 66 ..mu..g/dl, respectively. When both zinc and folic acid were given, the increases in serum zinc at hours 1, 2, 3 and 4 were 100, 140, 110 and 75 ..mu..g/dl, respectively. When the increases in serum zinc were plotted against time, there was no significant difference between the areas under the two curves. The everted jejunal sac from the rat was used to study the effect of folate on zinc transport using 100 ..mu..M zinc in the mucosal buffer. The addition of folic acid at levels up to 10/sup -3/M had no significant effect on zinc transport to the serosal side solution or on uptake by the intestinal mucosa. This in vivomore » study with humans and in vitro study with rat intestine does not support a direct adverse effect of folic acid on zinc absorption.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Univ. of California, Berkeley
OSTI Identifier:
6754294
Report Number(s):
CONF-8604222-
Journal ID: CODEN: FEPRA
Resource Type:
Journal Article
Resource Relation:
Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States); Journal Volume: 45:4; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; FOLIC ACID; BIOLOGICAL EFFECTS; ZINC; INTESTINAL ABSORPTION; METABOLISM; IN VITRO; IN VIVO; MAN; RATS; ABSORPTION; AMINO ACIDS; ANIMALS; AROMATICS; AZAARENES; CARBOXYLIC ACIDS; DRUGS; ELEMENTS; HEMATINICS; HEMATOLOGIC AGENTS; HETEROCYCLIC COMPOUNDS; HYDROXY COMPOUNDS; MAMMALS; METALS; ORGANIC ACIDS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; PRIMATES; PTERIDINES; RODENTS; UPTAKE; VERTEBRATES; VITAMIN B GROUP; VITAMINS 560300* -- Chemicals Metabolism & Toxicology

Citation Formats

Wada, L., Keating, S., King, J.C., and Stokstad, E.L.R. Effect of folic acid on zinc absorption. United States: N. p., 1986. Web.
Wada, L., Keating, S., King, J.C., & Stokstad, E.L.R. Effect of folic acid on zinc absorption. United States.
Wada, L., Keating, S., King, J.C., and Stokstad, E.L.R. 1986. "Effect of folic acid on zinc absorption". United States. doi:.
@article{osti_6754294,
title = {Effect of folic acid on zinc absorption},
author = {Wada, L. and Keating, S. and King, J.C. and Stokstad, E.L.R.},
abstractNote = {The effect of folic acid on zinc uptake was studied in the human and in the rat. The serum zinc response to a 25 mg oral dose or zinc was measured with and without a 10 mg dose of folic acid. Serum zinc levels were measured prior to the oral dose of zinc and at hourly intervals up to 4 hours after the dose. When zinc was given along, the increases in serum zinc from baseline at hours 1, 2, 3 and 4 were 92, 118, 92 and 66 ..mu..g/dl, respectively. When both zinc and folic acid were given, the increases in serum zinc at hours 1, 2, 3 and 4 were 100, 140, 110 and 75 ..mu..g/dl, respectively. When the increases in serum zinc were plotted against time, there was no significant difference between the areas under the two curves. The everted jejunal sac from the rat was used to study the effect of folate on zinc transport using 100 ..mu..M zinc in the mucosal buffer. The addition of folic acid at levels up to 10/sup -3/M had no significant effect on zinc transport to the serosal side solution or on uptake by the intestinal mucosa. This in vivo study with humans and in vitro study with rat intestine does not support a direct adverse effect of folic acid on zinc absorption.},
doi = {},
journal = {Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)},
number = ,
volume = 45:4,
place = {United States},
year = 1986,
month = 3
}
  • Recent observations suggest an inverse relationship between folic acid intake and zinc nutriture and indicate an interaction between folic acid and zinc at the intestinal level. To define that interaction, we designed in vivo and in vitro transport studies in which folic acid transport in the presence of zinc, as well as zinc transport in the presence of folic acid was examined. These studies show that zinc transport is significantly decreased when folate is present in the intestinal lumen. Similarly folic acid transport is significantly decreased with the presence of zinc. To determine whether this intestinal inhibition is secondary tomore » zinc and folate-forming complexes, charcoal-binding studies were performed. These studies indicate that zinc and folate from complexes at pH 2.0, but that at pH 6.0, these complexes dissolve. Therefore, our studies suggest that under normal physiological conditions a mutual inhibition between folate and zinc exists at the site of intestinal transport.« less
  • The fractional folic acid absorption (FAFol) was determined in 66 patients with various gastrointestinal diseases by a double-isotope technique, employing a single stool sample test (SSST) as well as a complete stool collection. The age of the patients ranged from 2.5 months to 16.8 years (mean 6.3 years). The test dose was administered orally and consisted of 50 micrograms of (3H)folic acid (monoglutamate) (approximately 20 muCi), carmine powder, and 2 mg 51CrCl3 (approximately 1.25 muCi) as the unabsorbable tracer. The whole-body radiation given to a 1-year-old child averaged 4.8 mrad only. The stool and napkin contents were collected and homogenizedmore » by the addition of 300 ml chromium sulfuric acid. A 300-ml sample of the homogenized stool and napkin contents, as well as 300 ml chromium sulfuric acid (75% vol/vol) containing the standards, were counted for the content of 51Cr in a broad-based well counter. The quantity of (3H)folic acid was determined by liquid scintillation, after duplicate distillation. Estimated by SSST, the FAFol, which employs the stool with the highest content of 51Cr corresponding to the most carmine-colored stool, correlated closely with the FAFol based on complete stool collection (r = 0.96, n = 39, p less than 0.0001). The reproducibility of FAFol determined by SSST was assessed from repeated tests in 18 patients. For a mean of 81%, the SD was 4.6%, which corresponded to a coefficient of variation of 5.7%.« less
  • Nonhuman primates fed folic acid-deficient diets +/- 30% kcal ethanol were used to determine alcohol effects on megaloblastic anemia development and folate bioavailability. Lower hemoglobin (Hb) and red blood cell (RBC) counts and higher mean corpuscular volume (MCV) occurred after 13 wk in alcohol-fed monkeys, later in controls. Plasma, RBC, and liver folate declined and urinary formiminoglutamic acid (FIGLU) was elevated in both groups with FIGLU increasing more among alcohol-fed monkeys at 38 wk. After 40 wk, the bioavailability of oral /sup 3/H-folic acid was investigated and showed increased fecal and reduced urinary tritium excretion in alcohol-fed monkeys compared withmore » controls while plasma uptake and liver and whole body tritium retention were similar in both groups. These observations demonstrate that chronic alcohol consumption impairs folate coenzymes, accelerates appearance of hematologic indices of megaloblastic anemia, and causes possible malabsorption of enterohepatically circulated folates in folate deficiency even when other essential nutrients are provided.« less
  • The folate in milk is largely bound to high-affinity folate-binding protein (FBP). With an in vivo intestinal loop technique, we examined the absorption of folic acid bound to FBP (FA-FBP) in the small intestine of the suckling rat. In contrast to unbound folic acid (FA), FA-FBP is absorbed more avidly in the ileum than in the jejunum (p less than 0.025) and its absorption is not inhibited by 1 mmol sulfasalazine/L. Folate-binding activities in the mucosa of the proximal (duodenum and jejunum combined) and distal (ileum) small intestine were also examined and found to be 0.32 and 1.31 pmol/mg protein,more » respectively (p less than 0.001). A 6-h fast produced a 42% decrease in folate-binding activity in the distal small intestine (p less than 0.01) but did not change activity in the proximal portion. Collectively, these observations suggest that FA-FBP is absorbed by a mechanism that is distinct from that responsible for the absorption of FA and that absorption does not require prior dissociation of the vitamin-binding protein complex.« less