Effect of phytic acid,tannic acid and pectin on fasting iron bioavailability both in the presence and absence of calcium

ObjectiveTo determine the effect of phytic acid, tannic acid and pectin on fasting non-heme iron bioavailability in both the presence and absence of calcium.Research methodsTwenty-eight apparently healthy adult females participated in two iron absorption studies using radioactive iron isotopes (⁵⁹Fe and ⁵⁵Fe). One group received 5 mg of iron (as FeSO₄) alone (control), together with 10 mg of phytic acid, 100 mg of tannic acid and 250 mg of pectin (study A), on different days. The second group received the same iron doses and compounds as the other group, plus 800 mg of calcium (CaCl₂) (study B). The compounds were administered after an overnight fast, and no food or beverages were consumed for the following 3 h. Iron status and circulating radioactivity were measured in venous blood samples.ResultsThe geometric means of iron bioavailability (range ± 1SD) for iron alone, iron with phytic acid, iron with tannic acid, and iron with citrus pectin were 25.0% (11.9–52.0); 18.9% (9.9–35.8); 16.8% (8.7–32.3); and 21.1% (10.2–43.9), respectively (repeated-measures ANOVA, p < 0.02 (Dunnett's post hoc: control vs tannic acid p < 0.05). When 800 mg of calcium was added (study B), iron bioavailability was 16.7% (10.1–27.5); 13.2% (7.1–24.6); 14.8% (8.8–25.1); and 12.6% (5.5–28.8), respectively (repeated-measures ANOVA, NS).ConclusionsTannic acid decreases the fasting bioavailability of non-heme iron, however this effect did not exist in the presence of calcium. No effect was observed by phytic acid or citrus pectin on fasting non-heme iron bioavailability in both the presence and absence of calcium.     

Influence of inositolhexaphosphori acid (phytic acid) on the copper distribution in tissues and the excretion of copper in rats

The aim of the present study was to investigate the effect of the administration of phytic acid on copper (Cu) concentrations in several different rat tissues. The animals used were divided into three groups: Group A (received a diet supplemented with 2% phytic acid), group B (received a diet supplemented with 10% phytic acid) and group C (control). At the end of the experiment, the animals were sacrificed and the concentration of copper was determined in the different tissues.

Phytic acid significantly increased Cu concentration in the duodenum of the animals of both groups as well as in the lungs and blood of the animals of group A. The copper concentration was also increased in the uterus and bone of the animals of group B.

On the other hand, the stomach copper concentration of the animals of both groups, the heart and lung copper concentrations of the animals of group B as well as the jejunum, colon and hair copper concentrations of the animals of group A were significantly decreased. Copper excretion through feces was significantly decreased in the animals of both groups, while the excretion through urine was not significantly affected by the administration of phytic acid.

In conclusion, the administration of phytic acid can produce translocation and/ or elimination of copper in various tissues of rats.     

Effects of copper,zinc, and cadmium ions on the production of phosphate from phytic acid by the phytase system in spruce forest soil

Summary The hydrolysis of phosphate from phytic acid by the acid soil phytase system was reduced in the presence of metal ions. Copper was most effective in this respect — zinc and cadmium were less inhibitory. Binding to metals did not completely inhibit the hydrolysis of phytic acid. At higher metal concentrations, where binding to other soil constituents, like humic acids, interfered less, the inhibition of the phytase activity was stronger than that of acid phosphatase.     

Effect of phytic acid on postprandial serum uric acid level in healthy volunteers: a randomized,double-blind,crossover study

Abstract

Phytic acid, a constituent of various plants, has been related to health benefits. Phytic acid has been shown to inhibit purine nucleotide metabolism in vitro and suppress elevation of plasma uric acid levels after purine administration in animal models. This study investigated the effect of phytic acid on postprandial serum uric acid (SUA) in humans. This randomized, double-blind, crossover design study included 48 healthy subjects with normal fasting SUA. Subjects consumed a control drink and a phytic acid drink with purine-rich food, and serum and urine uric acid levels were measured for 360?min after purine loading. Phytic acid lowered the incremental area under the curve (0–360?min) and incremental maximum concentration of SUA after purine loading (p?<?0.05); tended to lower cumulative urinary uric acid excretion (0–360?min) after purine loading (p?<?0.10); and suppressed postprandial SUA in this clinical study. Altogether, our findings suggest that phytic acid may play a beneficial role in controlling postprandial SUA.     

Cadmium accumulation, zinc status, and mineral bioavailability of growing rats fed diets high in zinc with increasing amounts of phytic acid

Five groups of individually housed albino rats (n=7, initial average weight=48 g) were fed diets based on egg albumen and cornstarch (basal diet 8.2 g Ca, 6.0 g P, 0.7 g Mg, 225 mg Zn, 150 mg Fe, 60 mg Mn, 8 mg Cu, and 5 mg Cd) over a 4-wk period. Group I (control) was fed the basal diet free of phytic acid (PA). In groups II, III, IV, and V, cornstarch was replaced by 3.5, 7.0, 10.5, and 14.0 g sodium phytate/kg diet, respectively. Daily gain, feed efficiency, Zn status (Zn in plasma, femur, testes, liver and kidneys, activity of the plasma alkaline phosphatase) and apparent absorption of Zn, Fe, Cu, and Mn remained unchanged by the different dietary treatments. PA decreased apparent Mg absorption significantly and apparent absorption of Ca in tendency. Increasing the amount of phytate caused a corresponding enhancement of amount of the digestible P. Cd accumulation in the liver was not significantly altered, and kidney Cd accumulation slightly increased owing to PA. In conclusion, it was shown that under conditions of high dietary Zn, PA had only little effect on the carryover of Cd in growing rats.     

Inhibition of xanthine oxidase by phytic acid and its antioxidative action

We examined if phytic acid inhibits the enzymatic superoxide source xanthine oxidase (XO). Half inhibition of XO by phytic acid (IC50) was about 30 mM in the formation of uric acid from xanthine, but generation of the superoxide was greatly affected by phytic acid; the IC50 was about 6 mM, indicating that the superoxide generating domain of XO is more sensitive to phytic acid. The XO activity in intestinal homogenate was also inhibited by phytic acid. However, it was not observed with intestinal homogenate that superoxide generation was more sensitive to phytic acid compared with the formation of uric acid as observed with XO from butter milk. XO-induced superoxide-dependent lipid peroxidation was inhibited by phytic acid, but not by myo-inositol. Reduction of ADP-Fe3+ caused by XO was inhibited by superoxide dismutase, but not phytic acid. The results suggest that phytic acid interferes with the formation of ADP-iron-oxygen complexes that initiate lipid peroxidation. Both phytic acid and myo-inositol inhibited XO-induced superoxide-dependent DNA damage. Mannitol inhibited the DNA strand break. Myo-inositol may act as a hydroxyl radical scavenger. The antioxidative action of phytic acid may be due to not only inhibiting XO, but also preventing formation of ADP-iron-oxygen complexes.     

l-Lysine supplementation does not affect the bioavailability of copper or iron in rats

l-lysine (Lys) is an essential amino acid that is added to foods and dietary supplements. Lys may interact with mineral nutrients and affect their metabolism. This study examined the effect of dietary Lys supplementation on the bioavailability of copper (Cu) and iron (Fe). Weanling male Sprague-Dawley rats were fed one of five diets (20% casein) for 4 weeks containing normal Cu and Fe (control) or low Cu or Fe without (LCu, LFe) or with (LCu + Lys, LFe + Lys) addition of 1.5% Lys. Final body weights, body weight gains and food consumption of the rats did not differ (P ≥ 0.05) among diet groups. Rats fed the low Cu or Fe diets showed changes in nutritional biomarkers compared to control rats, demonstrating reduced Cu and Fe status, respectively. Hematological parameters, serum ceruloplasmin activity and Cu and Fe concentrations in serum, liver, kidney and intestinal mucosa were unaffected (P ≥ 0.05) by Lys supplementation. These results indicate that in the context of an adequate protein diet, Lys supplementation at a relatively high level does not affect Cu or Fe bioavailability in rats.     

Usefulness of the dietary phytic acid/ zinc molar ratio as an index of zinc bioavailability to rats and humans

Evidence suggests that rats can tolerate a dietary phytate/Zn molar ratio greater than 15 if the dietary Zn concentration is high. High dietary Ca exacerbates the effect of phytic acid on Zn utilization by rats. In a short term (15 d) balance trial with adult men, we observed slightly greater Zn balance when whole compared to dephytinized wheat bran was consumed (molar ratios 12 and 1.2, respectively). There was, however, greater fecal excretion of Zn during the first 5 d whole bran was consumed. In a second study, Na phytate was the major source of phytic acid and Zn balance was less when the phytate/Zn molar ratio was greater than 16 compared to 4. The difference was not significant, however, and there was evidence of physiological adjustments to maintain homeostasis when the high ratio diet was consumed. Mean Zn intake averaged 17 mg (0.26 mmole) and 11 mg (0.17 mmole) daily for the bran and Na phytate studies, respectively. The level of Zn intake may influence the response of humans to varying phytate/Zn ratios. Comparison of isotope retention studies and the balance data is discussed. Some information on the relationship of dietary Ca to the phytate/Zn effect in human diets is gathered from current literature. The phytate/Zn molar ratio is a useful index of Zn bioavailability.     

Anti-cancer activity of the cell membrane-permeable phytic acid prodrug

Phytic acid (IP6) is an ingredient in cereals and legumes, and limited amounts of this compound are considered to enter the cell and exert anti-cancer effects. These effects have been seen by studying cells treated with around 1–5 mM IP6. However, such a large amount of IP6 chelates metals and changes the pH in cell culture medium. To overcome this problem, we synthesized a prodrug of IP6 (Pro-IP6) and elucidated generation of IP6 from Pro-IP6 in cells. Cellular experiments using Pro-IP6 demonstrated selective anti-cancer effects including apoptosis and inhibition of Akt activation. Furthermore, an in vivo study using mice with adult T-cell leukemia also showed that Pro-IP6 reduced the size of the cancer. Taken together, Pro-IP6 is a useful biological tool and may lead to development of new anti-cancer drugs.     

Linkage mapping of two mutations that reduce phytic acid content of barley grain

 This study describes the inheritance and linkage map positions of two low phytic acid barley (Hordeum vulgare) mutations, lpa1-1 and lpa2-1, that dramatically reduce grain phytic acid content and increase inorganic seed phosphorus (P). Wide-cross, F₂ mapping populations were constructed by mating six-rowed varieties, ‘Steptoe’ and/or ‘Morex’, with two-rowed ‘Harrington’lpa donor lines homozygous for either lpa1-1 or lpa2-1. The barley lpa1-1 mutation showed normal inheritance patterns, whereas a deficiency of homozygous lpa2-1/lpa2-1 F₂ plants was observed. We identified a codominant, STS-PCR marker (aMSU21) that cosegregated with lpa1-1 in a population of 41 F₂ plants. The aMSU21 marker was then mapped to a locus on barley chromosome 2H, using a North American Barley Genome Mapping Project (NABGMP) doubled haploid population (‘Harrington’בMorex’). We determined that lpa2-1 is located within a recombination interval of approximately 30 cM between two AFLP markers that were subsequently mapped to barley chromosome 7H by integration with the same NABGMP population. Recent comparative mapping studies indicate conserved genetic map orders of several homologous molecular marker loci in maize and the Triticeae species that also show corresponding linkage to the biochemically similar lpa2 mutations of maize and barley. This observation suggests that barley and maize lpa2 mutations may affect orthologous genes. No such evidence for correspondence of the phenotypically similar lpa1 mutations of barley and maize has been revealed. Received: 22 September 1997 / Accepted: 2 December 1997     

Effects of zinc deficiency on the fatty acid composition and metabolism in rats fed a fat-free diet

The effects of dietary zinc deficiency (ZD) on the composition and metabolism of the fatty acyl chains of phospholipids in rat liver were investigated with a fat-free diet. The levels of (n−9) fatty acids such as 18∶1 and 20∶3(n−9) in liver phospholipids (PL) were significantly lower in ZD-rats (19.4% and 5.4%, respectively) than in PF-rats (25.2 and 8.3%). On the other hand, the level of (n−6) acids such as 18∶2 and 20∶4 were higher in ZD-rats (3.3 and 19.1%, respectively) than in PF-rats (2.1 and 14.9%). In order to study the metabolism of fatty acids in vivo,¹⁴C-18∶0 or¹⁴C-18∶2 was intravenously injected, and then the conversion to the respective metabolite was examined. After the injection of¹⁴C-18∶0, the radioactivity was found in 18∶0 (49.3% of the total), 18∶1 (33.2%), and 20∶3 (n−9) (9.1%) in liver PL in PF-rats at 24h. In ZD-rats, the radioactivity was dramatically lower in 18∶1 (23.5%) and 20∶ (n−9) (3.6%), suggesting that the conversion of 18∶0 to 18∶1 and 20∶3 (n−9) was strongly inhibited in ZD-rats. When¹⁴C-18∶2 was injected, the radioactivity was mainly found in 18∶2, 20∶3(n−6), and 20∶4. The radioactivity in 20∶4 in ZD-rats was slightly higher than that in control rats. These results indicate that zinc deficiency affects the fatty acid metabolism in liver, in particular, it causes a reduction in δ9 desaturase activity, when rats are fed a fat-free diet.     

EDTA disodium zinc has superior bioavailability compared to common inorganic or chelated zinc compounds in rats fed a high phytic acid diet

Different zinc (Zn) compounds have unique properties that may influence the amount of Zn absorbed particularly in the presence of phytic acid (PA), a common food component that binds Zn and decreases its bioavailability. In this study, 30-day-old male rats (n = 12/diet group) were fed diets supplemented with PA (0.8%) and low levels (8 mg Zn/kg diet) of inorganic (Zn oxide, Zn sulphate) or chelated (Zn gluconate, Zn acetate, Zn citrate, EDTA disodium Zn, Zn orotate) Zn compounds for 5 weeks. Two control groups were fed diets supplemented with low or normal (30 mg Zn/kg diet) Zn (as Zn oxide) without added PA. Control rats fed the low Zn oxide diet showed depressed Zn status. Addition of PA to this diet exacerbated the Zn deficiency in rats. Growth (body weight gain and femur length) and Zn concentrations in plasma and tissues were similar in rats fed Zn oxide, Zn sulphate, Zn gluconate, Zn acetate, Zn citrate or Zn orotate. Rats fed EDTA disodium Zn showed enhanced growth compared to rats fed Zn oxide or Zn gluconate and had higher Zn concentrations in plasma and femur compared to rats fed all other Zn compounds. Only the haematological profile of rats fed EDTA disodium Zn did not differ from control rats fed normal Zn. These data indicate that in rats fed a high PA diet, bioavailability of commonly used inorganic or chelated Zn compounds does not differ appreciably, but Zn supplied as an EDTA disodium salt has superior bioavailability.     

Bone and faecal minerals and scanning electron microscopic assessments of femur in rats fed phytic acid extract from sweet potato (<Emphasis Type="Italic">Ipomoea batatas</Emphasis>)

Phytic acid was extracted from sweet potato (Ipomoea batatas) and fed to Wistar rats with or without zinc for 3 weeks. Animals were then sacrificed and bone and faecal minerals were assessed. The ultra-structure of the bones was examined via scanning electron microscopy. Phytic acid extract or commercial phytic acid supplemented diets (D + Zn + PE or D + PE) displayed reduced bone calcium levels (101.27 ± 59.11 and 119.27 ± 45.36 g/kg) compared to the other test groups. Similarly, reduced calcium were observed in the control groups (D + Zn and D) fed formulated diets with or without zinc supplementation (213.14 ± 15.31 and 210 ± 6.88 g/kg) compared to the other test groups. The group fed supplemented commercial phytic acid diet (D + CP) demonstrated the lowest femur magnesium (3.72 ± 0.13 g/kg) while the group fed phytic acid extract supplementation (D + PE) recorded the highest level (4.84 ± 0.26 g/kg) amongst the groups. Femur iron was highest in the group fed commercial phytic acid supplemented diet (D + CP −115.74 ± 2.41 g/kg) compared to the other groups. Faecal magnesium levels were significantly higher in the two test groups fed phytic acid extract with or without zinc (D + Zn + PE or D + PE) compared to all other groups. All the groups which had phytic acid supplemented diets had significantly thinner bone in the trabecular region, compared to the groups fed formulated diet or zinc supplemented formulated diet (D or D + Zn). These observations suggest that the consumption of foods high in phytic acid may contribute to a reduction in the minerals available for essential metabolic processes in rats.     

Role of zinc in blockade of excitotoxic action of quinolinic acid by picolinic acid

Summary This study examined whether picolinic acid (PIC) inhibits quinolinic acid (QUIN) — induced excitotoxicity through zinc chelation. Injection of QUIN into the nucleus basalis magnocellularis significantly depleted cortical choline acetyltransferase activity 7 days post injection and PIC inhibited this response. Zinc augmented the QUIN- but not NMDA-induced response. When PIC was co-administered with zinc, PIC failed to attenuate the QUIN-induced response. The inhibition of QUIN — induced cholinergic toxicity by PIC may involve chelation of zinc.     

Determination of relative bioavailability of zinc in a petit suisse cheese using weight gain and bone zinc content in rats as markers

The aim of the study was to determine the relative bioavailability of zinc gluconate stabilized with glycine in a Petit Suisse cheese from an infant dessert. Weight gain and bone zinc content were the nutritional responses evaluated for the diets of different zinc content: 2 ppm (basal) and 5, 10, and 30 ppm from zinc gluconate stabilized with glycine and zinc sulfate. Nonlinear regression analysis of the fitted curves for weight gain determined a relative zinc bioavailability of 100% for the Y _max ratio and 96% for Y _max/t _1/2 ratio for zinc gluconate stabilized with glycine (R ²=0.7996 for zinc sulfate and 0.8665 for zinc gluconate stabilized with glycine). The slope ratio analysis from linear regression of femur zinc determined a relative zinc bioavailability of 93% for zinc gluconate stabilized with glycine (R ²=0.8693 for zinc sulfate and 0.8307 for zinc gluconate stabilized with glycine). Zinc gluconate stabilized with glycine has similar bioavailability as zinc sulfate in a Petit Suisse cheese nutritional matrix, with the advantage that the stabilized compound does not modify the sensorial characteristics of the fortified cheese.     

Postnatal changes in the distribution and elemental composition of Paneth cells in normal and corticosteroid-treated rats

Summary Paneth cells containing zinc-rich granules were found in the small intestine of 6-day-old rats. These cells were more numerous in older animals and were consistently most common in the distal ileum. The zinc content of granules from 10-day-old rats was similar to that found in adults (ca 300 mg atoms/kg dry weight) but no calcium could be detected. An injection of cortisone acetate at 5 days resulted in a premature increase in the numbers of Paneth cells in 10-day-old rats. The cell granules contained normal, adult levels of zinc, a calcium concentration of ca 400 mg atoms/kg dry weight and also an increased concentration of phosphorus.     

Dietary zinc effects on zinc, calcium, and magnesium content in bones of growing rats

The aim of the present study was to assess dietary zinc effects on femur weight and mineral content in growing rats. For this purpose, 70 weanling Sprague-Dawley rats were divided into four groups. Each group was subject to a diet containing 2 (BZ), 5 (DZ), 10 (MZ), and 30 (CZ) ppm zinc. The calcium and magnesium content in all diets was 5 g/kg and 507 mg/kg, respectively. The animals were kept on this regime for 28 d and then sacrificed and their femurs were removed for analysis using atomic absorption spectrophotometry. The weights of the BZ and DZ groups were significantly different from the MZ and CZ groups (38.5±10.5, 89.9±13.7, 118.6±13.6 and 134±19.9 g, p<0.01) respectively. There were no differences between the MZ and CZ groups. Femur weight also varied with dietary zinc, as it was significantly different among all groups (BZ, 265±49 mg; DZ, 380±40 mg; MZ, 452±54 mg; CZ, 735±66 mg; p<0.01). The femur zinc content varied with diets, following a different pattern than the above parameters. Femur zinc from the BZ group (51.5±5.4 ppm) was significantly different from the MZ and CZ groups (115.9±14.2 and 175.0±13.5 ppm, respectively), whereas the DZ group (62.5±11.3 ppm) did not differ from the other three groups. The femur content of calcium (BZ, 83.2±9.8 mg/g; DZ, 88.0±9.2 mg/g; MZ, 90.2±13.6 mg/g; CZ, 83.1±14.7 mg/g) and magnesium (BZ, 1.82±0.13 mg/g; DZ, 1.98±0.09 mg/g; MZ, 1.93±14 mg/g; CZ, 1.83±0.19 mg/g) were not significantly different among the groups, nor was the calcium-magnesium ratio. These results suggest that although dietary zinc deficiency retards growth and causes bone fragility, bone deposition of calcium and magnesium and its ratio are not affected.     

Early effects of surgery on zinc and metallothionein levels in female rats

Time-response effects of experimental surgery on zinc (Zn) and metallothionein (MT) homeostasis were investigated in female rats up to 24 h. Hepatic Zn content increased at 20 and 24 h postsurgery, whereas serum Zn levels decreased. Hepatic MT increased significantly by 9 h postsurgery and peaked at up to twofold of control at 12 h after surgery. Following the peak at 12 h, hepatic MT content decreased with time but did not reach control levels at the end of this study. When MT isoforms were evaluated, MT-II levels were elevated to the highest extent by 12 h after surgery, whereas MT-I levels started to decrease after 3 h postsurgery but then increased by 20 h. The early increases in MT content are probably mediated by nonmetallic mediators released during the postsurgical inflammatory process, favoring the plasma/tissue mobilization of Zn. This process might be part of the overall mechanisms occurring in the inflammation.     

The binding of zinc in root cells of crop plants by phytic acid

Appreciable quantities of Zn are bound as Zn phytate (myo-inositol kis-hexaphosphate) within small vacuoles of cortical cells in the elongation zone of root tips of zinc tolerant Deschampsia caespitosa. These Zn/P-containing globular deposits have now been shown to occur in the roots of soybean, lucerne, lupins, tomato, rapeseed, cabbage, radish, wheat and maize. The globules are most frequent in the endodermis and pericycle but may also occur in the stele and inner cortex. The X-ray data again confirmed the presence of phytate with a relatively stable proportion of Zn and a species-dependent, variable, proportion of K, Mg and Ca to P.Analysis of soybean plants by atomic absorption spectroscopy showed that the Zn concentration in the shoots doubled in response to an increase in Zn supply from 1 to 100 M while the concentration of Zn in the root symplast was approximately 22 times greater than in the shoot, suggesting restricted transport to the shoot. It is suggested that the genetic expression of the capacity to bind heavy metals by means of phytate in endodermal cells may provide a strategy for keeping the above-ground content of heavy metals low. It may be possible to incorporate the trait into transformed roots that can be utilized for the treatment of industrial wastes.     

Effect of gypsum,pressmud, fulvic acid and zinc sources on yield and zinc uptake by rice crop in a saline-sodic soil

Summary The application of fulvic acid to a saline-sodic soil augmented the solubility of zinc by thousands fold. Zinc fulvate when applied at levels equivalent to that of zinc sulphate was more effective in enhancing diffusion of zinc in the soil. Application of gypsum, zinc sulphate and fulvic acid significantly increased dry matter yield and uptake of zinc by rice crop in a saline-sodic soil. Application of gypsum with pressmud or with fulvic acid and zinc sulphate resulted in significantly higher yield and zinc uptake than in other treatments.