• Journal of Nutrition and Health
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• v.30 no.4
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• pp.394-405
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• 1997

Endogenous zinc is important for maintaining zinc homeostasis because the size of endogenous zinc pool is almost 3-4 times bigger than that of dietary zinc. The purpose of this study was to examine the phytate effect on the reabsorption of endogenous zinc and the additional Ca effect on the phytate effect. Rats were fed a casein-based diet with added sodium phytate containing either high(1.6%) or low(0.8%) Ca concentrations for 4 weeks to reduce the body zinc pool. After the depletion period, $^{65}$ Zn was given by intraperitoneal injection to label the endogenous zinc pool. Rats were then assigned into phytate or non-phytate group within the same Ca group. feces were collected for 2 weeks of the initial collection period and 1 week after dietary crossover. The ratios of excreted fecal $^{65}$ Zn radioactivity of phytate group non-phytate group were determined as a measure of the phytate effect on the endogenous zinc. Mean fecal $^{65}$ Zn radioactivity was higher in the phytate group than in the non-phytate group during the entire 3 weeks of the collection period in the low Ca group, and during the initial collection period in the high Ca group(p <0.0001). This study showed an adverse phytate effect on endogenous zinc at both high and low dietary Ca levels. Elevated dietary Ca levels showed a synergistic effect on the phytate effect on endogenous zinc(p <0.05). These results imply greater phytate effect on zinc homeostasis rather than on zinc bioavailability through complexing with the endogenous zinc which is larger portion than the dietary zinc on zinc homeostasis.

• Journal of Nutrition and Health
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• v.30 no.4
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• pp.406-414
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• 1997

It has been known that dietary phytate decreases the absorption of body zinc pool which is composed of the dietary and endogenous zinc in the body. The purpose of this study was to examine the effect of phytate on the absorption of total bodyzinc in Zn-depleted rats. Rats were Zn-depleted with either low(0.8%) or high(1.6%) Ca diet containing sodium phytate for 4 weeks. After zinc depletion, rats were assigned into phytate or non-phytate dietary groups within each low-or high-Ca dietary group. ant feces were collected for 2 weeks of the initial collection and 1 week after dietary crossover, during which the phytate and the non-phytate diet was switched over within the same Ca group. The content of Zn and Ca measured by atomic absorption spectrophotometer and phytate content was analyzed. food intake was higher in the high Ca group than in the low Ca group(p <0.0001), and was also higher in the non-phytate group than in the phytate group(p <0.0001). Food intake and phytate level affected body weight gain in rats(p <0.0001). Zinc excretion in the total feces was higher in the phytate group than in the non-phytate group at both low and high Ca level(p <0.0001), except during the crossover collection period in high Ca group. Calcium, however, didn't show any synergistic effect on phytate effect(p <0.05). This study showed that phytate decreased the absorption of total body zinc at both low and high Ca levels in Zn-depleted rats. A large portion of total body zinc originated from the endogenous zinc pool in these rats. The results of the present study showed the same effect of phytate on the endogenous zinc in Zn-depleted rats as in a previous study, confirming that phytate adversely affects zinc bioavailability, especially under marginal and poor zinc nutrition.

• Preventive Nutrition and Food Science
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• v.2 no.1
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• pp.35-41
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• 1997

The pancreas is an important organ in the maintenance of zinc homeostasis. Endogenous zinc is con-tinuously secreted via pancreatic exocrine fluid or to a lesser extent in bile. Much of the endogenous secretion must be reabsorbed to sustain zinc homeostasis. The objective of this study was to estimate the relative size of the pancreatic/biliary zinc pool in comparision to the dietary zinc intake, and to study the effect of the phytate and calcium on the zinc homeostasis using a rat model. At the termination of the experiment, pan-creatic/biliary fluid was collected from the rats. Both radioactivity and total zinc were measured and the relative size of the pancreatic/biliary zinc pool was estimated. To determine the effect of phytate and calcium on zinc homeostsis, dietary zinc intake, the amount of zinc in pancreatic.biliary fluid and fecal zinc excretion were measured. The flow rate of pancreatic/biliary fluid, as corrected for tubing constriction, gives the corrected zinc concentration in the pancreatic/biliary fluid was 2.2 times higher than dietary zinc intake. To maintain zinc homeostasis, zinc absorption/reabsorption was very efficient in the current model; 76%, 88% of absorption/reabsorption for low calcium group and high calcium group 81% for phytate group and non-phytate group, respectively.

• Nutritional Sciences
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• v.7 no.2
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• pp.83-87
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• 2004

To investigate the effects of dietary phytate reduction and zinc supplementation on biochemical iron parameters in elderly Korean women consuming inadequate iron, fifteen healthy women aged 64-75 years were recruited for a feeding study. A high-phytate diet (27.8 phytate:zinc molar ratio) was provided for 9 days, followed by a nine-day low-phytate diet(12.3) and a subsequent 28-day period of unregulated meals with zinc supplementation (22 mg/d as zinc gluconate). Serum iron increased significantly with the low-phytate diet (130.4 $\mu g$/L) but returned to the level observed during the high-phytate diet (113.0 $\mu g$ /L) period when subjects were taking zinc supplements (105.8 $\mu g$ /L). However, serum ferritin in the subjects decreased significantly with the low-phytate diet (73.8 $\mu g$ /L) as well as with zinc supplementation (57.2 $\mu g$ /L), compared to levels following consumption of the high-phytate diet (89.6 $\mu g$ /L). Transferrin receptor and transferrin saturation were unchanged with the treatments. In summary, zinc supplementation might result in deteriorated iron status in elderly Korean women who consume inadequate iron, while there was no significant effect from reducing dietary phytate.

• Preventive Nutrition and Food Science
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• v.9 no.1
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• pp.79-84
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• 2004

Zinc intake and status of South Koreans from rural, urban and metropolitan areas were investigated. The dietary habits of 760 healthy male and female adult subjects with a mean age of 54 were assessed using a food frequency questionnaire and were verified using 24 h dietary recall. Daily Zn intakes for men and women were 7.4$\pm$5.4 mg and 7.0$\pm$5.4 mg, respectively, which were 62% and 70% of the Korean RDA. The phytate : zinc and phytate ${\times}$ calcium : zinc molar ratios were 38 and 398, respectively. Both the low intake of zinc and the high extremely phytate and phytate ${\times}$ calcium ratios with Zinc suggest that South Koreans may be at risk of zinc deficiency. Plasma zinc (86$\pm$61 $\mu\textrm{g}$/dL), urinary zinc (33$\pm$27 $\mu\textrm{g}$/dL) and plasma alkaline phosphatase (102$\pm$52 mU/mL) levels within the normal range did not however suggest marked Zinc deficiency in these subjects. However, conventional zinc biomarkers aye known to be unreliable for assessment of marginal zinc deficiency. Based on zinc intake alone, it is likely that at least a proportion of these subjects were marginally zinc deficient and the wider consumption of zinc rich, phytate deficient foods, particularly in rural areas, would be beneficial.

• Journal of Nutrition and Health
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• v.28 no.10
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• pp.986-994
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• 1995

This study was to examine the effect of phytate on the protein digestibility and calcium, iron and zinc availability in phytase treated soymilks digested with pepsin and pepsin-pancreatin in vitro. Also, the bending between phytate and protein in soymilks was investigated by means of SDS-PAGE. The content of phytate in soymilk was reduced by phytase treatment. As the content of phytate decreased, the protein digestibility increased in soymilk treated with the digest enzymes in vitro. The reduction of phytate content in soymilk improved the availability of all calcium, iron and zinc. Although the availability of calcium increased, the amount of change was small. The phytate reduction increased most the availability of iron. A number of bands of high molecular weight protein in soymilk disappleared in SDS-PAGE by lowering the phytate content with phytase treatement on soymilk.

• International Journal of Human Ecology
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• v.4 no.1
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• pp.25-34
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• 2003

High dietary phytate is a known factor in reducing the bioavailability of minerals such as zinc and calcium which are already chronically low in the Korean diet. This study was conducted to develop methods for reducing dietary phytate through the addition of phytate and/or the substitution of high phytate foods with low phytate foods. Ten units of phytase per 100g of uncooked brown rice were added to brown rice gruel resulted in a 16.2% phytate reduction after a 3-hour incubation period; an 18.2% reduction was produced after a 6-hour incubation period. The addition of ten units of phytase per 100g of soybean curd residue at 45$^{\circ}C$, followed by refrigeration for 3 hours, resulted in a 19.1% phytate reduction. The addition of 20 units of phytase under the same conditions reduced phytate content by 24.6%. In this study, two typical Korean meals consisting of legumes and unrefined cereals were prepared as high phytate meals; these were then compared to low phytate meals that had been prepared by treating the foods with phytase and substituting unrefined with refined cereals (i.e., brown rice with white rice, whole wheat bread with white bread). The phytate content of the two high phytate meals was 1878.2mg and 1811.8mg. After the addition of phytase and the food substitution, the phytate content of the low phytate meals was reduced to 788.9mg and 606.0mg. The phytate to zinc molar ratio of high phytate diets was 22.4 and 21.3 and 9.4 and 7.9 for the low phytate meals. These results indicate that the nutritional status of Koreans in terms zinc and other minerals can be improved by phytate reduction. This can be accomplished through the change of milling process for some cereals and/or the enzyme treatment of some high phytate food items.

• Nutritional Sciences
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• v.2 no.2
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• pp.82-87
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• 1999

Zinc nutriture in South Koreans was evaluated by estimating Zn, Ca, and phytate intake, and the molar ratios of phytate : Zn and the millimolar ratios of phytate $\times$ Ca Zn. food consumption data from the 95 National Nutrition Survey was used. For the present study, data from the nationwide, large city and urban area level were used. No standard deviation measures were provided in the 95 National Nutrition Survey : only mean values were reported. Nationwide daily intake of Zn and Ca were 10.1 mg/day and 426.5 mg/day, respectively. The estimated daily phytate intake was 1676.6 mg/day nationwide. The molar ratio of phvtate : Zn, the millimolar ratio of phytate $\times$ Ca : Zn and the phytate $\times$ Ca Zn mmol per 4.2 MJ (1000 kcal) were 15.9, 168.9 and 91.8 in nationwide, respectively. The major food groups for zinc intake were meat, poultry products (43%), and cereals and grain products (18%). Sixty two percent of Zinc was from animal food sources. Cereal and grain products supplied most of the phytate intake (46%), followed by seasonings, fruits, and legume products. The major food source of phytate was rice (39%) . The results of the present study suggest that Zn status of Koreans maybe influenced by high dietary intake of phytate and high molar ratios of phytate : Zn and phytate $\times$ Ca : Zn. These results raise concerns about Zn status of Koreans, who consume a diet higher in phytate than Western diets. further research is necessary to confirm whether such poorly available dietary Zn has any impact on the health of Koreans.

• Journal of Nutrition and Health
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• v.26 no.2
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• pp.154-154
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• 1993

A factorial experiment was conducted to determine the influence of phytate(0 or 10g/kg diet) and calcium (Ca)(3 or 10g/kg diet) intakes on Ca, P and Zn metabolism by growing female rats. Food intake and weight were similar for the all groups, however, phytate ingestion for six weeks depressed femur growth. The low Ca plus phytate group showed the lowest Ca content of total femur and this was related to a significant decrease of Ca retention. Phytate intake depressed zinc(Zn) absorption in the first metabolic collection. This inhibitory effect of phytate on Zn absorption was improved in the low Ca plus phytate group after several weeks. Impared Zn absorption however remained in the high Ca plus phytate group which was reflected in the lowest Zn content of femur, phytate intake with high Ca also depressed phosphorous(P) absorption and serum and urinary P. These adverse effects of phytate on Zn and P absorption when the dietary Ca was high could explain reduced femur weight despite the highest concentration of femur Ca(mg/g ash) in this group. Results suggest that phytate can adversely affect not only Ca metabolism but Zn and P utilization. Thus, for the normal bone growth when phytate intake is high, the ingesion of Ca, P, Zn and other minerals should be enhanced.

• Journal of the Korean Dietetic Association
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• v.13 no.4
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• pp.301-310
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• 2007

The purpose of this study was to analyze the relationships among zinc status, protein and phytate intake, and diabetic control indices of type 2 diabetic women. The mean age and the duration of diabetes were respectively 57.9±6.9 years old and 8.0±6.5 years. The mean daily energy intake of diabetic subjects was 1562 kcal. Both the zinc intake (6.2mg/day) and the zinc %RI (% of The Recommended Intake for zinc: 79.5%) of the diabetic participants were significantly lower than those of the control group (respectively p<0.01). As for the diabetic group, the higher the energy intake (kcal/day), the higher were the zinc intake (p<0.001) and %RI for zinc (p<0.001). Zinc intake was positively correlated with the protein (p<0.001), animal protein (p<0.001), and fat intake (p<0.001), but negatively correlated with the carbohydrate intake (p<0.001). Foods with high amount of phytate were the major source of zinc (p<0.01), but did not contribute to high zinc densities. The urinary zinc excretion was twice as high as in the diabetic group compared to the control group (p<0.001). In addition, the urinary zinc loss was positively correlated with the duration of diabetes (p<0.05), hyperglycemia (p<0.001) and insulin resistance (p<0.05). %RI for zinc was negatively correlated with the HbA1C (p<0.05). These results lead us to conclude that the appropriate intake of energy controlled by diet therapy could improve the total zinc intake and %RI for zinc in diabetic women. Also, normal blood glucose level controlled by diet therapy could improve the hyperzincuria. Dietetic practitioners should encourage consumption patterns that provide zinc-rich foods in the form of animal protein to improve the bioavailability as well as the total daily intake of zinc.