34;Based on a symposium sponsored by the ACS Division of Agricultural and Food Chemistry at the 183rd meeting of the American Chemical Society, Las Vegas, Nevada, March 28-April. The appearance of the code at the bottom of the first page of each article in this volume indicates the copyright holder's consent that reprographic copies of the article may be made for personal or internal use or for the personal or internal use of specific clients. The copying fee for each chapter is indicated in the code at the bottom of the first page of the chapter.
The format of the series is similar to that of the ongoing A D V A N C E S I N C H E M I S T R Y S E R I E S, except that to save time the papers are not typeset but reproduced as submitted by the authors in camera-ready form. Papers are reviewed under the supervision of the Editors with the assistance of the Series Advisory Board and are selected to maintain the integrity of the symposia; however, verbatim reproductions of previously published articles will not be accepted. Thionein contributes to the regulation of zinc absorption from the mucous membranes in the body.
I would like to thank the contributions of the authors and reviewers who made this book possible. Marginal zinc deficiency appears to be common in many populations in developed countries and more severe deficiencies are widespread in many parts of the world.
RECEIVED September 29, 1982
WELSH AND MARSTON Zinc Levels in the U.S. Food Supply 19
Due to differences in the bioavailability of the zinc from foods of animal and vegetable origin, the RDA1s are based on the consumption of a mixture of these foods. Although the food supply represents a mixed diet, individual diets may differ greatly from the average pattern. 34; Recommended Dietary Allowances (RDA) are the levels of intake of essential nutrients which, in the judgment of the Committee on Dietary Allowances of the Food and Nutrition Board on the basis of available scientific knowledge, are considered sufficient to meet the known nutritional needs. of practically a l l healthy persons.
The RDA (apart from energy) is estimated to exceed the requirements of most individuals, thus ensuring that the needs of almost one l l of the population are met. Differences in methodology do not reduce the discrepancy between the RDA and food supply levels of zinc. Relative to the RDA, the present results therefore provide further evidence that the American diet is marginal in zinc.
National Academy of Sciences, National Research Council, Food and Nutrition Board: "Recommended Dietary Allowances", 8th ed.
National Academy of Sciences National Research Council Food and Nutrition Board
RECEIVED September 9,1982
Assessment of the Bioavailability of Dietary Zinc in Humans Using the Stable Isotopes 70 Zn
Sample analysis is in progress from a study in which 6?Zn w a was used to determine the effects of phtate and cellulose on human zinc absorption. Other key issues in zinc absorption that will be studied with stable isotopes are the bioavailability of zinc in human infants from breast milk and formulas and the comparison of the availability of internal and external zinc labels.
Literature Cited
Kelsay, J.L., Cerea
RECEIVED September 3, 1982
Stable Isotope Approaches for Measurement of Dietary Zinc Availability in Humans
JANGHORBANi ET AL. Approaches for Measurement of Dietary Zinc 47
JANGHORBANI ET AL. Approaches for Measurement of Dietary Zinc 59 Literature Cited
Zinc Absorption in Humans Effects of Age, Sex, and Food
After absorption, part of the zinc goes directly into the blood, another part passes first through the portal circulation and then into the systemic circulation. Activity in blood can be exchanged with tissue pools, excreted in the urine or excreted back into the gastrointestinal tract. The activity in the liver area increased rapidly in the period between 5 and 48 hours to approx. 7Οψο of the absorbed activity (49% of the administered activity) and then decreased.
Activity in the thigh area increased more slowly, reaching maximum values at about 50 days, and then decreased. This kinetic model for zinc in humans is based on average data obtained after oral and i.v. 69m Zn activity in plasma, red blood cells, urine, liver and thigh as well as stable zinc parameters including dietary intake, serum and urinary concentration.
The SA AM 27 computer program was used to obtain the simplest set of mathematical relationships that would satisfy the data characteristics for each measurement point in the study and remain consistent with accepted concepts of zinc metabolism. 69m Zn limited the data collection period, this model allowed analysis of the fast phases of zinc metabolism (approximately 10% of total body zinc) and the derivation of some basic stationary parameters (see Table I).
Simulation of the pattern of blood concentration over time for three situations in which > the total absorption of a given substance remained constant as the time of peak concentration varied Ρ from 1 to 2 to 3V2 h after ingestion. This figure shows that small changes in the absorption pattern w can result in large changes in blood concentration values measured at specific times after administration. Variability of intestinal zinc absorption calculated from retention measured on days 7, 14 and 21 after oral administration of 65Zn to normal fasting volunteers.
All measurements were in good agreement: the values measured on day 7 were slightly less than the mean, those on day 14 slightly more than the mean, and those measured on day 21 essentially equal to the mean. These small and evenly distributed differences indicate that fecal excretion was more than 99% complete by day 7. The plotted curve is a linear least squares fit to the experimental points which are mean values with a range of ± 1 SEM.
80 NUTRITIONAL BIOAVAILABILITY OF ZINC be fully defined by single static measurements such as zinc
NIH)76-730)
RECEIVED October 25, 1982
A Redefinition of Zinc Deficiency
HENKIN
ROGER L. AAMODT
Phyisol., 1979, 237, R340-R349
RECEIVED October 13, 1982
Utilization of Zinc by Humans
Gerontology 1981, 36, 558-563
Zinc Bioavailability from Vegetarian Diets Influence of Dietary Fiber, Ascorbic Acid, and
Past Dietary Practices
1983 American Chemical Society
Effect of Fiber and Oxalic Acid on Zinc Balance of Adult Humans
The Role of Phytate in Zinc Bioavailability and Homeostasis
OBERLEAS
Chick growth after 4 weeks under the influence of phytate and supplementary zinc Basal diet contained 9 mg/kg zinc. RATIO OF ZINC EXCREMETED BY RATS ON SOYA PROTEIN DIET VS. CASEIN PROTEIN DIET AFTER INTRAPERITONEAL INJECTION.
![Figure 1. 1,2,3,4,5,6-Hexakis(phosphonooxo)cyclohexane [phytate] (39).](https://thumb-ap.123doks.com/thumbv2/123dok/10251412.0/149.648.140.491.365.572/figure-hexakis-phosphonooxo-cyclohexane-phytate.webp)
Dietary Phytate/Zinc Molar Ratio and Zinc Balance in Humans
National Research Council "Recommended Dietary Allowances"
34;Approved Methods of the American Association of Cereal Chemists" American of the American Association of Cereal Chemists" American Association of Cereal Chemists, St.
RECEIVED October 5, 1982
Zinc Bioavailability from Processed Soybean Products
Zinc Bioavailability from Cereal-Based Foods
Zinc Bioavailability in Infant Formulas and Cereals
198 NUTRITIONAL BIOAVAILABILITY OF ZINC Cereal products and the bioavailability of zinc are influenced by the addition of vegetable protein as a meat extender or by food additives such as EDTA and polyphosphates. The recent publicity for the health benefits of fiber has encouraged many people to increase their fiber intake. This may increase dietary zinc content, but the effect on zinc availability in the overall diet is uncertain (3).
As the number of processed and manufactured foods increases, so does the need to regulate the composition of foods to ensure nutritional quality. In addition, some cereal products are enriched with zinc to increase zinc intake. It is thus obvious that for regulatory purposes a good bioassay for determining zinc availability is essential, just as there is an A.O.A.C.
In an initial experiment, weanling male Wistar rats were depleted of zinc by feeding a low-zinc basal diet (0.6 pg/g zinc) for two weeks and then replenished by adding 12 yg/g zinc as zinc sulfate. The analysis of the zinc content of the different tissues at weekly intervals for four weeks revealed that the body weight and the total femur zinc were the parameters of choice because the responses were linear with the feeding duration. The results of this experiment also showed that since depletion did not reduce the variability in these parameters, it was not significant for the assay.
The choice of total femur zinc over body weight was made on the basis of linearity between the logarithm of total femur zinc and the level of dietary zinc from the standard (zinc sulfate) or the test source (zinc acetate) over a sufficiently wide range. The response of body weight or body weight gain to dietary zinc from 3 to 12 yg/g was not linear, but the logarithm of total femur zinc at 2 and 3 weeks had a linear relationship with dietary zinc level (Figure 1). Calculation of the relative bioavailability of zinc acetate at 2 and 3 weeks revealed that the 95% real limits were narrower at 3 weeks.
A bioassay was used to determine the bioavailability of zinc in milk- and soy-based infant formulas (7).
