Zinc Absorption from Representative Diet in a Chinese Elderly Population Using Stable Isotope Technique / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To determine the dietary zinc absorption in a Chinese elderly population and provide the basic data for the setting of zinc (Zn) recommended nutrient intakes (RNI) for Chinese elderly people.</p><p><b>METHODS</b>A total of 24 elderly people were recruited for this study and were administered oral doses of 3 mg 67Zn and 1.2 mg dysprosium on the fourth day. The primary macronutrients, energy, and phytic acid in the representative diet were examined based on the Chinese National Standard Methods. Fecal samples were collected during the experimental period and analyzed for zinc content, 67Zn isotope ratio, and dysprosium content.</p><p><b>RESULTS</b>The mean (± SD) zinc intake from the representative Chinese diet was 10.6 ± 1.5 mg/d. The phytic acid-to-zinc molar ratio in the diet was 6.4. The absorption rate of 67Zn was 27.9% ± 9.2%. The RNI of zinc, which were calculated by the absorption rate in elderly men and women, were 10.4 and 9.2 mg/d, respectively.</p><p><b>CONCLUSION</b>This study got the dietary Zn absorption in a Chinese elderly population. We found that Zn absorption was higher in elderly men than in elderly women. The current RNI in elderly female is lower than our finding, which indicates that more attention is needed regarding elderly females' zinc status and health.</p>

COMPARISON OF METABOLIC BALANCE AND FECAL MORNITORING METHODS FOR ESTIMATING THE DIETARY ZINC ABSORPTION IN TIBETAN MEN / 营养学报

Objective: To compare the methods of metabolic balance (MB) and fecal monitoring (FM) for evaluating the dietary zinc (Zn) absorption in Tibetan men. Methods: In 14 d field trial on 16 adult Tibetan men, capsules of carmine were given to mark the feces from D4 to D12, and samples of diet, water, feces and urine were collected during the period. In addition, 4.0 mg zinc tracer (enriched with 67Zn) and 1.0 mg recovery indicator ytterbium (Yb) were orally administrated to the subjects in the evening meal of the D5. The ratio of 67Zn/68Zn in fecal samples was determined by inductively coupled plasma mass spectrometry, and then the zinc absorption was calculated based on the principle of isotope dilution. Results: The dietary zinc absorption in Tibetan men was (23.8?3.9) % evaluated by MB and (21.4?4.3) % by FM with significant difference (by paired-samples t test) and linear correlation (Pearson). The unabsorbed zinc tracer and Yb had the similar behavior through the digestive tract, mostly excreted within5 d following the intake. Conclusion: In the 14d metabolic period, the dietary zinc absorption from MB was a little higher than that from FM. Using FM, the metabolic period can be shortened to 4-5 days according to excretion of Yb. Both methods suggested that the dietary zinc absorption in the adult Tibetan men was good.

EFFECTS OF LYSINE, PHENYLALANINE, TYROSINE, AND VALINE ON THE KINETICS OF ZINC ABSORPTION IN ILEUM OF RAT / 营养学报

The results of lysine, phenylalanine, tyrosine, and valine on kinetics of zinc absorption in rat ileurn using a two-compartment in situ perfusion model showed; 1. Phenylalanine can increase the zinc absorption micro-constants K21, K12, and K02, That is to say phenylalanine increases the a-mount of zinc from lumen to mucosa, from mucosa to lumen, and from mu-cosa to blood. Tyrosine and valine can increase the values of K21, so more zinc flows from lumen to mucosa; 2. The results of amino acids on the half times of zinc absorption showed that phenylalanine decreases both the half times of the fast phase and the slow phase, while valine decreases only the half time of the fast phase. Lysine and tyrosine have no effects on the half times of zinc absorption. The results of this study indicate that phenylalanine, tyrosine, and valine increase zinc absorption in the ileum of rat. The enhancing effects of amino acids on zinc absorption are related to the stability constants of zinc-amino acid chelators.

EFFECT OF DIFFERENT INTAKE LEVELS OF PROTEIN AND ZINC ON ZINC ABSORPTION AND RETENTION IN RATS / 营养学报

Thirty male weanling WAK strain rats were divided rondomly into 6 groups. All of the diets were pure synthetics according to AOAC. The 1st, 2nd and 3rd group were given diets containing 6, 15 and 24 ppm of zinc respectively, and 10% protein for all three groups, on the other hand, the 4th, 5th and 6th group were given diets containing 5% 10% and 20% of protein respectively, and 15 ppm of zinc.After feeding in stainless steel cage singly for 50 days rats were given intubately solution of 65Zn containing 1.5 ?Ci per 100g of body weight. Then the faeces and urine of rats were collected on 5 consecutive days, and the zinc absorption and retention of all of the tested rats were determined with method of 65Zn as tracer. The results indicated that. (1) The zinc absorption and retention of rats fed on the lowest zinc level were increased significantly. (2) The zinc absorption and retention of rats fed the lowest protein level were decreased significantly, and were improved clearly by increasing protein intake level. (3) The urine excretion of zinc is very low and can not be used as an index in zinc metabolism research. The methodology for determining zinc absorption and retention in organism with method of 65Zn and total zinc is discussed.

EFFECTS OF THE RATIOS AND QUANTITIES OF IRON AND ZINC ON ZINC ABSORPTION AND AVAILABILITY IN PRESCHOOL CHILDREN / 营养学报

Metabolic experiments were done in 30 preschool children before and after the supplement of different iron and zinc containing beverages. The concentrations of iron, zinc and other nutrients in faeces, urine and food were determined. The results showed that when the total amount of iron and zinc was equal to 32 mg and the ratio of them was 3.14 to 1 the absorption and availability of zinc declined.Therefore, during the process of manufacturing the fortified food, attention must be paid to the quantities and the optimal range of Fe/Zn ratio.It is better that the ratio of iron and zinc equals 1 to 1.

STUDY ON THE EFFECT OF ANDROGEN ON ZINC ABSORPTION / 营养学报

The absorption of zinc was studied with feeding method in rats. The zinc absorption of the castrated rat (44.21 ? 1.88%, x?SE) was significantly lower than that of the sham-operated rat (49.44?1.17%). The zinc absorption of the rat injected testosterone propionate (20 mg/kg, q.d.alt.) returned to the level of the sham-operated rat (49.13 ?1.88%). The results suggested that androgen could promote the absorption of zinc.