Showing papers by "John W. Erdman published in 1984"

Effects of Dietary Phytate, Calcium and Magnesium Levels on Zinc Bioavailability to Rats

Abstract: Young rats were fed diets containing 12 mg Zn/kg and varied levels of sodium phytate for 21-day ad libitum feeding periods. In experiment 1, Ca levels were 0.3, 0.5, 0.8 and 1.0%, and phytate:Zn molar ratio varied between 0 and 50. In experiment 2, Ca was maintained at 0.3%, Mg levels were 0.07, 0.22 and 0.37%, and phytate:Zn molar ratios were 0, 10, 20 and 30 at each Mg level. Major response criteria were body weight gain and tibia Zn accumulation. Weight gain was not influenced by Ca level in the absence of phytate or by phytate at 0.3% Ca; it was increasingly depressed as phytate was increased and by each increase in Ca in the presence of phytate. Total tibia Zn content was decreased at the highest Ca level in the absence of phytate; increasing the phytate progressively depressed tibia Zn at all Ca levels. Mg and phytate additions did not affect weight gain. Tibia Zn tended to be depressed by Mg and by phytate but these effects were significant only at the highest levels of the combined additions. These data corroborate and extend previously published findings on Ca and phytate effects on Zn utilization and show bone Zn accumulation to be a more sensitive criterion than weight gain in this connection. They also indicate that Mg exerts a less pronounced effect on Zn utilization in phytate-containing diets than does Ca.

The winged bean as an oil and protein source: A review

Abstract: Despite high protein contents in its ripe seeds, tubers and fresh leaves (ranging from 29.3–39.0%, 3.0–15.0% and 5.0–7.6% respectively) and the high quality of that protein, the winged bean (Psophocarpus tetragonolobus) remained an obscure food source until about 10 years ago. Recently, this legume has received increasing attention from scientists because of its potential multiple uses as a food protein source in the humid tropics. This article reviews the utilization and nutrition literature of winged bean published during the last 10 years. The following aspects are covered: classification of winged bean proteins, nutritional properties and antinutritional components of the protein, protein quality, functional properties, and protein-based food products. The oil content of winged bean seeds ranges from 15.0–20.4%, and use of the winged bean as a potential oilseed crop is discussed. Areas of needed research are identified and described.

The effect of soy protein isolate in the diet on retention by the rat of iron from radiolabeled test meals.

Abstract: The influence of soy protein isolate (SPI) in the diet on whole-body retention of extrinsically radiolabeled iron from test meals containing or not containing SPI was evaluated in marginally iron-deficient weanling rats. In experiment 1 SPI was compared with casein in a 2 X 2 factorial design: diets and test meals were either SPI-based or casein-based. Diets were fed for 13 days prior to the test meal and for 7 days subsequent to the test meal. Rats fed the SPI-based diet retained less iron from test meals than did rats fed the casein-based diet (66.1 vs. 74.8%, P less than 0.01). Experiment 2 showed that an SPI-based diet fed during the final 4 days of a 14-day pre-test meal period and subsequent to the test meal led to less iron retention compared to a casein-based diet. In addition to the observed diet effect, experiment 1 showed that iron retention was less from an SPI-based test meal than from a casein-based test meal, confirming previous reports of adverse effects of SPI on iron retention. The present experiments show that SPI can adversely affect from retention in two ways: by its presence in the diet before and after a test meal, andmore » by its presence in a test meal.« less

Bioavailability of zinc to rats from defatted soy flour, acid-precipitated soy concentrate and neutralized soy concentrate as determined by intrinsic and extrinsic labeling techniques.

Abstract: The bioavailability of 65Zn from intrinsically and extrinsically labeled soy flour, acid-precipitated soy concentrate and neutralized soy concentrate was evaluated in rats. Weanling rats were fed marginally zinc-deficient diets, providing 8 ppm zinc from one of these three soy products, for 7 days. The rats then received a radioactively labeled test meal, identical in composition to the previous diet except that the soy product was either intrinsically or extrinsically labeled with 65Zn. After the test meal the rats were again fed diets the same as those consumed prior to the test meal. Whole-body retention of 65Zn at 24 hours and 12 days as well as 65Zn retained in tibias of rats given meals containing neutralized concentrate-based meals was significantly lower than for rats given meals containing the soy flour or acid-precipitated concentrate. In addition, retention of 65Zn from the extrinsically labeled acid-precipitated concentrate-based meal was significantly higher than from the same product intrinsically labeled. These findings confirm the results of previous feeding studies from which it was suggested that neutralization of soy protein concentrates reduces zinc bioavailability to the rat. In addition, the results are taken to suggest that experimental conditions may influence the validity of the extrinsic labeling technique for zinc.

Relative Bioavailability of Dietary Iron from Three Processed Soy Products

Abstract: The relative bioavailability of iron from soy flour (SF), freeze-dried soy beverage (SB) and soy concentrate (SC) was determined utilizing a hemoglobin repletion bioassay. Weanling male rats were fed a low iron depletion diet (3.5 ppm Fe) for 4 wk. For the next 2 wk groups of rats were fed repletion diets containing 0, 6, 12, or 18 ppm added iron from ferrous sulfate, SF, SB, or SC. Slope ratio analysis revealed that the relative iron bioavailabilities from SC (92%) and SF (81%) were not different from the reference standard, ferrous sulfate added to a casein-based diet, whereas that from SB (66%) was significantly less (P SF>SB.

Bioavailability of Zinc and Iron from Mature Winged Bean Seed Flour

Abstract: The relative bioavailability of zinc and iron from mature winged bean (Psophocarpus tetragonolobus) flour was determined utilizing standard rat bioassay procedures. Weight gain of rats after 21 days and total bone (tibia) zinc resulting from zinc addition to the standard diet as zinc carbonate or from zinc endogenous to winged bean flour were compared. The relative bioavailability of winged bean zinc was calculated to be 85% (P < 0.05) and 93% (N.S.) when weight gain and log tibia zinc were the criteria of evaluation. The results of the hemoglobin repletion assay indicated that iron from winged bean was 89% (N.S.) as bioavailable iron from ferrous sulfate.

The effect of diet on retention by the rat of iron from a radiolabeled casein test meal

Abstract: Previous work has shown that weanling rats fed a soy protein isolate (SPI)-based diet retained less iron from a casein test meal than did rats fed a casein- based diet. In the present work this diet effect was further investigated. In experiment 1 rats were fed either SPI- or casein-based diet (about 25 ppm Fe) for 13 d, fasted over night, given a 59Fe-labeled casein-based test meal, and refed either the same or the other diet for 7 d. 59Feretention was determined by the percent of ingested label re tained after 7 d. SPI reduced 59Feretention when fed prior to the test meal (52.5 vs. 61.5%, P < 0.001) and also when fed following the test meal (50.8 vs. 63.2%, P < 0.001). In experiment 2a, exposure of SPI to steam at 108°Cfor 30 min did not lessen the observed diet effect. In experiment 2b rats were fed either an SPI- or casein- based diet, and casein test meals were fed as above on days 14, 35 and 56. The SPI- based diet reduced 58Fe retention from the casein test meal fed on d 14 (58.2 vs. 68.0 %, P < 0.005), for the meal on d 35 there was no difference, and for the final test meal rats fed SPI retained more 59Fe (53.0 vs. 40.2%, P < 0.01). In experiment 3 lactalbumin was shown to decrease59Fe retention to the same extent as SPI (54.9 and 53.4 %) as compared to casein (73.3 %), whereas neither rapeseed protein concentrate (68.8%) nor oxalic acid (72.2%) had any significant adverse effect. Clearly, protein source, duration of feeding, and diet before and after the test meal affect iron retention. J. Nutr. 115: 319-326, 1985.