Dietary factors that can impair calcium and zinc nutriture of the elderly.
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Aged↗
Biomedical subjects
F R Dintzis
Publications and source records attributed to F R Dintzis.
In vivo mineral contents of dietary fiber determined by EDX analysis.
EDX measurements of the mineral content of oat hulls in the pig GI tract revealed that the hulls from the rectum contained more Na, P and S than prior to ingestion; while contents of K and Ca were not significantly different than in initial hulls. X-ray measurements indicated that potassium was the only element of the five examined which was unloaded from the initial oat hulls during passage through the GI tract. During this passage, the flows of Na and K into and out of oat hulls were proportional to concentrations of these elements in digesta. Although Ca was loaded onto oat hulls in the stomach, it was unloaded during subsequent passage, even though the concentration of Ca in digesta increased significantly in the large intestine. The behavior of corn pericarp generally was similar to that of oat hulls. We consider it unwise to attempt quantitative comparisons of corn pericarp behavior in our previous work (Dintzis et al., in press) with results in this study. The data bases are very small and feeding situations and diets were not equivalent. However, results from both studies show similar behavior in loading and unloading of Na, Ca, and S from the plant tissues, and possible differences with K and P. The finding that X-ray count values were different for oat hulls and corn pericarp when the tissues were loaded with equal amounts of calcium or potassium serves as a stark warning that additional work is required before measurements of this sort can provide quantitative results and a basis for comparisons between different plant tissues. Nevertheless, EDX analysis has provided information about the loading of Na, K, Ca, S, and P onto plant tissues during passage in the GI tract of growing pigs. The techniques used in this study appear worthy of further effort, for we believe they have the potential to provide significant information about in vivo interactions between plant tissues and minerals in the diet.
Adsorption↗
Nitrogen-to-protein conversion factors in animal feed and fecal samples.
Nitrogen-to-protein conversion factors were calculated for diets and fecal samples from three animal species fed low- or high-fiber diets. The conversion factors based on protein contents determined by amino acid analyses were calculated from total N (Kjeldahl analyses) and recovered amino acid plus NH3-N (amino acid analyses). Conversion factors based on protein contents determined by a fluorescamine assay for amino acids were also calculated from total Kjeldahl-N. The conversion factors based on Kjeldahl-N averaged 5.3 +/- .7 for the diets and 4.0 +/- .5 for the feces in the six animal and diet comparisons when calculated from anhydrous amino acid formula weights. The greatest deviations from the traditional 6.25 conversion factor occurred in the fecal samples of ruminant animals fed a corn-alfalfa meal diet at a maintenance level of intake. In contrast, conversion factors based on amino acid plus NH3-N were quite stable. These factors averaged 5.7 +/- .1 for feeds and 5.5 +/- .1 for feces when calculated from anhydrous amino acid residue weights.
Amino Acids↗
Effect of browned and unbrowned corn products intrinsically labeled with 65Zn on absorption of 65Zn in humans.
Experimental browned and unbrowned corn products were formulated and processed from unenriched, degermed yellow corngrits. The browned product (cornflakes) contained more insoluble dietary fiber and bound more zinc (in vitro) than the unbrowned product (corngrits). During processing some of the cornflakes and corngrits were combined with a small amount of yellow corn endospermhull intrinsically labeled with 65Zn. The intrinsically labeled corn products were fed, in a crossover design, as components of two breakfasts to six normal, unconfined volunteers. Each volunteer absorbed more 65Zn from the corngrits than from the cornflakes. The reduced 65Zn absorption from cornflakes was attributed to heating and toasting reaction products, possibly Maillard, which bound zinc and consequently made the zinc less available for absorption.
Absorption↗
Mineral contents of brans passed through the human GI tract.
Concentrations of Cu, Fe, Zn, Ca, and phytate were measured in dry-milled corn bran, wheat brans, and soybean hulls prior to being baked in bread and after passage through the human GI tract. Significant changes in mineral concentrations in the retrieved remnants compared to the starting materials were as follows: Cu, Fe, and Zn increased by factors of from two to four and Ca increased at least ten-fold in dry milled corn bran; Ca increased and phytate decreased in wheat brans; Zn increased and Fe decreased in soy hulls. These studies show that indigestible remnants of wheat brans in the human colon associate preferentially with calcium and that dry milled corn bran remnants can be loaded with increased concentrations of all four minerals, and especially with calcium. Concentrations of minerals and phytate were significantly greater in whole fecal samples from wheat bran diets than in the corresponding retrieved bran remnants.
Adult↗
Effects of some cereal brans and textured vegetable protein on plasma lipids.
The hypothesis that dietary fiber lowers serum cholesterol was tested in 10 healthy men, 19 to 54 years old, who ate a mixed diet similar to the diets of many American adult males, that contained 16% of calories as protein (70% from animal), 40% as fat (P/S = 0.3), 44% as carbohydrate (9% of calories as sucrose) and 3 g of crude fiber. The energy intake ranged from 2700 to 3500 kcal adjusted to their height and weight. Weight and fitness were held constant. After 30 days of equilibration on the basal diet, they ate 26 g of either soft white wheat bran, corn bran (CB), soybean hulls (SH), textured vegetable protein, or hard red spring wheat bran (HRS) for periods of 28 to 30 days each in no particular sequence. Each fiber was fed to four to six subjects. The dietary fiber contents of soft white wheat bran, CB, SH, and HRS were: 44, 92, 87, and 51%, respectively. Mean daily fecal weight increased (P less than or equal to 0.01) from 72.4 to 144, 68 to 128, and 81 to 151 g when CB, SH, and HRS were fed respectively. No effects were noted with soft white wheat bran or textured vegetable protein. Total plasma cholesterol decreased 12% with HRS (P less than or equal to 0.05) and 14.0% with SH (P less than or equal to 0.05). Low density lipoprotein cholesterol decreased 21% with HRS (P less than or equal to 0.05). High density lipoprotein cholesterol did not change with any of the dietary fiber sources nor did the ratio of high density lipoprotein cholesterol to total cholesterol. Some triglyceride lowering effect was seen with all sources of dietary fiber (P less than or equal to 0.01). There was a significant direct correlation between the area under the oral glucose tolerance curves and the levels of total cholesterol (r = 0.57, P less than or equal to 0.0001) and low density lipoprotein cholesterol (r = 0.49, P less than or equal to 0.0007), and between fasting plasma glucose and triglycerides (r = 0.32, P less than or equal to 0.03). Results were replicated when subjects were fed the same fiber source on two occasions at 2 to 4 month intervals.
Adult↗
Influence of dietary fiber on trace element balance.
Five adult male volunteers were fed a diet containing (as percent of calories) 16% protein, 40% fat, and 44% carbohydrate, a diet similar to that consumed by many American males. Twenty-six grams of soft white wheat bran or corn bran were added to the daily bread, and the effects on zinc, iron, and copper balance were assessed during the last 12 days of each 30-day study period. The soft white wheat bran appeared to decrease retention of zinc in four subjects but not significantly so. Iron retention was similar in all three treatments. Copper balance was improved by addition of soft white wheat bran and to a lesser degree by corn bran. An apparent copper requirement of 1.28 mg/day for the volunteers was calculated by regression analysis.
Adult↗
Energy-dispersive X-ray analysis of the mineral content of corn bran treated in vitro and by passage through the pig gastrointestinal tract.
Energy-dispersive X-ray (EDX) analysis was tested as a method for examining the mineral contents of corn bran loaded in vitro or passed through the GI tract of pigs. Particles of dry-milled corn pericarp treated in vitro or retrieved from the stomach, ileum, and colon of killed pigs were prepared as microtomed bulk specimens directly embedded in resin. Because of heterogeneity caused by differences in substrate cell density and mineral content, X-ray count averages for a number of different specimens had a coefficient of variation greater than or equal to 0.24. Detectable amounts of K, Ca, S, and P, but not Na, Cu, Fe, or Zn were found in specimens of initial bran. Although detectable concentrations of Cu, Fe and Zn could be loaded in vitro, these elements generally were not detected in bran retrieved from the pig GI tract. During GI tract passage, sodium was loaded onto bran mainly in the small intestine and unloaded in the large intestine. Calcium was loaded in the stomach and unloaded mainly in the small intestine. At each GI tract location, content of Na, Ca, K, and P in retrieved bran was greater than in the initial bran. EDX microprobe methods can be applied successfully to plant tissues treated in vitro and in vivo to investigate interactions with minerals in a diet.
Animals↗
Amylose-iodine complex. I. Sedimentation behavior.
Sedimentation measurements are reported on solutions of blue amylose-iodine complexes in the range of 0.001 to 0.007% amylose. Amylose fractions B and F2, of weight average molecular weight average molecular weight 4.0 X 10(5) and 3.4 X 10(4), respectively, were used in this study. Iodine complexes of these fractions formed polydisperse solutions of limited solubility and stability. Sedimentation coefficients increased as a function of potassium iodide concentration. Values for fraction B complexes varied from (16.3 +/- 1.0) X 10(-13) at 1.2 X 10(-3) M KI to (57.2 +/- 7.5) X 10(-13) at 8.3 X 10(-3) M KI; values for fraction F2 complexes varied from (10.0 +/- 1.2) X 10(-13) at 1.2 X 10(-13) M KI to (24.8 +/- 3.9) X 10(-13) at 9.5 X 10(-3) M KI. At constant potassium iodide concentration, sedimentation coefficients, within our experimental error of 10 to 15% standard deviation, are independent of amylose concentration. Time dependence of sedimentation coefficient values was observed for solutions either saturated or unsaturated with respect to the iodine-binding capacity of amylose. For iodine-saturated complex solutions, sedimentation coefficients extrapolated to zero potassium iodide concentration were two to three times greater than for the parent amylose. Measurements are evaluated in terms of possible polyelectrolytic charge effects and aggregation. Under conditions used in these experiments, aggregation of amylose-iodide complexes appears to be the mechanism responsible for the large increase in sedimentation coefficients.
Amylose↗
Amylose-iodine complex. II. Molecular weight estimates.
Ultracentrifugation measurements made by the Archibald method on solutions of amylose-iodine-iodide (AI) complexes, containing 0.003% amylose of weight average molecular weight 4.0 X 10(5) at 3.6 X 10(-3) M KI, yield an apparent molecular weight at the meniscus of 8 X 10(5) when measurements are extrapolated to 1200 rpm. Sedimentation equilibrium measurements at 1200 rpm yield apparent molecular weight at the meniscus of 6 X 10(5) and at the cell bottom of 2.4 X 10(6). Heterogeneity and aggreagation are major features of AI complex solution behavior. Apparent molecular weights increase as a function of increasing potassium iodide concentration and with time. This behavior directly correlates with AI complex sedimentation coefficient behavior previously reported. Molecular weight estimates are of the same order for AI complex solutions saturated and 65-70% saturated with respect to the iodine-binding capacity of amylose. Qualitative estimates of net macroion charge effects upon apparent molecular weights are presented.
Amylose↗