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Iron deficiency represents one of the most common global nutritional disorders in humans. Our objective was to determine whether and how supplemental inulin improved utilization of iron intrinsically present in a corn and soybean meal diet by young pigs for hemoglobin repletion. In Expt. 1,3 groups (n = 8/group) of pigs were fed a corn and soybean meal-based diet (BD, without inorganic iron addition) or BD + 2 or 4% inulin (Synergy 1: a mixture of oligofructose and long-chain inulin HP, Orafti) for 5 wk. Final blood hemoglobin concentrations and the overall hemoglobin repletion efficiency of pigs were positively (r = 0.55 and 0.69, P< 0.01) correlated with dietary inulin concentrations. Compared with pigs fed the BD, those fed 4% inulin demonstrated a 28% improvement (P < 0.01) in hemoglobin repletion efficiency and 15% (P < 0.01) improvement in the final blood hemoglobin concentration. In Expt. 2, 12 weanling pigs (n = 6/group) were fed the BD or the BD + 4% inulin for 6 wk. Pigs fed 4% inulin had higher (P < 0.05) soluble Fe concentrations in the digesta of the proximal, mid, and distal colon, and lower (P < 0.05) sulfide concentrations in the digesta of the distal colon. Supplemental inulin had virtually no effect on pH or phytase activity of digesta from any of the tested segments. In conclusion, supplementing 4% inulin improved utilization of intrinsic iron in the corn and soybean meal diet by young pigs, and this benefit was associated with soluble Fe and sulfide concentrations but not pH or phytase activity in the digesta.

Our objectives were to use a soy protein isolate (SPI) diet containing 2-amino-2-methyl-1-propanol, an inhibitor of choline biosynthesis, to determine the bioavailable choline content of normal and overheated soybean meal (SBM), canola meal (CM) and peanut meal (PM). In the first four experiments, it was determined that weight gain of chicks fed the basal diet would respond linearly (P < 0.05) to graded levels of crystalline choline and would not respond to betaine, and that when fortified with adequate choline, no weight gain or feed intake response would occur upon addition of 100 g/kg SBM, CM or PM to the basal diet. Furthermore, addition of crystalline amino acids simulating the amino acid composition of 100 g/kg SBM did not alter the utilization of crystalline choline. In Experiment 5, feeding graded doses of choline, SBM, CM or PM resulted in linear (P < 0.05) increases in weight gain. Multiple linear regression analysis indicated bioavailable choline concentrations of 1708, 1545 and 1203 mg/kg for SBM, CM and PM, respectively. In Experiment 6, no differences (P > 0.05) in bioavailable choline concentrations occurred between normal and overheated SBM, CM or PM, and the bioavailable choline concentration of normal SBM, CM and PM was 2002, 1464 and 1320 mg/kg, respectively. Average bioavailable choline levels were 83, 24 and 76% of analytically determined choline levels in SBM, CM and PM, respectively. Canola meal, although three times as rich in total choline as SBM, has less bioavailable choline than SBM. A substantial portion of choline in SBM, CM and PM is unavailable, and overheating does not appear to decrease the bioavailability of choline in these products. KEY WORDS: * oilseed meals * choline * bioavailability * chicks

Ferritin and soybean meal were reevaluated as dietary treatments of iron deficiency in rats. Isotopes that had been used in the past were avoided because of contemporary knowledge of the physiological and structural complexity of ferritin protein and the solid iron mineral. Rats made anemic by iron-deficient diets were given equivalent amounts of iron as FeS[O.sub.4], horse spleen ferritin, baked soybean meal, or soybean meal plus ferritin. Full recovery (89-109%) from anemia and increased tissue iron occurred after 28 d of treatment with any of the iron sources, which contrasts to past bioavailability studies using 59Fe-labeled ferritin and generally shorter periods of observation. Cultivar-specific variability was observed in soybean seed soluble iron and ferritin content (1.9-2.0 times the control cultivar, Arksoy), which was apparently heritable. The combined data suggest that manipulating ferritin expression and other soluble components of seed iron in soybeans and possibly other seeds, using Mendelian and biotechnological approaches, could contribute to a sustainable solution to global problems of iron deficiency. INDEXING KEY WORDS: ferritin; iron deficiency; rats; soybeans

Three growth trials were conducted with young chicks to evaluate crude protein (CP) utilization in soybean meal (SBM) as affected by dietary addition of microbial phytase. In assay 1, chicks were fed two CP-deficient (50 or 150 g CP/kg) levels of dehulled SBM, and each SBM level was then supplemented with equimolar amounts of cystine or methionine (Met) or with 1200 U phytase/kg. At 50 g CP/kg, cystine or Met supplementation improved (P [is less than] 0.05) measures of growth performance, but when 150 g CP/kg from SBM was fed, only Met addition improved (P [is less than] 0.05) weight gain, food efficiency and protein efficiency ratio (PER). Thus, Cys was more limiting than Met in the diet that contained 50 g CP/kg, but Met was clearly first-limiting in the diet that contained 150 g CP/kg. Phytase supplementation did not improve (P [is greater than] 0.10) chick performance at either level of CP. Chicks in assay 2 were fed 100 g CP/kg furnished by SBM, casein or corn gluten meal in the absence and presence of 1200 U phytase/kg. Weight gain, gain/food and PER values were greater (P [is less than] 0.05) in chicks fed SBM than in those fed casein, and greater (P [is less than] 0.05) in chicks fed casein than in those fed corn gluten meal. Phytase supplementation had no effect (P [is greater than] 0.10) on any measure of chick performance, regardless of the protein source fed. In assay 3, three deficient levels of CP (50, 100 and 150 g/kg) from SBM were fed in the absence and presence of 1200 U dietary phytase/kg. Weight gain, food efficiency and protein accretion increased linearly (P [is less than] 0.05) as a function of protein intake, but phytase supplementation had no effect (P [is greater than] 0.10) on slopes of the body weight and protein accretion curves. Likewise, phytase addition did not affect (P [is greater than] 0.10) measures of protein utilization, i.e., weight gain/protein intake and protein gain/protein intake at any of the CP levels that were fed. Because sulfur amino acids are the growth-limiting factors when protein-deficient levels of SBM are fed to young chicks, we conclude that dietary addition of phytase does not improve sulfur amino acid utilization in SBM. J. Nutr. 131: 1792-1797, 2001. KEY WORDS: * dietary phytase * soybean meal * methionine * cystine * chicks * protein utilization

The incidence of atherosclerosis can be modified by diet, and plant-derived proteins have a beneficial effect, but the underlying mechanisms remain unclear. It has been suggested that oxidized LDL (oxLDL) and autoantibodies against oxLDL are important in the development of atherosclerosis. We analyzed these factors in rabbits fed a nonpurified diet supplemented with high cholesterol (10.0 g/kg) containing either 270.0 g/kg casein (CAS, n = 10) or 270.0 g/kg soy protein isolate (SPI, n = 10) for 2 mo. Plasma and purified serum LDL from rabbits were analyzed at d 0, 15, 30, 45 and 60 of treatment, and the size of atherosclerotic lesions was evaluated at d 60 of treatment. CAS-fed rabbits had significantly higher plasma cholesterol at d 15-45 and LDL cholesterol levels at d 15 and 30. Levels of trilinolein and phosphatidylcholine hydroperoxides were higher in the LDL fraction of rabbits fed CAS than in those fed SPI. Also, CAS-fed rabbits had higher levels of highly oxidized LDL [monoclonal antibody (mAb) 24-reactive oxLDL] in plasma at d 60, whereas SPI-fed rabbits had higher levels of minimally oxidized LDL (mAb 28-reactive oxLDL) at d 45. These results were consistent with the earlier formation of anti-oxLDL antibodies and the presence of a larger area of atherosclerotic lesion in rabbits fed the CAS diet. These data indicate the importance of both the type of dietary protein used in the induction of atherosclerosis and the relevance of immunologic mechanisms in addition to biochemical and physiologic factors in the pathogenesis of atherosclerosis. J. Nutr. 130: 2641-2647, 2000. KEY WORDS: * casein * soy protein isolate * lipoprotein oxidation * atherosclerosis * rabbits.

We examined the effects of dietary fat type (10% of either soybean oil, S, or beef tallow, T) and xylanase supplementation (-, without; +, with 1 g of Avizyme 1300 per kg diet) in rye- based diets (56%) on tissue protein synthesis in male broilers. Birds were injected with a large flooding dose of a phenylalanine solution (150 mmol/L, 38 atom percentage excess [[sup.15]N] phenylalanine) and tissues were obtained after a 10-min incorporation period. [[sup.15] N]-enrichment in tissue free phenylalanine and tissue protein bound phenylalanine were measured by gas-chromatography mass-spectrometry and by gas-chromatography combustion isotope ratio mass-spectrometry, respectively in order to calculate tissue specific fractional rates of protein synthesis ([k.sub.s]). The [k.sub.s] (%/d) in (S-), (S+), (T-) and (T+)-fed birds were 56, 64, 84 and 61 (SEM = 3.7) in duodenum, 51, 52, 75 and 58 in jejunum (SEM = 3.1), 66, 67, 105 and 68 (SEM = 7.0) in jejunal mucosa cells, 53, 56, 68 and 50 (SEM = 3.7) in ileum and 52, 45, 118 and 39 (SEM = 20.2) in pancreas, respectively. Significant fat, enzyme or interaction effects in these tissues were mainly caused by the elevated [k.sub.s] in (T-)-fed birds which was closely associated with intestinal viscosity. We conclude that the effect of soluble nonstarch polysaccharides (NSP) and of NSP-hydrolyzing enzymes may be explained partially by modification in tissue protein synthesis of the intestinal tract. J. Nutr. 130: 827-834, 2000. KEY WORDS: * broilers * protein synthesis rate * rye * fat type * xylanase

A diet low in cholesterol, total fat and saturated fat is the first step in the treatment of hypercholesterolemia. However, many children cannot achieve plasma cholesterol goals by using this dietary approach. It has been long recognized that there is a hypocholesterolemic effect of soy protein when it is partially substituted for animal protein. The objective of our study was to evaluate the effect of soy protein on LDL cholesterol reduction when soy products are used as part of a regular diet at home. The product used were Archer Daniels Midland isolated protein and textured protein (soy meat and soymilk). We carried out a clinical random study including 26 hypercholesterolemic children; 13 were in the control group and 13 were in the intervention group (mean age 10.3 [+ or -] 2.04 y, range 7-15 y). During the 8-wk experimental period, both groups consumed a Step 1 diet ([is less than] 30% total fat, [is less than] 10% saturated fat, [is less than] 250 mg cholesterol). The intervention group also consumed the soy products as part of their regular meals. Food intake and adherence to the protocol were assessed during weekly home visits. Daily soybean protein intake in the intervention group was 20.88 [+ or -] 5.59 g/d, range 14.24-33 g/d. Preliminary data from 18 children (9 in each group) showed that the mean LDL-cholesterol reduction was significantly (P [is less than] 0.005) higher in the intervention group (15.5%) than in the control group (5.5%). There were no significant differences in total cholesterol reduction. The addition of soy protein to a Step 1 diet in hypercholesterolemic children was associated with a specific reduction in LDL cholesterol. We therefore propose that soy protein may offer a nonpharmacologic alternative to reducing elevated LDL cholesterol in children. [Supported by Inciensa-FODESAF, Costa Rica; American Soybean Association and United Soybean Board.]

We previously showed that soy protein consumption improves lipoprotein concentrations and reduces progression of atherosclerosis in cynomolgus monkeys. The mechanism for these beneficial effects is unclear. The purpose of this study was to determine potential mechanisms for the atheroprotective effects and to determine whether these effects extend to diabetic monkeys. As such, we designed an experiment with a 2 x 2 factorial design in which adult male monkeys (n = 23) were fed an atherogenic diet; the protein source was soy isolate (n = 11) or casein lactalbumin (n = 12), and monkeys were either control (n = 12) or streptozotocin-induced diabetic (n = 11). Diabetics had significantly increased fasting glucose and glycated hemoglobin levels; this relationship was not affected by protein consumption. Soy consumption significantly reduced total cholesterol and increased HDL cholesterol concentrations in both control and diabetic monkeys. To determine plasma and arterial LDL metabolism, radiolabeled LDL was injected before necropsy, 125I-LDL was injected 48 h and 131I-tyramine cellobiose-LDL was injected 1 h before necropsy to determine arterial LDL concentration and permeability, respectively. An increase in whole-body plasma LDL fractional catabolic rate was found with soy consumption. Soy reduced arterial LDL concentration across all arterial sites and LDL permeability in the carotid bifurcation and internal carotid arteries. Arterial delivery of LDL was calculated as LDL permeability X plasma LDL concentration and was also reduced across all arterial sites. There was no additional effect of diabetes. In conclusion, these beneficial effects of soy on both plasma and arterial LDL metabolism would be expected to reduce atherosclerosis progression and were found in both control and diabetic monkeys.