Milk Protein Diet Research Articles

Abstract 035: Novel Metabolites Associated With Blood Pressure During Dietary Protein And Carbohydrate Interventions

Introduction: Dietary protein and carbohydrate intake have been associated with blood pressure (BP). However, molecular mechanisms for these associations are not well studied. Hypothesis: We hypothesize that novel metabolites – intermediate products of metabolic reactions of diet or genetic factors, may play a role in BP regulation during dietary protein and carbohydrate interventions. Methods: In the Protein and Blood Pressure (ProBP) trial, 80 participants were randomly assigned to take 40 grams/day of soy protein, milk protein, or carbohydrate supplementation each for 8 weeks in a cross-over design. We analyzed the associations of serum metabolites with BP at baseline and each dietary intervention, respectively. Age, sex, race, education, smoking, drinking, and body mass index were adjusted in all analyses. ProBP findings were evaluated for replication among 1206 participants of the Bogalusa Heart Study. Results: After Bonferroni correction for 77 independent metabolite clusters, we identified 17 metabolites (1 at baseline, 8 at carbohydrate diet, 4 at milk protein diet, and 5 at soy protein diet) positively associated with BP (P<6.49E-4). Furthermore, 12 of these metabolite-BP associations identified at dietary interventions were replicated in the BHS (P<0.05, Table ). Of the 12 metabolites, glycerol and hexadecadienoate (16:2n6) were associated with BP in previous studies, and all other metabolite-BP associations were novel. Conclusions: Several novel metabolites may play an important role in BP regulation during dietary protein and carbohydrate intake.

Complementary feeding and nutritional status of infants on cow's milk proteins elimination diet.

Objective:To evaluate the diet and nutritional status of infants on an elimination diet of cow’s milk proteins.Methods:Observational and cross-sectional study that compared: Infants on a cow’s milk protein elimination diet (n=60) assisted at a hypoallergenic formula distribution unit and a control group of same age and gender without dietary restrictions (n=60). Age ranged from 6 to 24 months. The diet was evaluated using the 24-hour food survey and weight and height were measured.Results:The macronutrient intake of both groups reached nutritional recommendations. The proportions of infants in the group of elimination of cow’s milk proteins with insufficient intake were lower, compared to controls, for iron (13.3 and 31.7%; p=0.029), zinc (5.0 and 18.3%; p=0.047), and vitamin D (25.0 and 71.7%; p<0.001). The hypoallergenic formula contributed to a greater supply of nutrients than dairy foods for the control group. Between 12 and 24 months, the number of infants on a restriction diet who never consumed meat, fish, cereals, and eggs was higher than in the control group (p<0.05). The length-age Z scores in infants on a cow’s milk protein elimination diet (-0.4±1.6) were lower (p=0.039) than in the control group (+0.2±1.3).Conclusions:The diet of infants with exclusion of cow’s milk protein was adequate despite the delay in the introduction of some complementary foods. Infants on an elimination cow’s milk protein diet showed lower linear growth without weight deficit.

Composição centesimal e comportamento reológico do extrato de aveia (Avena sativa)

O presente estudo tem como objetivo obter o extrato hidrossolúvel da aveia, determinar a sua composição centesimal e o seu comportamento reológico. O extrato hidrossolúvel foi obtido a partir da imersão dos flocos de aveia em água (70 °C) na proporção 1:3 (aveia/água), durante 15 minutos. O extrato foi caracterizado quanto aos seguintes parâmetros: umidade, atividade de água, sólidos totais, cinzas, proteínas, lipídeos, fibras e carboidratos; para leitura da viscosidade foi utilizado um viscosímetro de Brookfield, modelo DVII+Pro utilizando o splidlen nº 2 com as seguintes rotações: 50, 60, 70, 80, 100, 120, 140 rpm. Através da composição centesimal, percebeu-se que o extrato de aveia apresentou um alto teor de água, baixos valores de cinzas e moderados valores de proteínas, lipídeos e fibras; o aumento da velocidade de rotação acarretou um aumento da viscosidade aparente, o que dificulta o escoamento e a troca de calor durante processos térmicos; o extrato de aveia apresentou comportamento de um fluido não newtoniano com características de plástico de Bingham na temperatura analisada neste trabalho. Sendo portanto, uma ótima alternativa como ingrediente para preparações e dietas isentas de lactose e proteína do leite.

Degree of Dietary Refinement Alters Apparent Gut Permeability

Previous studies in our lab showed less refined diets reduced gut permeability (GI‐p) as assessed by 4hr plasma FITC‐dextran (FITC‐d) concentration in conjunction with reduced adiposity. To determine if degree of dietary refinement altered gut health and lipoprotein biology, we conducted a 14 week feeding trial in which weanling C57Bl/6 mice (n=15/diet) were fed one of four diets differing in dietary protein source (soy or milk protein) and degree of refinement. All diets provided 20%EN PRO, 30% EN fat, and 50% EN CHO. Purified diets contained either isolated soy protein (ISP) or dried whole milk powder (DWMP) as the protein source, while non‐purified diets contained either soybean meal (SPC), or dried whole milk powder (DMC) as protein sources. Purified diets contained 14% neutral detergent fiber (NDF) as cellulose, while non‐purified soy and milk protein diets provided 11.4% and 8.4% NDF, respectively, from wheat middlings, corn, corn gluten meal and soybean meal (SPC diet). All diets provided an average 3.3 %N as analyzed by Rapid N‐cube (Elementar, Germany). Mice fed purified diets were heavier than those fed non‐purified diets, with ISP‐fed mice being heaviest (p&lt;0.033). Mice consumed similar amounts of energy in the different diets. Fecal %N was significantly increased in the non‐purified SPC‐ and DMC‐fed mice (2.99%, 2.98% respectively), being almost double that of ISP or DWMP (1.52%, 1.76%; p&lt;0.000). At week 12, apparent GI‐p was highest in ISP‐fed mice (12.8 ng/mL), being significantly increased over DMC (8.96 ng/mL; p&lt;0.02). Purified diet feeding resulted in increased apparent GI‐p, regardless of protein source (12.1 ng/mL vs. 9.56 ng/mL; p&lt;0.004). Whole‐gut transit time averaged 2.5 hours longer for mice fed purified diets (6.6 hrs vs. 4.1 hrs, p&lt;0.0001). Division of the value of 4 h FITC concentration used as the GI‐p index, by gut transit time, abolished differences due to diet purification; raising the possibility, that gut permeability per se did not differ among dietary groups. Consistent with this, cytokines (TNF‐a, IL‐1b, IL‐6, IL‐10) measured in whole blood and intestine explants were generally low and non‐indicative of either tissue or systemic inflammation. Density distributions of NBD‐stained lipoproteins showed that diets containing milk protein increased lipoproteins of d &lt; 1.019 g/mL (TRL) (3.44% v. 5.4%) and HDL (d = 1.063 – 1.18 g/mL) (64.2% v. 60.6%) and decreased LDL (d=1.019–1.063 g/mL) (30.5% v. 36.0%, p&lt;0.04). Compared to all other diets, mice fed ISP had a 30% increase in small dense LDL (d=1.05 – 1.063 g/mL) (p&lt;0.000) and a ~ 4.0% decrease in HDL‐2b (d = 1.063–1.091 g/mL) (p&lt;0.000). Increasing FITC‐d concentrations in plasma were significantly associated with decreases in %TRL (p&lt;0.0127). In diets providing macronutrient distributions following the USDA's Dietary Guidelines for Americans, degree of purification seemingly has a greater effect on GI‐P, motility, and nitrogen utilization than protein source, while milk protein‐containing diets resulted in improved lipoprotein profiles regardless of purification.Support or Funding InformationThis project was supported in part by Texas AgriLife Research [Project 8738, R.L.W.)This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Fast digestive, leucine-rich, soluble milk proteins improve muscle protein anabolism, and mitochondrial function in undernourished old rats.

One strategy to manage malnutrition in older patients is to increase protein and energy intake. Here, we evaluate the influence of protein quality during refeeding on improvement in muscle protein and energy metabolism. Twenty-month-old male rats (n = 40) were fed 50% of their spontaneous intake for 12 weeks to induce malnutrition, then refed ad libitum with a standard diet enriched with casein or soluble milk proteins (22%) for 4weeks. A 13C-valine was infused to measure muscle protein synthesis and expression of MuRF1, and MAFbx was measured to evaluate muscle proteolysis. mTOR pathway activation and mitochondrial function were assessed in muscle. Malnutrition was associated with a decrease in body weight, fat mass, and lean mass, particularly muscle mass. Malnutrition decreased muscle mTOR pathway activation and protein FSR associated with increased MuRF1 mRNA levels, and decreased mitochondrial function. The refeeding period partially restored fat mass and lean mass. Unlike the casein diet, the soluble milk protein diet improved muscle protein metabolism and mitochondrial function in old malnourished rats. These results suggest that providing better-quality proteins during refeeding may improve efficacy of renutrition in malnourished older patients.

Precalving and early lactation factors that predict milk casein and fertility in the transition dairy cow

Multiparous Holstein cows (n=82) of either high or low genetic merit (GM) (for milk fat + protein yield) were allocated to 1 of 2 diets in a 2×2 factorial design. Diets differed in the ratio of rumen-undegradable protein (RUP) to rumen-degradable protein (37% RUP vs. 15% RUP) and were fed from 21 d precalving to 150 days in milk. This study evaluated the effects of these diets and GM on concentrations of milk casein (CN) variants and aimed to identify precalving and early lactation variables that predict milk CN and protein yield and composition and fertility of dairy cows. It explored the hypothesis that low milk protein content is associated with lower fertility and extended this hypothesis to also evaluate the association of CN contents with fertility. Yields (kg/d) for CN variants were 0.49 and 0.45 of α-CN, 0.38 and 0.34 of β-CN, 0.07 and 0.06 for κ-CN, and 0.10 and 0.09 of γ-CN for high- and low-RUP diets, respectively. Increased RUP increased milk, CN, and milk protein yields. Increased GM increased milk protein and γ-CN yields and tended to increase milk CN yield. The effects of indicator variables on CN variant yields and concentrations were largely consistent, with higher body weight and α-amino nitrogen resulting in higher yields, but lower concentrations. An increase in cholesterol was associated with decreased CN variant concentrations, and disease lowered CN variant yield. A diet high in RUP increased proportion of first services that resulted in pregnancy from 41 to 58%. Increased precalving metabolizable protein (MP) balance decreased the proportion of first services that resulted in pregnancy when evaluated in a model containing CN percentage, milk protein yield, diet, and GM. This finding suggests that the positive effects of increasing dietary RUP on fertility may be curvilinear because cows with a very positive MP balance before calving were less fertile than those with a lower, but positive, MP balance. Prepartum MP balance was important to production and reproductive outcomes, but surprisingly, metabolizable energy balance was not. The hazard of pregnancy in the first 150 d of lactation was 28% lower in cows producing milk with the lowest quartile of protein percentage compared with cows with milk in the upper 3 quartiles. Milk CN percentage was positively associated with improved pregnancy at first service. This study demonstrates the importance of protein metabolism to reproductive performance of the dairy cow.

Effects of skim milk powder intake and treadmill training exercise on renal, bone and metabolic parameters in aged obese rats.

Purposewe aim to examine whether adding exercise has impact on obesity prevention and bone metabolism in senior rats, to which dietary obesity was induced through skim milk intake.MethodsWe used 47, 14-week old Sprague -Dawley (SD) female rats (CLEA Japan, Inc.). The Rats were separated into four random groups: 1) a Non-Ex group with a normal diet (n = 12), 2) an Ex group with a normal diet (n = 12), 3) a Non-Ex group with a skim milk diet (n = 11), and 4) an Ex group with a skim milk diet (n = 12). As the exercise for each Ex group, rats ran on a treadmill starting at 27-week old (TREADMILL CONTROL LE8710 and TREADMILL CONTROL LE8700, Harvard Bioscience). Training protocol stipulated a frequency of five times a week for 12 weeks.ResultsThe leptin concentration differed with dietary content: compared to the Ex group with a skim milk diet, Non-Ex and Ex groups with a normal diet showed significantly higher values (p < 0.05). The Ex group had significantly lower values in both the normal diet and skim milk diet groups with or without exercise (p < 0.05). Compared to the Non-Ex group with a normal diet, BS/BV (mm2/mm3), BV/TV (%), Tb.Th (μm), TBPf (/mm) and Tb.N (/mm) had significantly lower in the Ex group, the Ex and Non-Ex groups with a whey protein diet, and the Ex group with a skim milk protein diet (p < 0.05).ConclusionThese findings suggest that senior female rats fed SMP would have higher bone structural and strength parameters than rats fed a normal diet.

First-pass uptake and oxidation of glucose by the splanchnic tissue in young goats fed soy protein-based milk diets with or without amino acid supplementation: Glucose metabolism in goat kids after soy feeding

The study was designed to examine whether feeding soy protein isolate as partial replacement of casein (CN) affects glucose metabolism in young goats and whether effects may be ameliorated by supplementation of those AA known to be lower concentrated in soy than in CN. Goat kids (d 20 of age) were fed comparable milk protein diets, in which 50% of the crude protein was either CN (control, CON), soy protein isolate (SPI), or soy protein isolate supplemented with AA (SPIA) for 43d (n=8 per group). On d 62 of age, a single bolus dose of d-[13C6]glucose (10mg/kg of BW) was given with the morning diet, and simultaneously, a single bolus dose of d-[6,6-2H2]glucose (5mg/kg of BW) was injected into a jugular vein. Blood samples were collected between −30 and +420min relative to the tracer administration to measure the 13C and 2H enrichments of plasma glucose and the 13C enrichment of blood CO2. Glucose first-pass uptake by the splanchnic tissues was calculated from the rate of appearance of differentially labeled glucose tracer in plasma. Glucose oxidation was calculated from 13C enrichment in blood CO2. In addition, plasma concentrations of triglycerides, nonesterified fatty acids, glucose, insulin, and glucagon were measured. On d 63 of age, kids were killed and jejunal mucosa and liver samples were collected to measure lactase mRNA levels and lactase and maltase activities in the jejunum and activities of pyruvate carboxylase and phosphoenolpyruvate carboxykinase (PEPCK) in the liver. Basal plasma glucose concentration tended to be higher in the CON than the SPIA group, whereas basal insulin was higher in the CON group than the SPI and SPIA groups, and glucagon was higher in the CON than the SPIA group. Plasma glucose and insulin concentrations increased during the first hour after feeding, whereas plasma glucagon increased immediately after feeding and after 1h of feeding. First-pass uptake and glucose oxidation were not affected by diet. Maltase activities in proximal and mid jejunum and lactase activities in mid jejunum were lower in the CON than in the SPIA group. Activities of PEPCK were higher in the SPIA than in the SPI group. In conclusion, feeding milk diets with soy protein isolate seems to affect glucose status in kids, but has no effect on first-pass uptake and oxidation of glucose. The highest activities of lactase and maltase were observed after supplementation with AA. Higher PEPCK activities in the liver may point at elevated gluconeogenic activities after AA supplementation in soy-fed kids.

Effects of a supra-sustained gelatin–milk protein diet compared with (supra-)sustained milk protein diets on body-weight loss

Diets higher in protein content result in increased satiety and energy expenditure. In the short term, gelatin showed stronger hunger suppression and less subsequent energy intake compared with other proteins. The present study investigated whether a supra-sustained gelatin-milk protein (GMP) diet promotes weight loss compared with a sustained milk protein (SMP) diet and a supra-sustained milk protein (SSMP) diet during an 8-week diet period. A total of seventy-two healthy subjects (31·2 (sd 4·8)kg/m2; 43 (sd 10) years) followed one of the three diets in a subject-specific amount: SMP, SSMP or GMP diet. During weeks 1-4, energy intake was 100% of individual energy requirement: 10, 40 and 50% of energy (En%) as protein, fat and carbohydrate, respectively (SMP diet), and 20, 30 and 50En% as protein, fat and carbohydrate, respectively (SSMP diet or GMP diet). During weeks 5-8, energy intake was 33% of individual energy requirement: 30, 35 and 35En% as protein, fat and carbohydrate, respectively (SMP diet), and 60, 5 and 35En% as protein, fat and carbohydrate, respectively (SSMP diet or GMP diet). Thus, absolute protein intake was kept constant throughout per subject. Significant decreases in BMI (P<0·0001) were similar between the GMP (-1·7 (sd 0·5)kg/m2) and the SMP (-2·1 (sd 0·8)kg/m2) and SSMP (-1·6 (sd 0·5)kg/m2) diets. Decreases in fat-free mass (FFM), fat mass (FM) and FM%, and increases in FFM% were similar between the GMP and both control diets. Changes in RQ differed (P<0·05) between the GMP (-0·01 (sd 0·06)) and SSMP (-0·04 (sd 0·04)) diets. Changes in HDL concentrations differed (P<0·05) between the GMP (-0·21 (sd 0·18)mmol/l) and the SMP and SSMP diets (-0·08 (sd 0·18)mmol/l and -0·09 (sd 0·26)mmol/l, respectively). In conclusion, a gelatin-milk protein diet does not induce more beneficial effects during an 8-week weight-loss period compared with a SMP or SSMP diet.

Morphology, proliferation, and ribonucleic acid and fractional protein syntheses in the small intestinal mucosa of young goats fed soy protein-based diets with or without amino acid supplementation

The study was designed to examine whether feeding soy protein isolate as partial replacement of casein (CN) affects jejunal protein synthesis and whether effects may be ameliorated by supplementation of those AA known to be at lower concentrations in soy protein isolate than in CN. Goat kids (14 d) were fed comparable milk protein diets, in which 50% of the crude protein was CN (CAS), soy protein isolate (SPI), or soy protein isolate supplemented with AA (SPIA) for 43 d (n=8 per group). On d 42, plasma concentrations of protein, urea, and AA were measured before and after morning feeding. In the morning of d 43, [15N]RNA from yeast [13mg/kg of body weight (BW)] was given with the diet to measure the reutilization of dietary RNA precursors for mucosal RNA biosynthesis. Four hours later, an oral dose of l-[1-13C]leucine (180mg/kg of BW) was administered and blood samples were collected between −15 and +45min relative to tracer administration for analysis of plasma 13C α-ketoisocaproic acid and 13C recovery in blood CO2. Kids were killed 60min after the tracer application, and jejunal tissue was collected to determine mucosal morphology, cell proliferation, enzyme activities, RNA synthesis, and fractional protein synthesis rate. Plasma protein concentrations were higher in CAS than in SPI and SPIA. Plasma concentrations of Thr were higher in CAS than in SPI and SPIA, and those of Met were lower in SPI than in CAS and SPIA. In mid-jejunum, villus circumferences were higher in CAS than in SPI and SPIA, and villus height and villus height:crypt depth ratio were higher in CAS than in SPI. In mid-jejunum, mucosal protein concentrations were higher in CAS than in SPI and SPIA and mucosal activities of aminopeptidase N tended to be higher in CAS than in SPI, whereas activities of dipeptidyl peptidase IV tended to be lower in SPI than in SPIA. Activities of 5′ nucleotidase and xanthine oxidase were lower in CAS than in SPI. The 13C recovery in blood CO2 tended to be higher in SPI than in CAS. In mid-jejunum, 15N enrichment of RNA tended to be higher in CAS than in SPI, and 13C enrichment of protein-bound Leu was higher in SPI than in CAS. In mid-jejunum, the fractional protein synthesis rate tended to be higher in SPI than in CAS. Our results revealed changes in intestinal growth after soy protein feeding that were associated with effects on intestinal RNA and protein synthesis but that were not ameliorated by AA supplementation.

No long-term weight maintenance effects of gelatin in a supra-sustained protein diet

In the short-term, gelatin showed stronger hunger suppression and less energy intake compared with other proteins. This study investigated if a supra-sustained gelatin–milk protein (GMP) diet improves weight maintenance (WM) compared with a sustained milk protein (SMP) diet and supra-sustained milk protein (SSMP) diet during a 4-months WM period after 8-week weight loss (WL) in sixty-five healthy subjects (28.6 ± 3.4 kg/m 2; 44 ± 10 years). Absolute protein intake was kept constant (sustained) throughout per subject. Diets were: protein(P)/fat(F)/carbohydrate(C): 15/40/45% of energy (En%) (SMP) and 30/25/45 En% (SSMP or GMP) for weeks 9–16. Diets on weeks 17–24: P/F/C: 30/35/35 En% (SMP) and 60/5/35 En% (SSMP or GMP). From weeks 8 to 16, and weeks 16 to 24, changes in BMI were similar between the GMP (− 0.4 ± 0.6 and 0.3 ± 0.7 kg/m 2 respectively), and the SMP (− 0.7 ± 0.9 and 0.1 ± 0.7 kg/m 2 respectively) and SSMP (− 0.6 ± 0.6 and 0.3 ± 0.6 kg/m 2 respectively) diets. Sparing of fat free mass (FFM): increases/decreases in FFM%/fat-mass% from weeks 8 to 16 were similar between the GMP and both control diets, and maintained from weeks 16 to 24. In conclusion, all 3 diets resulted in a successful WM period, while a GMP diet does not improve body weight maintenance and related variables after weight loss compared with a SMP and SSMP diet.

Selenium-enriched milk proteins and selenium yeast affect selenoprotein activity and expression differently in mouse colon

Certain forms of dietary Se may have an advantage in improving Se status and reducing cancer risk. The present study compared the effects of an Se-enriched milk protein product (dairy-Se) with an Se yeast (yeast-Se) on selenoprotein activity and expression in the mouse colon. Mice were fed four diets for 4 weeks: a control milk protein diet (Se at 0.068 parts per million (ppm)), dairy-Se diets with Se at 0.5 and 1 ppm, and a yeast-Se diet with Se at 1 ppm. Cytosolic glutathione peroxidase-1 (GPx-1) activity, mRNA of selenoprotein P (SeP), GPx-1, gastrointestinal glutathione peroxidase-2 (GPx-2) and thioredoxin reductase-1 (TrxR-1) were examined in the mouse colon. Dairy-Se diets did not significantly affect GPx-1 mRNA and GPx-1 activity but produced a dose-dependent increase in SeP and GPx-2 mRNA, with a significantly higher level achieved at 1 ppm Se (P < 0.05). Yeast-Se at 1 ppm significantly increased GPx-1 mRNA and GPx-1 activity (P < 0.01) but not GPx-2 mRNA. Neither Se supplement had any effect on TrxR-1. The present study indicates that selenoprotein levels in the mouse colon are regulated differently depending on the Se supplement. As we have previously shown that dairy-Se at 1 ppm was protective against colorectal cancer (CRC) in an azoxymethane-induced CRC mouse model, this up-regulation of colonic GPx-2 and SeP with Se supplementation may be crucial to its chemopreventive action.

Changes in Hypothalamic a‐MSH in Rats Fed a High Whole Milk Protein Diet

The melanocortin system has been suggested to contribute to an increase in satiety associated with consumption of a high protein diet. To test this association, male Wistar rats were fed isocaloric diets containing either 14% (n=13) or 55% (n=8) whole milk protein (WMP) for two weeks. On day 14, food was removed during the light phase and returned at dark onset. Rats in lower protein group were provided with either the same diet (P14/P14, n=7) or the higher protein diet (P14/P55, n=6). All rats on the higher protein diet continued to receive that diet (P55/P55). Food intake was measured after 2 hr, at which time rats were euthanized and brains rapidly removed and frozen. Hypothalami were dissected and homogenized before measuring a‐MSH and orexin by RIA. During the 14 day prefeeding period, food intake for P55 was 18% lower than P14 (p&lt;0.01); however, the amount of food consumed the 2 hr prior to euthanasia was similar (p=0.18) for all groups. There were no differences among groups in orexin (p=0.57). a–MSH concentrations (pg/mg protein) were also similar (p=0.16) among groups, though tended to be lower in rats fed the higher protein diet (P14/P14 = 36.5 ± 2.7 vs. P55/P55 = 28.7 ± 3.4) and intermediate in the P14/P55 group (33.1 ± 1.2). These results do not support an increase in a‐MSH activity contributing to greater satiety of a high protein diet when the protein source is WMP. Supported by the College of ACES James Scholar Honors Program.

Sex differences in the renal handling of protein from high casein and high soy diets in mice

Soy protein diet appears to reduce the rate of chronic kidney disease (CKD) compared to milk protein diet. The purpose of this study was to compare high soy with high casein consumption on protein excretion in mice. The study contained two exact protocols – one with males and one with females. Each protocol began with 25‐day old mice in metabolic cages. One group consumed 40% casein and the other consumed an isocaloric 40% soy diet for 25 days (n=6 per group). Daily measurements included food intake and protein excretion. In both protocols, the casein group excreted more protein (mg/day) than the soy group as measured on the 25th day (males: 22.9±2.5 vs 12.7±.9, p&lt;.009; females: 10.2±1.7 vs 5.4±8, p&lt;.03). Daily urine protein determined via urinalysis strips supported these differences. Females excreted significantly less protein compared to males despite equal protein consumption. We conclude that high soy intake induces less proteinuria compared to high casein. Female mice excrete less protein compared to males either on high soy or high casein. These data support the benefits of soy protein in CKD patients and indicate sex differences in the renal handling of high protein diets.

An NMR-based metabonomic investigation on effects of milk and meat protein diets given to 8-year-old boys

The objective of the study was to investigate the ability of an NMR-based metabonomic approach, applied to biofluids, to explore and identify overall exogenous and endogenous biochemical effects of a short-time high intake of milk protein or meat protein given to prepubertal children, the aim being to compare relative differences and not an absolute quantification. A total of twenty-four 8-year-old boys were asked to take 53 g protein as milk (n 12) or meat daily (n 12). At baseline and after 7 d, urine and serum samples were collected and high-resolution 1H NMR spectra were acquired on these using a 800 MHz spectrometer. The milk diet reduced the urinary excretion of hippurate, while the meat diet increased the urinary excretion of creatine, histidine and urea. The NMR measurements on serum revealed minor changes in the lipid profile, which most probably should be ascribed to an increase in the content of SCFA in the blood after consumption of the milk diet. The meat diet had no effect on the metabolic profile of serum. The study for the first time demonstrates the capability of proton NMR-based metabonomics to identify the overall biochemical effects of consumption of different animal proteins. The urine metabolite profile is more susceptible to perturbations as a result of short diet interventions than the serum metabolite profile. The milk diet-induced reduction in urinary excretion of hippurate suggests alterations in gut microflora, which may be useful information for further studies elucidating the effects of bioactive components in milk.

Yeast Proteins Enhance Satiety in Rats

This study was designed to characterize the suppressant effect of yeast protein and purified peptides on energy intake. For this purpose, 5 experiments were carried out using adult male Wistar rats. Rats that consumed ad libitum a standard yeast protein diet ate significantly less and were leaner over 21 d than rats that consumed ad libitum a standard milk protein diet (Expt. 1). Moreover, rats fed a high yeast protein load reduced their next meal and daily energy intake more than rats fed any other well-balanced, amino acid, high protein load (soy, total milk protein, or wheat gluten) and more than those fed a wheat starch diet (Expt. 2). Purified peptides from the yeast protein extract produced similar effects on subsequent energy intake (Expt. 3). Study of the behavioral satiety sequence showed that rats consuming P14-y or P55-y diets ad libitum did not acquire a conditioned food aversion (Expt. 4). Finally, a preliminary study of gastric emptying in rats fed yeast protein loads showed that yeast protein was emptied more rapidly through the pylorus than total milk protein during a meal, which may induce satiety (Expt. 5). Taken together, these experiments show that yeast proteins enhance satiety in rats more than other proteins.

Taking a bite out of hypertrophic cardiomyopathy: soy diet and disease

Some forms of hypertrophic cardiomyopathy (HCM) are caused by mutations in cardiac sarcomeric genes, but environmental factors are believed to influence the hypertrophic response. A highly variable but potentially significant environmental factor is diet. Since soy-rich diets have been speculated to confer protection against cardiovascular disease, Stauffer et al. have explored the influence of a soy diet on cardiac growth and function in a transgenic mouse model of HCM. They report that mice fed a soy diet exhibited significantly worse HCM than mice fed a soy-free (milk protein) diet. This study provides the first evidence of an environmental modifier--diet--on the hypertrophic phenotype and has implications for the way in which disease phenotypes are assessed in genetically altered murine models of disease.

Short-Term Soy and Probiotic Supplementation Does Not Markedly Affect Concentrations of Reproductive Hormones in Postmenopausal Women with and Without Histories of Breast Cancer

Observational studies suggest that dietary isoflavones reduce breast cancer risk, and this may be caused in part by effects on endogenous hormone concentrations. Because intestinal bacteria metabolize isoflavones, it was hypothesized that consumption of probiotic bacteria would enhance the biologic effects of isoflavones, including effects on endogenous hormones. Twenty (20) postmenopausal breast cancer survivors and 20 healthy postmenopausal women completed four 42-day diet periods in a randomized, crossover design. They received one of the following: isolated soy protein; isolated milk protein; soy + probiotic capsules; or milk + probiotic capsules. Each protein supplement provided 0.38 g protein/(kg body weight/day) (26.6 +/- 4.5 g protein/day) and soy protein provided 0.64 mg isoflavones/(kg body weight/day) (44.4 +/- 7.5 mg isoflavones/day). Probiotic capsules provided 10(9) colony-forming units Lactobacillus acidophilus (strain DDS-1), Bifidobacterium longum, and 15-20 mg fructo-oligosaccharide. Plasma samples were collected at baseline and after each diet for analysis of estrogens, follicle-stimulating hormone (FSH), androgens, and sex hormone?binding globulin (SHBG). Hormone levels were not affected by soy, probiotic supplements, or equol producer status, and neither cancer status nor equol producer status altered the effects of soy or probiotics. Furthermore probiotics did not alter the effects of soy consumption. Soy protein tended to decrease SHBG compared to milk protein diets (p = 0.05), although both proteins significantly decreased SHBG relative to baseline (p = 0.0001 and p = 0.03). These data suggest that short-term, moderate consumption of isoflavone-containing soy protein and consumption of these particular probiotic capsules do not significantly alter reproductive hormone concentrations in breast cancer survivors or controls, regardless of equol producer status.

A high-protein diet enhances satiety without conditioned taste aversion in the rat

In order to determine the respective roles of conditioned food aversion, satiety and palatability, we studied behavioral responses to a 50% total milk protein diet, compared with those to a normal protein diet containing 14% total milk protein. Different paradigms were employed, including meal pattern analysis, two-choice testing, flavor testing, a behavioral satiety sequence (BSS) and taste reactivity. Our experiments showed that only behavioral and food intake parameters were disturbed during the first day when an animal ate the high-protein (P50) diet, and that most parameters returned to baseline values as soon as the second day of P50. Rats adapted to P50 did not acquire a conditioned taste aversion (CTA) but exhibited satiety, and a normal BSS. The initial reduction in high-protein diet intake appeared to result from the lower palatability of the food combined with the satiety effect of the high-protein diet and the delay required for metabolic adaptation to the higher protein level.

Sensitization to cow's milk proteins during refeeding of guinea pigs recovering from polydeficient malnutrition.

We have previously shown that milk sensitization aggravates intestinal dysfunction in the malnourished guinea pigs, suggesting that it may also impair the recovery from malnutrition. To test this hypothesis, the growing guinea pigs were malnourished by feeding only maize for 7 d and then were refed for 21 d with a balanced diet containing either intact or hydrolyzed cow's milk proteins. The control animals received the hydrolyzed milk protein diet for 28 d. After an initial period of total inhibition of growth owing to maize, guinea pigs gained weight regularly, with both balanced diets, and there was no evidence of mucosal damage at the end of the refeeding period. However, refeeding with intact milk proteins induced milk sensitization, which was demonstrated on the systemic level by the presence of anti-beta-lactoglobulin IgG1 antibodies, and on the local level by the intestinal anaphylaxis measured by the increase in short circuit current induced by beta-lactoglobulin (16.4 +/- 2.6 microA/cm2) in jejunal segments mounted in Ussing chambers. Such an immune sensitization was associated with impaired intestinal permeability, as both the ionic conductance (21.0 +/- 1.6 versus 14.6 +/- 0.7 mS/cm2) and the transepithelial fluxes of horseradish peroxidase (537 +/- 203 versus 152 +/- 28 ng/h x cm2) were significantly increased in guinea pigs refed with the intact milk proteins compared with controls. In contrast, there was no difference in intestinal permeability between controls and guinea pigs refed with the hydrolyzed milk protein diet. These data show that sensitization to cow's milk proteins can develop in guinea pigs recovering from severe malnutrition and may impair full intestinal repair.