Soy-based Diet Research Articles

Conversion of protein from supplements into protein of hemolymph and fat bodies in worker honey bees (Apis mellifera L)

Adequate supplementation or replacement of pollen is necessary for maintaining healthy honey bee colonies during periods with limited pollen. Different supplemental protein diets could be metabolized in different ways by bees. We compared how protein supplements elaborated with free amino acids, with a soy-based diet, and with pollen, influence protein stores within individual honey bees. Caged bees were fed with one of three diets, and measurements were made based on protein content of hemolymph and fat bodies. The results show that these diets were metabolized in different way by bees. Bees fed with the free amino acid diet had significantly more proteins in hemolymph than bees fed with soya patty and pollen as they aged. The major amount of protein transported into the hemolymph by 27-day-old bees fed with free amino acid diet promoted the development of wax glands, and probably, it was the cause of a reduced storage of protein in fat bodies. Overall, our results suggest a connection between diets and physiological condition of honey bees.

The Effect of Reduced Dietary Fat and Soy Supplementation on Circulating Adipocytokines in Postmenopausal Women: A Randomized Controlled 2-Month Trial

ABSTRACTThe reduced risk of breast cancer observed in Asia has been linked with diets rich in soy foods, and observational studies suggest that regular soy food intake is related to lower circulating levels of some inflammatory markers which have been implicated in breast cancer risk. However, short-term intervention studies with soy-based diets in small numbers of women have shown few significant changes in adipocytokine levels. This 8-wk dietary intervention study in 57 healthy postmenopausal women investigated whether soy food supplementation (50 mg isoflavones or 15 g soy protein in the form of tofu) or a very low-fat diet (11.3% of total energy), similar to the traditional Asian diet, is associated with beneficial effects on serum levels of the following adipocytokines: TNF-α, IL-6, adiponectin, and resistin. We found no statistically significant changes in the levels of these adipocytokines in association with the very low-fat diet or soy supplementation. Only the change in TNF-α levels between the very low-fat and control diet groups had borderline statistical significance. We conclude that ingestion of a very low-fat diet or a soy food supplemented diet for 8 wk does not significantly alter important circulating adipocytokines.

Soy isoflavone metabolism in cats compared with other species: urinary metabolite concentrations and glucuronidation by liver microsomes

1. Soybean is a common source of protein in many pet foods. Slow glucuronidation of soy-derived isoflavones in cats has been hypothesized to result in accumulation with adverse health consequences. Here, we evaluated species’ differences in soy isoflavone glucuronidation using urine samples from cats and dogs fed a soy-based diet and liver microsomes from cats compared with microsomes from 12 other species.2. Significant concentrations of conjugated (but not unconjugated) genistein, daidzein and glycitein, and the gut microbiome metabolites, dihydrogenistein and dihydrodaidzein, were found in cat and dog urine samples. Substantial amounts of conjugated equol were also found in cat urine but not in dog urine.3. β-Glucuronidase treatment showed that all these compounds were significantly glucuronidated in dog urine while only daidzein (11%) and glycitein (37%) showed any glucuronidation in cat urine suggesting that alternate metabolic pathways including sulfation predominate in cats.4. Glucuronidation rates of genistein, daidzein and equol by cat livers were consistently ranked within the lowest 3 out of 13 species’ livers evaluated. Ferret and mongoose livers were also ranked in the lowest four species.5. Our results demonstrate that glucuronidation is a minor pathway for soy isoflavone metabolism in cats compared with most other species.

The role of diet and housing-temperature in the production of genetically modified mouse embryos and their developmental capacity after cryopreservation

Mutant mouse lines are unique models with an enormous scientific potential. Cryopreservation of preimplantation embryos or of spermatozoa is a common approach to save those lines. The breeding of a line can be discontinued if sufficient specimens have been cryopreserved. Prerequisites to economically cryopreserve embryos are high yields of embryos prepared from donors and a high recovery rate after revitalization. Diets for laboratory animals are often produced from phytoestrogen-containing soy; the present study shows that feeding the donor animals with a phytoestrogen-poor diet is more efficient compared to a phytoestrogen-containing, soy-based diet. Additionally, a uterotrophic bioassay indicating the estrogenic role of compounds showed a significant increase of the relative uterus size of females fed with a phytoestrogen-rich diet. The role of the housing-temperature was investigated, too, showing that a housing-temperature of 24 °C results in the best embryo yields. The production of two-cell embryos is more economic than the production of eight-cell embryos. Investigating the recovery rate of frozen/thawed embryos, a very high recovery rate was determined when both, two- and eight-cell embryos were thawed. However, the capacity to develop to the next embryonic stage in vitro was dramatically reduced when two-cell embryos were compared to eight-cell embryos. After embryo transfer, the sex ratio became uneven and more males were delivered. This effect might be due to the procedures to which animals and embryos were subjected. These data show that many parameters can influence the production of animals when using (frozen/thawed) embryos. These parameters need continuous surveillance.

High levels of dietary soy decrease mammary tumor latency and increase incidence in MTB-IGFIR transgenic mice.

BackgroundEpidemiologic data indicates that Asian diets, which are high in soy protein, reduce a women’s risk of developing breast cancer. However, it has been difficult to dissociate the benefits of soy from other variables including environmental and lifestyle factors. Since prospective studies in humans would take decades to complete, rodent models provide a valuable research alternative.MethodsIn this study, MTB-IGFIR transgenic mice, which develop mammary tumors resulting from overexpression of the type I insulin-like growth factor receptor (IGF-IR), were utilized. MTB-IGFIR mice were fed a soy-based or casein-based diet throughout all stages of development to reflect soy exposure in Asian cultures. Mammary tumors were initiated at 2 different developmental stages by commencing IGF-IR transgene expression either during puberty or in adult mice.ResultsMTB-IGFIR mice fed a soy-based diet displayed increased tumor incidence and accelerated tumor onset compared to MTB-IGFIR mice fed a casein diet. Two markers of estrogen receptor signaling, Pgr and Areg, were elevated in mammary tissue from mice fed the soy diet compared to mice fed the casein diet suggesting that high levels of soy may promote mammary tumor development through acting as an estrogen receptor agonist. Mammary tumors from mice fed a soy diet more frequently expressed metaplastic markers such as cytokeratins 5 and 14 as well as p63 and displayed reduced lung metastases compared to mammary tumors from mice fed a casein diet.ConclusionsDiets consisting of very high levels of soy protein promote mammary tumor development and decrease tumor latency possibly through activating estrogen receptor signaling. Additional studies are required to determine whether a more moderate amount of dietary soy can inhibit oncogene-induced mammary tumorigenesis.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1037-z) contains supplementary material, which is available to authorized users.

Fortification of dried distillers grains plus solubles with grape seed meal in the diet modulates methane mitigation and rumen microbiota in Rusitec

The role of dried distillers grains plus solubles (DDGS) and associative effects of different levels of grape seed meal (GSM) fortified in DDGS, used as both protein and energy sources in the diet, on ruminal fermentation and microbiota were investigated using rumen-simulation technique. All diets consisted of hay and concentrate mixture with a ratio of 48:52 [dry matter (DM) basis], but were different in the concentrate composition. The control diet contained soybean meal (13.5% of diet DM) and barley grain (37%), whereas DDGS treatments, unfortified DDGS (19.5% of diet DM), or DDGS fortified with GSM, either at 1, 5, 10, or 20% were used entirely in place of soybean meal and part of barley grain at a 19.5 to 25% inclusion level. All diets had similar DM, organic matter, and crude protein contents, but consisted of increasing neutral detergent fiber and decreasing nonfiber carbohydrates levels with DDGS-GSM inclusion. Compared with the soy-based control diet, the unfortified DDGS treatment elevated ammonia concentration (19.1%) of rumen fluid associated with greater crude protein degradation (~19.5%). Methane formation decreased with increasing GSM fortification levels (≥5%) in DDGS by which the methane concentration significantly decreased by 18.9 to 23.4 and 12.8 to 17.6% compared with control and unfortified DDGS, respectively. Compared with control, unfortified DDGS decreased butyrate proportion, and GSM fortification in the diet further decreased this variable. The proportions of genus Prevotella and Clostridium cluster XIVa were enhanced by the presence of DDGS without any associative effect of GSM fortification. The abundance of methanogenic archaea was similar, but their composition differed among treatments; whereas Methanosphaera spp. remained unchanged, proportion of Methanobrevibacter spp. decreased in DDGS-based diets, being the lowest with 20% GSM inclusion. The abundance of Ruminococcus flavefaciens, anaerobic fungi, and protozoa were decreased by the GSM inclusion. As revealed by principal component analysis, these variables were the microorganisms associated with the methane formation. Grape seed meal fortification level in the diet decreased DM and organic matter degradation, but this effect was more related to a depression of nonfiber carbohydrates degradation. It can be concluded that DDGS fortified with GSM can favorably modulate ruminal fermentation.

Transport of steroid hormones, phytoestrogens, and estrogenic activity across a swine lagoon/sprayfield system.

The inflow, transformation, and attenuation of natural steroid hormones and phytoestrogens and estrogenic activity were assessed across the lagoon/sprayfield system of a prototypical commercial swine sow operation. Free and conjugated steroid hormones (estrogens, androgens, and progesterone) were detected in urine and feces of sows across reproductive stages, with progesterone being the most abundant steroid hormone. Excreta also contained phytoestrogens indicative of a soy-based diet, particularly, daidzein, genistein, and equol. During storage in barn pits and the anaerobic lagoon, conjugated hormones dissipated, and androgens and progesterone were attenuated. Estrone and equol persisted along the waste disposal route. Following application of lagoon slurry to agricultural soils, all analytes exhibited attenuation within 2 days. However, analytes including estrone, androstenedione, progesterone, and equol remained detectable in soil at 2 months postapplication. Estrogenic activity in the yeast estrogen screen and T47D-KBluc in vitro bioassays generally tracked well with analyte concentrations. Estrone was found to be the greatest contributor to estrogenic activity across all sample types. This investigation encompasses the most comprehensive suite of natural hormone and phytoestrogen analytes examined to date across a livestock lagoon/sprayfield and provides global insight into the fate of these analytes in this widely used waste management system.

A hypothesis regarding the molecular mechanism underlying dietary soy-induced effects on seizure propensity.

Numerous neurological disorders including fragile X syndrome, Down syndrome, autism, and Alzheimer’s disease are co-morbid with epilepsy. We have observed elevated seizure propensity in mouse models of these disorders dependent on diet. Specifically, soy-based diets exacerbate audiogenic-induced seizures in juvenile mice. We have also found potential associations between the consumption of soy-based infant formula and seizure incidence, epilepsy comorbidity, and autism diagnostic scores in autistic children by retrospective analyses of medical record data. In total, these data suggest that consumption of high levels of soy protein during postnatal development may affect neuronal excitability. Herein, we present our theory regarding the molecular mechanism underlying soy-induced effects on seizure propensity. We hypothesize that soy phytoestrogens interfere with metabotropic glutamate receptor signaling through an estrogen receptor-dependent mechanism, which results in elevated production of key synaptic proteins and decreased seizure threshold.

Effect of taurine-enriched diets on the Hsp expression, MAPK activation and the antioxidant defence of the European sea bass (Dicentrarchus labrax)

This study aimed to identify and characterize the cellular and metabolic response in vital organs of Dicentrarchus labrax, after feeding on soy-based diets enriched with different taurine concentrations (T0.2, T0.5, T1.0 w/w). Molecular responses (expression of Hsp70, Hsp90, phosphorylation of p38 mitogen-activated protein kinase-p38MAPK and extracellular signal-regulated kinases-ERK1/2) were addressed. Metabolic and antioxidant capacities such as activities of citrate synthase (CS), malate and lactate dehydrogenase (MDH, L-LDH), superoxide dismutase (SOD), catalase (CAT) and levels of thiobarbituric acid-reactive substances (TBARS) were assessed. The most intense changes were detected in the liver and in the anterior intestine showing that taurine induces important protective biochemical mechanisms. Specifically, in the liver and the anterior intestine, Hsp and MAPK levels, as well as L-LDH activity levels were up-regulated under the effect of taurine diets. T diet had no major effect on the activity levels of CS, SOD and TBARS, except for MDH in the liver and catalase in the anterior intestine, where activity levels of these enzymes were increased under the effect of T0.2 and T1.0, respectively. These results may facilitate monitoring of adequate health status of farmed fish, exploiting the beneficial T effects and could assist at the formulation of aquaculture feeding strategies.

Dietary fish oil increases neutrophil development and recruitment to the colon in colitis‐prone mice (638.1)

Fish oil, containing n‐3 polyunsaturated fatty acids, is generally considered to have anti‐inflammatory and immune suppressing properties. We have previously shown that dietary fish oil rich in docosahexaenoic acid (DHA) resulted in exacerbated colon inflammation and progression to adenocarcinomas in Helicobacter hepacticus infected colitis‐prone mice. The objective of this study was to characterize the effect of dietary fish oil on colon inflammation and immune cell changes in the absence of infection in genetically colitis‐prone mice. We employed immunohistochemistry and flow cytometric analysis to characterized inflammatory cell development and infiltration in the colon of mice fed either 6% menhaden oil (MO) or a soy‐based control diet (CON). We observed increased neutrophil development in the bone marrow and spleen in MO compared to CON fed mice. Neutrophil percent in the colon increased from 1.6% in CON fed mice to 4.2% in MO fed mice. In addition, MO consumption altered the activation state and function of neutrophils. No differences in intestinal permeability as assessed by absorption of FITC‐dextran were observed, however fecal IgA increased with MO feeding. Interestingly, we observed differential responses to dietary fish oil depending on the gender of mice. Pre‐illness diet fatty acid content may have profound effects on IBD development in susceptible populations.Grant Funding Source: Supported by NIH RO3CA162427 to JIF

HUBUNGAN POLA DIET MAKANAN BERBASIS KEDELAI DENGAN KELUHAN GANGGUAN MENOPAUSE

Menopause is the process of cessation of menstruation permanently because of aging the ovary that is influential on secretions of estrogen, progesterone, and prostaglandins. Menopause result in condition vasomotor, cardiovascular, psychological and sexually will influence the quality of life woman. This condition necessary repairs through setting a diet of foods containing fitoestrogen an alternative as a substitute for estrogen natural. The purpose of this study is to see how the influence of soy-based food diet by female age group 51- 70 years against disturbances of menopause, especially disorders of cardiovascular disease by the method of Menopausal Rating Scale (MRS). This research using methods interview open observation lapangan kuisioner by method and menopausal rating scale. Data analyzed by employing correlation pearson through spss aid program. The results of data analysis of respondents indicated that there was no significant influence between consumption of especially food dna-based soybean with impaired complaint menopause. It is caused by the presence of factors of who also affecting, namely nutrition status, a disease that suffered and physical activity that is performed. The conclusion is consumption of especially food dna-based soybean only paid little influence against the minimization of disorder, complaints menopause because there were of factors of who participate in influence.

Testicular Development in Male Rats Is Sensitive to a Soy-Based Diet in the Neonatal Period1

Approximately 30% of infants in the United States are exposed to high doses of isoflavones resulting from soy infant formula consumption. Soybeans contain the isoflavones genistin and daidzin, which are hydrolyzed in the gastrointestinal tract to their genistein and daidzein aglycones. Both aglycones possess hormonal activity and may interfere with male reproductive development. Testosterone, which supports male fertility, is mainly produced by testicular Leydig cells. Our previous studies indicated that perinatal exposure of male rats to isoflavones induced proliferative activity in Leydig cells and increased testosterone concentrations into adulthood. However, the relevance of the neonatal period as part of the perinatal window of isoflavone exposure remains to be established. The present study examined the effects of exposure to isoflavones on male offspring of dams maintained on a casein-based control or whole soybean diet in the neonatal period, that is, Days 2 to 21 postpartum. The results showed that the soybean diet stimulated proliferative activity in developing Leydig cells while suppressing their steroidogenic capacity in adulthood. In addition, isoflavone exposure decreased production of anti-Müllerian hormone by Sertoli cells. Similar to our previous in vitro studies of genistein action in Leydig cells, daidzein induced proliferation and interfered with signaling pathways to suppress steroidogenic activity. Overall, the data showed that the neonatal period is a sensitive window of exposure to isoflavones and support the view that both genistein and daidzein are responsible for biological effects associated with soy-based diets.

Effects of Tomato and Soy on Serum Adipokine Concentrations in Postmenopausal Women at Increased Breast Cancer Risk: A Cross-Over Dietary Intervention Trial

Breast cancer risk among postmenopausal women increases as body mass index increases. Practical preventive methods to reduce risk of breast cancer are lacking. Few studies have investigated the effects of carotenoids and isoflavones on circulating adipokines in postmenopausal women. The aim was to examine the effects of lycopene- and isoflavone-rich diets on serum adipokines. This was a 26-week, two-arm, longitudinal crossover trial. Participants were recruited from clinics at The Ohio State University Comprehensive Cancer Center. Seventy postmenopausal women at increased breast cancer risk participated in the study. The mean age and body mass index of participants was 57.2 years and 30.0 kg/m(2), respectively; the study was comprised of 81.4% whites. The interventions included 10 weeks of consumption of a tomato-based diet (≥25 mg lycopene daily) and 10 weeks of consumption of a soy-based diet (≥40 g of soy protein daily), with a 2-week washout in between. Changes in serum adiponectin, leptin, and the adiponectin to leptin ratio were examined for each intervention through linear mixed models, with ratio estimates corresponding to postintervention adipokine concentrations relative to preintervention concentrations. After the tomato intervention, among all women, adiponectin concentration increased (ratio 1.09, 95% confidence interval (CI) 1.00-1.18), with a stronger effect observed among nonobese women (ratio 1.13, 95% CI 1.02-1.25). After the soy intervention, adiponectin decreased overall (ratio 0.91, 95% CI 0.84-0.97), with a larger reduction observed among nonobese women (ratio 0.89, 95% CI 0.81-0.98). Overall, no significant changes in leptin or the adiponectin to leptin ratio were observed after either intervention. Increasing dietary consumption of tomato-based foods may beneficially increase serum adiponectin concentrations among postmenopausal women at increased breast cancer risk, especially those who are not obese. Additional studies are essential to confirm these effects and to elucidate the specific mechanisms that may make phytonutrients found in tomatoes practical as breast cancer chemopreventive agents.

Dietary suppression of the mammary CD29hiCD24+ epithelial subpopulation and its cytokine/chemokine transcriptional signatures modifies mammary tumor risk in MMTV-Wnt1 transgenic mice

Diet is highly linked to breast cancer risk, yet little is known about its influence on mammary epithelial populations with distinct regenerative and hence, tumorigenic potential. To investigate this, we evaluated the relative frequency of lineage-negative CD29hiCD24+, CD29loCD24+ and CD29hiThy1+CD24+ epithelial subpopulations in pre-neoplastic mammary tissue of adult virgin MMTV-Wnt1-transgenic mice fed either control (Casein) or soy-based diets. We found that mammary epithelial cells exposed to soy diet exhibited a lower percentage of CD29hiCD24+Lin− population, decreased ability to form mammospheres in culture, lower mammary outgrowth potential when transplanted into cleared fat pads, and reduced appearance of tumor-initiating CD29hiThy1+CD24+ cells, than in those of control diet-fed mice. Diet had no comparable influence on the percentage of the CD29loCD24+Lin− population. Global gene expression profiling of the CD29hiCD24+subpopulation revealed markedly altered expression of genes important to inflammation, cytokine and chemokine signaling, and proliferation. Soy-fed relative to casein-fed mice showed lower mammary tumor incidence, shorter tumor latency, and reduced systemic levels of estradiol 17-β, progesterone and interleukin-6. Our results provide evidence for the functional impact of diet on specific epithelial subpopulations that may relate to breast cancer risk and suggest that diet-regulated cues can be further explored for breast cancer risk assessment and prevention.

First-limiting amino acids in soybean-based diets for white seabass Atractoscion nobilis

The present study aims to identify the limiting amino acids in low fish meal, soy-based diets in juvenile white seabass. Two 8-week trials were conducted. The first trial evaluated three diets containing 36, 18 and 9% fish meal in the diet (FM36, FM18, FM9, respectively), with the last two diets being supplemented with methionine and taurine. In the second trial, seven diets were formulated, including a high (36%) fish meal diet (HFM, similar to FM36) and five diets with medium (18%) fishmeal levels. These included an unsupplemented diet (MFM) and four with increasing levels of methionine (+M, +2M) and taurine (+2MT and +2M2T) supplementation. An additional diet was formulated with soy protein and poultry by-product meal to completely replace fish meal (PM). In trial 1, fish fed the FM18 diet grew significantly faster than fish fed the FM36 and FM9 diets. In trial 2, fish fed the +2M2T diet grew better than fish fed any other diets, and feed efficiency was highest in fish fed the +2M2T and PM diets. Fish fed the unsupplemented MFM diet had the lowest growth and feed efficiency. Methionine supplementation (+M and +2M) had a limited but significant effect on growth performance compared to MFM-fed fish. Fish fed the PM diet showed similar growth as those fed the +2MT and commercial diets, but was lower than +2M2T diet. Across both trials, growth rate was highly correlated with dietary taurine, except in diets containing less than 18% fish meal, i.e., diets PM and FM9. Both of these diets had equivalent or superior dietary taurine levels compared to diets +2M2T and FM18, but resulted in significantly poorer growth. This suggests that taurine is the first-limiting nutrient in feeds containing at least 18% fish meal while methionine was marginally deficient. In diets containing lower levels of fish meal however, methionine and taurine supplementation is ineffective; hence another (undetermined) nutrient became first-limiting. Additional research is necessary to identify this limiting nutrient, as well as determine the specific taurine requirement of WSB.

A review of the development and application of soybean-based diets for Pacific white shrimpLitopenaeus vannamei

The production of the Pacific white shrimp (Litopenaeus vannamei) has expanded to the point of being the most widely cultured species of shrimp. One of the advantages of this species is its acceptance of a wide variety of feed formulations including plant-based feeds. Given the increases in ingredient costs, particularly fish meal, there is considerable interest in the use of alternative feed formulations for cultured species. Given that soybean meal is one of the most widely available protein sources for which production can be expanded, the move to soy-based diets is inevitable. The successful use of alternative feed ingredients for shrimp production depends on a number of factors. This paper summarizes studies regarding the move towards high soy diets concerning manipulation of ingredients and nutrient profiles to maintain balanced feed formulations.

Separate feeding of calcium improves performance and ileal nutrient digestibility in broiler chicks

A total of 144 Cobb 500 broilers were used to investigate if modern commercial broilers could regulate their calcium (Ca) intake using choice feeding and whether separating the delivery of a portion of the Ca from the mixed ration would be advantageous for performance and nutrient recovery. Birds were fed corn+soy-based diets formulated to contain 2.5, 5.0, 7.5 or 10.0 g/kg total Ca and all groups had access to a separate Ca source (CaCO3). The trial was conducted from Day 1 to Day 21 and birds had ad libitum access to both the experimental diets and a separate Ca source throughout. Total feed and separate Ca intake were monitored daily, weight gain and feed intake weekly and on Day 21, the apparent ileal digestibility of DM, nitrogen, selected minerals and amino acids were determined. Consumption of the separate Ca source increased (P < 0.05) with decreasing total Ca concentration of the mixed ration. No differences (P > 0.05) in toe ash were found. Increasing dietary Ca concentration negatively influenced the apparent ileal digestibility of DM, nitrogen, minerals and amino acids. It can be concluded that broilers can select and consume Ca from a separate source to broadly maintain their requirement. Feeding a separate source of Ca in combination with reduced dietary Ca in the mixed ration had beneficial effects on nutrient digestibility, phosphorus excretion and performance.

Exploring the Soyfood Controversy

In Brief Despite their proposed health benefits and long history of consumption in Asia, soyfoods have become controversial. In recent years, the benefits of soy have been challenged, and concerns have been raised about possible adverse effects of soy consumption. Underlying most of the benefits and concerns is the presence of isoflavones (phytoestrogens) in soybeans. The evidence reviewed in this article indicates that soy consumption reduces risk of coronary heart disease and, if consumed early in life, potentially breast cancer. Concerns that soyfoods may be contraindicated for breast cancer patients and women at high risk of developing this disease are not supported by the clinical and epidemiologic evidence. The clinical evidence also does not support the notion that isoflavones or soyfoods feminize men. However, some question remains as to their effects in subclinical hypothyroid patients, although soyfoods do not adversely affect thyroid function in healthy subjects. The preponderance of the evidence indicates that for healthy individuals, with the exception of those relatively rare persons with allergies to soy protein, soyfoods can make important contributions to the diet. A look into a soy-based diet

Soy-Based Diet Exacerbates Seizures in Mouse Models of Neurological Disease

Seizures are a common phenotype in many neurological disorders including Alzheimer's disease, Down syndrome, and fragile X syndrome. Mouse models of these disorders overexpress amyloid-β protein precursor (AβPP) and amyloid-β (Aβ) and are highly susceptible to audiogenic-induced seizures (AGS). We observed decreased AGS in these mice fed a casein-based, purified diet (D07030301) as opposed to a standard soy protein-containing, non-purified diet (Purina 5015). Our objective in this manuscript was to determine if soy protein, and in particular soy isoflavones, in the Purina 5015 were contributing to the seizure phenotype. Wild running, AGS, and death rates were assessed in juvenile mice fed Purina 5015, D07030301, D07030301 containing soy protein, or D07030301 supplemented with individual isoflavones (750 mg/kg daidzein or genistein). A short treatment (3 days) with Purina 5015 induced wild running and AGS in Alzheimer's disease mice. A 3-day treatment with daidzein-supplemented diet, but not genistein, induced wild running in wild type mice. To understand the mechanism underlying daidzein activity, we assessed dendritic AβPP expression in primary, cultured, wild type neurons treated with daidzein or genistein. In vitro, daidzein significantly increased dendritic AβPP. Thus, the soy isoflavone daidzein recapitulated seizure induction in vivo and altered AβPP expression in vitro. These results have important implications for individuals on soy-based diets as well as for rodent model research.

Cadmium-induced oxidative stress and histological damage in the myocardium. Effects of a soy-based diet

Cd exposure has been associated to an augmented risk for cardiovascular disease. We investigated the effects of 15 and 100ppm of Cd on redox status as well as histological changes in the rat heart and the putative protective effect of a soy-based diet. Male Wistar rats were separated into 6 groups and treated during 60days as follows: groups (1), (2) and (3) were fed a casein-based diet; groups (4), (5) and (6), a soy-based diet; (1) and (4) were given tap water; (2) and (5) tap water containing 15ppm of Cd2+; and (3) and (6) tap water containing 100ppm of Cd2+. Serum lipid peroxides increased and PON-1 activity decreased in group (3). Lipoperoxidation also increased in the heart of all intoxicated groups; however protein oxidation only augmented in (3) and reduced glutathione levels diminished in (2) and (3). Catalase activity increased in groups (3) and (6) while superoxide dismutase activity increased only in (6). Glutathione peroxidase activity decreased in groups (3) and (6). Nrf2 expression was higher in groups (3) and (6), and MTI expression augmented in (3). Histological examination of the heart tissue showed the development of hypertrophic and fusion of cardiomyocytes along with foci of myocardial fiber necrosis. The transmission electron microscopy analysis showed profound ultra-structural damages. No protection against tissue degeneration was observed in animals fed the soy-based diet. Our findings indicate that even though the intake of a soy-based diet is capable of ameliorating Cd induced oxidative stress, it failed in preventing cardiac damage.