Soy Protein Consumption Research Articles

The effect of steamed tempeh on total and LDL cholesterol in Wistar-male rats

Introduction: The increase in total and LDL cholesterol is one of the major risk factors of atherosclerosis, which may cause coronary heart disease. Consumption of soy protein in place of animal protein may reduce levels of total and LDL cholesterol. Tempeh is made from fermented soybeans by Rhizopus oryzae sp., which is often consumed by Indonesian. The objective of this study was to determine the effect of 2.4 and 4.5 g steamed tempeh on level of total and LDL cholesterol. Method: The laboratory experimental study with completely randomised design was applied in this research. The 24 Wistar-male rats were divided into four groups (n = 6) during 4 weeks. Group I were fed standard diet (pellets), group II were fed high fat diet and Propyl thio uracil (PTU) 0.01%, group III were fed 2.4 g/day steamed tempeh, high fat diet, and PTU 0.01%, and group IV were fed 4.5 g/day steamed tempeh, high fat diet, and PTU 0.01%. The total and LDL cholesterol levels were measured on first day and 29th. Data were analyzed by One-way ANOVA, and followed by Post-Hoc using Duncan’s test with 95% confidence interval ( = 0.05%). Result: The study showed that steamed tempeh had significant value (p < 0.05) in reducing total and LDL cholesterol levels. There was no significant difference between 2.4 group and 4.5 group in percentage of reducing total and LDL cholesterol levels (p < 0.001%). The mean reduction of total cholesterol levels in group of 2, 4 g steamed-tempeh was 15.50 (5.08)mg/dL or 23.75%, and in the group of 4.5 steamed-tempeh was 19.5 (11.67)mg/dL or 27.71%, compared to 3.0 (1.09)mg/dl or 4.54% in the standard diet group, while the high fat diet group had increased by 13.83 (6.61)mg/dl or 20.38%. The mean reduction of LDL cholesterol in 2.4 g steamed-tempeh group was 9.33 (1.03)mg/dl or 56.15%, and the 4.5 g steamed-tempeh group was 11.00 (1.78)mg/dl or 64.06%, while the standard diet group and high fat diet group had increased by 0.16 (4.18)mg/dl or 1.52% and 13.5 (1.32)mg/dl or 14.4%, respectively. Conclusion: 2.4 and 4.5 g steamed tempeh per day reduced total and LDL cholesterol level, but there was no difference between the two groups in the percentage reduction in total and LDL cholesterol.

Soy Protein Supplementation May Play a Role in Decreasing the Risk of Bone Fracture through Affecting Hematopoietic Factors in Young and Old Men

Osteoporosis is a health problem which is associated with bone fracture and bone fragility. Bone loss is an accompaniment of aging which occurs at about age of 50 in men. Several studies have suggested that populations with high dietary soy intake have a lower prevalence of osteoporosis and bone fracture. Soy protein (SP) is a rich source of phytoestrogen which has been shown to diminish the loss of bone mineral density as well as decrease the risk of fracture. In this study, we have focused on 3‐month SP supplementation in young and old men in order to investigate the effect of SP on hematopoietic factors. Healthy men (59.2±17.6y) were assigned to consume 40g of either SP or milk‐based protein (MP) daily for 3 months in a double blind, randomized, controlled, paralleled design. ANOVA and paired t‐test were used to determine whether there were statistical significances in hematopoietic variables of interest. Red blood cells and hematocrit either increased (P=0.04) or tended to increase (P=0.09) in those who consumed SP, respectively. On the other hand basophil (BAS) value tended to increase (P=0.07) in those who were on MP diet. This suggests that MP may not be able to prevent the rise in BAS associated with aging. Increased apoptosis of BAS observed as a result of aging may be due to persistent inflammation. The findings of this study suggest that SP consumption may inhibit the age‐associate rise in certain hematopoietic parameters.

The Effects of Soy and Whey Protein Supplementation on Acute Hormonal Responses to Resistance Exercise in Men

Objective: For many resistance-trained men concerns exist regarding the production of estrogen with the consumption of soy protein when training for muscle strength and size. Thus, the purpose of this investigation was to examine the effects of soy and whey protein supplementation on sex hormones following an acute bout of heavy resistance exercise in resistance trained men. Methods: Ten resistance-trained men (age 21.7 ± 2.8 [SD] years; height 175.0 ± 5.4 cm; weight 84.2 ± 9.1 kg) volunteered to participate in an investigation. Utilizing a within subject randomized crossover balanced placebo design, all subjects completed 3 experimental treatment conditions supplementing with whey protein isolate (WPI), soy protein isolate (SPI), and maltodextrin placebo control for 14 days with participants ingesting 20 g of their assigned supplement each morning at approximately the same time each day. Following supplementation, subjects performed an acute heavy resistance exercise test consisting of 6 sets of 10 repetitions in the squat exercise at 80% of the subject's one repetition maximum. Results: This investigation observed lower testosterone responses following supplementation with soy protein in addition to a positive blunted cortisol response with the use of whey protein at some recovery time points. Although sex hormone binding globulin (SHBG) was proposed as a possible mechanism for understanding changes in androgen content, SHBG did not differ between experimental treatments. Importantly, there were no significant differences between groups in changes in estradiol concentrations. Conclusion: Our main findings demonstrate that 14 days of supplementation with soy protein does appear to partially blunt serum testosterone. In addition, whey influences the response of cortisol following an acute bout of resistance exercise by blunting its increase during recovery. Protein supplementation alters the physiological responses to a commonly used exercise modality with some differences due to the type of protein utilized.

Soy protein isoflavones differentially regulate liver X receptor isoforms to modulate lipid metabolism and cholesterol transport in the liver and intestine in mice

Liver X receptor (LXR)α regulates the genes involved in cholesterol, fatty acid and glucose metabolism. Soy protein (SP) consumption reduces the hepatic accumulation of cholesterol and triacylglycerol, and improves insulin sensitivity. However, it is not known whether these effects are mediated via LXRα. We therefore investigated whether the consumption of SP regulates metabolic changes in cholesterol metabolism and insulin sensitivity via LXRα. Wild-type (WT) and Lxrα(-/-) (Lxrα, also known as Nr1h3) mice were fed an SP diet with or without cholesterol for 28 days. The expression of LXRα target genes was measured in liver and intestine, as were hepatic lipid content and faecal bile acid concentration. Oral glucose and insulin tolerance tests were also performed. Hepatocytes were used to study the effect of isoflavones on LXR activity. The livers of WT and Lxrα(-/-) mice fed an SP high-cholesterol diet showed less steatosis than those fed casein. The SP diet increased the expression of the ATP-binding cassette (ABC) sub-family genes Abca1, Abcg5 and Abcg8 in the liver and intestine, as well as increasing total faecal bile acid excretion and insulin sensitivity in WT mice compared with mice fed a casein diet. However, these effects of SP were not observed in Lxrα(-/-) mice. The SP isoflavone, genistein, repressed the activation of LXRα target genes by T0901317, whereas it stimulated the activation of LXRβ target genes. The AMP-activated protein kinase inhibitor, compound C, had the opposite effects to those of genistein. Our results suggest that SP isoflavones stimulate the phosphorylation of LXRα or LXRβ, resulting in different biological effects for each LXR isoform.

Dietary soy protein induces hepatic lipogenic enzyme gene expression while suppressing hepatosteatosis in obese female Zucker rats bearing DMBA-initiated mammary tumors

Fatty liver is associated with obesity and breast cancer. We used an obese rat model of mammary cancer to examine whether hepatosteatosis is modifiable by diet and associated with altered expression of hepatic lipogenic enzyme genes, thyroid hormone system genes and cholesterol metabolism-related genes. Beginning at the age of 5weeks, lean and obese female Zucker rats were fed high-isoflavone soy protein- or casein (control protein)-containing diets. Rats were euthanized at 200days of age [corresponding to 147days after administration of carcinogen to induce mammary tumors; (Hakkak et al. in, Oncol Lett 2:29-36, 2011)]. Obese rats had a greater degree of liver steatosis than lean rats. Obese casein-fed rats had marked steatosis with small foci of mononuclear infiltration, whereas obese soy protein-fed rats had a significantly lower steatosis index. Comparisons between lean and obese casein-fed rats showed that obesity was associated with significant reductions in hepatic mRNA abundance for Glucose 6-Phosphate Dehydrogenase (G6PD), 6-Phosphogluconate Dehydrogenase (6PGD), Thyroid Receptor Alpha 1 (TRα1), Thyroid Receptor Beta 1 (TRβ1) and Iodothyronine Deiodinase 1 (DIO1). The soy protein diet was associated with increased expression of Fatty Acid Synthase (FASN), Malic Enzyme 1 (ME1), 6PGD, Sterol Regulatory Element Binding Protein-1c (SREBP-1c) and SREBP-2 genes in the livers of obese but not lean rats. Western blot analysis showed a significant induction of ME1 protein expression in the livers of obese, soy protein-fed rats, which paralleled the increased serum insulin level in this group. Long-term soy protein consumption can counter hepatic steatosis while coincidently promoting hepatic lipogenic gene expression, the latter likely a consequence of elevated serum insulin. We suggest that elevations in serum insulin, hepatic lipogenesis and cholesterol synthesis all contributed to the increased tumorigenesis previously observed for the obese, soy protein-fed rats.

Abstract 3563: Soy protein isolate consumption does not prevent biochemical failure after radical prostatectomy in high risk men: A randomized controlled trial

Abstract Epidemiologic and experimental data suggest that soy consumption may prevent prostate cancer and be beneficial for men with prostate cancer. Soy intake and risk of prostate cancer are inversely correlated; soy isoflavones inhibit growth of prostate cancer cells and reduce prostate carcinogenesis in animal models. We tested the hypothesis that soy consumption reduces biochemical recurrence after radical prostatectomy in a randomized controlled clinical trial with a soy protein supplement versus a casein-based placebo in men at increased risk for PSA failure in the first 2 years after radical prostatectomy. PSA was tested at 2-month intervals in year 1 and every 3 months in year 2. Eligibility criteria were: Gleason sum of &amp;gt;8, extra-capsular extension, seminal vesicle invasion, positive surgical margins, positive lymph nodes, and/or a preoperative PSA of &amp;gt;20 ng/ml. Biochemical recurrence was defined a priori as reaching a PSA value of α0.07 ng/ml, confirmed twice. A two-year PSA failure rate in eligible subjects of approximately 30% was expected, based on data from NYU and previous literature. With a planned sample size of 128 evaluable subjects per arm, the study had 80% power to detect a 50% reduction in PSA failure rate at a 2-sided significance level of 0.05. The soy protein isolate and placebo (generously provided by Solae LCC, St Louis, MO) were identical in composition, except for the protein source (19.2-19.8 g protein/day); the soy product provided daily 23.5 mg genistein and 40.9 mg total isoflavones (aglycone equivalents); the placebo was devoid of any soy-specific constituents. Accrual did not reach the intended level and 172 subjects were randomized and enrolled, of whom 142 were evaluable (completed two years on study or developed confirmed recurrence within two years). Soy protein consumption did not alter recurrence rate or time-to-recurrence (TTR). Of the 74 evaluable subjects in the soy arm 22 (30%) recurred as did 22 (32%) of the 68 subjects in the placebo arm recurred. The mean TTR was 40.7 + 29.3 (SD) weeks in the soy group and 44.5 + 28.0 weeks in men on placebo. Statistical analysis on intention-to-treat basis confirmed the absence of an effect on these primary endpoints. The drop-out rate was 17% and there were &amp;lt;5% missing values, none of which impacted the primary endpoints. Compliance by self-report was excellent and is being confirmed by serum isoflavone levels. There were no treatment-related adverse events, except a few cases of constipation. We previously ruled out effects of the intervention on anti-thyroid activity and iron status in a subset of subjects. Thus, soy consumption is safe, but unlikely to benefit men after radical prostatectomy, although the results of this study do not rule out preventive effects of soy prior to prostate cancer development. (Supported by NIH grants CA27790, CA166195 &amp; RR029879 and the Prevent Cancer Foundation) Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3563. doi:1538-7445.AM2012-3563

Soy Isoflavones and Cardiovascular Disease Epidemiological, Clinical and -Omics Perspectives

Cardiovascular disease (CVD) mortality rates are lower in Asian countries where dietary patterns are very different from Western diet. A number of studies have linked these lower rates to the inclusion of soy products as a staple food in those countries. Soy is the richest dietary source of isoflavones, a type of phytoestrogen associated with many potentially beneficial effects. Isoflavone-containing soy protein consumption has been linked to reduced levels of LDL cholesterol in hypercholesterolemic patients. This effect is increased with the concomitant administration of isoflavones, and seems to be also complemented by the isoflavone capacity to restore the endothelial function in patients with weak and moderated endothelial dysfunction. The effects are variable depending on individuals� � � metabolism and in particular to their ability to convert daidzein to equol that seems to be restricted to approximately 1/3 of the population. Equol production has been indeed linked to a decreased arterial stiffness and antiatherosclerotic effects via NO production. Because the relevance of isoflavones consumption on the modulation of cardiovascular risk still remains unclear, this paper aims to review the existing knowledge on the biological activity of the isoflavones on the human cardiovascular system from an epidemiological, clinical and -omics point of view.

Translocator Protein (TSPO) in Breast Cancer

Several molecular and cellular markers are currently used as prognostic indicators for diagnosis and therapeutic intervention of breast cancer. Although some of these markers have helped clinicians provide an earlier diagnosis (or prognosis), they have failed to provide adequate information about the mechanisms responsible for different stages of tumor malignancy so that more effective anticancer therapies can be developed. Recently translocator protein (TSPO), formerly known as the peripheral benzodiazepine receptor (PBR), has received attention as a potential target for anticancer drug development. It is a well-conserved protein, located at outer-inner mitochondrial membrane contact sites, and is expressed in almost all tissues, although the level of expression varies. TSPO is closely associated with the 32 kDa voltage-dependent anion channel (VDAC) and the 30 kDa adenine nucleotide translocase (ANT), considered to form the core of a mitochondria multiprotein complex [named the mitochondrial permeability transition pore (MPTP)] and plays a role in apoptotic cell death. As the major role of TSPO is steroid biosynthesis, TSPO expression is particularly high in organs involved in steroidogenesis such as the adrenals, testes, ovaries, placenta, prostate, colon, kidney, and cardiovascular system. It is well known that TSPO is over-expressed in highly aggressive tumors, especially those of the breast, and that expression correlates with advancing stages of this malignancy. TSPO expression, nuclear localization, and TSPO-mediated cholesterol transport into the nucleus are involved in breast cancer cell proliferation and aggressive phenotype expression. Hence, it can be used as a biomarker in the stage-dependent diagnosis of this cancer. In addition, cell proliferation, invasion and migration appears to be decreased when treated with high doses of TSPO ligand PK-11195, a compound that may represent a therapeutic agent for the control of breast cancer progression. Control of breast cancer development by consumption of dietary soy protein has been linked to down-regulation of the expression of TSPO-mediated angiogenic signaling molecules. This chapter provides insight into the potential of TSPO as a rational target for the development of novel therapeutics for breast cancer.

Study on Soy Isoflavone Consumption and Risk of Breast Cancer and Survival

Isoflavones in soy foods are part of a larger class of flayonoid compounds that have have been demonstrated to be potent dietary anti-cancer agents, and the effect of soy intake on the survival of ovarian cancer is conflicting. Therefore, we aimed to explore the whether soy intake is related to the risk of death of breast cancer. A prospective study was conducted. A total of 256 patients included in this study had breast cancer and were recruited between January 2004 and January 2006. All of them were followed up from since January 2011. A univariate Cox's regression analysis was used to assess the association between soy intake and survival. The education level, menopausal status, ER/PR status and TNM stage were significant difference in the survival of breast cancer. The highest soy isoflavone was associated with a decreased death risk of breast cancer (OR=0.25, 95% CI=0.09-0.54). Moreover, the higher consumption of soy protein also presented a trend decreased breast cancer risk, and the highest consumption significantly reduced the cancer risk compared with the lowest consumption (OR=0.38, 95% CI=0.17-0.86). The present study suggests soy intake is associated with a significant reduced death risk of breast cancer in Chinese population. Further large sample studies are warranted to confirm the inverse association of soy consumption and breast cancer survival by menopausal status.

Relationship of Dietary Soy Protein to Daidzein Metabolism by Cultures of Intestinal Microfloras from Monkeys

Soybeans have been shown to contain larger concentrations of isoflavones than other plant foods. The colonic micro-floras of some individuals metabolize isoflavones, including the soy phytoestrogen daidzein, to compounds with altered estrogenic activity that may affect health. Monkeys have been used as models to predict the effect of colonic microorganisms on the metabolism of phytoestrogens. We studied the effect of consumption of a diet rich in soy protein on the metabolism of added daidzein by the intestinal microfloras of monkeys. The metabolism of daidzein by cultures of the colonic microfloras from eight males and eight females of Macaca fascicularis, 6 - 12 years old, consuming diets containing either soy or casein, and two males and three females of Macaca nemestrina, 3 - 5 months old, consuming infant formula, was investigated using high-performance liquid chromatographic analyses. Cultures from ten of the 16 adult monkeys and all five infant monkeys metabolized the added daidzein within 24 h. Daidzein was metabolized within 48 h by cultures from five other monkeys, but it remained even after 72 h in a culture from one female monkey on a casein diet. Equol and dihydrodaidzein were the only metabolites found. Individual variation among monkeys in the efficiency of daidzein metabolism was observed, but there appeared to be no correlation between diet and daidzein metabolism by the intestinal microflora. The intestinal microfloras of most monkeys tested were efficient in the biotransformation of daidzein to equol, regardless of the animals’ consumption of soy protein. Differences in the metabolism of isoflavones by the colonic microfloras of humans and experimental animals should be considered when extrapolating results from animals to humans.

Development of Soy‐Based Bread with Acceptable Sensory Properties

Consumption of soy protein has been associated with benefits related to numerous areas of health. Due to the widespread consumption of bread, one means of contributing to the health of individuals is through the incorporation of soy protein into bread. To this end, soy flour (SF) or soy protein isolates (SPIs) in 20% and 12% substitution levels, respectively, were added to flour during bread manufacture. The developed breads were tested using a consumer panel for acceptability, using a refined white bread as a control. These data were compared to attribute intensity data collected by the trained panel to identify specific flavor and texture characteristics affecting liking. The sensory profile of the 20% SF bread was acceptable and comparable to the control bread, despite a significantly stronger beany flavor. No significant differences in sensory properties of the SF and control breads were detected by the trained panel for many sensory attributes. The SPI bread, however, had a sensory profile that was significantly more firm, dense, sour, beany, bitter, and astringent with a strong aftertaste in comparison to the wheat control bread. Consumer liking scores for the SPI bread was significantly lower than the liking of the control and the SF added bread. Many soy-enriched foods, while contributing positively to health, are considered unacceptable by consumers. This is due to negative sensory properties, such as beany, painty, and astringent notes, often perceived by consumers. This study provides information on the level of SF that can be included in bread in an amount that does not detract from consumer acceptability. This level also allows for a Food and Drug Administration (FDA) health claim to be made.

Glyceollin-Elicited Soy Protein Consumption Induces Distinct Transcriptional Effects As Compared to Standard Soy Protein

Glyceollins are stress-induced compounds in soybeans with bioactive properties distinct from parent soy isoflavones. The goals of this study were to evaluate the effects of dietary glyceollin-enriched and standard soy protein isolates and identify candidate target pathways of glyceollins on transcriptional profiles within mammary gland tissue. Thirty female postmenopausal cynomolgus monkeys were randomized to diets containing one of three protein sources for 3 weeks: (1) control casein/lactalbumin (C/L), (2) standard soy protein containing 194 mg/day isoflavones (SOY), and (3) glyceollin-enriched soy protein containing 189 mg/day isoflavones + 134 mg/day glyceollins (GLY). All diets contained a physiologic dose of estradiol (E2) (1 mg/day). All doses are expressed in human equivalents scaled by caloric intake. Relative to the control C/L diet, the GLY diet resulted in greater numbers of differentially regulated genes, which showed minimal overlap with those of SOY. Effects of GLY related primarily to pathways involved in lipid and carbohydrate metabolism, including peroxisome proliferator-activated receptor (PPAR)-γ and AMP-activated protein kinase (AMPK) signaling, adipocytokine expression, triglyceride synthesis, and lipase activity. Notable genes upregulated by the GLY diet included PPAR-γ, adiponectin, leptin, lipin 1, and lipoprotein lipase. The GLY diet also resulted in lower serum total cholesterol, specifically nonhigh-density lipoprotein cholesterol, and increased serum triglycerides as compared to the C/L diet. No effects of GLY or SOY were seen on serum insulin, adipocytokines, or vascular and bone turnover markers. These preliminary findings suggest that glyceollin-enriched soy protein has divergent effects from standard soy with some specificity for adipocyte activity and nutrient metabolism.

Critical Role of Peroxisome Proliferator Activated Receptor-δ on Body Fat Reduction in C57BL/6J and Human Apolipoprotein E2 Transgenic Mice Fed Delipidated Soybean

The consumption of soy protein and fiber reduces body fat accumulation; however, the mechanism of this effect has not been clearly understood. We investigated the antiobesogenic effect of soy protein and fiber in two different mouse models. Normolipidemic nonobese C57BL/6J and hyperlipidemic obese human apolipoprotein E2 transgenic mice were fed either delipidated soybean (DLSB) containing soy protein and fiber or a control diet. The DLSB-fed mice showed a significant reduction in body weight gain and adiposity compared with controls, in both C57BL/6J and apoE2 mice. All metabolic parameters were significantly improved in the DLSB group compared with controls: total cholesterol, low-density lipoprotein cholesterol, insulin, and leptin levels were significantly reduced. Adiponectin concentrations were significantly elevated, and glucose tolerance was improved. In both types of DLSB-fed mice, the specific induction of PPAR-δ protein expression was evident in muscle and adipose tissues. The expression of PPAR-δ target genes in the DLSB-fed mice was also significantly altered. Acetyl-CoA carboxylase-1 and fatty acid synthase levels in adipose tissue were downregulated, and uncoupling protein-2 in muscle was upregulated. Intestinal expression of fatty acid transport protein-4, cluster of differentiation-36, and acyl-CoA synthetase were significantly downregulated. We propose that marked activation of PPAR-δ is the primary mechanism mediating the antiobesogenic effect of soybean and that PPAR-δ has multiple actions: induction of thermogenesis in muscle, reduction of fatty acid synthesis in adipose tissue, and reduction of fatty acid uptake in intestinal tissue.

Consumption of Soy Protein Isolate Reduces Hepatic SREBP-1c and Lipogenic Gene Expression in Wild-Type Mice, but Not in FXR-Deficient Mice

We examined to determine whether hepatic gene expression is affected in mice in which blood lipid levels remain unchanged fed soy protein isolate (SPI) for a short time. We also examined SPI-mediated effects in farnesoid X receptor (FXR)-deficient mice. Compared with casein, SPI affected the expression of various hepatic genes related to lipid metabolism in the wild-type mice. No effects of SPI were observed in the FXR-deficient mice, suggesting the importance of FXR. Hepatic peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) gene expression was reduced by SPI, and this might be associated with a decrease in FXR expression. Decreased FXR led to decreased expression of its target, the bile-salt export pump necessary for bile acid secretion and dietary lipid absorption. The earliest response to SPI was a decrease in hepatic sterol regulatory element-binding protein (SREBP)-1c mRNA, on day 3. SPI activated hepatic adenosine monophosphate-activated protein kinase (AMPK), which can lead to a reduction in SREBP-1c mRNA. These data indicate the importance of SREBP-1c and PGC-1α/FXR in SPI-mediated alterations in hepatic gene expression.

Soy protein diet and exercise training increase relative bone volume and enhance bone microarchitecture in a mouse model of uremia

Soy protein consumption and exercise training have been widely studied for their effects on the vasculature and bone in healthy populations, but little is known about the effectiveness of these interventions in chronic kidney disease (CKD). Cardiovascular disease and bone fracture risk are significantly elevated in CKD, and current pharmacological interventions have been unsuccessful in treating these conditions simultaneously. The purpose of this study was to compare the effects of a soy protein diet and endurance exercise training, alone or in combination, on cardiovascular and bone health in a mouse model of renal insufficiency. At 8 weeks of age, 60 female apolipoprotein E(-/-) mice underwent a two-step surgical procedure to induce uremia. These mice were then randomized at 12 weeks of age to one of four treatment groups for the 16-week intervention period: sedentary, control diet (n = 16); sedentary, soy protein diet (n = 18); exercise, control diet (n = 14); and exercise, soy protein diet (n = 12). There were no significant treatment effects on atherosclerotic lesion areas or aortic calcium deposits. We demonstrated a significant main effect of both diet and exercise on relative bone volume, trabecular number, trabecular separation, and trabecular connective density in the proximal femur as measured by microcomputed tomography. There were no treatment effects on trabecular thickness. We also showed a main effect of diet on plasma urea levels. These data suggest that soy protein intake and exercise training exert beneficial effects on properties of bone and plasma urea levels in mice with surgically induced renal impairment.

Modified Soybean Affects Cholesterol Metabolism in Rats Similarly to a Commercial Cultivar

The consumption of soy protein lowers blood cholesterol in humans and animals. Breeding may alter the physiological effects of soybeans, such as its cholesterol-lowering property. Our hypothesis is that breeding affects the hypocholesterolemic effect of soy by modulating the expression of key hepatic enzymes related to cholesterol and bile acid biosynthesis, as well as altering fecal neutral and acidic steroid excretion. Therefore the aim of this study was to evaluate the effect of a new Brazilian soybean cultivar (UFV-116), lacking lipoxygenases 2 and 3, compared with a commercial cultivar (OCEPAR-19), on 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR) and cholesterol 7α-hydroxylase (CYP7A) mRNA expression and fecal steroid output in rats. Thirty-six male rats were fed UFV-116, OCEPAR-19, or casein as the protein source, with or without addition of dietary cholesterol (0.25%). Blood and liver cholesterol, HMGR and CYP7A mRNA abundance, and fecal excretion of steroids were measured. Blood and liver cholesterol levels were lowered by both soybean cultivars, with and without cholesterol, but UFV-116 was more effective when included in the cholesterol-free diet. Both soy diets promoted lower levels of HMGR mRNA, higher levels of CYP7A mRNA, and higher excretion of fecal secondary bile acids. There was higher fecal neutral steroid output when cholesterol was added to all diets. These data show that both soybean cultivars acted similarly in lowering serum and hepatic cholesterol; therefore, breeding did not affect the hypocholesterolemic effect of the new cultivar.

Effects of maternal consumption of low‐protein diet with soy as protein source on hepatic glucose and lipid metabolism of the rat offspring

Maternal protein restriction (PR) induces dyslipidemia and impaired glucose homeostasis in offspring, which is associated with metabolic disease development in later life. Recent studies showed that maternal soy protein diet improves insulin sensitivity and lipid profile of offspring. Therefore, we investigated effects of maternal PR diet with soy as protein source on hepatic glucose and lipid metabolism in offspring. SD rats were fed 20% casein, 20% isoflavone‐poor soy protein isolate (SPI) or 10% SPI during pregnancy and lactation. Male offspring was studied at postnatal d21. Body weight and relative liver weight were significantly lower in offspring of dam fed 10% SPI diet (10% SPI). Serum glucose, triglyceride (TG), insulin concentrations and HOMA‐IR were significantly lower in 20% SPI compared to those in 20% casein. SPI level did not significantly change serum glucose concentration and HOMA‐IR. Serum and hepatic TG concentrations were significantly lower in 10% SPI compared to those in 20% SPI. Hepatic mRNA expression of peroxisome proliferator‐activated receptor alpha, a transcription factor involved in the regulation of glucose and lipid homeostasis, was not significantly different among groups. Therefore, these findings indicate that maternal consumption of soy protein may alleviate the PR‐mediated metabolic disease development in rat offspring. Supported by Korea Research Foundation.

Soy Components vs. Whole Soy: Are We Betting Our Bones on a Long Shot?1–3

Soybeans are a good source of bone-healthy nutrients. Epidemiological studies in Asia evaluating diets containing traditional whole soy foods show a positive association with bone mineral density and fracture protection. Smaller scale intervention studies in Western nations mainly feature isolated soy protein (SP) and purified or concentrated soy isoflavones (SI) rather than whole soy foods and they have produced inconsistent results. Consumption of SP does not alter calcium (Ca) retention even though urinary Ca excretion is less in diets with SP compared with proteins higher in sulfur-containing amino acids. SI, often consumed at higher concentrations than would be available in traditional Asian diets, are not yielding the type of incontrovertible evidence that might be expected in support of their benefit to bone health. This forces one to ask whether whole soy might provide a superior effect on bone.

Effects of soy protein on lipoprotein lipids and fecal bile acid excretion in men and women with moderate hypercholesterolemia

Soy protein (SP) and low-fat dairy product consumption have been suggested to have hypocholesterolemic effects, although the responsible mechanisms are poorly understood. This randomized, controlled, parallel arm trial evaluated the effects of an insoluble fraction of SP and total milk proteins (TMPs) with high calcium content on the fasting lipid profile. It also assessed the potential contributions of increased excretion of bile acids and neutral sterols to their lipid-altering effects. Subjects with hypercholesterolemia (low-density lipoprotein cholesterol [LDL-C] 100-199 mg/dL) followed the Therapeutic Lifestyle Changes diet for 4 weeks, followed by a 2-week lead-in with 3.75 g/d colesevelam HCl. Individuals with LDL-C lowering of ≥5.0% with colesevelam HCl were randomly assigned to one of two groups after a 3-week washout: 1) 25 g/d of an insoluble fraction of partially hydrolyzed SP or 2) 25 g/d TMP. Both SP and TMP reduced atherogenic lipoproteins, as indicated by changes in total cholesterol (-7.4% and -3.6%), LDL-C (-10.9% and -5.9%), nonhigh-density lipoprotein cholesterol (-10.8% and -3.9%), and apolipoprotein B (-9.7% and -2.4%), respectively (P < .05 for between group differences except LDL-C, P = .085). No significant increases were observed in either group for fecal bile acids or neutral sterols. These results confirm that SP consumption exerts a hypocholesterolemic effect and indicate that TMP elicits a less pronounced response. However, these findings do not support the hypothesis that increased bile acid excretion is an important contributor to the hypocholesterolemic effects of either protein source.

Scientific Opinion on the substantiation of a health claim related to soy protein and reduction of blood cholesterol concentrations pursuant to Article 14 of the Regulation (EC) No 1924/2006

Following an application from HarlandHall Ltd. on behalf of the Soya Protein Association (SPA), the European Vegetable Protein Federation (EUVEPRO), and the European Natural Soyfood Manufacturers Association (ENSA) submitted pursuant to Article 14 of Regulation (EC) No 1924/2006 via the Competent Authority of United Kingdom, the Panel on Dietetic Products, Nutrition and Allergies was asked to deliver a scientific opinion on soy protein and reduction of blood cholesterol concentrations. The scope of the application was proposed to fall under a health claim referring to reduction of a disease risk. The food constituent that is the subject of the health claim is soy protein, i.e. the protein component of the soybean Glycine max. The Panel considers that soy protein is sufficiently characterised. The claimed effect is “reduces blood cholesterol and may therefore reduce the risk of (coronary) heart disease”. The target population is healthy adults. The Panel considers that lowering LDL-cholesterol is a beneficial physiological effect by reducing the risk of coronary heart disease. In weighing the evidence, the Panel took into account that the results from the four human intervention studies identified by the applicant as being controlled for the macronutrient composition of the test products do not support an effect of the protein component of soy on LDL-cholesterol concentrations, and that the proposed mechanism by which the protein component of soy would exert the claimed effect is not supported by available scientific evidence. The Panel concludes that a cause and effect relationship has not been established between the consumption of soy protein and the reduction of LDL-cholesterol concentrations. © European Food Safety Authority, 2010