Sun-Ok Lee

Characterization of a Novel Resistant-Starch and Its Effects on Postprandial Plasma-Glucose and Insulin Responses

ABSTRACT Objectives of this study were to understand the physicochemical properties of a novel resistant starch (RS) made by complexing high-amylose maize starch VII (HA7) with palmitic acid (PA), and its effects on reducing postprandial plasma-glucose and insulin responses. The HA7 starch was heat-treated and debranched using isoamylase (ISO) to enhance the starch-lipid complex formation. The RS content of the HA7 starch debranched with ISO and complexed with PA (HA7+ISO+PA) was 52.7% determined using AOAC Method 991.43 for dietary fiber, which was greater than that of the HA7 control (35.4%). The increase in the RS content of the HA7+ISO+PA sample was attributed to the formation of retrograded debranched-starch and starch-lipid complex. The postprandial plasma-glucose and insulin responses of 20 male human-subjects after ingesting bread made from 60% (dry basis) HA7+ISO+PA were reduced to 55 and 43%, respectively, when compared with those after ingesting control white bread (as 100%) containing the same...

Soyasaponins lowered plasma cholesterol and increased fecal bile acids in female golden Syrian hamsters.

A study was conducted in hamsters to determine if group B soyasaponins improve plasma cholesterol status by increasing the excretion of fecal bile acids and neutral sterols, to identify group B soyasaponin metabolites, and to investigate the relationship between a fecal group B soyasaponin metabolite and plasma lipids. Twenty female golden Syrian hamsters, 11–12 weeks old and 85–125 g, were randomly assigned to a control diet or a similar diet containing group B soyasaponins (containing no isoflavones), 2.2 mmol/kg, for 4 weeks. Hamsters fed group B soyasaponins had significantly lower plasma total cholesterol (by 20%), non–high-density lipoprotein (HDL) cholesterol (by 33%), and triglycerides (by 18%) compared with those fed casein (P < 0.05). The ratio of total cholesterol to HDL cholesterol was significantly lower (by 13%) in hamsters fed group B soyasaponins than in those fed casein (P < 0.05). The excretion of fecal bile acids and neutral sterols was significantly greater (by 105% and 85%, respectively) in soyasaponin-fed hamsters compared with those fed casein (P < 0.05). Compared with casein, group B soyasaponins lowered plasma total cholesterol levels and non-HDL cholesterol levels by a mechanism involving greater excretion of fecal bile acids and neutral sterols. Hamsters fed group B soyasaponins statistically clustered into two fecal soyasaponin metabolite–excretion phenotypes: high excreters (n = 3) and low excreters (n = 7). When high and low producers of this soyasaponin metabolite were compared for plasma cholesterol status, the high producers showed a significantly lower total-cholesterol-to-HDL-cholesterol ratio compared with the low producers (1.38 ± 0.7 vs. 1.59 ± 0.13; P < 0.03). Greater production of group B soyasaponin metabolite in hamsters was associated with better plasma cholesterol status, suggesting that gut microbial variation in soyasaponin metabolism may influence the health effects of group B soyasaponins.

Soy protein with or without isoflavones, soy germ and soy germ extract, and daidzein lessen plasma cholesterol levels in golden Syrian hamsters.

Dietary isolated soy protein (ISP, containing approximately equal amounts of daidzein and genistein), ethanol-extracted ISP (ISP (–)), soygerm or soygerm extract (containing large amounts of daidzein and glycitein and little genistein) and the isoflavone, daidzein, were hypothesized to lessen plasma cholesterol in comparison with casein. Sixty male and 60 female golden Syrian hamsters (6–8 weeks of age) were randomly assigned to six treatments fed for 10 weeks. Four of the experimental diets (ISP, daidzein, soygerm, and soygerm extract) contained 1.3 mmol total isoflavones/kg. The ISP (–) diet contained 0.013 mmol isoflavone/kg, whereas the casein diet contained no isoflavones. Hamsters fed ISP, ISP (–), daidzein, soygerm, and soygerm extract had significantly less plasma total cholesterol (by 16%–28%), less non-HDL cholesterol (by 15%–50%) and less non-HDL/HDL cholesterol ratios compared with hamsters fed casein (P < 0.01). For male hamsters, there were no differences among treatments in plasma HDL concentrations. Female hamsters fed ISP (–) had significantly greater HDL levels (P < 0.01) than females fed casein or daidzein. Triglyceride concentration was significantly less in hamsters fed ISP (–) compared with the casein-fed females. Because soy protein with or without isoflavones, soygerm and soygerm extract, and daidzein lessened plasma cholesterol to an approximately equal extent, soy protein alone, varying mixtures of isoflavones, and other extractable components of soy are responsible for cholesterol-lessening effects of soy foods, mainly due to their effects to lessen LDL cholesterol.

Artichoke extract lowered plasma cholesterol and increased fecal bile acids in Golden Syrian hamsters.

A study was conducted in hamsters to determine if artichoke leaf extract (ALE) could lower plasma total and non‐HDL cholesterol by increasing fecal excretion of neutral bile acids and sterols. Sixty‐four Golden Syrian hamsters (8 week old) were fed control diet or a similar diet containing ALE (4.5 g/kg diet) for 6 weeks. No significant changes for total cholesterol, HDL, non‐HDL cholesterol triglycerides or fecal neutral sterols and bile acids were found after 21 days for ALE‐fed animals compared with controls. But after 42 days, ALE‐fed male hamsters had significantly lower total cholesterol (15%), non‐HDL cholesterol (30%) and triglycerides (22%) and female hamsters fed ALE showed reductions of 15% for total cholesterol, 29% for non‐HDL cholesterol and 29% for triglycerides compared with controls. Total neutral sterol and bile acids concentrations increased significantly by 50% and 53% in fecal samples of ALE fed males, and 82.4% and 25% in ALE fed females compared with controls. The ALE lowered hamster plasma cholesterol levels by a mechanism involving the greater excretion of fecal bile acids and neutral sterols after feeding for 42 days. Copyright

The Role of Prebiotics and Probiotics in Human Health

There has recently been a significant increase in research on the potential health benefi ts associated with probiotics and prebiotics. Some effects attributed to selected probiotics or prebiotics have been proved by clinical trials, while others have been acquired on the basis of in vitro tests which need to be replicated in vivo in order to be validated. Clinical reports in the literature for the application of probiotics have been done for the treatment of infectious diseases including viral, bacterial or antibiotic associated diarrhea, lowering of serum cholesterol, decreased risk of colon cancer, improved lactose digestion, and altered intestinal microbiota. However, information on probiotic species, a specific strain-therapeutic application, and adequate dosages, is not yet sufficient to allow rational consumption. Moreover, prebiotic oligosaccharides are poorly understood in regard to their fermentation profi les and dosages required for health effects. The present review summarizes some of the literature in regard to clinical or therapeutic trials of probiotics and prebiotics.

Effect of Aronia melanocarpa (Black Chokeberry) supplementation on the development of obesity in mice fed a high-fat diet

BACKGROUND: Products derived from black chokeberry are claimed to be beneficial in treating chronic diseases, such as obesity and diabetes. OBJECTIVE: The objective of this study was to determine if supplementation with Aronia melanocarpa (black chokeberry) juice concentrate (AJC) has anti-obesity properties in mice fed obesogenic diets. METHODS: Male C57BL/6J mice (n = 10/dietary treatment) were placed on either a low-fat, high-sucrose (LFHS; 5% fat), LFHS+AJC (1.44 g AJC/kg diet), high-fat (HF; 30% fat), or HF+AJC for 12-weeks. RESULTS: Final body weight was lower in LFHS+AJC compared to LFHS, HF and HF+AJC (∼14, 20% and ∼16%, respectively; P < 0.05). Mice receiving LFHS and LFHS+AJC had significantly higher (P = 0.001) energy intake than HF and HF+AJC. LFHS-fed mice had less (–30%) epididymal fat (p < 0.05) than HF-fed mice, however mice on the LFHS+AJC had less epididymal fat per gram body weight than LFHS controls. There was no effect of diet or AJC on adipose tissue gene expression. There was no difference in plasma insulin, glucose or triglycerides between groups, however there was a positive effect of AJC on adiponectin (P = 0.059). There was also a significant effect of diet (LFHS versus HF) on HOMA-IR (P = 0.004) and HOMA-BCF (P = 0.002). CONCLUSIONS: The results from this study demonstrate that AJC supplementation has the potential to prevent weight gain and markers of obesity. Further research is needed to determine mechanisms of action.

Effect of Elicitor Spray at Different Reproductive Stages on Saponin Content of Soybean

The beneficial health effects of soybeans may be enhanced by increasing bioactive compounds including soyasaponins (ssp). The objective of this study is to elucidate the effect of elicitors sprayed on Ozark variety soybeans, on ssp content. Different concentrations of elicitors, ethyl acetate (EA) and methyl jasmonate (MJ), were sprayed at 4 different growth stages (1-bloom, 2-pod development, 3-seed development, and 4-seed maturity). Seeds were ground, defatted, ssp was extracted and identified and quantified with HPLC. Elicitor and growth stage had an effect on βg and βa contents of soybeans compared with control (P < 0.05). Elicitor had an effect on total ssp content (P < 0.001) and αg and γg content of soybeans compared with control (P < 0.05). Total ssp content of EA 0.05 M, MJ 0.001 M, and 0.005 M sprayed soybeans were higher than EA 0.001 M, which is higher than control (P < 0.05; 3.62, 3.56, 3.56, 3.29, and 2.98 μmol/g soybean, respectively). The overall effect of elicitor on total ssp content was not dependent on growth stage, however, elicitors sprayed at growth stages 1, 2, and 3 showed differences among elicitor applied soybeans. Elicitors applied at growth stage 4 did not have any effect on total ssp content compared to control. Elicitors EA 0.05 M, MJ 0.001, and 0.005 M can be applied on any growth stage to increase total saponin content of soybean variety Ozark. Higher saponin content may improve the beneficial health effects of soybean consumption.

Parboiled Brown Rice Product Reduces Postprandial Plasma Glucose Response in Men

A staple crop such as rice provides an ideal starch source for creating a functional starch ingredient. Functional starch fractions can act as a functional ingredient by controlling glucose and insulin levels with application for glucose control for health in addition diabetes mellitus. The objective of this human study was to investigate the effect of a parboiled brown rice flour pudding on postprandial plasma glucose and insulin levels. Wells brown rice was parboiled at 120°C for 20 min and ground into flour, and in vitro nutritional starch fractions were measured. A randomized-crossover design was used to observe plasma glucose and insulin responses from 14 healthy, male subjects. Compared with the control, significant reductions after consumption of parboiled brown rice pudding in mean glucose levels at 15, 30, 45, 60, 75, and 90 minutes were observed (P < 0.05). Mean glucose incremental Area Under the Curve (iAUC) were also significantly lower (3795 ± 602 mg/dL) than the control solution (5880 ± 658mg/dL) (P<0.05). Plasma insulin mean incremental response reduced also from 3066 ± 525 μU/L iAUC to 2219 ± 715 μU/L iAUC of the control and rice pudding treatments, respectively. Results suggest optimal parboiling of brown rice provided in a flour application could assist in managing plasma glucose levels for individuals, and with additional research functional starch fractions may help in the prevention of diabetes and obesity.

Menhaden Oil Inhibited γ-Glutamyltransferase-Positive Altered Hepatic Foci in Female Sprague-Dawley Rats

Feeding menhaden oil, high in n-3 fatty acids, or a mixture of lard and corn oil with a polyunsaturated-to-monounsaturated fatty acid ratio of 1:1 was hypothesized to inhibit promotion of hepatocarcinogenesis in rats by decreasing hepatic prostaglandin (PG) levels. Ten-day-old female Sprague-Dawley rats were injected with diethylnitrosamine (DEN, 15 mg/kg body wt ip). At 4 wk of age, rats were fed fumonisin B1(50 mg/kg diet) for 5 wk in diets containing 14% lard + 6% corn oil, 10% lard + 10% corn oil, 14% menhaden oil + 6% corn oil, and 7% menhaden oil + 13% corn oil. Plasma alanine aminotransferase activity was 20% lower in rats fed 10% lard than in rats fed the other diets (P < 0.05). In menhaden oil-fed rats, total plasma cholesterol concentrations decreased 26% (P <5) and hepatic phospholipid C20:5n-3, C22:5n-3, and C22:6n-3 fatty acid concentrations increased compared with lard-fed rats. Hepatic n-3 fatty acids were threefold greater in rats fed 10% lard than in rats fed 14% lard. The liver-associated natural killer cell activity in rats fed menhaden oil was 58% lower than in rats fed lard (P <3). Rats fed lard had threefold (P <5) greater area of γ-glutamyltransferase-positive altered hepatic foci (AHF) than did rats fed menhaden oil. There was no significant difference in placental glutathione S-transferase-positive AHF among the groups. Hepatic PGF2αproduction was 60-80% greater in rats fed 14% lard than in rats fed the other diets (P <5). Hepatic PGE2was 48% less in rats fed 14% menhaden oil than in rats fed 14% lard (P <5). Although γ-glutamyltransferase-positive focal area was inhibited by menhaden oil, only 14% menhaden oil inhibited PGE2;. Feeding 10% lard inhibited PGF2α, but not the development of AHF. Therefore, decreased hepatic PGs did not explain the inhibition of carcinogenesis.

A High-Protein Diet Reduces Weight Gain, Decreases Food Intake, Decreases Liver Fat Deposition, and Improves Markers of Muscle Metabolism in Obese Zucker Rats

A primary factor in controlling and preventing obesity is through dietary manipulation. Diets higher in protein have been shown to improve body composition and metabolic health during weight loss. The objective of this study was to examine the effects of a high-protein diet versus a moderate-protein diet on muscle, liver and fat metabolism and glucose regulation using the obese Zucker rat. Twelve-week old, male, Zucker (fa/fa) and lean control (Fa/fa) rats were randomly assigned to either a high-protein (40% energy) or moderate-protein (20% energy) diet for 12 weeks, with a total of four groups: lean 20% protein (L20; n = 8), lean 40% protein (L40; n = 10), obese 20% protein (O20; n = 8), and obese 40% protein (O40; n = 10). At the end of 12 weeks, animals were fasted and euthanized. There was no difference in food intake between L20 and L40. O40 rats gained less weight and had lower food intake (p < 0.05) compared to O20. O40 rats had lower liver weight (p < 0.05) compared to O20. However, O40 rats had higher orexin (p < 0.05) levels compared to L20, L40 and O20. Rats in the L40 and O40 groups had less liver and muscle lipid deposition compared to L20 and L40 diet rats, respectively. O40 had decreased skeletal muscle mechanistic target of rapamycin complex 1 (mTORC1) phosphorylation and peroxisome proliferator-activated receptor gamma (PPARγ) mRNA expression compared to O20 (p < 0.05), with no difference in 5′ AMP-activated protein kinase (AMPK), eukaryotic translation initiation factor 4E binding protein 1 (4EBP1), protein kinase B (Akt) or p70 ribosomal S6 kinase (p70S6K) phosphorylation. The data suggest that high-protein diets have the potential to reduce weight gain and alter metabolism, possibly through regulation of an mTORC1-dependent pathway in skeletal muscle.