Battling Obesity with Resistant Starch

f everyone in the United States simply adopted the U.S. Dietary Guidelines of 2005 (http://www. cnpp.usda.gov/GAs2005Guidelines .htm), obesity would be on its way out. Exercising 30-90 minutes a day, eating at least half of our grains as whole grains, and eating four servings of fruits and five servings of vegetables \u27a day are simple prac­ tices that are advised because of their ability to improve energy bal­ ance, keeping us from gaining weight and helping us to lose weight if we need to

Mycotoxins

Mycotoxins, toxins produced by fungi that commonly contaminate food crops, remain an important global food safety concern. Aflatoxins and fumonisins mainly pose a cancer risk, whereas deoxynivalenol poses a risk to gastrointestinal and immune function. Ochratoxin A poses a risk for kidney disease. Grains and some legumes are the predominant sources of these toxins, but they vary in the range of foods that they contaminate. For example, fumonisins occur mainly in corn, whereas deoxynivalenol is mainly found in wheat, barley and corn. Aflatoxins are mainly found in peanuts and corn. The nature of the fungi that produce each toxin seems to be the main determinant of which crop species will be the main sources of the mycotoxins

Nutritional, nutraceutical and functional properties of soybeans

Soybeans, foods derived from soybeans (e.g., tofu, soymilk, soy infant formula, tempeh) and food and dietary supplement ingredients derived from soybeans (e.g., soybean oil, soybean proteins, isoflavones) have been under intensive research for their health effects especially over the past 25 years. 2 This intensive research derives from the recognition of soybeans as having desirable nutritional properties, containing about twice the protein of other legumes/serving, with good protein quality, such that some soybean protein ingredients have protein digestibility corrected amino acid scores commensurate with proteins thought to be optimal to meet human protein needs (Messina 1999). Soybean oil is used as the nutritional standard fat source for the AIN-93G diet for growing rodents(Reeves 1997); its high content of polyunsaturated fats, including a high ratio of α-linolenic: linoleic acids (~ 1: 7.5)(Messina 1999) make it well-aligned to meet human as well as rodent requirements for n-3 and n-6 essential fatty acids

Metabolism of Glycitein (7,4-Dihydroxy-6-methoxy-isoflavone) by Human Gut Microflora

Gut microbial disappearance and metabolism of the soy isoflavone glycitein, 7,4‘-dihydroxy-6-methoxyisoflavone, were investigated by incubating glycitein anaerobically with feces from 12 human subjects. The subjects\u27 ages ranged from 24 to 53 years with a body mass index (BMI) of 20.9−25.8 kg/m2 (mean BMI = 24.0 ± 1.1 kg/m2). Glycitein disappearance followed an apparent first-order rate loss. Fecal glycitein disappearance rates for the subjects segregated into three different groups described as high (k = 0.67 ± 0.14/h), moderate (k = 0.34 ± 0.04/h), and low (k = 0.15 ± 0.07/h) glycitein degraders (p \u3c 0.0001). There was no dose effect on the disappearance rates for each subject from 10 to 250 μM glycitein (averagek = 0.32 ± 0.03/h, p \u3e 0.05). Four putative glycitein metabolites, characterized by liquid chromatography−mass spectrometry (electrospray ionization using positive ionization mode), were dihydroglycitein, dihydro-6,7,4‘-trihydroxyisoflavone, and 5‘-O-methyl-O-desmethylangolensin. Two subjects produced a metabolite tentatively identified as 6-O-methyl-equol, and one subject produced daidzein as an additional metabolite of glycitein. These results show that glycitein is metabolized by human gut microorganisms and may follow metabolic pathways similar to other soy isoflavones

Human Gut Microbial Degradation of Flavonoids: Structure−Function Relationships

The relationship between chemical structure and gut microbial degradation rates of 14 flavonoids, flavone, apigenin, chrysin, naringenin, kaempferol, genistein, daidzein, daidzin, puerarin, 7,4‘-dihydroxyflavone, 6,4‘-dihydroxyflavone, 5,4‘-dihydroxyflavone, 5,3‘-dihydroxyflavone, and 4‘-hydroxyflavone, was investigated by anaerobically fermenting the flavonoids with human gut microflora (n = 11 subjects). Degradation rates for the 5,7,4‘-trihydroxyl flavonoids, apigenin, genistein, naringenin, and kaempferol, were significantly faster than the other structural motifs. Puerarin was resistant to degradation by the gut microflora. Extensive degradation of flavonoids by gut microflora may result in lower overall bioavailability than those flavonoids that are slowly degraded because rapidly degrading flavonoids are less likely to be absorbed intact

Greater Apparent Absorption of Flavonoids Is Associated with Lesser Human Fecal Flavonoid Disappearance Rates

-OH-flavonoids disappeared more rapidly from human fecal incuba- tions and were less absorbable by humans than flavonoids without 5-OH moieties. Anaerobic fecal disappearance rates over 24 h were determined for 15 flavonoids in samples from 20 men and 13 women. In these anaerobic fecal mixtures, flavonoids with 5,7,40-OH groups, genistein, apigenin, naringenin, luteolin, kaempferol, and quercetin (disappearance rate, k = 0.46 ( 0.10 h-1), and methoxylated flavonoids, hesperetin and glycitein (k = 0.24 ( 0.21 h-1), disappeared rapidly compared with flavonoids lacking 5-OH (e.g., daidzein, k = 0.07 ( 0.03 h-1). Apparent absorption of flavonoids that disappeared rapidly from in vitro fecal incubations, genistein, naringenin, quercetin, and hesperetin, was compared with that of daidzein, a slowly disappearing flavonoid, in 5 men and 5 women. Subjects ingested 104 μmol of genistein and 62 μmol of daidzein (soy milk), 1549 μmol of naringenin and 26 μmol of hesperetin (grapefruit juice), and 381 μmol of quercetin (onions) in three test meals, each separated by 1 week. Blood and urine samples were collected over 24 h after each test meal. Plasma flavonoid concentrations ranged from 0.01 to 1 μM. The apparent absorption, expressed as percentage of ingested dose excreted in urine, was significantly less for naringenin (3.2 ( 1.7%), genistein (7.2 ( 4.6%), hesperetin (7.3 ( 3.2%), and quercetin (5.6 ( 3.7%) compared with daidzein (43.4 ( 15.5%, p = 0.02). These data affirmed the hypothesis that the 5,7,40-OH of flavonoids limited apparent absorption of these compounds in humans

Excretion of Fumonisin B1, Hydrolyzed Fumonisin B1, and the Fumonisin B1−Fructose Adduct in Rats

The excretion of fumonisin B1 (FB1), hydrolyzed FB1 (HFB1), and FB1−fructose addition products (FB1−fructose) was determined in male Fisher 344/NHsd rats. Rats were dosed by gavage with 0.69, 6.93, or 69.3 μmol/kg of body weight FB1, HFB1, or FB1−fructose. Excretion of unchanged FB1, HFB1, and HFB1 after hydrolysis was determined in urine and feces by analytical reverse phase HPLC and fluorometric detection of the o-phthaldialdehyde derivatives. Average total FB1 backbone excretion in feces was 101, 76, and 50% of the dose for FB1, HFB1, and FB1−fructose, respectively. No effect of dose level was found on the percentage of the dose excreted as total FB1 after hydrolysis. FB1−fructose appears to be absorbed to the highest extent, followed by HFB1. FB1 appears to be excreted nearly completely in the feces. The greater absorption of HFB1 may explain the greater toxicity of HFB1 compared to FB1 on a molar basis. However, the detoxification of FB1 by formation of the fructose adduct cannot be explained by reduced absorption. Average total FB1 backbone excretion in urine was 2.7, 5.0, and 5.3% of the dose for FB1, HFB1, or FB1−fructose, respectively

Quantification of the Group B Soyasaponins by High-PerformanceLiquid Chromatography

High-performance liquid chromatographic methods were developed for the isolation and quantitative determination of the group B soyasaponins, including 2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran- 4-one (DDMP)-conjugated soyasaponins Rg, f3g, and f3a, and their non-DDMP counterparts, soyasaponins V, I, and II, respectively, with formononetin used as the internal standard. The limits of quantification for soy products were 0.11-4.86 µmol/g. The within-day and between-days assay coefficients of variation were \u3c9.8 and \u3c 14.3%, respectively. The group B soyasaponin concentrations in 46 soybean varieties ranged from 2.50 to 5.85 µmol/g. Soy ingredients (soybean flour, toasted soy hypocotyls, soy protein isolates, textured vegetable protein, soy protein concentrates, and Novasoy) and soy foods (commercial soy milk, tofu, and tempeh) contained the group B soyasaponins from 0.20 to 114.02 µmol/g. There was no apparent correlation between isoflavone and soyasaponin concentrations in the soy products examined

Excretion of 14C-Fumonisin B1, 14C-Hydrolyzed Fumonisin B1, and 14C-Fumonisin B1-Fructose in Rats

14C-Fumonisin B1 (FB1) was produced by Fusarium proliferatum M-5991 in modified Myro liquid medium and purified to \u3e95% purity with a specific activity of 1.7 mCi/mmol. Nine male and nine female F344/N rats were each dosed by gavage with 0.69 μmol of 14C-FB1, 14C-hydrolyzed FB1, or 14C-FB1-fructose/kg body weight. Urinary excretion of 14C-FB1 and 14C-FB1-fructose was 0.5% and 4.4% of the total dose, respectively, and was similar between male and female rats. Urinary excretion of 14C-hydrolyzed HFB1 was significantly greater (P \u3e 0.05) in female rats as compared with male rats (17.3% vs 12.8% of the total dose, respectively). There were no significant (P \u3e 0.05) differences in biliary excretion of the three fumonisin compounds with a mean of 1.4% of the dose excreted at 4 h after dosing. Lesser amounts continued to be excreted up to 9.25 h after dosing. Although biliary excretion of the14C-FB1, 14C-hydrolyzed FB1, and 14C-FB1-fructose was similar, increased urinary excretion of the 14C-hydrolyzed FB1 as compared to 14C-FB1 and 14C-FB1-fructose indicated a greater absorption of the hydrolyzed form

Human Fecal Metabolism of Soyasaponin I

The metabolism of soyasaponin I (3-O-[alpha-L-rhamnopyranosyl-beta-D-galactopyranosyl-beta-D-glucuronopyranosyl]olean-12-ene-3beta,22beta,24-triol) by human fecal microorganisms was investigated. Fresh feces were collected from 15 healthy women and incubated anaerobically with 10 mmol soyasaponin I/g feces at 37 degrees C for 48 h. The disappearance of soyasaponin I in this in vitro fermentation system displayed apparent first-order rate loss kinetics. Two distinct soyasaponin I degradation phenotypes were observed among the subjects: rapid soyasaponin degraders with a rate constant k = 0.24 +/- 0.04 h(-)(1) and slow degraders with a k = 0.07 +/- 0.02 h(-)(1). There were no significant differences in the body mass index, fecal moisture, gut transit time, and soy consumption frequency between the two soyasaponin degradation phenotypes. Two primary gut microbial metabolites of soyasaponin I were identified as soyasaponin III (3-O-[beta-D-galactopyranosyl-beta-D-glucuronopyranosyl]olean-12-ene-3beta,22beta,24-triol) and soyasapogenol B (olean-12-ene-3beta,22beta,24-triol) by NMR and electrospray ionized mass spectroscopy. Soyasaponin III appeared within the first 24 h and disappeared by 48 h. Soyasapogenol B seemed to be the final metabolic product during the 48 h anaerobic incubation. These results indicate that dietary soyasaponins can be metabolized by human gut microorganisms. The sugar moieties of soyasaponins seem to be hydrolyzed sequentially to yield smaller and more hydrophobic metabolites