Lupin kernel fiber consumption modifies fecal microbiota in healthy men as determined by rRNA gene flourescent in situ by hybridization

Background Changes in the composition of gastrointestinal microbiota by dietary interventions using pro- and prebiotics provide opportunity for improving health and preventing disease. However, the capacity of lupin kernel fiber (LKFibre), a novel legume-derived food ingredient, to act as a prebiotic and modulate the colonic microbiota in humans needed investigation.

Aim of the study The present study aimed to determine the effect of LKFibre on human intestinal microbiota by quantitative fluorescent in situ hybridization (FISH) analysis.

Design A total of 18 free-living healthy males between the ages of 24 and 64 years consumed a control diet and a LKFibre diet (containing an additional 17–30 g/day fiber beyond that of the control—incorporated into daily food items) for 28 days with a 28-day washout period in a single-blind, randomized, crossover dietary intervention design.
Methods Fecal samples were collected for 3 days towards the end of each diet and microbial populations analyzed by FISH analysis using 16S rRNA gene-based oligonucleotide probes targeting total and predominant microbial populations.

Results Significantly higher levels of Bifidobacterium spp. (P = 0.001) and significantly lower levels of the clostridia group of C. ramosum, C. spiroforme and C. cocleatum (P = 0.039) were observed on the LKFibre diet compared with the control. No significant differences between the LKFibre and the control diet were observed for total bacteria, Lactobacillus spp., the Eubacterium spp., the C. histolyticum/C. lituseburense group and the Bacteroides–Prevotella group.
Conclusions Ingestion of LKFibre stimulated colonic bifidobacteria growth, which suggests that this dietary fiber may be considered as a prebiotic and may beneficially contribute to colon health.

Dietary intakes and food sources of Omega-6 and Omega-3 polyunsaturated fatty acids.

Both n−6 and n−3 polyunsaturated fatty acids (PUFA) are recognized as essential nutrients in the human diet, yet reliable data on population intakes are limited. The aim of the present study was to ascertain the dietary intakes and food sources of individual n−6 and n−3 PUFA in the Australian population. An existing database with fatty acid composition data on 1690 foods was updated with newly validated data on 150 foods to estimate the fatty acid content of foods recorded as eaten by 10,851 adults in the 1995 Australian National Nutrition Survey. Average daily intakes of linoleic (LA), arachidonic (AA), α-linolenic (LNA), eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosahexaenoic (DHA) acids were 10.8, 0.052, 1.17, 0.056, 0.026, and 0.106 g, respectively, with longchain (LC) n−3 PUFA (addition of FPA, DPA, and DHA) totaling 0.189 g; median intakes were considerably lower (9.0 g LA, 0.024 g AA, 0.95 g LNA, 0.008 g EPA, 0.006 g DPA, 0.015 g DHA, and 0.029 g LC n−3 PUFA). Fats and oils, meat and poultry, cereal-based products and cereals, vegetables, and nuts and seeds were important sources of n−6 PUFA, while cereal-based products, fats and oils, meat and poultry, cereals, milk products, and vegetable products were sources of LNA. As expected, seafood was the main source of LC n−3 PUFA, contributing 71%, while meat and eggs contributed 20 and 6%, respectively. The results indicate that the majority of Australians are failing to meet intake recommendations for LC n−3 PUFA (>0.2 g per day) and emphasize the need for strategies, to increase the availability and consumption of n−3-containing foods.

A short-term, high-fat diet up-regulates lipid metabolism and gene expression in human skeletal muscle

Background: Dietary fatty acids may be important in regulating gene expression. However, little is known about the effect of changes in dietary fatty acids on gene regulation in human skeletal muscle.
Objective: The objective was to determine the effect of altered dietary fat intake on the expression of genes encoding proteins necessary for fatty acid transport and ß-oxidation in skeletal muscle.
Design: Fourteen well-trained male cyclists and triathletes with a mean (± SE) age of 26.9 ± 1.7 y, weight of 73.7 ± 1.7 kg, and peak oxygen uptake of 67.0 ± 1.3 mL ˙ kg-1 ˙ min-1 consumed either a high-fat diet (HFat: > 65% of energy as lipids) or an isoenergetic high-carbohydrate diet (HCho: 70–75% of energy as carbohydrate) for 5 d in a crossover design. On day 1 (baseline) and again after 5 d of dietary intervention, resting muscle and blood samples were taken. Muscle samples were analyzed for gene expression [fatty acid translocase (FAT/CD36), plasma membrane fatty acid binding protein (FABPpm), carnitine palmitoyltransferase I (CPT I), ß-hydroxyacyl-CoA dehydrogenase (ß-HAD), and uncoupling protein 3 (UCP3)] and concentrations of the proteins FAT/CD36 and FABPpm.
Results: The gene expression of FAT/CD36 and &szlig; -HAD and the gene abundance of FAT/CD36 were greater after the HFat than after the HCho diet (P < 0.05). Messenger RNA expression of FABPpm, CPT I, and UCP-3 did not change significantly with either diet.
Conclusions: A rapid and marked capacity for changes in dietary fatty acid availability to modulate the expression of mRNA-encoding proteins is necessary for fatty acid transport and oxidative metabolism. This finding is evidence of nutrient-gene interactions in human skeletal muscle.

Regulation of metabolic genes in human skeletal muscle by short-term exercise and diet manipulation

Changes in dietary macronutrient intake alter muscle and blood substrate availability and are important for regulating gene expression. However, few studies have examined the effects of diet manipulation on gene expression in human skeletal muscle. The aim of this study was to quantify the extent to which altering substrate availability impacts on subsequent mRNA abundance of a subset of carbohydrate (CHO)- and fat-related genes. Seven subjects consumed either a low- (LOW; 0.7 g/kg body mass CHO) or high- (HIGH; 10 g/kg body mass CHO) CHO diet for 48 h after performing an exhaustive exercise bout to deplete muscle glycogen stores. After intervention, resting muscle and blood samples were taken. Muscle was analyzed for the gene abundances of GLUT4, glycogenin, pyruvate dehydrogenase kinase-4 (PDK-4), fatty acid translocase (FAT/CD36), carnitine palmitoyltransferase I (CPT I), hormone-sensitive lipase (HSL), β-hydroxyacyl-CoA dehydrogenase (΄β-HAD), and uncoupling binding protein-3 (UCP3), and blood samples for glucose, insulin, and free fatty acid (FFA) concentrations. Glycogen-depleting exercise and HIGH-CHO resulted in a 300% increase in muscle glycogen content (P < 0.001) relative to the LOW-CHO condition. FFA concentrations were twofold higher after LOW- vs. HIGH-CHO (P < 0.05). The exercise-diet manipulation exerted a significant effect on transcription of all carbohydrate-related genes, with an increase in GLUT4 and glycogenin mRNA abundance and a reduction in PDK-4 transcription after HIGH-CHO (all P < 0.05). FAT/CD36 (P < 0.05) and UCP3 (P < 0.01) gene transcriptions were increased following LOW-CHO. We conclude that 1) there was a rapid capacity for a short-term exercise and diet intervention to exert coordinated changes in the mRNA transcription of metabolic related genes, and 2) genes involved in glucose regulation are increased following a high-carbohydrate diet.

Water-binding capacity and viscosity of Australian sweet lupin kernel fibre under in vitro conditions simulating the human upper gastrointestinal tract

There is currently little understanding of the physicochemical properties in the human gastrointestinal tract of Australian sweet lupin (Lupinus angustifolius) kernel fibre (LKF), a novel food ingredient with potential for the fibre enrichment of foods such as baked goods. Since physicochemical properties of dietary fibres have been related to beneficial physiological effects in vitro, this study compared water-binding capacity and viscosity of LKF with that of other fibres currently used for fibre-enrichment of baked goods, under in vitro conditions simulating the human upper gastrointestinal tract. At between 8.47 and 11.07g water/g dry solids, LKF exhibited water-binding capacities that were significantly higher (P<0.05) than soy fibre, pea hull fibre, cellulose and wheat fibre at all of the simulated gastrointestinal stages examined. Similarly, viscosity of LKF was significantly higher (P<0.05) than that of the other fibres at all simulated gastrointestinal stages. The relatively high water-binding capacity and viscosity of LKF identified in this study suggests that this novel fibre ingredient may elicit different and possibly more beneficial physiological effects in the upper human gastrointestinal tract than the conventional fibre ingredients currently used in fibre-enriched baked goods manufacture. We are now performing human studies to investigate the effect of LKF in the diet on health-related gastrointestinal events.

Failure of conjugated linoleic acid supplementation to enhance biosynthesis of docosahexaenoic acid from α-linolenic acid in healthy human volunteers

A rate-limiting step in docosahexaenoic acid (DHA) formation from α-linolenic acid (ALA) involves peroxisomal oxidation of 24:6n-3 to DHA. The aim of the study was to determine whether conjugated linoleic acid (CLA) would enhance conversion of ALA to DHA in humans on an ALA-supplemented diet. The subjects (n=8 per group) received daily supplementation of ALA (11g) and either CLA (3.2g) or placebo for 8 weeks. At baseline, 4 and 8 weeks, blood was collected for plasma fatty acid analysis and a number of physiological measures were examined. The ALA-supplemented diet increased plasma levels of ALA and eicosapentaenoic acid (EPA). The addition of CLA to the ALA diet resulted in increased plasma levels of CLA, as well as ALA and EPA. Plasma level of DHA was not increased with either the ALA alone or ALA plus CLA supplementation. The results demonstrated that CLA was not effective in enhancing DHA levels in plasma in healthy volunteers.

Altering dietary nutrient intake that reduces glycogen content leads to phosphorylation of nuclear p38 MAP kinase in human skeletal muscle: association with IL-6 gene transcription during contraction

To determine the effect of glycogen availability and contraction on intracellular signaling and IL-6 gene transcription, eight males performed 60 min of exercise on two occasions: either with prior ingestion of a normal (Con) or low carbohydrate (LCHO) diet that reduced pre-exercise muscle glycogen content. Muscle biopsies were obtained and analyzed for IL-6 mRNA. In addition, nuclear proteins were isolated from the samples and analyzed for the mitogen- activated protein kinases (MAPK) c-jun amino-terminal kinase (JNK) 1 and 2 and p38 MAPK. Nuclear fractions were also analyzed for the phosphorylated forms of JNK (p-JNK) and p38 MAPK (p-p38 MAPK) and the abundance of the nuclear transcription factors nuclear factor of activated T cells (NFAT) and nuclear factor kappa-β (NF-κβ). No differences were observed in the protein abundance of total JNK 1/2, p38 MAPK, NFAT, or NF-κβ before exercise, but the nuclear abundance of p-p38 MAPK was higher (P<0.05) in LCHO. Contraction resulted in an increase (P<0.05) in nuclear p-JNK 1/2, but there were no differences when comparing CON with LCHO. The fold increase in IL-6 mRNA with contraction was potentiated (P<0.05) in LCHO. A correlation between pre-exercise nuclear phosphorylated p38 MAPK and contraction-induced fold increase in IL-6 mRNA was performed, revealing a highly significant correlation (r=0.96; P<0.01). We next incubated L6 myotubes in ionomycin (a compound known to induce IL-6 mRNA) with or without the pyridinylimidazole p38 MAPK inhibitor SB203580. Treatments did not affect total nuclear p38 MAPK, but ionomycin increased (P<0.05) both nuclear p-p38 MAPK and IL-6 mRNA. The addition of SB203580 to ionomycin decreased (P<0.05) nuclear p-p38 MAPK and totally abolished (P<0.05) the ionomycin- induced increase in IL-6 mRNA. These data suggest that reduced carbohydrate intake that results in low intramuscular glycogen leads to phosphorylation of p38 MAPK at the nucleus. Furthermore, phosphorylation of p38 MAPK in the nucleus appears to be an upstream target for IL-6, providing new insights into the regulation of IL-6 gene transcription.

Macronutrient innovations: the role of fats and sterols in human health

Dietary intake of fats and sterols has long been known to play a critical role in human health. High proportions of saturated fat, which increase blood cholesterol levels, are mainly found in animal fat and some plant oil (e.g. cocoa butter, palm oil etc.). The predominant polyunsaturated fatty acid (PUFA) in the Western diet is linoleic acid (LA; 18:2n-6), an essential fatty acid, which is commonly found in vegetable seed oils. This is the parent fatty acid of n-6 series PUFA, which can be converted in vivo to C20 and C22 n-6 long chain (LC) PUFA. α‐linolenic acid (ALA; 18:3n-3) is less abundant than LA and is another essential fatty acid; ALA is also present in some vegetable oils such as perilla, flaxseed, canola, soybean and walnut oils, and is the precursor of C20 and C22 n-3 LC PUFA. Sterols are widely distributed in animal tissue and plants, with cholesterol being the major sterol in animal tissue and β-sitosterol, campesterol and stigmasterol being the main sterols in plants. It has long been recognized that an increased dietary intake of saturated fat and (to a lesser extent) cholesterol, raises plasma/serum total and low-density lipoprotein (LDL)-cholesterol, and PUFA decreases these levels. Results from recent studies have shown that plasma/serum levels of lipids and lipoprotein lipids can also be decreased by plant sterols (phytosterols) and diacylglycerol (DAG). Conjugated linoleic acid (CLA, cis-9,trans-11−18:2) has been reported to have anticancer and antidiabetic activities. Fat as the DAG form has also been reported to have anti-obesity effects. Omega-3 PUFA have a beneficial effect on increased heart rate variability, decreased risk of stroke, reduction of both systolic and diastolic blood pressure and may be effective in managing depression in adults. Gamma-linolenic acid (GLA) and phytosterols have an anti-inflammatory activity. The GLA, when combined with docosahexaenoic acid (DHA), have been reported to have a beneficial effect in hyperactive children. These data show that various lipids are powerful bioactive compounds.

Low-sodium dietary approaches to stop hypertension-type diet including lean red meat lowers blood pressure in postmenopausal women

Low-sodium Dietary Approaches to Stop Hypertension (DASH) diets are base producing but restrict red meat without clear justification. We hypothesized that a vitality diet (VD), a low-sodium DASH-type diet with a low dietary acid load containing 6 servings of 100 g cooked lean red meat per week, would be more effective in reducing blood pressure (BP) compared with a higher acid load reference healthy diet (RHD) based on general dietary guidelines to reduce fat intake and increase intake of breads and cereals. A randomized, parallel dietary intervention study was conducted to compare the BP-lowering effect of these 2 diets in postmenopausal women with high/normal BP. Women were randomly assigned to follow either VD or RHD for 14 weeks. Home BP was measured daily with an automated BP monitor under standard conditions. Of 111 women commencing the study, 95 completed (46 VD, 49 RHD). Systolic BP (SBP) throughout the intervention was lower in the VD group compared to the RHD group (repeated-measures analysis of variance time by diet, P = .04), such that at the end of the study, the VD had a fall of SBP by 5.6 ± 1.3 mm Hg (mean ± SEM) compared with a fall of 2.7 ± 1.0 mm Hg in the RHD (group difference, P = .08). When only those taking antihypertensive medications were assessed, the VD (n = 17) had a significant fall of 6.5 ± 2.5 mm Hg SBP (P = .02) and 4.6 ± 1.4 mm Hg diastolic BP (P = .005) after 14 weeks, and their BP was lower than that of the RHD group (n = 18) throughout the study (P < .05). We concluded that a low-sodium DASH diet with a low dietary acid load, which also included lean red meat on most days of the week, was effective in reducing BP in older women, particularly in those taking antihypertensive medications.

Associations between growth and diet in adolescence

There is much interest in the nature and quality of the diet consumed by adolescents. To determine whether there are significant associations between diet and gain in height and weight in this age group, the present study analysed data on food intake and weight and height obtained on three occasions over a 30-month period from a total of 326 adolescents aged between 12 and 15 years. Information on sociodemographic and other lifestyle factors, including an indicator of physical activity, was also obtained. Energy intake was found to be a significant positive predictor of both height and weight gain. In addition intake of fat, calcium and riboflavin were found to be significant positive predicators of height gain and intake of carbohydrate and starch significant positive predictors of weight gain. After controlling for energy intake only riboflavin approached significance as a positive predictor of height gain. A food group analysis identified intake of dairy foods as a significant predictor of height gain. Although statistically significant the dietary predictors explained only a small proportion of the variability in height and weight (≤3.5%). Given the difficulties in obtaining complete dietary records from this age group and the generally adequate nature of the diet in the study group, the small proportion of height and weight gain explained by diet is not unexpected. Nevertheless the nutrient predictors identified are consistent with nutrient requirements for growth during adolescence and highlight the importance, for this age group, of an adequate intake of nutrients specifically provided by dairy foods. Few significant associations were found between growth rates and the sociodemographic and the lifestyle factors measured in this study. The ethnic diversity of the study sample may have contributed to this outcome.

Constipation, laxative use and diet

This study found that constipation estimates varied considerably from 9-42%, depending on the criteria used, and there was extensive laxative use. Those who were constipated reported a significantly poorer quality-of-life. Participants could not achieve current dietary recommendations and therefore managing constipation through dietary modification is impractical for many older people.

Oral sensitivity to fatty acids, food consumption and BMI in human subjects

Fatty acids are the chemical moieties that are thought to stimulate oral nutrient sensors, which detect the fat content of foods. In animals, oral hypersensitivity to fatty acids is associated with decreased fat intake and body weight. The aims of the present study were to investigate oral fatty acid sensitivity, food selection and BMI in human subjects. The study included two parts; study 1 established in thirty-one subjects (29 (sem 1·4) years, 22·8 (sem 0·5) kg/m²) taste thresholds using 3-AFC (3-Alternate Forced Choice Methodology) for oleic, linoleic and lauric acids, and quantified oral lipase activity. During study 2, fifty-four subjects (20 (sem 0·3) years, 21·5 (sem 0·4) kg/m2) were screened for oral fatty acid sensitivity using oleic acid (1·4 mm), and they were defined as hypo- or hypersensitive via triplicate triangle tests. Habitual energy and macronutrient intakes were quantified from 2 d diet records, and BMI was calculated from height and weight. Subjects also completed a fat ranking task using custard containing varying amounts (0, 2, 6 and 10 %) of fat. Study 1 reported median lipase activity as 2 μmol fatty acids/min per l, and detection thresholds for oleic, linoleic and lauric acids were 2·2 (sem 0·1), 1·5 (sem 0·1) and 2·6 (sem 0·3) mm. Study 2 identified twelve hypersensitive subjects, and hypersensitivity was associated with lower energy and fat intakes, lower BMI (P < 0·05) and an increased ability to rank custards based on fat content (P < 0·05). Sensitivity to oleic acid was correlated to performance in the fat ranking task (r 0·4, P < 0·05). These data suggest that oral fatty acid hypersensitivity is associated with lower energy and fat intakes and BMI, and it may serve as a factor that influences fat consumption in human subjects.

Anabolic signalling in skeletal muscle : impact of diet and disease

This thesis examines the role of dietary proteins on the maintenance of skeletal muscle mass in men who may or may not be insulin-resistant. It identified that dairy foods are powerful stimulators of muscle growth however this response is reduced during insulin-resistance.