Effects of 22 traditional anti-diabetic medicinal plants on DPP-IV enzyme activity and glucose homeostasis in high-fat fed obese diabetic rats.

The present study investigated the effects of hot water extracts of 22 medicinal plants used traditionally to treat diabetes on Dipeptidyl peptidase-IV (DPP-IV) activity both in vitro and in vivo in high-fat fed (HFF) obese-diabetic rats. Fluorometric assay was employed to determine the DPP-IV activity. For in vivo studies, HFF obese-diabetic rats were fasted for 6 h and blood was sampled at different times before and after the oral administration of the glucose alone (18 mmol/kg body weight) or with either of the four most active plant extracts (250 mg/5 ml/kg, body weight) or established DPP-IV inhibitors (10 µmol/5 ml/kg). DPP-IV inhibitors: sitagliptin, vildagliptin and diprotin A, decreased enzyme activity by a maximum of 95-99% (P<0.001). Among the 22 natural anti-diabetic plants tested, AnogeissusLatifolia exhibited the most significant (P<0.001) inhibitory activity (96 ± 1%) with IC50 and IC25 values of 754 and 590 µg/ml. Maximum inhibitory effects of other extracts: Aegle marmelos, Mangifera indica, Chloropsis cochinchinensis, Trigonella foenum-graecum and Azadirachta indica were (44 ±7%; 38 ± 4%; 31±1%; 28±2%; 27±2%, respectively). A maximum of 45% inhibition was observed with >25 µM concentrations of selected phytochemicals (rutin). A.latifolia, A. marmelos, T. foenum-graecum and M. indica extracts improved glucose tolerance, insulin release, reduced DPP-IV activity and increased circulating active GLP-1 in HFF obese-diabetic rats (P<0.05-0.001). These results suggest that ingestion of selected natural anti-diabetic plants, in particular A. latifolia, A. marmelos, T. foenum-graecum and M. indica can substantially inhibit DPP-IV and improve glucose homeostasis, thereby providing a useful therapeutic approach for the treatment of T2DM.

Micronutrient supplementation in maintenance haemodialysis patients enhances activity of antioxidant enzymes.

BACKGROUND: Haemodialysis patients are exposed to high levels of oxidative stress, perhaps contributing to increased rates of cardiovascular and malignant disease. In this context, the body's defence mechanisms against oxidative insult, including activity of the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx), are known to be deranged. METHODS: This randomised double-blind study assessed the effects of a novel micronutrient cocktail containing physiological doses of antioxidant vitamins and trace minerals on antioxidant enzyme activity in maintenance haemodialysis. Thirty-seven patients were randomised to receive placebo or micronutrient. SOD and GPx activity was analysed at baseline and after 6 months of treatment. RESULTS: SOD levels did not change in the treatment group but fell significantly (p=0.0443) in controls, while activity of GPx remained unchanged in controls but rose significantly (p=0.0123) in treated patients. CONCLUSIONS: These results are consistent with a beneficial effect of the cocktail on antioxidant enzyme activity and may contribute to an indication for large-scale studies to assess clinical outcome measures.

Increased portion size leads to a sustained increase in energy intake over 4 d in normal-weight and overweight men and women.

Large food portions may be facilitating excess energy intake (EI) and adiposity among adults. The present study aimed to assess the extent to which EI and amounts of foods consumed are influenced by the availability of different-sized food portions. A randomised within-subject cross-over, fully residential design was used, where forty-three (twenty-one men and twenty-two women) normal-weight and overweight adults were randomly allocated to two separate 4 d periods where they were presented with either 'standard' or 'large' food portions of the same foods and beverages. The main outcome measures were the amount of food (g) and EI (MJ) consumed throughout each study period. Mean EI over 4 d was significantly higher on the large portion condition compared with the standard condition in the total group (59.1 (sd 6.6) v. 52.2 (sd 14.3) MJ; P = 0.020); men and women increased their EI by 17 % (10 (sd 6.5) MJ; P < 0.001) and 10 % (4 (sd 6.5) MJ; P = 0.005) respectively when served the large food portions relative to the standard food portions. The increased intakes were sustained over the 4 d in the large portion condition with little evidence of down-regulation of EI and food intake being made by subjects. Increased food portion size resulted in significant and sustained increases in EI in men and women over 4 d under fully residential conditions. The availability and consumption of larger portions of food may be a significant factor contributing to excess EI and adiposity.

Associations between the portion sizes of food groups consumed and measures of adiposity in the British National Diet and Nutrition Survey.

The objective of the present study was to examine the associations between the portion sizes of food groups consumed with measures of adiposity using data from the National Diet and Nutrition Survey of British adults. Seven-day weighed dietary records, physical activity diaries and anthropometric measurements were used. Foods eaten were assigned to thirty different food groups and analyses were undertaken separately for men and women. The median daily portion size of each food group consumed was calculated. The potential mis-reporting [corrected] of dietary energy intake (EI) was identified using the following equation: EI--estimated energy requirements/EER [corrected] x 100 = percentage of under-reporting (UR) of energy needs. Multinomial logistic regression (adjusted for age, social class, physical activity level and UR) was used to determine the portion sizes of food groups most strongly associated with obesity status. Few positive associations between the portion sizes of food groups consumed and obesity status were found. However, UR was prevalent, with a median UR of predicted energy needs of 34 and 33 % in men and women, respectively. After the adjustment was made for UR, more associations between the food groups and obesity status became apparent in both sexes. The present study suggests that the true effect of increased portion size of foods on obesity status may be masked by high levels of UR. Alternatively, these data may indicate that an increased risk of obesity is not associated with specific foods/food groups but rather with an overall increase in the range of foods and food groups being consumed.

Snacking patterns among adolescents: a comparison of type, frequency and portion size between Britain in 1997 and Northern Ireland in 2005.

Despite the potential link between snack food intake and obesity and the reportedly high prevalence of snacking among adolescents, adolescent snack food patterns (types of foods consumed, frequency and portion size) have not been extensively examined. This study examines these issues using data on the snacking patterns of adolescents aged 13-16 years who took part in the 1997 National Diet and Nutrition Survey (NDNS) and that from a Northern Irish (NI) cohort of adolescents collected 8 years later, in 2005. Overall energy intake was significantly higher in the NI adolescents in 2005 compared with the NDNS adolescents in 1997 (P < 0.01). Consequently, energy intake from snacks was significantly higher in the NI cohort (P < 0.01) and a trend for a higher % energy intake from snacks compared with the NDNS group was observed (median 32.5% v. 29.8%, respectively). Sugar-sweetened carbonated and soft drinks remained the most popular choice of snack over this 8-year period; however, both the portion size consumed and frequency of consumption were significantly higher among the adolescents in 2005 compared with those in 1997 (P = 0.022 and P = 0.014, respectively). Despite the lower popularity, and correspondingly lower frequency of milks and beverages, the portion size of both food groups was significantly higher among the adolescents in 2005 compared with those in 1997 (P < 0.001 and P = 0.007, respectively). These findings may provide scope for policy interventions to place particular emphasis on reducing typical portion sizes consumed of popular snack choices, in particular high-energy carbonated and soft drinks, among UK adolescents.

Energy density of the diet and change in body fatness from childhood to adolescence; is there a relation?

BACKGROUND: The contribution of energy density (ED) of the total diet to increased risk of obesity from childhood into adolescence is unclear. OBJECTIVE: We assessed the relation between the ED of the diet in childhood, calculated in a number of ways, and change in adiposity from childhood to adolescence. DESIGN: In a prospective study, 48 children (30 boys, 18 girls) were initially studied at age 6-8 y (baseline) and followed up at age 13-17 y. Daily ED, energy intake, and food intake were assessed at baseline by 7-d weighed food records concurrent with estimates of total energy expenditure (TEE) by doubly labeled water. ED was calculated with the use of 5 published methods. Obesity risk was defined with the use of body fat from total body water by isotope dilution. Body fat was normalized for height and expressed as fat mass index (FMI). Change in adiposity was calculated as follow-up FMI minus baseline FMI. RESULTS: Misreporting of energy intake at the group level at baseline was low relative to the TEE. ED of the total diet at baseline by the 3 methods for calculating ED that excluded all or most beverages was prospectively associated with change in FMI. However, ED of the total diet by any of the methods was not associated with change in the percentage body fat, body mass index, or waist circumference z scores. CONCLUSION: The methods used to calculate ED and to assess obesity risk lead to different conclusions about the relation between the ED of the diet in childhood and gain in fat into adolescence.

Determining bioavailability of food folates in a controlled intervention study.

BACKGROUND: The concept of dietary folate equivalents (DFEs) in the United States recognizes the differences in bioavailability between natural food folates and the synthetic vitamin, folic acid. However, many published reports on folate bioavailability are problematic because of several confounding factors. OBJECTIVE: We compared the bioavailability of food folates with that of folic acid under controlled conditions. To broadly represent the extent to which natural folates are conjugated in foods, we used 2 natural sources of folate, spinach (50% polyglutamyl folate) and yeast (100% polyglutamyl folate). DESIGN: Ninety-six men were randomly assigned according to their screening plasma homocysteine (tHcy) concentration to 1 of 4 treatment groups for an intervention period of 30 d. Each subject received (daily under supervision) either a folate-depleted "carrier" meal or a drink plus 1) placebo tablet, 2) 200 microg folic acid in a tablet, 3) 200 microg natural folate provided as spinach, or 4) 200 microg natural folate provided as yeast. RESULTS: Among the subjects who completed the intervention, responses (increase in serum folate, lowering of tHcy) relative to those in the placebo group (n = 18) were significant in the folic acid group (n = 18) but not in the yeast folate (n = 19) or the spinach folate (n = 18) groups. Both natural sources of folate were significantly less bioavailable than was folic acid. Overall estimations of folate bioavailability relative to that of folic acid were found to be between 30% (spinach) and 59% (yeast). CONCLUSION: Relative bioavailability estimates were consistent with the estimates from the metabolic study that were used as a basis to derive the US DFE value.