A systematic review of in vitro studies evaluating the inhibitory effects of polyphenol-rich fruit extracts on carbohydrate digestive enzymes activity: a focus on culinary fruits consumed in Europe

Evidence shows that polyphenols can attenuate postprandial blood glucose responses to meals containing digestible carbohydrate. Polyphenol-rich plant extracts are emerging as potential ingredients in functional foods and/or beverages despite limited understanding of their physiological effects. Many studies have investigated the mechanisms of polyphenol-rich fruit extracts on inhibition of digestive enzymes. However, the evidence available has yet to be critically evaluated systematically. This report reviews the in vitro literature to quantify the effect of fruit polyphenol extracts on the activities of digestive carbohydrases. A systematic literature search was conducted using six science databases. Included studies, totaling 34 in number, were in vitro digestion models which quantified gut digestive enzyme(s) activity on starch digestion in the presence of fruit polyphenol extracts. Most studies assessed the effects of fruit extracts on either α-amylase (n = 30) or α-glucosidase (n = 30) activity. Studies were consistent overall in showing stronger inhibition of α-amylase compared to α-glucosidase by proanthocyanidin- and/or ellagitannin-rich fruit extracts. Recommendations are proposed for future reporting of this type of research to enable meaningful synthesis of the literature as a whole. Such knowledge could allow effective choices to be made for development of novel functional foods and beverages.

What are interesterified fats and should we be worried about them in our diet?

Interesterified (IE) fats are used in a wide range of food products and were introduced as a replacement for trans fats, which are known to be detrimental to cardiovascular health. However, the effects of interesterification on metabolism and subsequent effects on cardiovascular health are not understood and previous studies have seldom investigated industrially-relevant IE fats. No legislation currently exists regarding the labelling of IE fats in food products and therefore estimates of average consumption rates in the UK population are currently unavailable. In order to meet the urgent need for a systematic investigation of the health effects of consumer-relevant IE fats, it is essential to estimate current IE fat intakes and to investigate biological mechanisms that might mediate acute and chronic cardiometabolic effects of commercially relevant IE fats.

Lack of effect of supplementation with EPA or DHA on platelet-monocyte aggregates and vascular function in healthy men

BACKGROUND AND AIMS

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) found in fish oil are postulated to have favourable effects on platelet, endothelial and vascular function. We investigated whether EPA has differential effects on in vivo platelet aggregation and other markers of cardiovascular risk compared to DHA.

METHODS AND RESULTS

Following a 2 wk run-in taking encapsulated refined olive oil, 48 healthy young men were randomly allocated using a parallel design to receive EPA-rich (3.1 g EPA/d) or DHA-rich (2.9 g DHA/d) triglyceride concentrates or refined olive oil (placebo), for a total supplementary lipid intake of 5 g/d. The specified primary outcome was change in platelet monocyte aggregates (PMA); secondary outcomes were capillary density, augmentation index, digital pulse volume measurements, 24 h ambulatory BP, plasma 8-isoprostanes-F2α. Changes in the proportions of DHA and EPA in erythrocytes and non-esterified fatty acid composition indicated compliance to the intervention. There was no significant treatment effect on PMA (P = 0.382); mean changes (%) (95% CI) were placebo -0.5 (-2.0, 1.04), EPA 0.4 (-0.8, 1.6), DHA 0.3 (-1.5, 2.0). R-QUICKI, an index of insulin sensitivity, was greater following EPA compared to placebo (P < 0.05). No other significant differences were noted.

CONCLUSION

Neither EPA- nor DHA-rich fish oil supplementation influence platelet-monocyte aggregation or several markers of vascular function after 6 wk in healthy young males. This trial was registered at clinicaltrials.gov as NCT01735357.

Evidence for associations between common polymorphisms of estrogen receptor beta gene with homocysteine and nitric oxide

BACKGROUND

Homocysteine and asymmetric dimethylarginine (ADMA) affect nitric oxide (NO) concentration, thereby contributing to cardiovascular disease (CVD). Both amino acids can be reduced in vivo by estrogen. Variation in the estrogen receptor (ER) may influence homocysteine and ADMA, yet no information is available on associations with single nucleotide polymorphisms in the estrogen receptor genes ERalpha (PvuII and XbaI) and ERbeta (1730G-->A and cx + 56 G-->A).

OBJECTIVE

To find relationships between common polymorphisms associated with cardiovascular disease and cardiovascular risk factors homocysteine and ADMA.

METHODS

In a cross-sectional study with healthy postmenopausal women (n = 89), homocysteine, ADMA, nitric oxide metabolites (NOx), plasma folate and ERalpha and beta polymorphisms ERalpha PvuII, ERalpha XbaI; ERbeta 1730G-->A (AluI), ERbeta cx + 56 G-->A (Tsp509I) were analyzed.

RESULTS

Women who are homozygotic for ERbetacx + 56 G-->A A/A exhibited higher homocysteine (p = 0.012) and NOx (p = 0.056) levels than wildtype or heterozygotes. NOx concentration was also significantly affected by ERbeta 1730 G -->A polymorphism (p = 0.025). The ERbeta (p < 0.001) and ERalpha (p < 0.001) polymorphisms were in linkage disequilibrium.

CONCLUSIONS

Women who are homozygotic for ERbetacx + 56 G-->A A/A may be at increased risk for cardiovascular disease due to higher homocysteine levels.

Development and certification of the new SRM 695 trace elements in multi-nutrient fertilizer

During the past seven years, several states within the US have enacted regulations that limit the amounts of selected non-nutritive elements in fertilizers. Internationally, several countries, including Japan, China, and Australia, and the European Union also limit the amount of selected elements in fertilizers. The elements of interest include As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Se, and Zn. Fertilizer manufacturers and state regulatory authorities, faced with meeting and verifying these limits, need to develop analytical methods for determination of the elements of concern and to validate results obtained using these methods. Until now, there were no certified reference materials available with certified mass fraction values for all elements of interest in a blended, multi-nutrient fertilizer matrix. A new standard reference material (SRM) 695 trace elements in multi-nutrient fertilizer, has been developed to help meet these needs. SRM 695 has recently been issued with certified mass fraction values for seventeen elements, reference values for an additional five elements, and information values for two elements. The certificate of analysis includes an addendum listing percentage recovery for eight of these elements, determined using an acid-extraction inductively-coupled plasma optical-emission spectrometry (ICP-OES) method recently developed and tested by members of the Association of American Plant Food Control Officials.

Soya isoflavone-enriched cereal bars affect markers of endothelial function in postmenopausal women

Soya isoflavones are thought to be cardioprotective due to their structural similarity to oestrogen. In order to investigate the effect of soya isoflavones on markers of endothelial function we conducted a randomised, double-blind, placebo-controlled, cross-over study with thirty healthy postmenopausal women. The women consumed cereal bars, with or without soya isoflavones (50 mg/d), for 8 weeks, separated by an 8-week washout period. Systemic arterial compliance (SAC), isobaric arterial compliance (IAC), flow-mediated endothelium-dependent vasodilation (FMD) and nitroglycerine-mediated endothelium-independent vasodilation (NMD) were measured at the beginning of the study and after each intervention period. Blood pressure (BP) and plasma concentrations of nitrite and nitrate (NOx) and endothelin-1 (ET-1) were measured at the beginning and end of each intervention period. NMD was 13.4 (SEM 2.0)% at baseline and 15.5 (SEM 1.1) % after isoflavone treatment compared with 12.4 (SEM 1.0)% after placebo treatment (P=0.03). NOx increased from 27.7 (SEM 2.7) to 31.1 (SEM 3.2) microM after isoflavones treatment compared with 25.4 (SEM 1.5) to 20.4 (SEM 1.1) microM after placebo treatment (P=0.003) and a significant increase in the NOx:ET-1 ratio (P=0.005) was observed after the isoflavone treatment compared with placebo. A significant difference in SAC after the isoflavone and placebo treatment was observed (P=0.04). No significant difference was found in FMD, IAC, BP and ET-1. In conclusion, 8 weeks' consumption of cereals bars enriched with 50 mg soya isoflavones/d increased plasma NOx concentrations and improved endothelium-independent vasodilation in healthy postmenopausal women.

Metabolic syndrome: what is it and what are the implications?

Obesity and overweight are linked with a cluster of metabolic and vascular disorders that have been termed the metabolic syndrome. Although there is not yet a universally-accepted set of diagnostic criteria, most expert groups agree that the syndrome is characterised by impaired insulin sensitivity and hyperglycaemia, dyslipidaemia (elevated blood triacyglycerols with depressed HDL-cholesterol), abdominal obesity and hypertension. Based on existing published criteria estimates suggest that the syndrome affects a substantial percentage of the middle-aged and elderly populations of most European countries (10-20%) and confers increased risk of type 2 diabetes (2-8.8-fold) and CVD (1.5-6-fold), as well as having a marked effect on morbidity. Although the pathophysiology is incompletely understood, insulin resistance and abdominal obesity are central to subsequent abnormalities in circulating glucose and lipoproteins, and vascular function that lead to type 2 diabetes, atherosclerosis and CVD. The link between metabolic syndrome, type 2 diabetes and CVD, as well as inability to reverse the present rising rates of obesity, will lead to economically-unsustainable costs of health care in the next 10-20 years. Preventative strategies for metabolic syndrome are required to slow rates of progression and to reduce dependence on costly medical management. A notable development is recent evidence that shows that diet and exercise are more effective than drug treatment in preventing the development of type-2 diabetes in high-risk individuals. The LIPGENE project will investigate dietary fat quality as a strategy for the prevention of metabolic syndrome and identify food chain approaches that can support consumer attempts to alter their dietary patterns.

Physiological mechanisms mediating aspartame-induced satiety

Aspartame has been previously shown to increase satiety. This study aimed to investigate a possible role for the satiety hormones cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1) in this effect. The effects of the constituents of aspartame, phenylalanine and aspartic acid, were also examined. Six subjects consumed an encapsulated preload consisting of either 400 mg aspartame, 176 mg aspartic acid+224 mg phenylalanine, or 400 mg corn flour (control), with 1.5 g paracetamol dissolved in 450 ml water to measure gastric emptying. A 1983-kJ liquid meal was consumed 60 min later. Plasma CCK, GLP-1, glucose-dependent insulinotropic polypeptide (GIP), glucose, and insulin were measured over 0-120 min. Gastric emptying was measured from 0 to 60 min. Plasma GLP-1 concentrations decreased following the liquid meal (60-120 min) after both the aspartame and amino acids preloads (control, 2096.9 pmol/l min; aspartame, 536.6 pmol/l min; amino acids, 861.8 pmol/l min; incremental area under the curve [AUC] 60-120 min, P<.05). Desire to eat was reduced from 60 to 120 min following the amino acids preload (control, -337.1 mm min; aspartame, -505.4 mm min; amino acids, -1497.1 mm min; incremental AUC 60-120 min, P<.05). However, gastric emptying rates, plasma CCK, GIP, insulin, and glucose concentrations were unaffected. There was a correlation between the increase in plasma phenylalanine and decrease in desire to eat after the liquid meal following the constituent amino acids (r=-.9774, P=.004). In conclusion, it is unlikely that aspartame increases satiety via CCK- or GLP-1-mediated mechanisms, but small changes in circulating phenylalanine concentrations may influence appetite.

Casein and whey exert different effects on plasma amino acid profiles, gastrointestinal hormone secretion and appetite

Protein, generally agreed to be the most satiating macronutrient, may differ in its effects on appetite depending on the protein source and variation in digestion and absorption. We investigated the effects of two milk protein types, casein and whey, on food intake and subjective ratings of hunger and fullness, and on postprandial metabolite and gastrointestinal hormone responses. Two studies were undertaken. The first study showed that energy intake from a buffet meal ad libitum was significantly less 90 min after a 1700 kJ liquid preload containing 48 g whey, compared with an equivalent casein preload (P<0.05). In the second study, the same whey preload led to a 28 % increase in postprandial plasma amino acid concentrations over 3 h compared with casein (incremental area under the curve (iAUC), P<0.05). Plasma cholecystokinin (CCK) was increased by 60 % (iAUC, P<0.005), glucagon-like peptide (GLP)-1 by 65 % (iAUC, P<0.05) and glucose-dependent insulinotropic polypeptide by 36 % (iAUC, P<0.01) following the whey preload compared with the casein. Gastric emptying was influenced by protein type as evidenced by differing plasma paracetamol profiles with the two preloads. Greater subjective satiety followed the whey test meal (P<0.05). These results implicate post-absorptive increases in plasma amino acids together with both CCK and GLP-1 as potential mediators of the increased satiety response to whey and emphasise the importance of considering the impact of protein type on the appetite response to a mixed meal.

Colorado family practice graduates' preparation for and practice of emergency medicine

BACKGROUND

Family physicians provide care in emergency departments, especially in rural areas; however, no published data describe how they perceive their preparation for emergency practice. We surveyed graduates of Colorado family practice residencies concerning their emergency medicine practice, their comfort working in emergency departments, and their perceived preparation for practicing emergency medicine.

METHODS

Seventy recent graduates of Colorado residencies were surveyed regarding their location, work in emergency departments, contact with emergency medical services (EMS) personnel, and perceptions about their emergency medical training.

RESULTS

Forty-five percent of respondents practiced in rural settings, 33% worked in emergency departments (56% rural, 14% urban), 60% reported contact with EMS personnel (91% rural, 32% urban), 54% believed their training adequately prepared them for working in emergency departments (82% rural vs 32% urban), 63% of rural and 22% of urban respondents indicated they wanted more major trauma experience during training, 70% reported discomfort with managing trauma, and 44% were interested in a 6-month emergency medicine fellowship.

CONCLUSIONS

Most respondents believed their training in emergency medicine was adequate; however, most also reported discomfort with trauma management. Improved training for family physicians who provide emergency care could include expanded trauma care opportunities, increased work with EMS personnel, and postresidency training.

A new in vivo method for quantitative analysis of stroke lesions using diffusion-weighted magnetic resonance microscopy

Using three-dimensional diffusion-weighted MR microscopy and a rat model of focal cerebral ischemia, we evaluated the statistical characteristics of two parameters: absolute stroke volumes and change in stroke volumes over 6 h of middle cerebral artery (MCA) occlusion. In all rats, the absolute stroke volumes increased linearly over the 6-h MCA occlusion time period. On average, stroke volume growth rate was 2.1 +/- 0.5%/h. Sample size power analysis of our data demonstrated that to demonstrate a 10% reduction of the 6-h volumes, sample size per group would require 29 animals (these calculations are based on alpha = 0.05, beta = 0.20 using normal approximation). A similar 30% reduction of stroke volume at 6 h poststroke (from approximately equal to 200 to 140 mm3) would, in our "slope model," translate into a reduction of stroke growth rate from the normal + 11.25 mm3/h (150 to 200 mm3 over 4 h) to 7 mm3/h (150 to 178 mm3 over 4 h); power analysis in this case demonstrated that sample size is reduced to 15 animals per group (these calculations are based on alpha = 0.05, beta = 0.20 using normal approximation). We conclude that from a statistical standpoint our study demonstrates that stroke growth rate might be a more suitable parameter for evaluating the effect of treatment in both clinical and experimental stroke trials.

Rational people and why they do irrational things: the theory of psychological reversals

The theory of psychological reversals developed by Michael Apter, a British psychologist, is used to explain behavior and motivation in employees. The article explains that such behaviors are neither haphazard nor necessarily undesirable. Reversal theory provides a structured way of analyzing employee behaviors through the use of four pairs of exclusive, opposite states. An employee may reverse back and forth between these states.

Astringent-tasting compounds alter ion transport across isolated canine lingual epithelia

The effects of acid and astringent compounds on ion transport across isolated canine lingual epithelia were measured in an Ussing chamber. Lowering the pH from 7.4 to 3.2 decreases ion transport, as measured by the short-circuit current (Isc), when the dorsal surface of the tongue is bathed in 0.5 M NaCl and increases Isc when it is bathed in 0.05 M NaCl, tannic acid (0.1 M) inhibits Isc at both pH 3.2 and 7.4. At 0.05 M NaCl, pH 7.4 tannic acid also inhibits Isc. Thus, inhibition of Isc by tannic acid does not depend upon the pH, meaning that the reduction in transport arises from tannic acid. In the presence of NaCl (at both 0.05 and 0.5 M NaCl), 0.1 M AlK (SO4)2 or 0.1 M AlNH4(SO4)2 also inhibit Isc. For these salts, the decrease in Isc arises from the aluminum ion and not from K+, NH4+, or SO(4-)-. Other less astringent compounds (gallic and tartaric acids) had only slight effects on Isc. The main findings of this study are that both tannic acid and the aluminum salts inhibited ion transport, likely Na+ influx, via amiloride-inhibitable channels in isolated lingual epithelia. Inhibition of such Na+ channels may contribute to astringent taste.