PMID: 

Am J Clin Nutr. 2017 Dec ;106(6):1413-1421. Epub 2017 Oct 18. PMID: 29046302

Abstract Title: 

A 1-h time interval between a meal containing iron and consumption of tea attenuates the inhibitory effects on iron absorption: a controlled trial in a cohort of healthy UK women using a stable iron isotope.

Abstract: 

Tea has been shown to be a potent inhibitor of nonheme iron absorption, but it remains unclear whether the timing of tea consumption relative to a meal influences iron bioavailability.The aim of the study was to investigate the effect of a 1-h time interval of tea consumption on nonheme iron absorption in an iron-containing meal in a cohort of iron-replete, nonanemic female subjects with the use of a stable isotope (Fe).Twelve women (mean± SD age: 24.8 ± 6.9 y) were administered a standardized porridge meal extrinsically labeled with 4 mgFe as FeSOon 3 separate occasions, with a 14-d time interval between each test meal (TM). The TM was administered with water (TM-1), with tea administered simultaneously (TM-2), and with tea administered 1 h postmeal (TM-3). Fasted venous blood samples were collected for iron isotopic analysis and measurement of iron status biomarkers. Fractional iron absorption was estimated by the erythrocyte iron incorporation method.Iron absorption was 5.7%± 8.5% (TM-1), 3.6% ± 4.2% (TM-2), and 5.7% ± 5.4% (TM-3). Mean fractional iron absorption was found to be significantly higher (2.2%) when tea was administered 1 h postmeal (TM-3) than when tea was administered simultaneously with the meal (TM-2) (= 0.046). An∼50% reduction in the inhibitory effect of tea (relative to water) was observed, from 37.2% (TM-2) to 18.1% (TM-3).This study shows that tea consumed simultaneously with an iron-containing porridge meal leads to decreased nonheme iron absorption and that a 1-h time interval between a meal and tea consumption attenuates the inhibitory effect, resulting in increased nonheme iron absorption. These findings are not only important in relation to the management of iron deficiency but should also inform dietary advice, especially that given to those at risk of deficiency. This trial was registered at clinicaltrials.gov as NCT02365103.

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PMID: 

Eur J Nutr. 2019 Mar ;58(2):843-851. Epub 2018 May 16. PMID: 29766292

Abstract Title: 

Gut-derived lipopolysaccharides increase post-prandial oxidative stress via Nox2 activation in patients with impaired fasting glucose tolerance: effect of extra-virgin olive oil.

Abstract: 

PURPOSE: Post-prandial phase is characterized by enhanced oxidative stress but the underlying mechanism is unclear. We investigated if gut-derived lipopolysaccharide (LPS) is implicated in this phenomenon and the effect of extra virgin olive oil (EVOO) in patients with impaired fasting glucose (IFG).METHODS: This is a randomized cross-over interventional study including 30 IFG patients, to receive a lunch with or without 10 g of EVOO. Serum LPS, Apo-B48, markers of oxidative stress such as oxidized LDL (oxLDL) and soluble Nox2-derived peptide (sNox2-dp), a marker of nicotinamide-adenine-dinucleotide-phosphate oxidase isoform Nox2 activation, and plasma polyphenols were determined before, 60 and 120 min after lunch.RESULTS: In patients not given EVOO oxidative stress as assessed by sNox2-dp and oxLDL significantly increased at 60 and 120 min concomitantly with an increase of LPS and Apo-B48. In these patients, changes of LPS were correlated with Apo-B48 (Rs = 0.542, p = 0.002) and oxLDL (Rs = 0.463, p = 0.010). At 120 min, LPS (β - 15.73, p 

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PMID: 

Clin Nutr. 2019 12 ;38(6):2727-2734. Epub 2018 Dec 7. PMID: 30573355

Abstract Title: 

Grape pomace polyphenols improve insulin response to a standard meal in healthy individuals: A pilot study.

Abstract: 

BACKGROUND & AIMS: Dietary polyphenols have beneficial effects on glucose/lipid metabolism in subjects at high risk to develop type 2 diabetes; however, the underlying mechanisms are not clear. We aimed to evaluate: 1) the acute effects of the consumption of a drink rich in polyphenols from red grape pomace (RGPD) on glucose/insulin and triglyceride responses to a standard meal in healthy individuals, and, 2) the relationship between plasma levels of phenolic metabolites and metabolic parameters.METHODS: Twelve healthy men, aged 20-40 years participated in a randomized, controlled study according to a cross-over design. After a 3-day low-polyphenol diet, all participants consumed, on two different days and separated by a one week interval, after an overnight fast, a drink rich in polyphenols (1.562 g gallic acid equivalents (GAE)) or a control drink (CD, no polyphenols), followed after 3 h by a standard meal (960 kcal, 18% protein, 30% fat, 52% CHO). Blood samples were taken at fasting, 3 h after the drink, over 5 h after the standard meal and at fasting on the next day to measure plasmaconcentrations of glucose, insulin, triglyceride and phenolic metabolites.RESULTS: Glycemic and triglyceride post-meal responses were similar after both the RGPD and the control drink. In contrast, postprandial insulin incremental area (iAUC) was 31% lower (p 

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PMID: 

Food Funct. 2019 Jun 19 ;10(6):3127-3134. PMID: 31140506

Abstract Title: 

Inhibition of intestinal glucose transport by polyphenols: a mechanism for indirect attenuation of cholesterol absorption?

Abstract: 

Cholesterol uptake and chylomicron synthesis are promoted by increasing glucose concentrations in both healthy and diabetic individuals during the postprandial phase. The goal of this study was to test whether acute inhibition of glucose uptake could impact cholesterol absorption in differentiated human intestinal Caco-2 cells. As expected, high glucose upregulated intestinal cholesterol metabolism promoting its uptake and incorporation in lipoproteins. This was accompanied by an increase in the gene expression of Niemann-Pick C1 Like 1 and proprotein convertase subtillisin/kexin type 9. Cholesterol uptake was attenuated by acute inhibition of glucose absorption by cytochalasin B, by a chamomile extract and by one of its main constituent polyphenols, apigenin 7-O-glucoside; however, chylomicron secretion was only reduced by the chamomile extract. These data support a potential indirect role for bioactives in modulating intestinal lipid pathways through effects on intestinal glucose uptake. This working hypothesis warrants further testing in an in vivo setting such as in hypercholesterolaemic or prediabetic individuals.

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PMID: 

Nutr Metab Cardiovasc Dis. 2013 Feb ;23(2):136-43. Epub 2011 Jul 29. PMID: 21802266

Abstract Title: 

Flaxseed dietary fibers suppress postprandial lipemia and appetite sensation in young men.

Abstract: 

BACKGROUND AND AIM: Dietary fibers (DF) are linked to a reduced risk of life-style diseases, which relate to their physiological effects in the gastrointestinal tract. The aim was to examine whether flaxseed DF-enriched meals suppress postprandial lipemia and reduce appetite.METHODS AND RESULTS: Four different iso-caloric meals were tested in 18 young men in a double-blind randomized crossover design. Test meals were served after an overnight fast. DF content and source were: control (C): 1.4 g/MJ; whole flaxseed (WF): 2.4 g/MJ from whole flaxseeds; low-mucilage dose (LM): 2.4 g/MJ from flaxseed DF; high-mucilage dose (HM): 3.4 g/MJ from flaxseed DF. During the 7 h test day, subjective appetite sensation was assessed using visual analogue scales and appetite-regulating hormones, and lipemia and glycemia were measured, after which ad libitum energy intake was recorded. There was a significant time × meal effect on triacylglycerols (TG) (p = 0.02) and an 18% smaller area under the curve (AUC) for TG after meal HM compared to meal C was observed (p 

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PMID: 

Acta Diabetol. 2013 Apr ;50(2):273-6. Epub 2011 Aug 11. PMID: 21833777

Abstract Title: 

The association of hs-CRP with fasting and postprandial plasma lipids in patients with type 2 diabetes is disrupted by dietary monounsaturated fatty acids.

Abstract: 

The aim of the study was to evaluate whether two dietary approaches recommended for diabetes mellitus and cardiovascular prevention-high-MUFA or complex carbohydrates/fiber-differently influence inflammation. A 4-week crossover study in 12 individuals with type 2 diabetes was performed. Fasting and postprandial hs-CRP plasma levels were not significantly different after a high-carbohydrate/high-fiber/low-glycemic index (CHO/fiber) and a high-MUFA diet. Compared with fasting, hs-CRP levels decreased significantly after the MUFA but not after the CHO/fiber meal. Triglyceride-rich lipoproteins were significantly lower after the CHO/fiber than the MUFA diet. At fasting and postprandially, hs-CRP correlated with triglyceride in whole plasma, chylomicrons, small and large VLDL after the CHO/fiber but not after the MUFA diet. In conclusion, a MUFA-rich diet and a carbohydrate/fiber-rich diet induced similar effects on plasma hs-CRP concentrations. However, these dietary approaches seem to influence hs-CRP levels through different mechanisms. i.e., direct acute postprandial effects by MUFA and triglyceride-rich lipoproteins mediated effects by CHO/fiber.

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PMID: 

Nutr Metab Cardiovasc Dis. 2014 Aug ;24(8):837-44. Epub 2014 Jan 28. PMID: 24598599

Abstract Title: 

A whole-grain cereal-based diet lowers postprandial plasma insulin and triglyceride levels in individuals with metabolic syndrome.

Abstract: 

BACKGROUND AND AIM: Until recently, very few intervention studies have investigated the effects of whole-grain cereals on postprandial glucose, insulin and lipid metabolism, and the existing studies have provided mixed results. The objective of this study was to evaluate the effects of a 12-week intervention with either a whole-grain-based or a refined cereal-based diet on postprandial glucose, insulin and lipid metabolism in individuals with metabolic syndrome.METHODS AND RESULTS: Sixty-one men and women age range 40-65 years, with the metabolic syndrome were recruited to participate in this study using a parallel group design. After a 4-week run-in period, participants were randomly assigned to a 12-week diet based on whole-grain products (whole-grain group) or refined cereal products (control group). Blood samples were taken at the beginning and end of the intervention, both fasting and 3 h after a lunch, to measure biochemical parameters. Generalized linear model (GLM) was used for between-group comparisons. Overall, 26 participants in the control group and 28 in the whole-grain group completed the dietary intervention. Drop-outs (five in the control and two in the whole-grain group) did not affect randomization. After 12 weeks, postprandial insulin and triglyceride responses (evaluated as average change 2 and 3 h after the meal, respectively) decreased by 29% and 43%, respectively, in the whole-grain group compared to the run-in period. Postprandial insulin and triglyceride responses were significantly lower at the end of the intervention in the whole-grain group compared to the control group (p = 0.04 and p = 0.05; respectively) whereas there was no change in postprandial response of glucose and other parameters evaluated.CONCLUSIONS: A twelve week whole-grain cereal-based diet, compared to refined cereals, reduced postprandial insulin and triglycerides responses. This finding may have implications for type 2 diabetes risk and cardiovascular disease.

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PMID: 

Br J Nutr. 2020 Mar 3:1-22. Epub 2020 Mar 3. PMID: 32122411

Abstract Title: 

Dietary substitution of saturated with monounsaturated fatty acids within high-fat diets attenuates hyperinsulinemia and pancreatic islet dysfunction.

Abstract: 

Preliminary evidence suggested that high-fat diets (HFD) enriched with saturated fatty acids (SFA) but not monounsaturated fatty acids (MUFA), promoted hyperinsulinemia and pancreatic hypertrophy with insulin resistance. The objective of this study was to determine whether substitution of dietary MUFA within a HFD could attenuate the progression of pancreatic islet dysfunction seen with prolonged SFA-HFD. For 32 weeks, C57BL/6J mice were fed either: 1) low fat diet, 2) SFA-HFD, or 3) SFA-HFD for 16 weeks then switched to MUFA-HFD for 16 weeks (SFA-to-MUFA-HFD). Fasting insulin was assessed throughout the study; islets were isolated following the intervention. Substituting SFA-to-MUFA-HFD prevented the progression of hyperinsulinemia observed in SFA-HFD mice (p

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PMID: 

Adv Nutr. 2020 Mar 5. Epub 2020 Mar 5. PMID: 32135008

Abstract Title: 

The Effects of Diets Enriched in Monounsaturated Oleic Acid on the Management and Prevention of Obesity: a Systematic Review of Human Intervention Studies.

Abstract: 

Obesity is associated with an increased risk of several major noncommunicable diseases, and is an important public health concern globally. Dietary fat content is a major contributor to the increase in global obesity rates. Changes in dietary habits, such as the quality of fatty acids in the diet, are proposed to prevent obesity and its metabolic complications. In recent years, a number of studies have found that oleic acid (OA), the most common MUFA in daily nutrition, has protective effects against human disease. Importantly, there is emerging evidence indicating the beneficial effects of OA in regulating body weight. Accordingly, the objective of this systematic review was to investigate the effects of diets enriched in monounsaturated OA on the management and prevention of obesity, emphasizing possible mechanisms of action of OA in energy homeostasis. Searches were performed in PubMed/MEDLINE, ScienceDirect, Scopus, ProQuest, and Google Scholar databases for clinical trials that examined the effects of diets rich in OA on obesity. Of 821 full-text articles assessed, 28 clinical trials were included in the present study. According to the studies examined in this review, diets enriched in OA can influence fat balance, body weight, and possibly energy expenditure. Importantly, abdominal fat and central obesity can be reduced following consumption of high-OA-containing meals. Mechanistically, OA-rich diets can be involved in the regulation of food intake, body mass, and energy expenditure by stimulating AMP-activated protein kinase signaling. Other proposed mechanisms include the prevention of the nucleotide-binding oligomerization domain-like receptor 3/caspase-1 inflammasome pathway, the induction of oleoylethanolamide synthesis, and possibly the downregulation of stearoyl-CoA desaturase 1 activity. In summary, current findings lend support to advice not restricting consumption of OA-rich meals so as to maintain a healthy body weight.

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PMID: 

J Nutr Sci. 2019 Nov 29 ;9:e6. Epub 2019 Nov 29. PMID: 32076549

Abstract Title: 

Increasing the proportion of plasma MUFA, as a result of dietary intervention, is associated with a modest improvement in insulin sensitivity.

Abstract: 

The effect of modifying dietary fatty acid (FA) composition on insulin sensitivity remains unclear. We aimed to investigate whether changes in plasma phospholipid (PL) FA composition, as a result of dietary intervention, correspond with changes in insulin sensitivity. The RISCK study was a 6-month randomised controlled dietary intervention study, which assessed the effect of modifying dietary fat and the glycaemic index (GI) of carbohydrates on insulin sensitivity. Total NEFA levels, fasting plasma PL FA profiles and an insulin sensitivity index (Si), derived from intravenous glucose tolerance minimal-model analysis, were available from 533 participants, all at elevated risk of type 2 diabetes. Bivariate correlations between changes in saturated PL FA (SFA), MUFA (as a percentage of total plasma NEFA) and changes in Si were assessed according to treatment group. Age, sex, ethnicity, percentage change in body mass and change in dietary GI were controlled for. Increasing total NEFA concentration was associated with worsening Si (0·152;= 0·001). In the high-MUFA/low-GI diet group, change in PL-MUFA was positively and independently associated with change in Si (0·297;= 0·002). Among MUFA, change in oleic acid (18 : 1) was most strongly correlated with change in Si (0·266= 0·005), as was change in minor FA 24 : 1 (0·244;= 0·011) and 17 : 1 (0·196;= 0·042). In the high-SFA/high-GI group, change in SFA concentration was not significantly associated with change in Si. In conclusion, increases in the proportion of plasma PL-MUFA following a high-MUFA dietary intervention were associated with improvements in insulin sensitivity.

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