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Purpose: It has been proposed that a higher habitual protein intake may increase cancer risk, possibly via upregulated insulin-like growth factor signalling. Since a systematic evaluation of human studies on protein intake and cancer risk based on a standardised assessment of systematic reviews (SRs) is lacking, we carried out an umbrella review of SRs on protein intake in relation to risks of different types of cancer. Methods: Following a pre-specified protocol (PROSPERO: CRD42018082395), we retrieved SRs on protein intake and cancer risk published before January 22th 2024, and assessed the methodological quality and outcome-specific certainty of the evidence using a modified version of AMSTAR 2 and NutriGrade, respectively. The overall certainty of evidence was rated according to predefined criteria. Results: Ten SRs were identified, of which eight included meta-analyses. Higher total protein intake was not associated with risks of breast, prostate, colorectal, ovarian, or pancreatic cancer incidence. The methodological quality of the included SRs ranged from critically low (kidney cancer), low (pancreatic, ovarian and prostate cancer) and moderate (breast and prostate cancer) to high (colorectal cancer). The outcome-specific certainty of the evidence underlying the reported findings on protein intake and cancer risk ranged from very low (pancreatic, ovarian and prostate cancer) to low (colorectal, ovarian, prostate, and breast cancer). Animal and plant protein intakes were not associated with cancer risks either at a low (breast and prostate cancer) or very low (pancreatic and prostate cancer) outcome-specific certainty of the evidence. Overall, the evidence for the lack of an association between protein intake and (i) colorectal cancer risk and (ii) breast cancer risk was rated as possible. By contrast, the evidence underlying the other reported results was rated as insufficient. Conclusion: The present findings suggest that higher total protein intake may not be associated with the risk of colorectal and breast cancer, while conclusions on protein intake in relation to risks of other types of cancer are restricted due to insufficient evidence. [ABSTRACT FROM AUTHOR]

Introduction: This umbrella review aimed to investigate the evidence of an effect of dietary intake of total protein, animal and plant protein on blood pressure (BP), and hypertension (PROSPERO: CRD42018082395). Methods: PubMed, Embase and Cochrane Database were systematically searched for systematic reviews (SRs) of prospective studies with or without meta-analysis published between 05/2007 and 10/2022. The methodological quality and outcome-specific certainty of evidence were assessed by the AMSTAR 2 and NutriGrade tools, followed by an assessment of the overall certainty of evidence. SRs investigating specific protein sources are described in this review, but not included in the assessment of the overall certainty of evidence. Results: Sixteen SRs were considered eligible for the umbrella review. Ten of the SRs investigated total protein intake, six animal protein, six plant protein and four animal vs. plant protein. The majority of the SRs reported no associations or effects of total, animal and plant protein on BP (all "possible" evidence), whereby the uncertainty regarding the effects on BP was particularly high for plant protein. Two SRs addressing milk-derived protein showed a reduction in BP; in contrast, SRs investigating soy protein found no effect on BP. The outcome-specific certainty of evidence of the SRs was mostly rated as low. Discussion/conclusion: This umbrella review showed uncertainties whether there are any effects on BP from the intake of total protein, or animal or plant proteins, specifically. Based on data from two SRs with milk protein, it cannot be excluded that certain types of protein could favourably influence BP. [ABSTRACT FROM AUTHOR]

Purpose: Protein-rich foods show heterogeneous associations with the risk of type 2 diabetes (T2D) and it remains unclear whether habitual protein intake is related to T2D risk. We carried out an umbrella review of systematic reviews (SR) of randomised trials and/or cohort studies on protein intake in relation to risks of T2D. Methods: Following a pre-specified protocol (PROSPERO: CRD42018082395), we retrieved SRs on protein intake and T2D risk published between July 1st 2009 and May 22nd 2022, and assessed the methodological quality and outcome-specific certainty of the evidence using a modified version of AMSTAR 2 and NutriGrade, respectively. The overall certainty of evidence was rated according to predefined criteria. Results: Eight SRs were identified of which six contained meta-analyses. The majority of SRs on total protein intake had moderate or high methodological quality and moderate outcome-specific certainty of evidence according to NutriGrade, however, the latter was low for the majority of SRs on animal and plant protein. Six of the eight SRs reported risk increases with both total and animal protein. According to one SR, total protein intake in studies was ~ 21 energy percentage (%E) in the highest intake category and 15%E in the lowest intake category. Relative Risks comparing high versus low intake in most recent SRs ranged from 1.09 (two SRs, 95% CIs 1.02–1.15 and 1.06–1.13) to 1.11 (1.05–1.16) for total protein (between 8 and 12 cohort studies included) and from 1.13 (1.08–1.19) to 1.19 (two SRs, 1.11–1.28 and 1.11–1.28) (8–9 cohort studies) for animal protein. However, SRs on RCTs examining major glycaemic traits (HbA1c, fasting glucose, fasting insulin) do not support a clear biological link with T2D risk. For plant protein, some recent SRs pointed towards risk decreases and non-linear associations, however, the majority did not support an association with T2D risk. Conclusion: Higher total protein intake was possibly associated with higher T2D risk, while there is insufficient evidence for a risk increase with higher intakes of animal protein and a risk decrease with plant protein intake. Given that most SRs on plant protein did not indicate an association, there is possibly a lack of an effect. [ABSTRACT FROM AUTHOR]

Purpose: This umbrella review aimed to assess whether dietary protein intake with regard to quantitative (higher vs. lower dietary protein intake) and qualitative considerations (total, plant-based or animal-based protein intake) affects body weight (BW), fat mass (FM) and waist circumference (WC). Methods: A systematic literature search was conducted in PubMed, Embase and Cochrane Database of Systematic Reviews for systematic reviews (SRs) with and without meta-analyses of prospective studies published between 04 October 2007 and 04 January 2022. Methodological quality and outcome-specific certainty of evidence of the retrieved SRs were assessed by using AMSTAR 2 and NutriGrade, respectively, in order to rate the overall certainty of evidence using predefined criteria. Results: Thirty-three SRs were included in this umbrella review; 29 were based on randomised controlled trials, a few included cohort studies. In studies without energy restriction, a high-protein diet did not modulate BW, FM and WC in adults in general (all "possible" evidence); for older adults, overall certainty of evidence was "insufficient" for all parameters. Under hypoenergetic diets, a high-protein diet mostly decreased BW and FM, but evidence was "insufficient" due to low methodological quality. Evidence regarding an influence of the protein type on BW, FM and WC was "insufficient". Conclusion: "Possible" evidence exists that the amount of protein does not affect BW, FM and WC in adults under isoenergetic conditions. Its impact on the reduction in BW and FM under hypoenergetic conditions remains unclear; evidence for an influence of protein type on BW, FM and WC is "insufficient". [ABSTRACT FROM AUTHOR]

Purpose: Changes in dietary protein intake metabolically affect kidney functions. However, knowledge on potential adverse consequences of long-term higher protein intake (HPI) for kidney health is lacking. To summarise and evaluate the available evidence for a relation between HPI and kidney diseases, an umbrella review of systematic reviews (SR) was conducted. Methods: PubMed, Embase and Cochrane Database of SRs published until 12/2022 were searched for the respective SRs with and without meta-analyses (MA) of randomised controlled trials or cohort studies. For assessments of methodological quality and of outcome-specific certainty of evidence, a modified version of AMSTAR 2 and the NutriGrade scoring tool were used, respectively. The overall certainty of evidence was assessed according to predefined criteria. Results: Six SRs with MA and three SRs without MA on various kidney-related outcomes were identified. Outcomes were chronic kidney disease, kidney stones and kidney function-related parameters: albuminuria, glomerular filtration rate, serum urea, urinary pH and urinary calcium excretion. Overall certainty of evidence was graded as 'possible' for stone risk not to be associated with HPI and albuminuria not to be elevated through HPI (above recommendations (> 0.8 g/kg body weight/day)) and graded as 'probable' or 'possible' for most other kidney function-related parameters to be physiologically increased with HPI. Conclusion: Changes of the assessed outcomes may have reflected mostly physiological (regulatory), but not pathometabolic responses to higher protein loads. For none of the outcomes, evidence was found that HPI does specifically trigger kidney stones or diseases. However, for potential recommendations long-term data, also over decades, are required. [ABSTRACT FROM AUTHOR]

This umbrella review aimed at assessing whether a protein intake exceeding the current recommendation for younger (0.8 g/kg body weight [BW]/day) and older (1.0 g/kg BW/day) adults affects bone mineral density and fracture risk. Moreover, the effect of animal or plant protein was evaluated. A systematic literature search was conducted in PubMed, Embase, and Cochrane Database of Systematic Reviews for systematic reviews (SRs) with or without meta-analysis of prospective studies published between 11/2008 and 08/2021. Methodological quality, outcome-specific certainty of evidence, and overall certainty of evidence of the retrieved SRs were assessed using established tools and predefined criteria. Eleven SRs of randomized controlled trials (RCTs) and/or cohort studies were included. In SRs of cohort studies and RCTs, protein intake/kg BW/day ranged between 0.21–0.95 g (low intake) and > 1.24 g (high intake), respectively, and between 0.67–1.1 g (control groups) and 1.01–1.69 g (intervention groups), respectively. The vast majority of outcome-specific certainty of evidence was rated "low" or "very low." The overall certainty of evidence for an association (cohort studies) or effect (RCTs) of total, animal or plant protein intake on each of the investigated outcomes was rated "insufficient," with the exception of possible evidence for a reduced hip fracture risk by high vs. low protein intake. Since protein intakes in low/control and high/intervention groups were very heterogeneous and with low certainty of evidence, it remains unclear whether a dose above the current recommendation or type of protein intake (animal or plant protein) affects bone health overall. However, there is possible evidence for reduced hip fracture risk with high versus low protein intake. [ABSTRACT FROM AUTHOR]

Purpose: Low-grade inflammation in obesity is associated with insulin resistance and other metabolic disturbances. In response to high-energy meal intake, blood concentrations of inflammatory markers, glucose and insulin rise. The aim of this study was to examine whether a basal inflammatory state influences postprandial responses. Methods: A randomized crossover trial was performed in 60 participants with a cardiometabolic risk phenotype (age 70 ± 5 years; BMI 30.9 ± 3.1 kg/m2). Each participant consumed three different iso-energetic meals (4300 kJ): a Western diet-like high-fat meal (WDHF), a Western diet-like high-carbohydrate meal (WDHC) and a Mediterranean diet-like meal (MED). Blood samples were collected when fasted and hourly for 5 h postprandially and analyzed for glucose, insulin, interleukin-1β (IL-1β), interleukin-6 (IL-6) and endothelial adhesion molecules. Based on fasting serum C-reactive protein (CRP) concentrations, participants were assigned to a high inflammation (CRP ≥ 2.0 mg/L; n = 30) or low inflammation (CRP < 2.0 mg/L; n = 30) group, and postprandial outcomes were compared. Results: Plasma IL-6, glucose and serum insulin increased after all meals, while IL-1β and endothelial adhesion molecules were unchanged. The high inflammation group had higher fasting and postprandial IL-6 concentrations than the low inflammation group, although the IL-6 response slope was similar between groups. In response to the WDHC meal, participants in the high inflammation group experienced a higher glycaemic response than those in the low inflammation group. Conclusion: A basal proinflammatory state results in higher absolute fasting and postprandial IL-6 concentrations, but the increase in IL-6 relative to basal levels is not different between high and low inflammation groups. Elevated glycaemic response in the high inflammation group may be due to inflammation-induced short-term insulin resistance. The trial was registered at http://www.germanctr.de and http://www.drks.de under identifier DRKS00009861 (registration date, January 22, 2016). [ABSTRACT FROM AUTHOR]

Purpose: The present work aimed to delineate (i) a revised protocol according to recent methodological developments in evidence generation, to (ii) describe its interpretation, the assessment of the overall certainty of evidence and to (iii) outline an Evidence to Decision framework for deriving an evidence-based guideline on quantitative and qualitative aspects of dietary protein intake. Methods: A methodological protocol to systematically investigate the association between dietary protein intake and several health outcomes and for deriving dietary protein intake recommendations for the primary prevention of various non-communicable diseases in the general adult population was developed. Results: The developed methodological protocol relies on umbrella reviews including systematic reviews with or without meta-analyses. Systematic literature searches in three databases will be performed for each health-related outcome. The methodological quality of all selected systematic reviews will be evaluated using a modified version of AMSTAR 2, and the outcome-specific certainty of evidence for systematic reviews with or without meta-analysis will be assessed with NutriGrade. The general outline of the Evidence to Decision framework foresees that recommendations in the derived guideline will be given based on the overall certainty of evidence as well as on additional criteria such as sustainability. Conclusion: The methodological protocol permits a systematic evaluation of published systematic reviews on dietary protein intake and its association with selected health-related outcomes. An Evidence to Decision framework will be the basis for the overall conclusions and the resulting recommendations for dietary protein intake. [ABSTRACT FROM AUTHOR]

Purpose: Flavonoid consumption during adolescence could contribute to preventing adult onset of type 2 diabetes mellitus. We investigated the prospective association between habitual intake of flavonoids from fruit and vegetables (FlavFV) during adolescence and risk markers of type 2 diabetes in early adulthood. Methods: This analysis included participants of the DONALD Study, who had provided a fasting blood sample in adulthood (18–39 years), data on FlavFV-intake during adolescence (females: 9–15 years, males: 10–16 years) and relevant covariates. Habitual FlavFV-intake was either estimated using repeated 3-day weighed dietary records (n = 268), or the validated biomarker hippuric acid (uHA)-excretion in repeated 24-h urine samples (n = 241). Multivariable linear regressions were performed to analyse the prospective associations of FlavFV or uHA with homeostasis model assessment insulin sensitivity (HOMA2-%S), hepatic steatosis index (HSI), fatty liver index (FLI) and a pro-inflammatory score. Results: Higher FlavFV-intake was independently related to higher HOMA2-%S among females (Ptrend = 0.03), but not among males. Both FlavFV-intake and uHA-excretion were inversely associated with HSI (Ptrend < 0.0001 and Ptrend = 0.02, respectively) and the pro-inflammatory score (Ptrend = 0.02 and Ptrend = 0.008, respectively), but not with FLI. Conclusions: Our data indicate that flavonoid consumption from fruit and vegetables during adolescence is associated with a favourable risk factor profile for type 2 diabetes in early adulthood. [ABSTRACT FROM AUTHOR]

Purpose: Chronic low-level systemic and adipose tissue inflammation has been identified as a major etiologic factor in many chronic diseases, including hypertension and cardiovascular diseases. Evidence from experimental studies suggests anti-inflammatory effects of dietary flavonols such as quercetin. Methods: We investigated the effects of regular intake of quercetin on leptin, adiponectin, biomarkers of inflammation, glucose and insulin in overweight-to-obese patients with pre- and stage 1 hypertension. Another objective was to assess the safety of daily quercetin supplementation measured by parameters of liver and kidney function and of hematology. Subjects ( n = 70) were randomized to receive a supra-nutritional dose of 162 mg/d quercetin or placebo in a double-blinded, placebo-controlled crossover trial with 6-week treatment periods separated by a 6-week washout period. Two subjects dropped out for personal reasons. Only data from the remaining 68 subjects were included in the analysis. Results: Compared to placebo, quercetin did not significantly affect serum concentrations of leptin and adiponectin, HOMA-AD or the ratios of leptin/adiponectin and adiponectin/leptin. Neither quercetin nor placebo significantly changed serum C-reactive protein and plasma tumor necrosis factor alpha. Compared to placebo, quercetin did not significantly affect glucose, insulin, HOMA-IR, blood biomarkers of liver and renal function, hematology and serum electrolytes. Conclusion: A supra-nutritional dose of 162 mg/d quercetin from onion skin extract for 6 weeks is safe but without significant effects on parameters of systemic and adipose tissue inflammation as well as glucose and insulin in overweight-to-obese subjects with (pre-)hypertension. This trial was registered at and as DRKS00000555. [ABSTRACT FROM AUTHOR]

Purpose: To determine whether postprandial metabolic and vascular responses induced by a high-fat and high-carbohydrate meal are attenuated by ingestion of the flavonol quercetin. Methods: Twenty-two overweight-to-obese hypertensive patients participated in a randomized, double-blind, controlled, crossover meal study. They consumed a test meal (challenge) rich in energy (4754 kJ), fat (61.6 g), saturated fatty acids (53 % of total fatty acids), and carbohydrates (113.3 g) with either placebo or 54 mg quercetin. Blood pressure, reactive hyperemia index (RHI), high-sensitive C-reactive protein (hs-CRP), soluble endothelial-derived adhesion molecules, parameters of lipid and glucose metabolism, and markers of antioxidant status were measured before the meal and at 2 and 4 h postprandially. Results: Systolic and diastolic blood pressure increased significantly over time, but were not affected by treatment (placebo or quercetin). During both treatments, serum endothelin-1, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and plasma asymmetric dimethylarginine slightly decreased over time, whereas RHI increased. Serum triglycerides, total cholesterol, and insulin significantly increased, whereas HDL cholesterol and glucose significantly decreased over time, again with no effect of treatment. Plasma α-tocopherol significantly increased, and plasma Trolox equivalent antioxidative capacity decreased over time. Serum hs-CRP, plasma retinol, and β-carotene did not significantly change during the trial. Conclusion: In hypertensive patients, a high-energy meal did not lead to postprandial impairment of vascular endothelial function. Postprandial metabolic responses induced by the challenge, such as lipemia and insulinemia, were not attenuated by the concomitant ingestion of quercetin. Clinical trial: This trial was registered at and as DRKS00000555. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the plasma kinetics of quercetin derived from hard capsules filled with onion skin extract powder or quercetin dihydrate in humans. Methods: In a randomized, single-blind, diet-controlled crossover study, 12 healthy subjects (six men and six women) aged 21-33 years were administered a single oral supra-nutritional dose of approximately 163 mg quercetin derived from onion skin extract powder (containing 95.3 % of total flavonoids as quercetin aglycone) or quercetin dihydrate (134 mg quercetin aglycone equivalent). Blood samples were collected before and during a 24-h period after quercetin administration. The concentrations of quercetin and its two monomethylated derivatives, isorhamnetin (3′- O-methyl quercetin), and tamarixetin (4′- O-methyl quercetin), were measured using HPLC with fluorescence detection after plasma enzymatic treatment. Results: The systemic availability, determined by comparing the plasma concentration-time curves of quercetin, was 4.8 times higher, and the maximum plasma concentration ( C ) was 5.4 times higher after ingestion of the onion skin extract than after ingestion of pure quercetin dihydrate. By contrast, t did not differ significantly between the two formulations. The C values for isorhamnetin and tamarixetin were 3.8 and 4.4 times higher, respectively, after administration of onion skin extract than after pure quercetin dihydrate. The plasma kinetics of quercetin were not significantly different in men and women. Conclusion: Quercetin aglycone derived from onion skin extract powder is significantly more bioavailable than that from quercetin dihydrate powder filled hard capsules. [ABSTRACT FROM AUTHOR]

Background: Osteomalacia and cardiometabolic disorders are favored in morbidly obese patients due to an inadequate vitamin D (VD) status. Former trials supplementing orally VD (20-50 μg/day) in crystalline form after sleeve gastrectomy (SG) could not stabilize serum 25-hydroxycholecalciferol levels at predefined concentrations (≥50 nmol/l). We hypothesized that VD in an oily suspension would increase its bioavailability resulting in normal serum VD levels minimizing markers of cardiometabolic risk. Methods: Morbidly obese patients ( n = 94, BMI 51.8 ± 11.5 kg/m) received orally 80 μg/day VD dissolved in oil or placebo (pure oil) in a randomized, double-blind, parallel-group study for 12 weeks after SG. 25-hydroxycholecalciferol, parathyroid hormone, albumin, alkaline phosphatase, phosphate, magnesium, calcium, creatinine, C-reactive protein, lipids, glucose, and glycated hemoglobin were determined in serum/plasma before surgery and after 4 and 12 weeks of supplementation. Intake of energy, fat, and VD were monitored using a 3-day food record. Results: Seventy-nine patients were included in statistical analysis. Preoperatively, 77.2 and 40.5 % presented 25-hydroxycholecalciferol levels <75 and <50 nmol/l, respectively. After 12 weeks of supplementation, significantly more patients in the VD group exhibited levels >50 nmol/l (92 %) and >75 nmol/l (68 %) compared to the placebo group (54 and 22 %, respectively). Parameters of mineral metabolism and cardiometabolic risk were not modulated by intervention. Conclusion: Supplementation of 80 μg/day VD by oil is an effective and safe measure to prevent VD deficiency and to treat a preexisting undersupply in patients after SG. Cardiometabolic risk factors were, however, not affected; probably, higher VD doses might be necessary. Clinical Trial Registration: This trial was registered retrospectively on November 14, 2014, at the German Clinical Trials Register as DRKS00007143. [ABSTRACT FROM AUTHOR]

Purpose: Fruit and vegetable (FV) consumption and salt intake are known dietary influences on blood pressure (BP) in adults, but data on their long-term relevance during growth for later BP are rare. We aimed to examine the independent and concomitant influences of adolescent FV and salt intakes on BP in young adulthood. Methods: In total, 206 participants (108 males) provided a plausible BP measurement in young adulthood (18-25 years) as well as three repeated 3-day weighed dietary records, 24-h urine samples and BP measurements during adolescence (11-16 years). FV intake was assessed based on dietary records and its urinary biomarkers such as potassium, oxalate and hippuric acid. Urinary sodium chloride (NaCl) was used to estimate salt intake. Prospective associations of adolescent FV and salt intake with adult BP were examined in sex-stratified linear regression models. Results: In multivariable models, a 100 g higher FV intake during adolescence was prospectively related to 0.9 mmHg lower systolic BP in young adult females ( P = 0.02), but not in males ( P = 0.8). Biomarkers supported the findings for FV regarding systolic BP. Concurrently, a 1 g higher salt intake was related to 1.7 mmHg higher systolic BP in young men only ( P = 0.01). For diastolic BP, results were inconsistent. Conclusions: Our findings suggest that in adolescent healthy girls, a higher FV intake may be more relevant for BP than a reduced salt intake and the opposite appears to apply for boys. The physiological implications of the observed sex-specific diet-BP relationships need deeper examination. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the influence of dietary proteins (casein, soy protein) and skimmed milk on the plasma kinetics of green tea (GT) catechins. Methods: In a randomized cross-over design with one-week intervals, 24 healthy normal-weight women consumed a test drink containing 1.75 g GT extract with or without the addition of different proteins. Treatments were GT (control), GT with skimmed milk (GT + M), GT with caseinate (GT + CS), or GT with soy protein (GT + S). Venous blood samples were taken before and several times during a period of 4.5 h after consumption of the test drink. Plasma concentrations of catechins were analyzed by HPLC with electrochemical detection. Results: Compared to control, consumption of GT with milk, caseinate, or soy protein significantly reduced the bioavailability (mean area under the plasma concentration-time curve) of total catechins (means ± SEM; GT + M, 87 ± 5%; GT + CS, 79 ± 5%; GT + S, 88 ± 4%), epigallocatechin gallate (GT + M, 68 ± 4%; GT + CS, 63 ± 5%; GT + S, 76 ± 5%), and epicatechin gallate (GT + M, 68 ± 5%; GT + CS, 66 ± 6%; GT + S, 77 ± 6%), while the bioavailability of non-galloylated catechins such as epigallocatechin (GT + M, 134 ± 9%; GT + CS, 118 ± 9 %; GT + S, 123 ± 8%) and epicatechin (GT + M, 125 ± 10%; GT + CS, 114 ± 11%; GT + S, 110 ± 8%) significantly increased. No significant differences in bioavailability of GT catechins were observed between the treatments GT + M, GT + CS, or GT + S. Conclusion: Simultaneous ingestion of dietary proteins reduces the bioavailability of galloylated catechins from GT in humans. [ABSTRACT FROM AUTHOR]

Our objective was to investigate the effect of quercetin supplementation on fasting resting energy expenditure (REE) and respiratory quotient (RQ) in humans. Six healthy, normal-weight women (mean age 25.5 ± 1.6 years, body mass index 21.4 ± 1.5 kg/m(2)) participated in a randomized, placebo-controlled, double-blinded crossover study. Treatments were administered as capsules of 150 mg quercetin (aglycone) or placebo. The acute response was measured by indirect calorimetry for 3 h following ingestion. Blood pressure and pulse rate were assessed in 30-min intervals. On the following day, 24 h after capsule intake, a follow-up measurement was performed. Baseline (t (0)) REE adjusted for fat-free mass was 4.7 ± 0.26 kJ/min (quercetin) and 4.8 ± 0.35 kJ/min (placebo) and did not significantly change between baseline and end (t (180)) in either group (P = 0.992 for time effect in repeated measures analysis of variance; P = 0.581 for time × treatment interaction). Mean RQ was 0.78 ± 0.04 (quercetin) and 0.77 ± 0.04 (placebo). RQ values decreased slowly and to a similar extent during both treatments (P < 0.001 for time; quercetin, -0.09 ± 0.05; placebo, -0.08 ± 0.03; P = 0.877 for time × treatment interaction). Resting systolic and diastolic blood pressure, pulse pressure as well as resting pulse rate did not significantly change between baseline and end in either treatment group. No significant differences were found between the results of the baseline measurement and 24 h after treatment. In conclusion, the present pilot study provides no evidence for a thermic effect of quercetin in humans. [ABSTRACT FROM AUTHOR]

Objective: To study the effects of the dietary fat content on cardiovascular disease risk factors in humans when the fatty acid composition and types of carbohydrates are kept constant. Methods: A controlled dietary study in healthy volunteers with 2 dietary groups and a parallel design consisting of 2 dietary periods was conducted. First, participants received a 2-week wash-in diet rich in saturated fatty acids (SFA; 47% of total fatty acids) and were then randomly assigned to either a high-fat (40% of energy) or a low-fat diet (29% of energy) for 4 weeks. Both diets were isocaloric, rich in monounsaturated fatty acids (MUFA; 51% of total fatty acids) and had similar fatty acid and carbohydrate compositions. Results: Compared to the wash-in diet, the high-fat and low-fat diets significantly lowered LDL-cholesterol (−0.34 and −0.41 mmol/l, respectively; P < 0.001 for time effect in RM-ANOVA), and HDL-cholesterol (−0.13 and −0.18 mmol/l, respectively; P < 0.001 for time), without any differences between the high-fat and low-fat diets ( P = 0.112 and P = 0.085 for time × group interaction in RM-ANOVA, respectively). The size of the major LDL fraction, the LDL susceptibility to oxidation and the plasma concentrations of oxidized LDL (ox-LDL) were significantly reduced by both the high-fat and low-fat diet, again without significant differences between the diets. The ratio of ox-LDL/LDL-cholesterol, serum triacylglycerols and urinary F2-isoprostanes were not significantly affected by the diets. Conclusion: A high-fat and a low-fat diet, both rich in MUFA, had similar effects on lipid-related cardiovascular disease risk factors in metabolically healthy men and women. [ABSTRACT FROM AUTHOR]