Georg Hoffmann

Diet Quality as Assessed by the Healthy Eating Index, the Alternate Healthy Eating Index, the Dietary Approaches to Stop Hypertension Score, and Health Outcomes: A Systematic Review and Meta-Analysis of Cohort Studies

Dietary patterns consider synergistic effects compared with isolated foods or nutrients on health outcomes. The aim of this systematic review and meta-analysis was to examine the associations of diet quality as assessed by the Healthy Eating Index (HEI), the Alternate Healthy Eating Index (AHEI), and the Dietary Approaches to Stop Hypertension (DASH) score and the risk of all-cause mortality, cardiovascular mortality or incidence, cancer mortality or incidence, type 2 diabetes mellitus, and neurodegenerative diseases. A literature search was performed using the electronic databases MEDLINE, SCOPUS, and EMBASE with an end date of May 10, 2014. Study-specific risk ratios were pooled using a random effect model by the Cochrane software package Review Manager 5.2. Fifteen cohort studies (34 reports), including 1,020,642 subjects, met the criteria and were included in the meta-analysis. Diets of the highest quality, as assessed by the HEI, AHEI, and DASH score, resulted in a significant risk reduction (RR) for all-cause mortality (RR 0.78, 95% CI 0.76 to 0.80; P<0.00001; I²=61%, 95% CI 20% to 81%), cardiovascular disease (incidence or mortality) (RR 0.78, 95% CI 0.75 to 0.81; P<0.00001; I²=45%, 95% CI 13% to 66%), cancer (incidence or mortality) (RR 0.85, 95% CI 0.82 to 0.88; P<0.00001; I²=77%, 95% CI 68% to 84%), and type 2 diabetes mellitus (RR 0.78, 95% CI 0.72 to 0.85; P<0.00001; I²=74%, 95% CI 52% to 86%). Differences observed for neurodegenerative diseases were not significant. Egger regression tests provided no evidence of publication bias. Diets that score highly on the HEI, AHEI, and DASH are associated with a significant reduction in the risk of all-cause mortality, cardiovascular disease, cancer, and type 2 diabetes mellitus by 22%, 22%, 15%, and 22%, respectively, and therefore is of high public health relevance.

Mediterranean dietary pattern, inflammation and endothelial function: a systematic review and meta-analysis of intervention trials.

BACKGROUNDnHigh adherence to a Mediterranean diet (MD) is associated with reduced all-cause and cardiovascular mortality risk. To our knowledge, there is no systematic review and meta-analysis of randomized controlled trials that has compared the effects of an MD on outcomes of endothelial function and inflammation.nnnMETHODS AND RESULTSnLiterature search was performed using the electronic databases MEDLINE, EMBASE, and the Cochrane Trial Register. Inclusion criteria were: randomized controlled trials, 19 + years of age, and minimum intervention period of 12 weeks. Study specific weighted mean differences (WMD) were pooled using a random effect model. Seventeen trials including 2300 subjects met the objectives. MD regimens resulted in a significantly more pronounced increase in flow mediated dilatation [WMD: 1.86%, 95% CI 0.23 to 3.48, p = 0.02; I(2) = 43%], and adiponectin [WMD: 1.69 μg/ml, 95% CI 0.27 to 3.11, p = 0.02; I(2) = 78%], while high-sensitive C reactive protein [WMD: -0.98 mg/l, 95% CI -1.48 to -0.49, p < 0.0001; I(2) = 91%], interleukin-6 [WMD: -0.42 pg/ml, 95% CI -0.73 to -0.11, p = 0.008; I(2) = 81%], and intracellular adhesion molecule-1 [WMD: -23.73 ng/ml, 95% CI -41.24 to -6.22 p = 0.008; I(2) = 34%] turned out to be significantly more decreased.nnnCONCLUSIONnThe results of the present meta-analysis provide evidence that an MD decreases inflammation and improves endothelial function.

Adherence to Mediterranean diet and risk of cancer: A systematic review and meta‐analysis of observational studies

The aim of this research study was to meta‐analyze the effects of adherence to Mediterranean diet (MD) on overall cancer risk, and different cancer types. Literature search was performed using the electronic databases MEDLINE, SCOPUS and EMBASE until January 10, 2014. Inclusion criteria were cohort or case–control studies. Study specific risk ratios (RRs) were pooled using a random effect model by the Cochrane software package Review Manager 5.2. Twenty‐one cohort studies including 1,368,736 subjects and 12 case–control studies with 62,725 subjects met the objectives and were enclosed for meta‐analyses. The highest adherence to MD category resulted in a significantly risk reduction for overall cancer mortality/incidence (cohort; RR: 0.90, 95% CI 0.86–0.95, pu2009<u20090.0001; I2u2009=u200955%), colorectal (cohort/case–control; RR: 0.86, 95% CI 0.80–0.93, pu2009<u20090.0001; I2u2009=u200962%], prostate (cohort/case–control; RR: 0.96, 95% CI 0.92–0.99, pu2009=u20090.03; I2u2009=u20090%) and aerodigestive cancer (cohort/case–control; RR: 0.44, 95% CI 0.26–0.77, pu2009=u20090.003; I2u2009=u200983%). Nonsignificant changes could be observed for breast cancer, gastric cancer and pancreatic cancer. The Egger regression tests provided limited evidence of substantial publication bias. High adherence to a MD is associated with a significant reduction in the risk of overall cancer mortality (10%), colorectal cancer (14%), prostate cancer (4%) and aerodigestive cancer (56%).

Long-term effects of low glycemic index/load vs. high glycemic index/load diets on parameters of obesity and obesity-associated risks: a systematic review and meta-analysis.

AIMnThe aim of the present meta-analysis was to investigate the long-term effects of glycemic index-related diets in the management of obesity with a special emphasis on the potential benefits of low glycemic index/load (GI/GL) in the prevention of obesity-associated risks.nnnDATA SYNTHESISnElectronic searches for randomized controlled trials (RCTs) comparing low glycemic index/load versus high glycemic index/load diets were performed in MEDLINE, EMBASE and the Cochrane Library. Outcome of interest markers included anthropometric data as well as biomarkers of CVD and glycemic control. Study specific weighted mean differences were pooled using a random effect model. 14 studies were included in the primary meta-analysis. Weighted mean differences in change of C-reactive protein [WMD: -0.43 mg/dl, (95% CI -0.78 to -0.09), p = 0.01], and fasting insulin [WMD: -5.16 pmol/L, (95% CI -8.45 to -1.88), p = 0.002] were significantly more pronounced in benefit of low GI/GL diets. However decrease in fat free mass [WMD: -1.04 kg (95% CI -1.73 to -0.35), p = 0.003] was significantly more pronounced following low GI/GL diets as well. No significant changes were observed for blood lipids, anthropometric measures, HbA1c and fasting glucose. Sensitivity analysis was performed for RCTs excluding subjects with type 2 diabetes. Decreases in C-reactive protein and fasting insulin remained statistically significant in the low GI/GL subgroups.nnnCONCLUSIONSnThe present systematic review provides evidence for beneficial effects of long-term interventions administering a low glycemic index/load diet with respect to fasting insulin and pro-inflammatory markers such as C-reactive protein which might prove to be helpful in the primary prevention of obesity-associated diseases.

Monounsaturated fatty acids, olive oil and health status: a systematic review and meta-analysis of cohort studies

BackgroundThe aim of the present meta-analysis of cohort studies was to focus on monounsaturated fat (MUFA) and cardiovascular disease, cardiovascular mortality as well as all-cause mortality, and to distinguish between the different dietary sources of MUFA.MethodsLiterature search was performed using the electronic databases PUBMED, and EMBASE until June 2nd, 2014. Study specific risk ratios and hazard ratios were pooled using a inverse variance random effect model.ResultsThirty-two cohort studies (42 reports) including 841,211 subjects met the objectives and were included. The comparison of the top versus bottom third of the distribution of a combination of MUFA (of both plant and animal origin), olive oil, oleic acid, and MUFA:SFA ratio in each study resulted in a significant risk reduction for: all-cause mortality (RR: 0.89, 95% CI 0.83, 0.96, pu2009=u20090.001; I2u2009=u200964%), cardiovascular mortality (RR: 0.88, 95% CI 0.80, 0.96, pu2009=u20090.004; I2u2009=u200950%), cardiovascular events (RR: 0.91, 95% CI 0.86, 0.96, pu2009=u20090.001; I2u2009=u200958%), and stroke (RR: 0.83, 95% CI 0.71, 0.97, pu2009=u20090.02; I2u2009=u200970%). Following subgroup analyses, significant associations could only be found between higher intakes of olive oil and reduced risk of all-cause mortality, cardiovascular events, and stroke, respectively. The MUFA subgroup analyses did not reveal any significant risk reduction.ConclusionThe results indicate an overall risk reduction of all-cause mortality (11%), cardiovascular mortality (12%), cardiovascular events (9%), and stroke (17%) when comparing the top versus bottom third of MUFA, olive oil, oleic acid, and MUFA:SFA ratio. MUFA of mixed animal and vegetable sources per se did not yield any significant effects on these outcome parameters. However, only olive oil seems to be associated with reduced risk. Further research is necessary to evaluate specific sources of MUFA (i.e. plant vs. animal) and cardiovascular risk.

Monounsaturated Fatty Acids and Risk of Cardiovascular Disease: Synopsis of the Evidence Available from Systematic Reviews and Meta-Analyses

No dietary recommendations for monounsaturated fatty acids (MUFA) are given by the National Institute of Medicine, the United States Department of Agriculture, European Food and Safety Authority and the American Diabetes Association. In contrast, the Academy of Nutrition and Dietetics, and the Canadian Dietetic Association both promote <25% MUFA of daily total energy consumption, while the American Heart Association sets a limit of 20% MUFA in their respective guidelines. The present review summarizes systematic reviews and meta-analyses of randomized controlled trials and cohort studies investigating the effects of MUFA on cardiovascular and diabetic risk factors, cardiovascular events and cardiovascular death. Electronic database Medline was searched for systematic reviews and meta-analyses using “monounsaturated fatty acids”, “monounsaturated fat”, and “dietary fat” as search terms with no restriction to calendar date or language. Reference lists and clinical guidelines were searched as well. Sixteen relevant papers were identified. Several studies indicated an increase of HDL-cholesterol and a corresponding decrease in triacylglycerols following a MUFA-rich diet. The effects on total and LDL-cholesterol appeared not consistent, but no detrimental effects on blood lipids were observed. Values for systolic and diastolic blood pressure were found to be reduced both during short- and long-term protocols using high amounts of MUFA as compared to low-MUFA diets. In type 2 diabetic subjects, MUFA exerted a hypoglycemic effect and reduced glycosylated hemoglobin in the long term. Data from meta-analyses exploring evidence from long-term prospective cohort studies provide ambiguous results with respect to the effects of MUFA on risk of coronary heart disease (CHD). One meta-analysis reported an increase in CHD events, however, most meta-analyses observed a lesser number of cases in participants subjected to a high-MUFA protocol. Although no detrimental side effects of MUFA-rich diets were reported in the literature, there still is no unanimous rationale for MUFA recommendations in a therapeutic regimen. Additional long-term intervention studies are required to characterized efficacy and effectiveness of recommending MUFA-rich diet among general and clinical populations.

Adherence to Mediterranean diet and risk of cancer: an updated systematic review and meta-analysis of observational studies.

The aim of the present systematic review and meta‐analysis of observational studies was to gain further insight into the effects of adherence to Mediterranean Diet (MD) on overall cancer mortality, incidence of different types of cancer, and cancer mortality risk in cancer survivors. Literature search was performed using the electronic databases PubMed, and EMBASE until 2 July 2015. We included either cohort (for specific tumors only incidence cases were used) or case–control studies. Study specific risk ratios, hazard ratios, and odds ratios (RR/HR/OR) were pooled using a random effect model. The updated review process showed 23 observational studies that were not included in the previous meta‐analysis (total number of studies evaluated: 56 observational studies). An overall population of 1,784,404 subjects was included in the present update. The highest adherence score to an MD was significantly associated with a lower risk of all‐cause cancer mortality (RR: 0.87, 95% CI 0.81–0.93, I2 = 84%), colorectal cancer (RR: 0.83, 95% CI 0.76–0.89, I2 = 56%), breast cancer (RR: 0.93, 95% CI 0.87–0.99, I2=15%), gastric cancer (RR: 0.73, 95% CI 0.55–0.97, I2 = 66%), prostate cancer (RR: 0.96, 95% CI 0.92–1.00, I2 = 0%), liver cancer (RR: 0.58, 95% CI 0.46–0.73, I2 = 0%), head and neck cancer (RR: 0.40, 95% CI 0.24–0.66, I2 = 90%), pancreatic cancer (RR: 0.48, 95% CI 0.35–0.66), and respiratory cancer (RR: 0.10, 95% CI 0.01–0.70). No significant association could be observed for esophageal/ovarian/endometrial/and bladder cancer, respectively. Among cancer survivors, the association between the adherence to the highest MD category and risk of cancer mortality, and cancer recurrence was not statistically significant. The updated meta‐analyses confirm a prominent and consistent inverse association provided by adherence to an MD in relation to cancer mortality and risk of several cancer types.

Adherence to a Mediterranean diet and risk of diabetes: a systematic review and meta-analysis.

OBJECTIVEnAdherence to a Mediterranean diet is associated with significant improvements in health status. However, to date no systematic review and meta-analysis has summarized the effects of Mediterranean diet adherence on the risk of type 2 diabetes mellitus.nnnDESIGNnElectronic searches for randomized controlled trials and cohort studies were performed in MEDLINE, SCOPUS, EMBASE and the Cochrane Trial Register until 2 April 2014. Pooled effects were calculated by an inverse-variance random-effect meta-analysis using the statistical software Review Manager 5.2 by the Cochrane Collaboration.nnnSETTINGnMeta-analysis of randomized controlled trials and cohort studies.nnnSUBJECTSnnnnELIGIBILITY CRITERIAn19+years of age.nnnRESULTSnOne randomized controlled trial and eight prospective cohort studies (122 810 subjects) published between 2007 and 2014 were included for meta-analysis. For highest v. lowest adherence to the Mediterranean diet score, the pooled risk ratio was 0.81 (95 % CI 0.73, 0.90, P<0.0001, I 2=55 %). Sensitivity analysis including only long-term studies confirmed the results of the primary analysis (pooled risk ratio=0.75; 95 % CI 0.68, 0.83, P<0.00001, I 2=0 %). The Egger regression test provided no evidence of substantial publication bias (P=0.254).nnnCONCLUSIONSnGreater adherence to a Mediterranean diet is associated with a significant reduction in the risk of diabetes (19 %; moderate quality evidence). These results seem to be clinically relevant for public health, in particular for encouraging a Mediterranean-like dietary pattern for primary prevention of type 2 diabetes mellitus.

Effects of monounsaturated fatty acids on cardiovascular risk factors: a systematic review and meta-analysis.

The appropriate pattern of macronutrient distribution for dietary protocols aimed at treating or preventing obesity and its associated cardiovascular diseases is still a controversial topic of discussion. Recommendations considering a specific percentage or range for monounsaturated fatty acids (MUFA) are rare. It was the aim of this study to analyze long-term, randomized, controlled dietary intervention trials and to investigate the effects of MUFA on the biomarkers of obesity and cardiovascular risk factors. Dietary regimens with a high amount of MUFA (>12%) were compared to those with ≤12%. The biomarkers taken into account were weight, waist circumference, fat mass, total cholesterol, LDL cholesterol, HDL cholesterol, triacylglycerols, systolic and diastolic blood pressure, as well as C-reactive protein. A total of 12 studies met the inclusion criteria. Data analysis was performed using the Review Manager 5.0.25 software. Significant differences between high- and low-MUFA protocols could be observed with respect to fat mass [–1.94 kg (confidence interval –3.72, –0.17), p = 0.03], systolic blood pressure [–2.26 mm Hg (confidence interval –4.28, –0.25), p = 0.03] and diastolic blood pressure [–1.15 mm Hg (confidence interval –1.96, –0.34), p = 0.005] favoring the dietary protocols with >12% MUFA. Therefore, MUFA might represent a useful tool in the design of dietary regimens for obesity and cardiovascular disease.

Effects of Monounsaturated Fatty Acids on Glycaemic Control in Patients with Abnormal Glucose Metabolism: A Systematic Review and Meta-Analysis

Background/Aims: In 2008, the American Diabetes Association recommended low-carbohydrate or low-fat diets for weight management in patients with established type 2 diabetes (T2D), while the amount of monounsaturated fatty acids (MUFA) was not specified. This systematic review focused on the effects of diets high in MUFA versus diets low in MUFA on important risk factors of T2D (i.e. plasma glucose, insulin, homeostasis model assessment of insulin resistance and glycosylated haemoglobin, HbA1c). Methods: Nine randomized controlled intervention trials with a total of 1,547 participants and a running time of at least 6 months, comparing diets high versus low in MUFA among adults with abnormal glucose metabolism (T2D, impaired glucose tolerance and insulin resistant), being overweight or obese, have been included in the meta-analysis. We performed a random effects meta-analysis to determine the weighted mean differences with 95% confidence intervals using the software package Review Manager 5.0.25 of the Cochrane Collaboration. Results: Significant differences in HbA1c were found (weighted mean difference –0.21%, 95% CI –0.40 to –0.02; p = 0.03), favouring the high MUFA groups. In contrast, fasting plasma glucose, fasting plasma insulin as well as the homeostasis model assessment of insulin resistance were not affected by the amounts of MUFA in the dietary protocols. Conclusions: In summary, this systematic review found that high MUFA diets appear to be effective in reducing HbA1c, and therefore, should be recommended in the dietary regimes of T2D.