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BMJ Open Aug 2015To summarise the evidence about the efficacy of a Mediterranean diet on the management of type 2 diabetes and prediabetic states. (Meta-Analysis)
Meta-Analysis Review
OBJECTIVES
To summarise the evidence about the efficacy of a Mediterranean diet on the management of type 2 diabetes and prediabetic states.
DESIGN
A systematic review of all meta-analyses and randomised controlled trials (RCTs) that compared the Mediterranean diet with a control diet on the treatment of type 2 diabetes and prediabetic states was conducted. Electronic searches were carried out up to January 2015. Trials were included for meta-analyses if they had a control group treated with another diet, if they were of sufficient duration (at least 6 months), and if they had at least 30 participants in each arm. A random-effect model was used to pool data.
PARTICIPANTS
Adults with or at risk for type 2 diabetes.
INTERVENTIONS
Dietary patterns that described themselves as using a 'Mediterranean' dietary pattern.
OUTCOME MEASURES
The outcomes were glycaemic control, cardiovascular risk factors and remission from the metabolic syndrome.
RESULTS
From 2824 studies, 8 meta-analyses and 5 RCTs were eligible. A 'de novo' meta-analysis of 3 long-term (>6 months) RCTs of the Mediterranean diet and glycaemic control of diabetes favoured the Mediterranean diet as compared with lower fat diets. Another 'de novo' meta-analysis of two long-term RCTs showed a 49% increased probability of remission from the metabolic syndrome. 5 meta-analyses showed a favourable effect of the Mediterranean diet, as compared with other diets, on body weight, total cholesterol and high-density lipoprotein cholesterol. 2 meta-analyses demonstrated that higher adherence to the Mediterranean diet reduced the risk of future diabetes by 19-23%.
CONCLUSIONS
The Mediterranean diet was associated with better glycaemic control and cardiovascular risk factors than control diets, including a lower fat diet, suggesting that it is suitable for the overall management of type 2 diabetes.
Topics: Adult; Blood Glucose; Cardiovascular Diseases; Cholesterol, HDL; Diabetes Mellitus, Type 2; Diet, Fat-Restricted; Diet, Mediterranean; Humans; Randomized Controlled Trials as Topic; Risk Factors; Weight Loss
PubMed: 26260349
DOI: 10.1136/bmjopen-2015-008222 -
Nutrients Mar 2022Background: Vitamin D deficiency is associated with sleep disorders and poor sleep quality. Whether vitamin D supplementation (VDS) helps resolve these problems remains... (Meta-Analysis)
Meta-Analysis Review
Background: Vitamin D deficiency is associated with sleep disorders and poor sleep quality. Whether vitamin D supplementation (VDS) helps resolve these problems remains unclear. Objective: To systematically review the effect of VDS on sleep quantity, quality, and disorders, and perform a meta-analysis of available data. Methods: The reporting of this review followed the PRISMA statement. VDS human interventions studies that reported on sleep quality, quantity, or disorders were included. Medline, CINAHL, EMBASE, PsycInfo, the Cochrane Library, Clinicaltrials.gov, and the ICTRP were searched, in addition to the references of the included articles and previous relevant reviews, without language or time restrictions. Included studies were critically appraised, findings were narratively synthesized, and a meta-analysis was conducted. Furthermore, the overall certainty of the evidence was assessed. Results: A total of 19 studies were included (13 randomized controlled trials (RCTs), 1 opportunistic addition to an RCT, 4 pre−post studies, and 1 pre−post study analyzed as a case series); 3 RCTs were meta-analyses. The risk of bias was generally low. Pre−post studies showed a significant improvement in sleep quality with VDS. Similarly, the results of the meta-analysis revealed a statistically significant decrease in the Pittsburgh Sleep Quality Index with VDS compared with placebo (mean difference, −2.33 (95% CI, −3.09, −1.57); p < 0.001; I2 = 0%), with a moderate certainty of evidence. The results regarding the effect of VDS on sleep-related impairment, difficulty, and disorders, as well as sleepiness and restless legs syndrome, were not unanimous. Conclusions: VDS is promising in improving sleep quality; however, its effect on sleep quantity and disorders needs to be further investigated.
Topics: Dietary Supplements; Humans; Randomized Controlled Trials as Topic; Sleep; Sleep Wake Disorders; Vitamin D; Vitamin D Deficiency
PubMed: 35268051
DOI: 10.3390/nu14051076 -
QJM : Monthly Journal of the... Oct 2022The evidence regarding the efficacy of vitamin D supplementation in reducing severity of COVID-19 is still insufficient. This is partially due to the lack of primary...
BACKGROUND
The evidence regarding the efficacy of vitamin D supplementation in reducing severity of COVID-19 is still insufficient. This is partially due to the lack of primary robust trial-based data and heterogeneous study designs.
AIM
This evidence summary, aims to study the effect of vitamin D supplementation on morbidity and mortality in hospitalized COVID-19 patients.Design: Evidence summary of systematic reviews.
METHODS
For this study, systematic reviews and meta-analysis published from December 2019 to January 2022 presenting the impact of vitamin D supplementation on COVID-19 severity were screened and selected from PubMed and Google scholar. After initial screening, 10 eligible reviews were identified and quality of included reviews were assessed using AMSTAR and GRADE tools and overlapping among the primary studies used were also assessed.
RESULTS
The number of primary studies included in the systematic reviews ranged from 3 to 13. Meta-analysis of seven systematic reviews showed strong evidence that vitamin D supplementation reduces the risk of mortality (Odds ratio: 0.48, 95% CI: 0.346-0.664; P < 0.001) in COVID patients. It was also observed that supplementation reduces the need for intensive care (Odds ratio: 0.35; 95%CI: 0.28-0.44; P < 0.001) and mechanical ventilation (Odds ratio: 0.54; 95% CI: 0.411-0.708; P < 0.001) requirement. The findings were robust and reliable as level of heterogeneity was considerably low. However the included studies were of varied quality. Qualitative analysis showed that supplements (oral and IV) are well tolerated, safe and effective in COVID patients.
CONCLUSION
The findings of this study show that vitamin D supplementation is effective in reducing the COVID-19 severity. Hence, vitamin D should be recommended as an adjuvant therapy for COVID-19.However, more robust and larger trials are required to substantiate it further.
Topics: Humans; COVID-19; Dietary Supplements; Meta-Analysis as Topic; Systematic Reviews as Topic; Vitamin D
PubMed: 35166850
DOI: 10.1093/qjmed/hcac040 -
Nutrients Aug 2020Although a cholesterol-lowering diet and the addition of plant sterols and stanols are suggested for the lipid management of children and adults with familial... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Although a cholesterol-lowering diet and the addition of plant sterols and stanols are suggested for the lipid management of children and adults with familial hypercholesterolemia, there is limited evidence evaluating such interventions in this population.
OBJECTIVES
To investigate the impact of cholesterol-lowering diet and other dietary interventions on the incidence or mortality of cardiovascular disease and lipid profile of patients with familial hypercholesterolemia.
SEARCH METHODS
Relevant trials were identified by searching US National Library of Medicine National Institutes of Health Metabolism Trials Register and clinicaltrials.gov.gr using the following terms: diet, dietary, plant sterols, stanols, omega-3 fatty acids, fiber and familial hypercholesterolemia.
SELECTION CRITERIA
Randomized controlled trials evaluating the effect of cholesterol-lowering diet or other dietary interventions in children and adults with familial hypercholesterolemia were included.
DATA COLLECTION AND ANALYSIS
Two authors independently assessed the eligibility of the included trials and their bias risk and extracted the data which was independently verified by other colleagues.
RESULTS
A total of 17 trials were finally included, with a total of 376 participants across 8 comparison groups. The included trials had either a low or unclear bias risk for most of the assessed risk parameters. Cardiovascular incidence or mortality were not evaluated in any of the included trials. Among the planned comparisons regarding patients' lipidemic profile, a significant difference was noticed for the following comparisons and outcomes: omega-3 fatty acids reduced triglycerides (mean difference (MD): -0.27 mmol/L, 95% confidence interval (CI): -0.47 to -0.07, < 0.01) when compared with placebo. A non-significant trend towards a reduction in subjects' total cholesterol (MD: -0.34, 95% CI: -0.68 to 0, mmol/L, = 0.05) and low-density lipoprotein cholesterol (MD: -0.31, 95% CI: -0.61 to 0, mmol/L, = 0.05) was noticed. In comparison with cholesterol-lowering diet, the additional consumption of plant stanols decreased total cholesterol (MD: -0.62 mmol/L, 95% CI: -1.13 to -0.11, = 0.02) and low-density lipoprotein cholesterol (MD: -0.58 mmol/L, 95% CI: -1.08 to -0.09, = 0.02). The same was by plant sterols (MD: -0.46 mmol/L, 95% CI: -0.76 to -0.17, < 0.01 for cholesterol and MD: -0.45 mmol/L, 95% CI: -0.74 to -0.16, < 0.01 for low-density lipoprotein cholesterol). No heterogeneity was noticed among the studies included in these analyses.
CONCLUSIONS
Available trials confirm that the addition of plant sterols or stanols has a cholesterol-lowering effect on such individuals. On the other hand, supplementation with omega-3 fatty acids effectively reduces triglycerides and might have a role in lowering the cholesterol of patients with familial hypercholesterolemia. Additional studies are needed to investigate the efficacy of cholesterol-lowering diet or the addition of soya protein and dietary fibers to a cholesterol-lowering diet in patients with familial hypercholesterolemia.
Topics: Adult; Anticholesteremic Agents; Cardiovascular Diseases; Child; Cholesterol; Cholesterol, LDL; Clinical Trials as Topic; Diet; Dietary Supplements; Fatty Acids, Omega-3; Female; Heart Disease Risk Factors; Humans; Hyperlipoproteinemia Type II; Male; Phytosterols; Triglycerides
PubMed: 32823643
DOI: 10.3390/nu12082436 -
Nutrients Jul 2020To explore the vitamin D levels of periodontitis patients in comparison with periodontally healthy ones, and to assess the influence of vitamin D supplementation as an... (Meta-Analysis)
Meta-Analysis
To explore the vitamin D levels of periodontitis patients in comparison with periodontally healthy ones, and to assess the influence of vitamin D supplementation as an adjunctive during nonsurgical periodontal treatment (NSPT). Five databases (Pubmed, Embase, Scholar, Web of Sciences, and Cochrane Library) were searched until May 2020. Mean difference (MD) meta-analysis with corresponding 95% confidence interval (95% CI) and sensitivity tests via meta-regression were used. We followed Strength of Recommendation Taxonomy (SORT) to appraise the strength and quality of the evidence. Sixteen articles were included, fourteen case-control and two intervention studies, all reporting 25-hydroxyvitamin D (25(OH)D) levels. Compared with the healthy controls, the circulating 25(OH)D levels were significantly lower in chronic periodontitis patients (pooled MD = -6.80, 95% CI: -10.59 to -3.02). Subgroup analysis revealed differences among 25(OH)D measurements, with liquid chromatography-mass spectrometry being the most homogeneous method (pooled MD = -2.05, 95% CI: -3.40 to -0.71). Salivary levels of 25(OH)D showed no differences between groups. Due to the low number of studies, conclusions on aggressive periodontitis and in the effect of vitamin D supplementation after NSPT were not possible to ascribe. Compared with healthy controls, 25(OH)D serum levels are significantly lower in chronic periodontitis patients, with an overall SORT A recommendation. Future studies are needed to clarify the effect of vitamin D supplementation and the biological mechanisms linking vitamin D to the periodontium.
Topics: Databases, Factual; Dietary Supplements; Humans; Non-Randomized Controlled Trials as Topic; Observational Studies as Topic; Periodontitis; Randomized Controlled Trials as Topic; Vitamin D; Vitamin D Deficiency
PubMed: 32708032
DOI: 10.3390/nu12082177 -
Gastroenterology Jan 2017Certain subsets of colorectal serrated polyps (SP) have malignant potential. We performed a systematic review and meta-analysis to investigate the association between... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND & AIMS
Certain subsets of colorectal serrated polyps (SP) have malignant potential. We performed a systematic review and meta-analysis to investigate the association between modifiable lifestyle factors and risk for SPs.
METHODS
We conducted a systematic search of Medline, Embase, and Web of Science for observational or interventional studies that contained the terms risk or risk factor, and serrated or hyperplastic, and polyps or adenomas, and colorectal (or synonymous terms), published by March 2016. Titles and abstracts of identified articles were independently reviewed by at least 2 reviewers. Adjusted relative risk (RR) and 95% confidence interval (CI) were combined using random effects meta-analyses to assess the risk of SP, when possible.
RESULTS
We identified 43 studies of SP risk associated with 7 different lifestyle factors: smoking, alcohol, body fatness, diet, physical activity, medication, and hormone-replacement therapy. When we compared the highest and lowest categories of exposure, factors we found to significantly increase risk for SP included tobacco smoking (RR, 2.47; 95% CI, 2.12-2.87), alcohol intake (RR, 1.33; 95% CI, 1.17-1.52), body mass index (RR, 1.40; 95% CI, 1.22-1.61), and high intake of fat or meat. Direct associations for smoking and alcohol, but not body fat, tended to be stronger for sessile serrated adenomas/polyps than hyperplastic polyps. In contrast, factors we found to significantly decrease risks for SP included use of nonsteroidal anti-inflammatory drugs (RR, 0.77; 95% CI, 0.65-0.92) or aspirin (RR, 0.81; 95% CI, 0.67-0.99), as well as high intake of folate, calcium, or fiber. No significant associations were detected between SP risk and physical activity or hormone replacement therapy.
CONCLUSIONS
Several lifestyle factors, most notably smoking and alcohol, are associated with SP risk. These findings enhance our understanding of mechanisms of SP development and indicate that risk of serrated pathway colorectal neoplasms could be reduced with lifestyle changes.
Topics: Adenoma; Alcohol Drinking; Anti-Inflammatory Agents, Non-Steroidal; Body Mass Index; Colon; Colonic Polyps; Diet; Exercise; Humans; Hyperplasia; Life Style; Protective Factors; Rectal Diseases; Rectum; Risk Factors; Smoking
PubMed: 27639804
DOI: 10.1053/j.gastro.2016.09.003 -
European Heart Journal Jul 2023Due to growing environmental focus, plant-based diets are increasing steadily in popularity. Uncovering the effect on well-established risk factors for cardiovascular... (Meta-Analysis)
Meta-Analysis
AIMS
Due to growing environmental focus, plant-based diets are increasing steadily in popularity. Uncovering the effect on well-established risk factors for cardiovascular diseases, the leading cause of death worldwide, is thus highly relevant. Therefore, a systematic review and meta-analysis were conducted to estimate the effect of vegetarian and vegan diets on blood levels of total cholesterol, low-density lipoprotein cholesterol, triglycerides, and apolipoprotein B.
METHODS AND RESULTS
Studies published between 1980 and October 2022 were searched for using PubMed, Embase, and references of previous reviews. Included studies were randomized controlled trials that quantified the effect of vegetarian or vegan diets vs. an omnivorous diet on blood lipids and lipoprotein levels in adults over 18 years. Estimates were calculated using a random-effects model. Thirty trials were included in the study. Compared with the omnivorous group, the plant-based diets reduced total cholesterol, low-density lipoprotein cholesterol, and apolipoprotein B levels with mean differences of -0.34 mmol/L (95% confidence interval, -0.44, -0.23; P = 1 × 10-9), -0.30 mmol/L (-0.40, -0.19; P = 4 × 10-8), and -12.92 mg/dL (-22.63, -3.20; P = 0.01), respectively. The effect sizes were similar across age, continent, duration of study, health status, intervention diet, intervention program, and study design. No significant difference was observed for triglyceride levels.
CONCLUSION
Vegetarian and vegan diets were associated with reduced concentrations of total cholesterol, low-density lipoprotein cholesterol, and apolipoprotein B-effects that were consistent across various study and participant characteristics. Plant-based diets have the potential to lessen the atherosclerotic burden from atherogenic lipoproteins and thereby reduce the risk of cardiovascular disease.
Topics: Adult; Humans; Diet, Vegan; Diet, Vegetarian; Randomized Controlled Trials as Topic; Lipids; Vegetarians; Cholesterol, LDL; Lipoproteins; Cardiovascular Diseases; Atherosclerosis; Apolipoproteins
PubMed: 37226630
DOI: 10.1093/eurheartj/ehad211 -
Advances in Nutrition (Bethesda, Md.) Jul 2023The effects of supplementation with whey protein alone or with vitamin D on sarcopenia-related outcomes in older adults are unclear. We aimed to assess the effect of... (Meta-Analysis)
Meta-Analysis Review
The effects of supplementation with whey protein alone or with vitamin D on sarcopenia-related outcomes in older adults are unclear. We aimed to assess the effect of whey protein supplementation alone or with vitamin D on lean mass (LM), strength, and function in older adults with or without sarcopenia or frailty. We searched PubMed, Web of Science, and SCOPUS databases. Randomized controlled trials (RCT) that investigated the effect of whey protein supplementation with or without vitamin D on sarcopenia outcomes in healthy and sarcopenic or frail older adults were included. Standardized mean differences (SMDs) were calculated for LM, muscle strength, and physical function data. The analysis showed that whey protein supplementation had no effect on LM and muscle strength; nevertheless, a significant improvement was found in physical function (SMD = 0.561; 95% confidence interval [CIs]: 0.256, 0.865, n = 33), particularly gait speed (GS). On the contrary, whey protein supplementation significantly improved LM (SMD = 0.982; 95% CI: 0.228, 1.736; n = 11), appendicular lean mass and physical function (SMD = 1.211; 95% CI: 0.588, 1.834; n = 16), and GS in sarcopenic/frail older adults. By contrast, co-supplementation with vitamin D enhanced LM gains (SMD =0.993; 95% CI: 0.112, 1.874; n = 11), muscle strength (SMD =2.005; 95% CI: 0.975, 3.035; n = 11), and physical function (SMD = 3.038; 95% CI: 2.196, 3.879; n = 18) significantly. Muscle strength and physical function improvements after whey protein supplementation plus vitamin D were observed without resistance exercise (RE) and short study duration subgroups. Moreover, the combination of whey protein and vitamin D with RE did not enhance the effect of RE. Whey protein supplementation improved LM and function in sarcopenic/frail older adults but had no positive effect in healthy older persons. By contrast, our meta-analysis showed that co-supplementation with whey protein and vitamin D is effective, particularly in healthy older adults, which is likely owing, we propose, to the correction of vitamin D insufficiency or deficiency. The trial was registered at https://inplasy.com as INPLASY202240167.
Topics: Humans; Aged; Aged, 80 and over; Sarcopenia; Vitamin D; Whey Proteins; Dietary Supplements; Vitamins; Muscle Strength; Muscle, Skeletal; Randomized Controlled Trials as Topic
PubMed: 37196876
DOI: 10.1016/j.advnut.2023.05.011 -
The Cochrane Database of Systematic... Sep 2018Falls in care facilities and hospitals are common events that cause considerable morbidity and mortality for older people. This is an update of a review first published... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Falls in care facilities and hospitals are common events that cause considerable morbidity and mortality for older people. This is an update of a review first published in 2010 and updated in 2012.
OBJECTIVES
To assess the effects of interventions designed to reduce the incidence of falls in older people in care facilities and hospitals.
SEARCH METHODS
We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (August 2017); Cochrane Central Register of Controlled Trials (2017, Issue 8); and MEDLINE, Embase, CINAHL and trial registers to August 2017.
SELECTION CRITERIA
Randomised controlled trials of interventions for preventing falls in older people in residential or nursing care facilities, or hospitals.
DATA COLLECTION AND ANALYSIS
One review author screened abstracts; two review authors screened full-text articles for inclusion. Two review authors independently performed study selection, 'Risk of bias' assessment and data extraction. We calculated rate ratios (RaR) with 95% confidence intervals (CIs) for rate of falls and risk ratios (RRs) and 95% CIs for outcomes such as risk of falling (number of people falling). We pooled results where appropriate. We used GRADE to assess the quality of evidence.
MAIN RESULTS
Thirty-five new trials (77,869 participants) were included in this update. Overall, we included 95 trials (138,164 participants), 71 (40,374 participants; mean age 84 years; 75% women) in care facilities and 24 (97,790 participants; mean age 78 years; 52% women) in hospitals. The majority of trials were at high risk of bias in one or more domains, mostly relating to lack of blinding. With few exceptions, the quality of evidence for individual interventions in either setting was generally rated as low or very low. Risk of fracture and adverse events were generally poorly reported and, where reported, the evidence was very low-quality, which means that we are uncertain of the estimates. Only the falls outcomes for the main comparisons are reported here.Care facilitiesSeventeen trials compared exercise with control (typically usual care alone). We are uncertain of the effect of exercise on rate of falls (RaR 0.93, 95% CI 0.72 to 1.20; 2002 participants, 10 studies; I² = 76%; very low-quality evidence). Exercise may make little or no difference to the risk of falling (RR 1.02, 95% CI 0.88 to 1.18; 2090 participants, 10 studies; I² = 23%; low-quality evidence).There is low-quality evidence that general medication review (tested in 12 trials) may make little or no difference to the rate of falls (RaR 0.93, 95% CI 0.64 to 1.35; 2409 participants, 6 studies; I² = 93%) or the risk of falling (RR 0.93, 95% CI 0.80 to 1.09; 5139 participants, 6 studies; I² = 48%).There is moderate-quality evidence that vitamin D supplementation (4512 participants, 4 studies) probably reduces the rate of falls (RaR 0.72, 95% CI 0.55 to 0.95; I² = 62%), but probably makes little or no difference to the risk of falling (RR 0.92, 95% CI 0.76 to 1.12; I² = 42%). The population included in these studies had low vitamin D levels.Multifactorial interventions were tested in 13 trials. We are uncertain of the effect of multifactorial interventions on the rate of falls (RaR 0.88, 95% CI 0.66 to 1.18; 3439 participants, 10 studies; I² = 84%; very low-quality evidence). They may make little or no difference to the risk of falling (RR 0.92, 95% CI 0.81 to 1.05; 3153 participants, 9 studies; I² = 42%; low-quality evidence).HospitalsThree trials tested the effect of additional physiotherapy (supervised exercises) in rehabilitation wards (subacute setting). The very low-quality evidence means we are uncertain of the effect of additional physiotherapy on the rate of falls (RaR 0.59, 95% CI 0.26 to 1.34; 215 participants, 2 studies; I² = 0%), or whether it reduces the risk of falling (RR 0.36, 95% CI 0.14 to 0.93; 83 participants, 2 studies; I² = 0%).We are uncertain of the effects of bed and chair sensor alarms in hospitals, tested in two trials (28,649 participants) on rate of falls (RaR 0.60, 95% CI 0.27 to 1.34; I² = 0%; very low-quality evidence) or risk of falling (RR 0.93, 95% CI 0.38 to 2.24; I² = 0%; very low-quality evidence).Multifactorial interventions in hospitals may reduce rate of falls in hospitals (RaR 0.80, 95% CI 0.64 to 1.01; 44,664 participants, 5 studies; I² = 52%). A subgroup analysis by setting suggests the reduction may be more likely in a subacute setting (RaR 0.67, 95% CI 0.54 to 0.83; 3747 participants, 2 studies; I² = 0%; low-quality evidence). We are uncertain of the effect of multifactorial interventions on the risk of falling (RR 0.82, 95% CI 0.62 to 1.09; 39,889 participants; 3 studies; I² = 0%; very low-quality evidence).
AUTHORS' CONCLUSIONS
In care facilities: we are uncertain of the effect of exercise on rate of falls and it may make little or no difference to the risk of falling. General medication review may make little or no difference to the rate of falls or risk of falling. Vitamin D supplementation probably reduces the rate of falls but not risk of falling. We are uncertain of the effect of multifactorial interventions on the rate of falls; they may make little or no difference to the risk of falling.In hospitals: we are uncertain of the effect of additional physiotherapy on the rate of falls or whether it reduces the risk of falling. We are uncertain of the effect of providing bed sensor alarms on the rate of falls or risk of falling. Multifactorial interventions may reduce rate of falls, although subgroup analysis suggests this may apply mostly to a subacute setting; we are uncertain of the effect of these interventions on risk of falling.
Topics: Accidental Falls; Aged; Aged, 80 and over; Calcium, Dietary; Exercise; Female; Hospitals; Humans; Male; Nursing Homes; Randomized Controlled Trials as Topic; Safety Management; Vitamin D; Vitamins
PubMed: 30191554
DOI: 10.1002/14651858.CD005465.pub4 -
BMJ (Clinical Research Ed.) Apr 2016To examine the traditional diet-heart hypothesis through recovery and analysis of previously unpublished data from the Minnesota Coronary Experiment (MCE) and to put... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
To examine the traditional diet-heart hypothesis through recovery and analysis of previously unpublished data from the Minnesota Coronary Experiment (MCE) and to put findings in the context of existing diet-heart randomized controlled trials through a systematic review and meta-analysis.
DESIGN
The MCE (1968-73) is a double blind randomized controlled trial designed to test whether replacement of saturated fat with vegetable oil rich in linoleic acid reduces coronary heart disease and death by lowering serum cholesterol. Recovered MCE unpublished documents and raw data were analyzed according to hypotheses prespecified by original investigators. Further, a systematic review and meta-analyses of randomized controlled trials that lowered serum cholesterol by providing vegetable oil rich in linoleic acid in place of saturated fat without confounding by concomitant interventions was conducted.
SETTING
One nursing home and six state mental hospitals in Minnesota, United States.
PARTICIPANTS
Unpublished documents with completed analyses for the randomized cohort of 9423 women and men aged 20-97; longitudinal data on serum cholesterol for the 2355 participants exposed to the study diets for a year or more; 149 completed autopsy files.
INTERVENTIONS
Serum cholesterol lowering diet that replaced saturated fat with linoleic acid (from corn oil and corn oil polyunsaturated margarine). Control diet was high in saturated fat from animal fats, common margarines, and shortenings.
MAIN OUTCOME MEASURES
Death from all causes; association between changes in serum cholesterol and death; and coronary atherosclerosis and myocardial infarcts detected at autopsy.
RESULTS
The intervention group had significant reduction in serum cholesterol compared with controls (mean change from baseline -13.8%v-1.0%; P<0.001). Kaplan Meier graphs showed no mortality benefit for the intervention group in the full randomized cohort or for any prespecified subgroup. There was a 22% higher risk of death for each 30 mg/dL (0.78 mmol/L) reduction in serum cholesterol in covariate adjusted Cox regression models (hazard ratio 1.22, 95% confidence interval 1.14 to 1.32; P<0.001). There was no evidence of benefit in the intervention group for coronary atherosclerosis or myocardial infarcts. Systematic review identified five randomized controlled trials for inclusion (n=10,808). In meta-analyses, these cholesterol lowering interventions showed no evidence of benefit on mortality from coronary heart disease (1.13, 0.83 to 1.54) or all cause mortality (1.07, 0.90 to 1.27).
CONCLUSIONS
Available evidence from randomized controlled trials shows that replacement of saturated fat in the diet with linoleic acid effectively lowers serum cholesterol but does not support the hypothesis that this translates to a lower risk of death from coronary heart disease or all causes. Findings from the Minnesota Coronary Experiment add to growing evidence that incomplete publication has contributed to overestimation of the benefits of replacing saturated fat with vegetable oils rich in linoleic acid.
Topics: Adult; Aged; Aged, 80 and over; Cause of Death; Cholesterol; Coronary Artery Disease; Coronary Disease; Diet, Fat-Restricted; Dietary Fats; Double-Blind Method; Female; History, 20th Century; Humans; Kaplan-Meier Estimate; Linoleic Acid; Male; Middle Aged; Minnesota; Myocardial Infarction; Plant Oils; Randomized Controlled Trials as Topic; Risk Factors; Young Adult
PubMed: 27071971
DOI: 10.1136/bmj.i1246