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Long-term consumption of a mediterranean diet or a low-fat diet on kidney function in coronary heart disease patients: The CORDIOPREV randomized controlled trial.
Podadera-Herreros, A, Alcala-Diaz, JF, Gutierrez-Mariscal, FM, Jimenez-Torres, J, Cruz-Ares, S, Arenas-de Larriva, AP, Cardelo, MP, Torres-Peña, JD, Luque, RM, Ordovas, JM, et al
Clinical nutrition (Edinburgh, Scotland). 2022;(2):552-559
Abstract
BACKGROUND & AIMS Lifestyle and dietary habits influence kidney function, playing an important role in the prevention and development of chronic kidney disease (CKD). The effectiveness of the Mediterranean diet in preserving kidney function has been seen in primary prevention. However, no scientific evidence is currently available to determine which dietary pattern is more effective in the management of CKD in secondary cardiovascular disease prevention. Thus, our aim was to evaluate the efficacy of the long-term consumption of two healthy dietary patterns (a Mediterranean diet rich in extra-virgin olive oil (EVOO) compared to a low-fat diet rich in complex carbohydrates) in preserving kidney function in coronary heart disease (CHD) patients. METHODS CHD patients (n = 1002) from the CORDIOPREV study were randomized to follow a Mediterranean diet (35% fat, 22% MUFA, <50% carbohydrates) or a low-fat diet (28% fat, 12% MUFA, >55% carbohydrates). Kidney function was assessed by the determination of serum creatinine-based estimated glomerular filtration rate (eGFR) at baseline and after 5-years of dietary intervention. Patients were classified according to their type 2 diabetes (T2DM) status, using baseline eGFR (normal eGFR: ≥ 90 mL/min/1.73 m2; mildly-impaired eGFR: 60 to <90 mL/min/1.73 m2, severely-impaired eGFR: <60 mL/min/1.73 m2) to evaluate its influence on the progression of kidney function. Multiple linear regression analysis were performed to determine the contribution of different clinical and anthropometric parameters to changes in eGFR. RESULTS Although eGFR declined after both dietary interventions compared to baseline (all p < 0.001), the Mediterranean diet produced a lower decline of eGFR compared to the low-fat diet in patients with T2DM (p = 0.040). This effect was also observed when the overall population was considered (p = 0.033). No significant differences were observed in eGFR between the two diets in non-T2DM patients. In addition, this differential effect of the Mediterranean diet was mainly observed in patients with mildly-impaired eGFR in which this diet slowed eGFR progression (p = 0.002). CONCLUSIONS The long-term consumption of a Mediterranean diet rich in EVOO, when compared to a low-fat diet, may preserve kidney function, as shown by a reduced decline in eGFR in CHD patients with T2DM. Patients with mildly-impaired eGFR may benefit more from the beneficial effect of the consumption of the Mediterranean diet in preserving kidney function. These findings reinforce the clinical benefits of the Mediterranean diet in the context of secondary cardiovascular disease prevention. CLINICAL TRIAL REGISTRATION URL, http://www.cordioprev.es/index.php/en. Clinicaltrials.gov number, NCT00924937.
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Low-fat diets and testosterone in men: Systematic review and meta-analysis of intervention studies.
Whittaker, J, Wu, K
The Journal of steroid biochemistry and molecular biology. 2021;:105878
Abstract
BACKGROUND Higher endogenous testosterone levels are associated with reduced chronic disease risk and mortality. Since the mid-20th century, there have been significant changes in dietary patterns, and men's testosterone levels have declined in western countries. Cross-sectional studies show inconsistent associations between fat intake and testosterone in men. METHODS Studies eligible for inclusion were intervention studies, with minimal confounding variables, comparing the effect of low-fat vs high-fat diets on men's sex hormones. 9 databases were searched from their inception to October 2020, yielding 6 eligible studies, with a total of 206 participants. Random effects meta-analyses were performed using Cochrane's Review Manager software. Cochrane's risk of bias tool was used for quality assessment. RESULTS There were significant decreases in sex hormones on low-fat vs high-fat diets. Standardised mean differences with 95 % confidence intervals (CI) for outcomes were: total testosterone [-0.38 (95 % CI -0.75 to -0.01) P = 0.04]; free testosterone [-0.37 (95 % CI -0.63 to -0.11) P = 0.005]; urinary testosterone [-0.38 (CI 95 % -0.66 to -0.09) P = 0.009]; and dihydrotestosterone [-0.3 (CI 95 % -0.56 to -0.03) P = 0.03]. There were no significant differences for luteinising hormone or sex hormone binding globulin. Subgroup analysis for total testosterone, European and North American men, showed a stronger effect [-0.52 (95 % CI -0.75 to -0.3) P < 0.001]. CONCLUSIONS Low-fat diets appear to decrease testosterone levels in men, but further randomised controlled trials are needed to confirm this effect. Men with European ancestry may experience a greater decrease in testosterone, in response to a low-fat diet.
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Changes in Quantity and Sources of Dietary Fiber from Adopting Healthy Low-Fat vs. Healthy Low-Carb Weight Loss Diets: Secondary Analysis of DIETFITS Weight Loss Diet Study.
Offringa, LC, Hartle, JC, Rigdon, J, Gardner, CD
Nutrients. 2021;(10)
Abstract
The daily intake of dietary fiber is well below the recommended levels in the US. The effect of adopting a low-fat vs. a low-carbohydrate weight loss diet on fiber intake is of interest but not well-documented, especially when both approaches promote high-quality food choices. The objective of this paper is to compare the quantity and sources of dietary fiber between a healthy low-fat (HLF) vs. healthy low-carbohydrate (HLC) diet group when consumed over 12 months in a weight loss diet study. In this secondary analysis of the Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) study, the amount and sources of dietary fiber were examined in generally healthy adults, 18-50 years of age, Body Mass Index (BMI) 28-40 kg/m2, randomized to HLF or HLC for 12 months, who had available 24-h recalls at 0 (n = 609), 3 (n = 549), 6 (n = 491), and 12 (n = 449) months. The dietary intake was estimated by the Nutrition Data System for Research (NDS-R). The sources of fiber were determined for the major food groups. Significantly more total dietary fiber was consumed by HLF at every post-randomization time point, and, at 12 m, was 23.04 ± 9.43 g vs. 18.61 ± 8.12 g for HLF vs. HLC, respectively, p < 0.0001. In both diet groups at 12 months, the highest amount of dietary fiber came from non-starchy vegetables (4.13 ± 3.05 g and 5.13 ± 3.59 g). The other primary sources of fiber at 12 months for the HLF group were from whole grains (3.90 ± 3.13 g) and fruits (3.40 ± 2.87 g), and, for the HLC group, were from plant protein and fat sources, such as nuts and seeds, their butters, and avocados (2.64 ± 2.64 g). In the DIETFITS study, the difference in the total fiber intake for the HLF vs. HLC groups was more modest than expected. The HLC group consumed reasonably high amounts of fiber from high-protein and high fat plant-based sources.
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Effects of Randomized Controlled Infancy-Onset Dietary Intervention on Leukocyte Telomere Length-The Special Turku Coronary Risk Factor Intervention Project (STRIP).
Pitkänen, N, Pahkala, K, Rovio, SP, Saijonmaa, OJ, Nyman, AE, Jula, A, Lagström, H, Viikari, JSA, Rönnemaa, T, Niinikoski, H, et al
Nutrients. 2021;(2)
Abstract
Reduced telomere length (TL) is a biological marker of aging. A high inter-individual variation in TL exists already in childhood, which is partly explained by genetics, but also by lifestyle factors. We examined the influence of a 20-year dietary/lifestyle intervention on TL attrition from childhood to early adulthood. The study comprised participants of the longitudinal randomized Special Turku Coronary Risk Factor Intervention Project (STRIP) conducted between 1990 and 2011. Healthy 7-month-old children were randomized to the intervention group (n = 540) receiving dietary counseling mainly focused on dietary fat quality and to the control group (n = 522). Leukocyte TL was measured using the Southern blot method from whole blood samples collected twice: at a mean age of 7.5 and 19.8 years (n = 232; intervention n = 108, control n = 124). Yearly TL attrition rate was calculated. The participants of the intervention group had slower yearly TL attrition rate compared to the controls (intervention: mean = -7.5 bp/year, SD = 24.4 vs. control: mean = -15.0 bp/year, SD = 30.3; age, sex and baseline TL adjusted β = 0.007, SE = 0.004, p = 0.040). The result became stronger after additional adjustments for dietary fat quality and fiber intake, serum lipid and insulin concentrations, systolic blood pressure, physical activity and smoking (β = 0.013, SE = 0.005, p = 0.009). A long-term intervention focused mainly on dietary fat quality may affect the yearly TL attrition rate in healthy children/adolescents.
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Association between dietary fat intake and mortality from all-causes, cardiovascular disease, and cancer: A systematic review and meta-analysis of prospective cohort studies.
Kim, Y, Je, Y, Giovannucci, EL
Clinical nutrition (Edinburgh, Scotland). 2021;(3):1060-1070
Abstract
BACKGROUND & AIMS The association between dietary fat and mortality remains inconsistent, and recent results for the association between dietary saturated fat and chronic disease are controversial. To quantitatively assess this association, we conducted a meta-analysis of prospective cohort studies. METHODS The PubMed and Web of Science were searched up to February 2020. A random effects model was used. RESULTS Nineteen studies including 1,013,273participants and 195,515deaths were identified. Significant inverse associations between all-cause mortality and a 5% energy increment in intakes of total (RR = 0.99; 95% CI:0.98-1.00), monounsaturated (RR = 0.98; 95% CI:0.97-0.99), and polyunsaturated fat (RR = 0.93; 95% CI:0.89-0.97) were found. A 5% increase in energy from polyunsaturated fat was associated with 5% (RR = 0.95; 95% CI:0.91-0.98) and 4% (RR = 0.96; 95% CI:0.94-0.99) lower mortality from CVD and cancer, respectively. A 1% energy increment in dietary trans-fat was associated with 6% higher risk of mortality from all-causes (RR = 1.06; 95% CI:1.01-1.10) and CVD (RR = 1.06; 95% CI:1.02-1.11). We found a non-linear association between dietary saturated fat and all-cause mortality showing a significant increased risk up to 11% of energy from saturated fat intake. The risk of cancer mortality increased by 4% for every 5% increase in energy from saturated fat (RR = 1.04; 95% CI:1.02-1.06). CONCLUSIONS Diets high in saturated fat were associated with higher mortality from all-causes, CVD, and cancer, whereas diets high in polyunsaturated fat were associated with lower mortality from all-causes, CVD, and cancer. Diets high in trans-fat were associated with higher mortality from all-causes and CVD. Diets high in monounsaturated fat were associated with lower all-cause mortality.
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Associations Between Dietary Patterns and Subclinical Cardiac Injury: An Observational Analysis From the DASH Trial.
Juraschek, SP, Kovell, LC, Appel, LJ, Miller, ER, Sacks, FM, Christenson, RH, Rebuck, H, Chang, AR, Mukamal, KJ
Annals of internal medicine. 2020;(12):786-794
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Abstract
BACKGROUND The DASH diet has been found to lower blood pressure (BP) and low-density lipoprotein cholesterol levels. OBJECTIVE To compare diets rich in fruits and vegetables with a typical American diet in their effects on cardiovascular injury in middle-aged adults without known preexisting cardiovascular disease (CVD). DESIGN Observational study based on a 3-group, parallel-design, randomized trial conducted in the United States from 1994 to 1996. (ClinicalTrials.gov: NCT00000544). SETTING 3 of the 4 original clinical trial centers. PARTICIPANTS 326 of the original 459 trial participants with available stored specimens. INTERVENTION Participants were randomly assigned to 8 weeks of monitored feeding with a control diet typical of what many Americans eat; a diet rich in fruits and vegetables but otherwise similar to the control diet; or the DASH diet, which is rich in fruits, vegetables, low-fat dairy, and fiber and has low levels of saturated fat and cholesterol. Weight was kept constant throughout feeding. MEASUREMENTS Biomarkers collected at baseline and 8 weeks: high-sensitivity cardiac troponin I (hs-cTnI), N-terminal pro-B-type natriuretic peptide (NT-proBNP), and high-sensitivity C-reactive protein (hs-CRP). RESULTS The mean age of participants was 45.2 years, 48% were women, 49% were black, and mean baseline BP was 131/85 mm Hg. Compared with the control diet, the fruit-and-vegetable diet reduced hs-cTnI levels by 0.5 ng/L (95% CI, -0.9 to -0.2 ng/L) and NT-proBNP levels by 0.3 pg/mL (CI, -0.5 to -0.1 pg/mL). Compared with the control diet, the DASH diet reduced hs-cTnI levels by 0.5 ng/L (CI, -0.9 to -0.1 ng/L) and NT-proBNP levels by 0.3 pg/mL (CI, -0.5 to -0.04 pg/mL). Levels of hs-CRP did not differ among diets. None of the markers differed between the fruit-and-vegetable and DASH diets. LIMITATION Short duration, missing specimens, and an inability to isolate the effects of specific foods or micronutrients. CONCLUSION Diets rich in fruits and vegetables given over 8 weeks were associated with lower levels of markers for subclinical cardiac damage and strain in adults without preexisting CVD. PRIMARY FUNDING SOURCE National Institutes of Health, National Heart, Lung, and Blood Institute.
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The Effect of Low-Fat and Low-Carbohydrate Diets on Weight Loss and Lipid Levels: A Systematic Review and Meta-Analysis.
Chawla, S, Tessarolo Silva, F, Amaral Medeiros, S, Mekary, RA, Radenkovic, D
Nutrients. 2020;(12)
Abstract
BACKGROUND The rise in obesity has emphasised a focus on lifestyle and dietary habits. We aimed to address the debate between low-carbohydrate and low-fat diets and compare their effects on body weight, low-density lipoprotein cholesterol (LDL), high-density lipoprotein cholesterol (HDL), total cholesterol, and triglycerides in an adult population. METHOD Medline and Web of Science were searched for randomised controlled trials (RCTs) comparing low-fat and low-carbohydrate diets up to September 2019. Three independent reviewers extracted data. Risk of bias was assessed using the Cochrane tool. The meta-analysis was stratified by follow-up time using the random-effects models. RESULTS This meta-analysis of 38 studies assessed a total of 6499 adults. At 6-12 months, pooled analyses of mean differences of low-carbohydrate vs. low-fat diets favoured the low-carbohydrate diet for average weight change (mean difference -1.30 kg; 95% CI -2.02 to -0.57), HDL (0.05 mmol/L; 95% CI 0.03 to 0.08), and triglycerides (TG) (-0.10 mmol/L; -0.16 to -0.04), and favoured the low-fat diet for LDL (0.07 mmol/L; 95% CI 0.02 to 0.12) and total cholesterol (0.10 mmol/L; 95% CI 0.02 to 0.18). Conclusion and Relevance: This meta-analysis suggests that low-carbohydrate diets are effective at improving weight loss, HDL and TG lipid profiles. However, this must be balanced with potential consequences of raised LDL and total cholesterol in the long-term.
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The Nutritious Eating with Soul (NEW Soul) Study: Study design and methods of a two-year randomized trial comparing culturally adapted soul food vegan vs. omnivorous diets among African American adults at risk for heart disease.
Turner-McGrievy, G, Wilcox, S, Frongillo, EA, Murphy, A, Hutto, B, Williams, K, Crimarco, A, Wilson, M, Davey, M
Contemporary clinical trials. 2020;:105897
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Abstract
BACKGROUND Previous research has found that African American (AA) vegetarians/vegans have a significantly lower body mass index and risk of hypertension compared to omnivores. OBJECTIVES The Nutritious Eating with Soul (NEW Soul) study partnered with local soul food restaurants/chefs to deliver two behavioral nutrition interventions to AA adults. NEW Soul examines the impact of two different culturally tailored diets (vegan and omnivorous low-fat) on changes in risk factors for cardiovascular disease (CVD). METHODS AA adults with overweight or obesity are recruited from the community in the Midlands of South Carolina. Eligible participants are randomized to follow one of two different culturally-adapted, soul food diets: a vegan diet emphasizing minimally-processed whole foods from plants or a low-fat omnivorous diet. Participants attend weekly group classes for the first six months, bi-weekly for the next six months, and monthly meetings for the last year. In addition to face-to-face content, participants also have access to private Facebook groups for their diet, podcasts, and online newsletters starting at six months. Primary outcomes include changes in body weight and CVD risk factors (lipids, blood pressure, glucose, and insulin) at 12 months. Secondary outcomes include changes in dietary intake. Participants complete assessments at baseline and at months 6, 12, and 24. CONCLUSIONS The NEW Soul study is an innovative intervention aimed at improving dietary intake while maintaining traditional AA cultural food choices. Primary outcomes are expected by 2021.
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Nutritional adequacy of very low- and high-carbohydrate, low saturated fat diets in adults with type 2 diabetes: A secondary analysis of a 2-year randomised controlled trial.
Tay, J, Thompson, CH, Luscombe-Marsh, ND, Noakes, M, Buckley, JD, Wittert, GA, Brinkworth, GD
Diabetes research and clinical practice. 2020;:108501
Abstract
BACKGROUND Growing evidence supports use of very low-carbohydrate (LC) diets for glycaemic control in type 2 diabetes. However, limited data on the micronutrient adequacy of LC diets exist. OBJECTIVE This study compared the long-term effects of a very low-carbohydrate, high unsaturated/low saturated fat (LC) diet to a high-carbohydrate, low-fat (HC) diet on micronutrient biomarkers in adults with obesity and type 2 diabetes. METHODS 115 adults with type 2 diabetes (mean[SD]; BMI:34.6[4.3]kg/m2, age:58[7]yrs, HbA1c:7.3[1.1]%, 56[12]mmol/mol) were randomized to one of two planned, nutritionally-replete, energy-matched, hypocaloric diets (500-1000 kcal/day deficit): (1) LC:14% energy carbohydrate, 28%protein, 58%fat[<10% saturated fat]) or (2) HC:53%carbohydrate, 17%protein, 30%fat [<10%saturated fat]) for 2 years. Nutritional biomarkers- folate, β-carotene, vitamin B12, D, E, copper, zinc, selenium, calcium, magnesium, sodium, potassium, iron, ferritin, transferrin and transferrin saturation were measured in fasting blood at baseline, 24, 52 and 104 weeks. RESULTS 61 participants completed the study with similar dropouts in each group (P = 0.40). For all biomarkers assessed, there were no differential response between groups overtime (P ≥ 0.17 time × diet interaction). Mean vitamin and mineral levels remained within normal (laboratory-specific) reference ranges without any reported cases of clinical deficiencies. CONCLUSION In free-living individuals with type 2 diabetes, nutrition biomarkers within normal ranges at baseline did not change significantly after 2 years on a prescribed LC or HC diet. These results demonstrate the feasibility of delivering a nutritionally replete LC diet and the importance of considering nutritional factors in planning LC diets that have strong public health relevance to the dietary management of type 2 diabetes. TRIAL REGISTRATION http://www.anzctr.org.au/, ANZCTR No. ACTRN12612000369820.
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The Effect of Low-Carbohydrate and Low-Fat Diets on Pain in Individuals with Knee Osteoarthritis.
Strath, LJ, Jones, CD, Philip George, A, Lukens, SL, Morrison, SA, Soleymani, T, Locher, JL, Gower, BA, Sorge, RE
Pain medicine (Malden, Mass.). 2020;(1):150-160
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Abstract
OBJECTIVE Osteoarthritis is the most prominent form of arthritis, affecting approximately 15% of the population in the United States. Knee osteoarthritis (KOA) has become one of the leading causes of disability in older adults. Besides knee replacement, there are no curative treatments for KOA, so persistent pain is commonly treated with opioids, acetaminophen, and nonsteroidal anti-inflammatory drugs. However, these drugs have many unpleasant side effects, so there is a need for alternative forms of pain management. We sought to test the efficacy of a dietary intervention to reduce KOA. DESIGN A randomized controlled pilot study to test the efficacy of two dietary interventions. SUBJECTS Adults 65-75 years of age with KOA. METHODS Participants were asked to follow one of two dietary interventions (low-carbohydrate [LCD], low-fat [LFD]) or continue to eat as usual (control [CTRL]) over 12 weeks. Functional pain, self-reported pain, quality of life, and depression were assessed every three weeks. Serum from before and after the diet intervention was analyzed for oxidative stress. RESULTS Over a period of 12 weeks, the LCD reduced pain intensity and unpleasantness in some functional pain tasks, as well as self-reported pain, compared with the LFD and CTRL. The LCD also significantly reduced oxidative stress and the adipokine leptin compared with the LFD and CTRL. Reduction in oxidative stress was related to reduced functional pain. CONCLUSIONS We present evidence suggesting that oxidative stress may be related to functional pain, and lowering it through our LCD intervention could provide relief from pain and be an opioid alternative.