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Single-component versus multicomponent dietary goals for the metabolic syndrome: a randomized trial.
Ma, Y, Olendzki, BC, Wang, J, Persuitte, GM, Li, W, Fang, H, Merriam, PA, Wedick, NM, Ockene, IS, Culver, AL, et al
Annals of internal medicine. 2015;(4):248-57
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Abstract
BACKGROUND Few studies have compared diets to determine whether a program focused on 1 dietary change results in collateral effects on other untargeted healthy diet components. OBJECTIVE To evaluate a diet focused on increased fiber consumption versus the multicomponent American Heart Association (AHA) dietary guidelines. DESIGN Randomized, controlled trial from June 2009 to January 2014. (ClinicalTrials.gov: NCT00911885). SETTING Worcester, Massachusetts. PARTICIPANTS 240 adults with the metabolic syndrome. INTERVENTION Participants engaged in individual and group sessions. MEASUREMENTS Primary outcome was weight change at 12 months. RESULTS At 12 months, mean change in weight was -2.1 kg (95% CI, -2.9 to -1.3 kg) in the high-fiber diet group versus -2.7 kg (CI, -3.5 to -2.0 kg) in the AHA diet group. The mean between-group difference was 0.6 kg (CI, -0.5 to 1.7 kg). During the trial, 12 (9.9%) and 15 (12.6%) participants dropped out of the high-fiber and AHA diet groups, respectively (P = 0.55). Eight participants developed diabetes (hemoglobin A1c level ≥6.5%) during the trial: 7 in the high-fiber diet group and 1 in the AHA diet group (P = 0.066). LIMITATIONS Generalizability is unknown. Maintenance of weight loss after cessation of group sessions at 12 months was not assessed. Definitive conclusions cannot be made about dietary equivalence because the study was powered for superiority. CONCLUSION The more complex AHA diet may result in up to 1.7 kg more weight loss; however, a simplified approach to weight reduction emphasizing only increased fiber intake may be a reasonable alternative for persons with difficulty adhering to more complicated diet regimens. PRIMARY FUNDING SOURCE National Heart, Lung, and Blood Institute.
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Plasma alkylresorcinols reflect important whole-grain components of a healthy Nordic diet.
Magnusdottir, OK, Landberg, R, Gunnarsdottir, I, Cloetens, L, Åkesson, B, Önning, G, Jonsdottir, SE, Rosqvist, F, Schwab, U, Herzig, KH, et al
The Journal of nutrition. 2013;(9):1383-90
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Biomarkers of dietary intake can be important tools in nutrition research. Our aim was to assess whether plasma alkylresorcinol (AR) and β-carotene concentrations could be used as dietary biomarkers for whole-grain, fruits and vegetables in a healthy Nordic diet (ND). Participants (n = 166), 30-65 y with a body mass index of 27-40 kg/m(2) and two more features of metabolic syndrome (International Diabetes Federation definition, slightly modified), were recruited through six centers in the Nordic countries and randomly assigned to an ND or control diet for 18 or 24 wk, depending on study center. Plasma AR and β-carotene were analyzed and nutrient intake calculated from 4-d food records. Median fiber intake increased in the ND group from 2.5 g/MJ at baseline to 4.1 g/MJ (P < 0.001) at end point (week 18 or 24), and median (IQR) fasting plasma total AR concentration increased from 73 (88) to 106 (108) nmol/L, or 45%, from baseline to end point (P < 0.001). The AR concentration was significantly higher in the ND group (P < 0.001) than in the control group at end point. β-Carotene intake tended to increase in the ND group (P = 0.07), but the plasma β-carotene concentration did not change significantly throughout the study and did not differ between the groups at follow-up. In conclusion, an ND resulted in higher dietary fiber intake and increased plasma total AR concentration compared with the control diet, showing that the total AR concentration might be a valid biomarker for an ND in which whole-grain wheat and rye are important components. No significant difference in plasma β-carotene concentrations was observed between the ND and control groups, suggesting that β-carotene may not be a sensitive enough biomarker of the ND.
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Insulin-sensitizing effects on muscle and adipose tissue after dietary fiber intake in men and women with metabolic syndrome.
Robertson, MD, Wright, JW, Loizon, E, Debard, C, Vidal, H, Shojaee-Moradie, F, Russell-Jones, D, Umpleby, AM
The Journal of clinical endocrinology and metabolism. 2012;(9):3326-32
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CONTEXT Dietary fibers have been associated with a reduced incidence of type 2 diabetes mellitus in epidemiological studies; however, the precise mechanisms are unknown. OBJECTIVE The objective of the study was to evaluate the efficacy and site of action of an insoluble dietary fiber derived from maize (HAM-RS2) in improving insulin resistance in subjects at increased risk of type 2 diabetes mellitus. DESIGN This study was a randomized, controlled crossover, dietary intervention study. SETTING The study was conducted at the Centre for Diabetes, Endocrinology, and Research, Royal Surrey County Hospital, Guildford, United Kingdom. PARTICIPANTS Fifteen men and women with insulin resistance participated in the study. INTERVENTION The intervention included 40 g/d HAM-RS2 compared with a matched placebo for 8 wk. MAIN OUTCOME MEASURES After each supplement, participants underwent a two-step hyperinsulinemic-euglycemic clamp study with the addition of glucose tracers; a meal tolerance test; arteriovenous sampling across forearm muscle tissue; and a sc adipose tissue biopsy for assessment of gene expression. RESULTS There was enhanced uptake of glucose into the forearm muscle measured by arteriovenous sampling (65 ± 15% increase after resistant starch; P < 0.001). Adipose tissue function was also affected, with enhanced fatty acid suppression after HAM-RS2 treatment and an increase in gene expression for hormone sensitive lipase (P = 0.005), perilipin (P = 0.011), lipoprotein lipase (P = 0.014), and adipose triglyceride lipase (P = 0.03) in biopsy samples. There was no effect on the insulin sensitivity of hepatic glucose production or plasma lipids after HAM-RS2. CONCLUSION HAM-RS2 improved peripheral but not hepatic insulin resistance and requires further study as an intervention in patients with or at risk for type 2 diabetes.
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Effects of supplemented isoenergetic diets differing in cereal fiber and protein content on insulin sensitivity in overweight humans.
Weickert, MO, Roden, M, Isken, F, Hoffmann, D, Nowotny, P, Osterhoff, M, Blaut, M, Alpert, C, Gögebakan, O, Bumke-Vogt, C, et al
The American journal of clinical nutrition. 2011;(2):459-71
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BACKGROUND Despite their beneficial effects on weight loss and blood lipids, high-protein (HP) diets have been shown to increase insulin resistance and diabetes risk, whereas high-cereal-fiber (HCF) diets have shown the opposite effects on these outcomes. OBJECTIVE We compared the effects of isoenergetic HP and HCF diets and a diet with moderate increases in both cereal fibers and dietary protein (Mix diet) on insulin sensitivity, as measured by using euglycemic-hyperinsulinemic clamps with infusion of [6,6-(2)H(2)]glucose. DESIGN We randomly assigned 111 overweight adults with features of the metabolic syndrome to 1 of 4 two-phased, 18-wk isoenergetic diets by group-matching. Per 3-d food protocols, the percentages of energy derived from protein and carbohydrates and the intake of cereal fiber per day, respectively, were as follows-after 6 wk: 17%, 52%, and 14 g (control); 17%, 52%, and 43 g (HCF); 28%, 43%, and 13 g (HP); 23%, 44%, and 26 g (Mix); after 18 wk: 17%, 51%, and 15 g (control); 17%, 51%, and 41 g (HCF); 26%, 45%, and 14 g (HP); and 22%, 46%, and 26 g (Mix). Eighty-four participants completed the study successfully and were included in the final analyses. Adherence was supported by the provision of tailored dietary supplements twice daily in all groups. RESULTS Insulin sensitivity expressed as an M value was 25% higher after 6 wk of the HCF diet than after 6 wk of the HP diet (subgroup analysis: 4.61 ± 0.38 compared with 3.71 ± 0.36 mg · kg(-1) · min(-1), P = 0.008; treatment × time interaction: P = 0.005). Effects were attenuated after 18 wk (treatment × time interaction: P = 0.054), which was likely explained by lower adherence to the HP diet. HP intake was associated with a tendency to increased protein expression in adipose tissue of the translation initiation factor serine-kinase-6-1, which is known to mediate amino acid-induced insulin resistance. Biomarkers of protein intake indicated interference of cereal fibers with dietary protein absorption. CONCLUSION Greater changes in insulin sensitivity after intake of an isoenergetic HCF than after intake of an HP diet might help to explain the diverse effects of these diets on diabetes risk. This trial is registered at clinicaltrials.gov as NCT00579657.
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Comparison of high protein and high fiber weight-loss diets in women with risk factors for the metabolic syndrome: a randomized trial.
Te Morenga, LA, Levers, MT, Williams, SM, Brown, RC, Mann, J
Nutrition journal. 2011;:40
Abstract
BACKGROUND Studies have suggested that moderately high protein diets may be more appropriate than conventional low-fat high carbohydrate diets for individuals at risk of developing the metabolic syndrome and type 2 diabetes. However in most such studies sources of dietary carbohydrate may not have been appropriate and protein intakes may have been excessively high. Thus, in a proof-of-concept study we compared two relatively low-fat weight loss diets - one high in protein and the other high in fiber-rich, minimally processed cereals and legumes - to determine whether a relatively high protein diet has the potential to confer greater benefits. METHODS Eighty-three overweight or obese women, 18-65 years, were randomized to either a moderately high protein (30% protein, 40% carbohydrate) diet (HP) or to a high fiber, relatively high carbohydrate (50% carbohydrate, > 35 g total dietary fiber, 20% protein) diet (HFib) for 8 weeks. Energy intakes were reduced by 2000 - 4000 kJ per day in order to achieve weight loss of between 0.5 and 1 kg per week. RESULTS Participants on both diets lost weight (HP: -4.5 kg [95% confidence interval (CI):-3.7, -5.4 kg] and HFib: -3.3 kg [95% CI: -4.2, -2.4 kg]), and reduced total body fat (HP: -4.0 kg [5% CI:-4.6, -3.4 kg] and HFib: -2.5 kg [95% CI: -3.5, -1.6 kg]), and waist circumference (HP: -5.4 cm [95% CI: -6.3, -4.5 cm] and HFib: -4.7 cm [95% CI: -5.8, -3.6 cm]), as well as total and LDL cholesterol, triglycerides, fasting plasma glucose and blood pressure. However participants on HP lost more body weight (-1.3 kg [95% CI: -2.5, -0.1 kg; p = 0.039]) and total body fat (-1.3 kg [95% CI: -2.4, -0.1; p = 0.029]). Diastolic blood pressure decreased more on HP (-3.7 mm Hg [95% CI: -6.2, -1.1; p = 0.005]). CONCLUSIONS A realistic high protein weight-reducing diet was associated with greater fat loss and lower blood pressure when compared with a high carbohydrate, high fiber diet in high risk overweight and obese women.
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Comparison of hormonal and metabolic markers after a high-fat, Western meal versus a low-fat, high-fiber meal in women with polycystic ovary syndrome.
Katcher, HI, Kunselman, AR, Dmitrovic, R, Demers, LM, Gnatuk, CL, Kris-Etherton, PM, Legro, RS
Fertility and sterility. 2009;(4):1175-82
Abstract
OBJECTIVE To determine the effect of meal composition on postprandial T levels in women with polycystic ovary syndrome (PCOS). DESIGN Randomized, crossover design. SETTING Academic research center. PATIENT(S): Fifteen women with PCOS. INTERVENTION(S): We evaluated changes in T, sex hormone binding globulin (SHBG), DHEAS, cortisol, glucose, and insulin for 6 hours after a high-fat, Western meal (HIFAT) (62% fat, 24% carbohydrate, 1 g fiber) and an isocaloric low-fat, high-fiber meal (HIFIB) (6% fat, 81% carbohydrate, 27 g fiber). MAIN OUTCOME MEASURE(S): Change in T levels. RESULT(S): Testosterone decreased 27% within 2 hours after both meals. However, T remained below premeal values for 4 hours after the HIFIB meal and 6 hours after the HIFAT meal. Insulin was twofold higher for 2 hours after the HIFIB meal compared with the HIFAT meal. Glucose was higher for 1 hour after the HIFIB meal compared with the HIFAT meal. DHEAS decreased 8%-10% within 2-3 hours after both meals, then increased during the remainder of the study period. Cortisol decreased during the 6-hour period after both meals. CONCLUSIONS Diet plays a role in the regulation of T levels in women with PCOS. Further studies are needed to determine the role of diet composition in the treatment of PCOS.
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Design and methods for testing a simple dietary message to improve weight loss and dietary quality.
Merriam, PA, Ma, Y, Olendzki, BC, Schneider, KL, Li, W, Ockene, IS, Pagoto, SL
BMC medical research methodology. 2009;:87
Abstract
BACKGROUND The current food pyramid guidelines have been criticized because of their complexity and the knowledge required for users to understand the recommendations. Simplification of a dietary message to focus on a single key aspect of dietary quality, e.g., fiber intake, may make the message much easier to comprehend and adhere, such that respondents can achieve greater weight loss, better dietary quality and overall metabolic health. METHODS AND DESIGN This is a randomized controlled clinical trial with two equal sized arms. In total, 240 obese adults who meet diagnostic criteria for the metabolic syndrome will be randomized to one of the two conditions: 1) a high fiber diet and 2) the American Heart Association (AHA) diet. In the high fiber diet condition, patients will be given instruction only on achieving daily dietary fiber intake of 30 g or more. In the AHA diet condition, patients will be instructed to make the several dietary changes recommended by the AHA 2006 guidelines. The trial examines participant weight loss and dietary quality as well as changes in components of the metabolic syndrome, inflammatory biomarkers, low-density lipoprotein cholesterol levels, insulin levels, and glycosolated hemoglobin. Potential mediators, i.e., diet adherence and perceived ease of the diet, and the intervention effect on weight change will also be examined. DISCUSSIONS The purpose of this paper is to outline the study design and methods for testing the simple message of increasing dietary fiber. If the simple dietary approach is found efficacious for weight loss; and, improves dietary quality, metabolic health, and adherence, it might then be used to develop a simple public health message. TRIAL REGISTRATION NCT00911885.