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Association between plasma fatty acids and inflammatory markers in patients with and without insulin resistance and in secondary prevention of cardiovascular disease, a cross-sectional study.
Bersch-Ferreira, ÂC, Sampaio, GR, Gehringer, MO, Torres, EAFDS, Ross-Fernandes, MB, da Silva, JT, Torreglosa, CR, Kovacs, C, Alves, R, Magnoni, CD, et al
Nutrition journal. 2018;17(1):26
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It is known that people with cardiovascular disease (CVD) have increased inflammation and raised levels of circulating inflammatory molecules. The presence of insulin resistance is thought to increase these levels, as are certain fatty acids coming from dietary fats. The aims of this cross-sectional study were to compare the levels of inflammatory biomarkers in patients with CVD with and without insulin resistance, and to evaluate the possible link between the blood levels of fatty acids and inflammatory biomarkers among these patients. The authors concluded that the CVD patients with insulin resistance had a higher concentration of some inflammatory molecules in the blood than those without insulin resistance. They also observed that saturated fatty acids were linked to higher levels of inflammatory molecules in the blood, while unsaturated fatty acids correlated with lower levels.
Abstract
BACKGROUND Proinflammatory biomarkers levels are increased among patients with cardiovascular disease, and it is known that both the presence of insulin resistance and diet may influence those levels. However, these associations are not well studied among patients with established cardiovascular disease. Our objective is to compare inflammatory biomarker levels among cardiovascular disease secondary prevention patients with and without insulin resistance, and to evaluate if there is any association between plasma fatty acid levels and inflammatory biomarker levels among them. METHODS In this cross-sectional sub-study from the BALANCE Program Trial, we collected data from 359 patients with established cardiovascular disease. Plasma fatty acids and inflammatory biomarkers (interleukin (IL)-1β, IL-6, IL-8, IL-10, IL-12, high sensitive C-reactive protein (hs-CRP), adiponectin, and tumor necrosis factor (TNF)-alpha) were measured. Biomarkers and plasma fatty acid levels of subjects across insulin resistant and not insulin resistant groups were compared, and general linear models were used to examine the association between plasma fatty acids and inflammatory biomarkers. RESULTS Subjects with insulin resistance had a higher concentration of hs-CRP (p = 0.002) and IL-6 (p = 0.002) than subjects without insulin resistance. Among subjects without insulin resistance there was a positive association between stearic fatty acid and IL-6 (p = 0.032), and a negative association between alpha-linolenic fatty acid and pro-inflammatory biomarkers (p < 0.05). Among those with insulin resistance there was a positive association between monounsaturated fatty acids and arachidonic fatty acid and adiponectin (p < 0.05), and a negative association between monounsaturated and polyunsaturated fatty acids and pro-inflammatory biomarkers (p < 0.05), as well as a negative association between polyunsaturated fatty acids and adiponectin (p < 0.05). Our study has not found any association between hs-CRP and plasma fatty acids. CONCLUSIONS Subjects in secondary prevention for cardiovascular disease with insulin resistance have a higher concentration of hs-CRP and IL-6 than individuals without insulin resistance, and these inflammatory biomarkers are positively associated with saturated fatty acids and negatively associated with unsaturated fatty acids.
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Lifestyle and vascular risk effects on MRI-based biomarkers of Alzheimer's disease: a cross-sectional study of middle-aged adults from the broader New York City area.
Mosconi, L, Walters, M, Sterling, J, Quinn, C, McHugh, P, Andrews, RE, Matthews, DC, Ganzer, C, Osorio, RS, Isaacson, RS, et al
BMJ open. 2018;8(3):e019362
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Alzheimer’s disease (AD) is the most common form of dementia, affecting nearly 34 million people worldwide. It has been estimated that one in every three cases of AD may be attributable to diet and lifestyle factors. The aim of this study was to investigate the effects of lifestyle and vascular-related risk factors for AD. Researchers studied the brain scans of 116 healthy adults aged 30-60 years. They collected information on factors related to lifestyle, such as diet, physical activity and intellectual enrichment. They also looked at markers for vascular risk such as body mass index (BMI), cholesterol and homocysteine, as well as cognitive function. The researchers found that a Mediterranean-style diet and good insulin sensitivity were both associated with a healthier brain structure. A better score for intellectual enrichment and lower BMI were both associated with better cognition. They concluded that adopting a Mediterranean-style diet and maintaining a healthy weight might reduce the risk of developing AD.
Abstract
OBJECTIVE To investigate the effects of lifestyle and vascular-related risk factors for Alzheimer's disease (AD) on in vivo MRI-based brain atrophy in asymptomatic young to middle-aged adults. DESIGN Cross-sectional, observational. SETTING Broader New York City area. Two research centres affiliated with the Alzheimer's disease Core Center at New York University School of Medicine. PARTICIPANTS We studied 116 cognitively normal healthy research participants aged 30-60 years, who completed a three-dimensional T1-weighted volumetric MRI and had lifestyle (diet, physical activity and intellectual enrichment), vascular risk (overweight, hypertension, insulin resistance, elevated cholesterol and homocysteine) and cognition (memory, executive function, language) data. Estimates of cortical thickness for entorhinal (EC), posterior cingulate, orbitofrontal, inferior and middle temporal cortex were obtained by use of automated segmentation tools. We applied confirmatory factor analysis and structural equation modelling to evaluate the associations between lifestyle, vascular risk, brain and cognition. RESULTS Adherence to a Mediterranean-style diet (MeDi) and insulin sensitivity were both positively associated with MRI-based cortical thickness (diet: βs≥0.26, insulin sensitivity βs≥0.58, P≤0.008). After accounting for vascular risk, EC in turn explained variance in memory (P≤0.001). None of the other lifestyle and vascular risk variables were associated with brain thickness. In addition, the path associations between intellectual enrichment and better cognition were significant (βs≥0.25 P≤0.001), as were those between overweight and lower cognition (βs≥-0.22, P≤0.01). CONCLUSIONS In cognitively normal middle-aged adults, MeDi and insulin sensitivity explained cortical thickness in key brain regions for AD, and EC thickness predicted memory performance in turn. Intellectual activity and overweight were associated with cognitive performance through different pathways. Our findings support further investigation of lifestyle and vascular risk factor modification against brain ageing and AD. More studies with larger samples are needed to replicate these research findings in more diverse, community-based settings.
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Food sources of fructose-containing sugars and glycaemic control: systematic review and meta-analysis of controlled intervention studies.
Choo, VL, Viguiliouk, E, Blanco Mejia, S, Cozma, AI, Khan, TA, Ha, V, Wolever, TMS, Leiter, LA, Vuksan, V, Kendall, CWC, et al
BMJ (Clinical research ed.). 2018;363:k4644
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With increasing evidence linking fructose to metabolic disease, current dietary guidelines recommend a reduction of added free sugars, especially fructose-containing sugars from sugars-sweetened beverages (SSBs). However, it is currently unclear whether the negative impact of fructose on metabolic health is as implicative in the context of an overall dietary consumption pattern. The aim of this study was to assess the effect of different sources of fructose-containing sugars on glycaemic control in people with and without diabetes. This review analysed 155 controlled intervention studies and found that fructose-containing sugars in the form of fruit do not have a harmful effect on glycaemic control when compared to energy-matched macronutrient substitutions. Further, harmful effects on glycaemic control were found when excess energy in the form of fructose-containing sugars from SSBs were added to the diet. The authors conclude the food source of fructose-containing sugars on glycemic control is important in the conversation of metabolic health and glycaemic control. While further research is needed to assess a wider variety of food sources, public health professionals should consider the influence of food sources when developing dietary recommendations for the prevention and management of diabetes and other metabolic conditions.
Abstract
OBJECTIVE To assess the effect of different food sources of fructose-containing sugars on glycaemic control at different levels of energy control. DESIGN Systematic review and meta-analysis of controlled intervention studies. DATA SOURCES Medine, Embase, and the Cochrane Library up to 25 April 2018. ELIGIBILITY CRITERIA FOR SELECTING STUDIES Controlled intervention studies of at least seven days' duration and assessing the effect of different food sources of fructose-containing sugars on glycaemic control in people with and without diabetes were included. Four study designs were prespecified on the basis of energy control: substitution studies (sugars in energy matched comparisons with other macronutrients), addition studies (excess energy from sugars added to diets), subtraction studies (energy from sugars subtracted from diets), and ad libitum studies (sugars freely replaced by other macronutrients without control for energy). Outcomes were glycated haemoglobin (HbA1c), fasting blood glucose, and fasting blood glucose insulin. DATA EXTRACTION AND SYNTHESIS Four independent reviewers extracted relevant data and assessed risk of bias. Data were pooled by random effects models and overall certainty of the evidence assessed by the GRADE approach (grading of recommendations assessment, development, and evaluation). RESULTS 155 study comparisons (n=5086) were included. Total fructose-containing sugars had no harmful effect on any outcome in substitution or subtraction studies, with a decrease seen in HbA1c in substitution studies (mean difference -0.22% (95% confidence interval to -0.35% to -0.08%), -25.9 mmol/mol (-27.3 to -24.4)), but a harmful effect was seen on fasting insulin in addition studies (4.68 pmol/L (1.40 to 7.96)) and ad libitum studies (7.24 pmol/L (0.47 to 14.00)). There was interaction by food source, with specific food sources showing beneficial effects (fruit and fruit juice) or harmful effects (sweetened milk and mixed sources) in substitution studies and harmful effects (sugars-sweetened beverages and fruit juice) in addition studies on at least one outcome. Most of the evidence was low quality. CONCLUSIONS Energy control and food source appear to mediate the effect of fructose-containing sugars on glycaemic control. Although most food sources of these sugars (especially fruit) do not have a harmful effect in energy matched substitutions with other macronutrients, several food sources of fructose-containing sugars (especially sugars-sweetened beverages) adding excess energy to diets have harmful effects. However, certainty in these estimates is low, and more high quality randomised controlled trials are needed. STUDY REGISTRATION Clinicaltrials.gov (NCT02716870).
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A randomised trial of the feasibility of a low carbohydrate diet vs standard carbohydrate counting in adults with type 1 diabetes taking body weight into account.
Krebs, JD, Parry Strong, A, Cresswell, P, Reynolds, AN, Hanna, A, Haeusler, S
Asia Pacific journal of clinical nutrition. 2016;25(1):78-84
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With the advent of self-managed insulin by injection, Type 1 diabetics were able to eat a normal diet and not worry about their carbohydrate intake. However this regime requires careful carbohydrate counting and insulin dosing, which is not always easy to do. With interest in low carbohydrate diets in the management of Type 2 diabetes increasing, some Type 1 diabetics are restricting their carbohydrates in order to better control their blood glucose levels. This pilot study was a small, single-blinded randomised control trial of 10 individuals. It aimed to determine the effects of low carbohydrate diets on glycaemic control, daily insulin requirements and quality of life in Type 1 Diabetes, when compared to those on a normal diet. The results showed that HbA1C reduced significantly in the carbohydrate restricted group compared to the group eating a normal diet. The amount of injected insulin also showed a significant reduction in the low-carbohydrate group. There were no changes in blood pressure, creatinine or lipid profile in either of the groups. A low-carbohydrate diet is a feasible option for clients with Type 1 Diabetes who are looking for improved glycaemic control and reduced doses of insulin, particularly if they would like to lose weight.
Abstract
BACKGROUND AND OBJECTIVES To determine the effect of a low carbohydrate diet and standard carbohydrate counting on glycaemic control, glucose excursions and daily insulin use compared with standard carbohydrate counting in participants with type 1 diabetes. METHODS AND STUDY DESIGN Participants (n=10) with type 1 diabetes using a basal; bolus insulin regimen, who attended a secondary care clinic, were randomly allocated (1:1) to either a standard carbohydrate counting course or the same course with added information on following a carbohydrate restricted diet (75 g per day). Participants attended visits at baseline and 12 weeks for measurements of weight, height, blood pressure, HbA1c, lipid profile and creatinine. They also completed a 3-day food diary and had 3 days of continuous subcutaneous glucose monitoring. RESULTS The carbohydrate restricted group had significant reductions in HbA1c (63 to 55 mmol/mol (8.9-8.2%), p<0.05) and daily insulin use (64.4 to 44.2 units/day, p<0.05) and non-significant reductions in body weight (83.2 to 78.0 kg). There were no changes in blood pressure, creatinine or lipid profile and all outcomes in the carbohydrate counting group were unchanged. There was no change in glycaemic variability as measured by the mean amplitude of glycaemic excursion in either group. CONCLUSIONS A low carbohydrate diet is a feasible option for people with type 1 diabetes, and may be of benefit in reducing insulin doses and improving glycaemic control, particularly for those wishing to lose weight. 背景与目的:在1 型糖尿病患者中,与标准碳水化合物计数比较,确定低碳水 化合物饮食对血糖控制、血糖波动以及每日胰岛素使用的影响。方法与研究 设计:参加二级保健门诊使用普通膳食以注射胰岛素为治疗方案的10 例1 型 糖尿病患者,按照1:1 的比例随机分配到一个标准的碳水化合物计数组,或限 制碳水化合物饮食组(每天75 g)。测量了所有志愿者基线和12 周的体重、 身高、血压、糖化血红蛋白、血脂和肌酐,志愿者完成了为期3 天的食物日记 和3 天持续皮下血糖监测。结果:碳水化合物限制组HbA1c(63-55 mmol/mol (8.9-8.2 %),p<0.05)和每日胰岛素用量(64.4-44.2 U/d,p<0.05)显著减 少,体重(83.2-78 kg)的变化无显著差异。碳水化合物计数组血压、肌酐或 血脂所有指标均无显著改变。通过平均血糖波动幅度计算的血糖变异性在任何 一组中均无改变。结论:低碳水化合物饮食是1 型糖尿病患者一个可行的选 择,可以减少胰岛素剂量和改善血糖控制,特别是对那些希望减肥的患者。.
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Feasibility outcomes of a presurgical randomized controlled trial exploring the impact of caloric restriction and increased physical activity versus a wait-list control on tumor characteristics and circulating biomarkers in men electing prostatectomy for prostate cancer.
Demark-Wahnefried, W, Nix, JW, Hunter, GR, Rais-Bahrami, S, Desmond, RA, Chacko, B, Morrow, CD, Azrad, M, Frugé, AD, Tsuruta, Y, et al
BMC cancer. 2016;16:61
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There is a strong body of evidence associating obesity and increased risk for more aggressive and progressive cancer. This paper aims to assess the feasibility of a presurgical diet and exercise weight loss intervention in men with newly-diagnosed prostate cancer who elected for prostatectomy. It also aims to explore the intervention’s effects on tumour proliferation rates and other biomarkers. The 3-weeks randomised controlled study included 40 overweight or obese men newly-diagnosed with prostate cancer. Participants in experimental arm were assigned to a healthy energy-restricted diet versus wait-list control arm. All feasibility endpoints were achieved with accrual completed within 2 years, retention of 85%, adherence of 95% and no adverse events. Biologic outcomes were not included in this paper, as biological testing was still ongoing. Authors concluded that this study’s methods and data on feasibility could provide useful framework for the design of future trials. They also highlighted the importance of presurgical trials as a feasible and safe means to assess the impacts of diet and exercise on tumour tissue.
Abstract
BACKGROUND Obesity is associated with tumor aggressiveness and disease-specific mortality for more than 15 defined malignancies, including prostate cancer. Preclinical studies suggest that weight loss from caloric restriction and increased physical activity may suppress hormonal, energy-sensing, and inflammatory factors that drive neoplastic progression; however, exact mechanisms are yet to be determined, and experiments in humans are limited. METHODS We conducted a randomized controlled trial among 40 overweight or obese, newly-diagnosed prostate cancer patients who elected prostatectomy to explore feasibility of a presurgical weight loss intervention that promoted a weight loss of roughly one kg. week(-1) via caloric restriction and physical activity, as well as to assess effects on tumor biology and circulating biomarkers. Measures of feasibility (accrual, retention, adherence, and safety) were primary endpoints. Exploratory aims were directed at the intervention's effect on tumor proliferation (Ki-67) and other tumor markers (activated caspase-3, insulin and androgen receptors, VEGF, TNFβ, NFκB, and 4E-BP1), circulating biomarkers (PSA, insulin, glucose, VEGF, TNFβ, leptin, SHBG, and testosterone), lymphocytic gene expression of corresponding factors and cellular bioenergetics in neutrophils, and effects on the gut microbiome. Consenting patients were randomized in a 1:1 ratio to either: 1) weight loss via a healthful, guidelines-based diet and exercise regimen; or 2) a wait-list control. While biological testing is currently ongoing, this paper details our methods and feasibility outcomes. RESULTS The accrual target was met after screening 101 cases (enrollment rate: 39.6%). Other outcomes included a retention rate of 85%, excellent adherence (95%), and no serious reported adverse events. No significant differences by age, race, or weight status were noted between enrollees vs. non-enrollees. The most common reasons for non-participation were "too busy" (30%), medical exclusions (21%), and "distance" (16%). CONCLUSIONS Presurgical trials offer a means to study the impact of diet and exercise interventions directly on tumor tissue, and other host factors that are feasible and safe, though modifications are needed to conduct trials within an abbreviated period of time and via distance medicine-based approaches. Pre-surgical trials are critical to elucidate the impact of lifestyle interventions on specific mechanisms that mediate carcinogenesis and which can be used subsequently as therapeutic targets. TRIAL REGISTRATION NCT01886677.
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Insulin secretion and sensitivity in healthy adults with low vitamin D are not affected by high-dose ergocalciferol administration: a randomized controlled trial.
Mitchell, DM, Leder, BZ, Cagliero, E, Mendoza, N, Henao, MP, Hayden, DL, Finkelstein, JS, Burnett-Bowie, SA
The American journal of clinical nutrition. 2015;102(2):385-92
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Type 2 diabetes is a highly prevalent multifactorial disease associated with comorbidities and mortalities. Several epidemiological studies showed an association between low levels of vitamin D and incidence of type 2 diabetes. This double-blinded, randomized controlled trial aims to examine the effects of ergocalciferol (vitamin D2) on glucose and insulin metabolism. Healthy subjects with low vitamin D were weekly administered either a high dose of ergocalciferol or placebo for 12 weeks. The researchers found no significant difference in the first phase insulin secretion and sensitivity and concluded that supplementation with ergocalciferol doesn’t promote metabolic markers that could lead to decreased risk of type 2 diabetes. Future trials should address the effect of vitamin D administration in high-risk populations.
Abstract
BACKGROUND Epidemiologic data suggest that low serum 25-hydroxyvitamin D [25(OH)D] increases insulin resistance and the risk of type 2 diabetes. Few interventional trials have assessed the effect of vitamin D on insulin metabolism, and published results are discordant. OBJECTIVE The goal of this study was to perform a detailed assessment of the effect of ergocalciferol administration on glucose and insulin metabolism in healthy people with low total 25(OH)D(total). DESIGN This was a 12-wk, double-blinded, randomized controlled trial. We enrolled 90 healthy volunteers aged 18-45 y with serum 25(OH)D ≤20 ng/mL (by immunoassay) and administered 50,000 IU ergocalciferol/wk or placebo for 12 wk. Primary endpoints were change in first-phase insulin response and insulin sensitivity as measured by intravenous glucose tolerance test. Secondary endpoints included change in homeostasis model assessment of insulin resistance; fasting glucose, insulin, and lipids; body mass index (BMI); and blood pressure. RESULTS On-study 25(OH)D(total) was assessed by liquid chromatography-tandem mass spectrometry. In the treated group, 25(OH)D(total) rose from 18 ± 7 to 43 ± 12 ng/mL (P < 0.001) with no change in the placebo group. Despite this increase, at 12 wk, there were no between-group differences in either insulin response or insulin sensitivity; nor were there differences in any measured secondary endpoints. There was no evidence of effect modification by sex, race, glucose tolerance status, baseline 25(OH)D(total), or BMI. CONCLUSION In healthy persons with low 25(OH)D(total), ergocalciferol administration for 12 wk normalizes 25(OH)D(total) but does not improve insulin secretion, insulin sensitivity, or other markers of metabolic health.
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Metabolic profiling distinguishes three subtypes of Alzheimer's disease.
Bredesen, DE
Aging. 2015;7(8):595-600
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The causes of Alzheimer’s Disease (AD) remain incompletely defined and there are currently no truly effective drug therapies available. However, there is growing evidence that disordered blood glucose management and hormonal changes and deficiencies, amongst other things, are implicated in symptom onset. Optimising these various metabolic processes, therefore, may be used as a comprehensive way to avoid cognitive decline or achieve cognitive improvements in symptomatic individuals. This report provides the metabolic results of 3 case studies and suggests 3 different types of AD classification, depending on the individual metabolic profile. Further studies are required to elaborate on the metabolic profiles suggested in this report, however Nutrition Practitioners working with cognitive decline, can use this report as a basis for individualised nutrition protocols to optimise metabolic processes in clients with cognitive decline.
Abstract
The cause of Alzheimer's disease is incompletely defined, and no truly effective therapy exists. However, multiple studies have implicated metabolic abnormalities such as insulin resistance, hormonal deficiencies, and hyperhomocysteinemia. Optimizing metabolic parameters in a comprehensive way has yielded cognitive improvement, both in symptomatic and asymptomatic individuals. Therefore, expanding the standard laboratory evaluation in patients with dementia may be revealing. Here I report that metabolic profiling reveals three Alzheimer's disease subtypes. The first is inflammatory, in which markers such as hs-CRP and globulin:albumin ratio are increased. The second type is non-inflammatory, in which these markers are not increased, but other metabolic abnormalities are present. The third type is a very distinctive clinical entity that affects relatively young individuals, extends beyond the typical Alzheimer's disease initial distribution to affect the cortex widely, is characterized by early non-amnestic features such as dyscalculia and aphasia, is often misdiagnosed or labeled atypical Alzheimer's disease, typically affects ApoE4-negative individuals, and is associated with striking zinc deficiency. Given the involvement of zinc in multiple Alzheimer's-related metabolic processes, such as insulin resistance, chronic inflammation, ADAM10 proteolytic activity, and hormonal signaling, this syndrome of Alzheimer's-plus with low zinc (APLZ) warrants further metabolic, genetic, and epigenetic characterization.
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Calorie anticipation alters food intake after low-caloric not high-caloric preloads.
Hogenkamp, PS, Cedernaes, J, Chapman, CD, Vogel, H, Hjorth, OC, Zarei, S, Lundberg, LS, Brooks, SJ, Dickson, SL, Benedict, C, et al
Obesity (Silver Spring, Md.). 2013;21(8):1548-53
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Cognitive factors have been shown to influence short-term food intake. It is currently unclear whether cognitive cues modulate hormonal responses when the anticipated foods differ in their energy content, and whether these changes in hormone levels may contribute to possible differences in subsequent food intake. The aim of this study was to examine whether calorie anticipation impacts subsequent ad libitum food intake and hormone levels in 12 healthy women. Participants were evaluated under four conditions: in two conditions they consumed a low calorie preload and the other two conditions they consumed a high calorie preload. Before consumption, they were provided with either consistent or inconsistent information on the calorie content. his study found that intake was lower after the high calorie preloads when compared with the low calorie preloads, however post-prandial hormonal response was driven by actual calories consumed. These findings indicate that both metabolic and cognitive features of food affect subsequent intake decisions in healthy young women.
Abstract
OBJECTIVE Cognitive factors and anticipation are known to influence food intake. The current study examined the effect of anticipation and actual consumption of food on hormone (ghrelin, cortisol, and insulin) and glucose levels, appetite and ad libitum intake, to assess whether changes in hormone levels might explain the predicted differences in subsequent food intake. DESIGN AND METHODS During four breakfast sessions, participants consumed a yogurt preload that was either low caloric (LC: 180 kcal/300 g) or high caloric (HC: 530 kcal/300 g) and was provided with either consistent or inconsistent calorie information (i.e., stating the caloric content of the preload was low or high). Appetite ratings and hormone and glucose levels were measured at baseline (t = 0), after providing the calorie information about the preload (t = 20), after consumption of the preload (t = 40), and just before ad libitum intake (t = 60). RESULTS Ad libitum intake was lower after HC preloads (as compared to LC preloads; P < 0.01). Intake after LC preloads was higher when provided with (consistent) LC information (467±254 kcal) as compared to (inconsistent) HC information (346±210 kcal), but intake after the HC preloads did not depend on the information provided (LC information: 290±178 kcal, HC information: 333±179 kcal; caloric load*information P = 0.03). Hormone levels did not respond in an anticipatory manner, and the post-prandial responses depended on actual calories consumed. CONCLUSIONS These results suggest that both cognitive and physiological information determine food intake. When actual caloric intake was sufficient to produce physiological satiety, cognitive factors played no role; however, when physiological satiety was limited, cognitively induced satiety reduced intake to comparable levels.
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Effects of dietary glycemic index on brain regions related to reward and craving in men.
Lennerz, BS, Alsop, DC, Holsen, LM, Stern, E, Rojas, R, Ebbeling, CB, Goldstein, JM, Ludwig, DS
The American journal of clinical nutrition. 2013;98(3):641-7
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Clinical studies using functional brain imaging have found increased activity in the nucleus accumbens (thought to play a central role in reward and cravings) in obese subjects after viewing or eating highly palatable, calorific food. Additionally, studies have shown that striatal dopamine receptor activity was lower for obese subjects, suggesting that overeating may compensate for lower dopamine activity in these people. This study compared the brain activity following a high GI or a low GI meal, focusing on the areas of the brain that are responsible for eating behaviour, reward and addiction. Subjects were healthy overweight or obese men. The findings showed that compared to low GI meals, a high GI meal increased self-reported hunger, stimulated brain regions associated with reward and cravings, and decreased blood glucose (which could increase hunger and the hedonistic value of food).
Abstract
BACKGROUND Qualitative aspects of diet influence eating behavior, but the physiologic mechanisms for these calorie-independent effects remain speculative. OBJECTIVE We examined effects of the glycemic index (GI) on brain activity in the late postprandial period after a typical intermeal interval. DESIGN With the use of a randomized, blinded, crossover design, 12 overweight or obese men aged 18-35 y consumed high- and low-GI meals controlled for calories, macronutrients, and palatability on 2 occasions. The primary outcome was cerebral blood flow as a measure of resting brain activity, which was assessed by using arterial spin-labeling functional magnetic resonance imaging 4 h after test meals. We hypothesized that brain activity would be greater after the high-GI meal in prespecified regions involved in eating behavior, reward, and craving. RESULTS Incremental venous plasma glucose (2-h area under the curve) was 2.4-fold greater after the high- than the low-GI meal (P = 0.0001). Plasma glucose was lower (mean ± SE: 4.7 ± 0.14 compared with 5.3 ± 0.16 mmol/L; P = 0.005) and reported hunger was greater (P = 0.04) 4 h after the high- than the low-GI meal. At this time, the high-GI meal elicited greater brain activity centered in the right nucleus accumbens (a prespecified area; P = 0.0006 with adjustment for multiple comparisons) that spread to other areas of the right striatum and to the olfactory area. CONCLUSIONS Compared with an isocaloric low-GI meal, a high-GI meal decreased plasma glucose, increased hunger, and selectively stimulated brain regions associated with reward and craving in the late postprandial period, which is a time with special significance to eating behavior at the next meal. This trial was registered at clinicaltrials.gov as NCT01064778.
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Vegetarian diet improves insulin resistance and oxidative stress markers more than conventional diet in subjects with Type 2 diabetes.
Kahleova, H, Matoulek, M, Malinska, H, Oliyarnik, O, Kazdova, L, Neskudla, T, Skoch, A, Hajek, M, Hill, M, Kahle, M, et al
Diabetic medicine : a journal of the British Diabetic Association. 2011;28(5):549-59
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Non-vegetarians are twice as likely have type 2 diabetes compared to vegetarians. The aim of this study was to compare the effects of a vegetarian diet with a conventional diabetic diet, both alone and in combination with exercise. 37 participants with type 2 diabetes were given a low calorie, vegetarian diet for 12 weeks. A control group followed a conventional diabetic diet which contained the same calories as the vegetarian diet. In the second 12 weeks, both groups combined this with aerobic exercise. Whilst both groups experienced reductions in body weight, body fat and insulin resistance, the vegetarian group experienced significantly better improvements than the control group. The addition of exercise further enhanced the beneficial effects of the vegetarian diet. The authors concluded that vegetarian diets may provide a beneficial alternative for patients with Type 2 diabetes, especially in combination with exercise.
Abstract
AIMS: The aim of this study was to compare the effects of calorie-restricted vegetarian and conventional diabetic diets alone and in combination with exercise on insulin resistance, visceral fat and oxidative stress markers in subjects with Type 2 diabetes. METHODS A 24-week, randomized, open, parallel design was used. Seventy-four patients with Type 2 diabetes were randomly assigned to either the experimental group (n = 37), which received a vegetarian diet, or the control group (n = 37), which received a conventional diabetic diet. Both diets were isocaloric, calorie restricted (-500 kcal/day). All meals during the study were provided. The second 12 weeks of the diet were combined with aerobic exercise. Participants were examined at baseline, 12 weeks and 24 weeks. Primary outcomes were: insulin sensitivity measured by hyperinsulinaemic isoglycaemic clamp; volume of visceral and subcutaneous fat measured by magnetic resonance imaging; and oxidative stress measured by thiobarbituric acid reactive substances. Analyses were by intention to treat. RESULTS Forty-three per cent of participants in the experimental group and 5% of participants in the control group reduced diabetes medication (P < 0.001). Body weight decreased more in the experimental group than in the control group [-6.2 kg (95% CI -6.6 to -5.3) vs. -3.2 kg (95% CI -3.7 to -2.5); interaction group × time P = 0.001]. An increase in insulin sensitivity was significantly greater in the experimental group than in the control group [30% (95% CI 24.5-39) vs. 20% (95% CI 14-25), P = 0.04]. A reduction in both visceral and subcutaneous fat was greater in the experimental group than in the control group (P = 0.007 and P = 0.02, respectively). Plasma adiponectin increased (P = 0.02) and leptin decreased (P = 0.02) in the experimental group, with no change in the control group. Vitamin C, superoxide dismutase and reduced glutathione increased in the experimental group (P = 0.002, P < 0.001 and P = 0.02, respectively). Differences between groups were greater after the addition of exercise training. Changes in insulin sensitivity and enzymatic oxidative stress markers correlated with changes in visceral fat. CONCLUSIONS A calorie-restricted vegetarian diet had greater capacity to improve insulin sensitivity compared with a conventional diabetic diet over 24 weeks. The greater loss of visceral fat and improvements in plasma concentrations of adipokines and oxidative stress markers with this diet may be responsible for the reduction of insulin resistance. The addition of exercise training further augmented the improved outcomes with the vegetarian diet.