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White rice, brown rice and the risk of type 2 diabetes: a systematic review and meta-analysis.
Yu, J, Balaji, B, Tinajero, M, Jarvis, S, Khan, T, Vasudevan, S, Ranawana, V, Poobalan, A, Bhupathiraju, S, Sun, Q, et al
BMJ open. 2022;12(9):e065426
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The prevalence of type 2 diabetes (T2D) has continued to increase worldwide, especially in low-income and middle-income countries. Since rice is a staple food in many cultures and is predominant in most Asian diets, it is hypothesised that improving diet quality by replacing white rice with brown rice could play an important role in the prevention of T2D. The aim of this study was to assess the relationship between rice intake and the risk of T2D. This study is a systematic review and meta-analysis of nineteen studies – 8 cohort studies and 11 randomised controlled trials. Results from the meta-analyses of the cohort studies show a positive association between intake of white rice and risk of T2D. The associations were stronger in women compared with men. Additionally, brown rice was inversely associated with risk of T2D however, the results are based on limited data. Furthermore, the randomised controlled trials showed that the between-group difference in high-density lipoprotein cholesterol was statistically significant in favour of the brown rice group. Authors conclude that replacing white rice with brown rice or other whole grains has the potential to be a low-cost and feasible lifestyle strategy to improve diet quality and help reduce T2D risk.
Abstract
OBJECTIVE Intake of white rice has been associated with elevated risk for type 2 diabetes (T2D), while studies on brown rice are conflicting. To inform dietary guidance, we synthesised the evidence on white rice and brown rice with T2D risk. DESIGN Systematic review and meta-analysis. DATA SOURCES PubMed, EMBASE and Cochrane databases were searched through November 2021. ELIGIBILITY CRITERIA Prospective cohort studies of white and brown rice intake on T2D risk (≥1 year), and randomised controlled trials (RCTs) comparing brown rice with white rice on cardiometabolic risk factors (≥2 weeks). DATA EXTRACTION AND SYNTHESIS Data were extracted by the primary reviewer and two additional reviewers. Meta-analyses were conducted using random-effects models and reporting followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Risk of bias was assessed using the Newcastle Ottawa Scale for prospective cohort studies and the Cochrane Risk of Bias Tool for RCTs. Strength of the meta-evidence was assessed using NutriGrade. RESULTS Nineteen articles were included: 8 cohort studies providing 18 estimates (white rice: 15 estimates, 25 956 cases, n=5 77 426; brown rice: 3 estimates, 10 507 cases, n=1 97 228) and 11 RCTs (n=1034). In cohort studies, white rice was associated with higher risk of T2D (pooled RR, 1.16; 95% CI: 1.02 to 1.32) comparing extreme categories. At intakes above ~300 g/day, a dose-response was observed (each 158 g/day serving was associated with 13% (11%-15%) higher risk of T2D). Intake of brown rice was associated with lower risk of T2D (pooled RR, 0.89; 95% CI: 0.81 to 0.97) comparing extreme categories. Each 50 g/day serving of brown rice was associated with 13% (6%-20%) lower risk of T2D. Cohort studies were considered to be of good or fair quality. RCTs showed an increase in high-density lipoprotein-cholesterol (0.06 mmol/L; 0.00 to 0.11 mmol/L) in the brown compared with white rice group. No other significant differences in risk factors were observed. The majority of RCTs were found to have some concern for risk of bias. Overall strength of the meta-evidence was moderate for cohort studies and moderate and low for RCTs. CONCLUSION Intake of white rice was associated with higher risk of T2D, while intake of brown rice was associated with lower risk. Findings from substitution trials on cardiometabolic risk factors were inconsistent. PROSPERO REGISTRATION NUMBER CRD42020158466.
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Pasta meal intake in relation to risks of type 2 diabetes and atherosclerotic cardiovascular disease in postmenopausal women : findings from the Women's Health Initiative.
Huang, M, Lo, K, Li, J, Allison, M, Wu, WC, Liu, S
BMJ nutrition, prevention & health. 2021;4(1):195-205
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Among major sources of dietary carbohydrates, pasta has long been a staple food in diverse human cultures around the world. Interest in the health effects of pasta on the human body has steadily increased since the 1980s. The aim of this study was to evaluate the association between pasta meal intake and long-term risk of developing diabetes or atherosclerotic cardiovascular disease (ASCVD, including coronary heart disease (CHD) and stroke) in postmenopausal women. This study is a large prospective cohort study of 84, 555 post-menopausal women aged between 50 and 79 years. Results show a significant association between higher intakes of pasta meal and long-term risk of developing stroke and ASCVD, and a suggestive association between higher intakes of pasta meal and long-term risk of developing CHD, while no significant relation was observed between pasta meal intake and risk of developing diabetes. Authors conclude that substituting pasta meal for other commonly consumed starchy foods such as fried potato or white bread may possibly represent a feasible and easy-to-implement method of dietary modification to improve cardiometabolic outcomes.
Abstract
OBJECTIVE To evaluate the association between pasta meal intake and long-term risk of developing diabetes or atherosclerotic cardiovascular disease (ASCVD, including coronary heart disease (CHD) and stroke) in postmenopausal women. DESIGN Prospective cohort study. SETTING Women's Health Initiative (WHI) in the USA. PARTICIPANTS 84 555 postmenopausal women aged 50-79 in 1994, who were free of diabetes, ASCVD and cancer at baseline who were not in the dietary modification trial of the WHI, completed a validated food frequency questionnaire, and were evaluated for incident diabetes and ASCVD outcomes during the follow-up until 2010. MAIN OUTCOME MEASURE Diabetes and ASCVD. RESULTS Cox proportional hazards models were used to estimate the association (HR) between quartiles of pasta meal consumption (residuals after adjusting for total energy) and the risk of incidence diabetes, CHD, stroke or ASCVD, accounting for potential confounding factors, with testing for linear trend. We then statistically evaluated the effect of substituting white bread or fried potato for pasta meal on disease risk. When comparing the highest to the lowest quartiles of residual pasta meal intake, we observed significantly reduced risk of ASCVD (HR=0.89, 95% CI 0.83 to 0.96, p trend=0.002), stroke (HR=0.84, 95% CI 0.75 to 0.93, p trend=0.001), CHD (HR=0.91, 95% CI 0.83 to 1.00, p trend=0.058) and no significant alteration in diabetes risk (HR=1.02, 95% CI 0.96 to 1.07, p trend=0.328). Replacing white bread or fried potato with pasta meal was statistically associated with decreased risk of stroke and ASCVD. CONCLUSIONS Pasta meal intake did not have adverse effects on long-term diabetes risk and may be associated with significant reduced risk of stroke and ASCVD. The potential benefit of substituting pasta meal for other commonly consumed starchy foods on cardiometabolic outcomes warrants further investigation in additional high-quality and large prospective studies of diverse populations.
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Influence of GDM Diagnosis and Treatment on Weight Gain, Dietary Intake and Physical Activity in Pregnant Women with Obesity: Secondary Analysis of the UPBEAT Study.
Atakora, L, Poston, L, Hayes, L, Flynn, AC, White, SL
Nutrients. 2020;12(2)
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Obesity during pregnancy increases the risk of development of gestational diabetes (GDM), which can develop into type 2 diabetes postnatally. The UK has guidelines on diet and exercise in place following a positive result for GDM, however it is unclear how results from a GDM test may affect behaviours and weight gain in women with obesity during pregnancy. This secondary analysis of a randomised control trial; the UK pregnancies better eating and activity trial (UPBEAT), aimed to assess how a negative or positive diagnosis of GDM affects the diet, physical activity levels and weight gain of pregnant women with obesity. 1031 pregnant women who were positively and negatively diagnosed with GDM were randomly split into two groups for eight weeks. The intervention group received additional appointments with a health coach as well as regular antenatal appointments. The results showed that women who received a negative result to GDM gained significantly more weight than those with a positive diagnosis regardless of which treatment group they were allocated. GDM status also affected dietary intake, however no changes in amount of physical activity were seen with either diagnosis. It was concluded that pregnant women with obesity gained more weight if they received a negative result to GDM and a positive GDM result is associated with lower weight gain and dietary changes. This highlights the need for additional diet and weight gain strategies for pregnant women with obesity who return a negative GDM result. Clinicians could use this study to stress the importance of healthy eating and exercise to pregnant women with obesity, even if a negative GDM test is received.
Abstract
Obesity during pregnancy is associated with the development of gestational diabetes (GDM). This study aimed to assess if the result of an oral glucose tolerance test (OGTT) for GDM influences health (diet and physical activity) behaviours of pregnant women with obesity. In total, 1031 women who participated in the UK Pregnancies Better Eating and Activity Trial (UPBEAT) of a lifestyle intervention from early pregnancy were included. Changes in weight gain, dietary intake and physical activity following an OGTT undertaken between 27+0 and 28+6 weeks' and 34 and 36 weeks' gestation were examined using linear regression with appropriate adjustment for confounders. Obese women without GDM (IADPSG criteria) gained 1.9 kg (95% CI -2.2, -1.5, p < 0.001) more weight than women with GDM. Women with GDM demonstrated greater reductions in energy (-142kcal, 95%CI -242.2, -41.9, p = 0.006), carbohydrate intake (-1.5%E 95%CI -2.8, -0.3, p = 0.016) and glycaemic load (-15.2, 95%CI -23.6, -6.7, p < 0.001) and a greater increase in protein intake (2%E, 95%CI 1.3, 2.7, p < 0.001), compared to women without GDM. Trial intervention allocation did not influence any associations observed. The findings emphasise the need for strategies to optimise the health behaviours of pregnant women with obesity, following a negative OGTT for GDM.
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Sociodemographic and lifestyle-related risk factors for identifying vulnerable groups for type 2 diabetes: a narrative review with emphasis on data from Europe.
Kyrou, I, Tsigos, C, Mavrogianni, C, Cardon, G, Van Stappen, V, Latomme, J, Kivelä, J, Wikström, K, Tsochev, K, Nanasi, A, et al
BMC endocrine disorders. 2020;20(Suppl 1):134
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Type 2 diabetes mellitus (T2DM) results from progressive loss of insulin secretion, which is typically combined with various degrees of insulin resistance. The aim of this study is to provide a comprehensive overview of key sociodemographic and lifestyle-related risk factors for identifying vulnerable groups for T2DM with emphasis on data from Europe. This study is a narrative review which includes 101 publications. Literature shows that prevention of T2DM should be a collaborative effort which mobilizes multiple partners/ stakeholders at a national and international (e.g. European) level. In addition, a holistic approach is becoming increasingly essential in order to put into effect multidimensional public health programs and integrated interventions for effective T2DM prevention which will take into account both traditional and socioeconomic/socioecological factors. Authors conclude that a multidimensional approach for the prevention of T2DM may have a broader impact against the current diabesity epidemic within and across countries in Europe.
Abstract
BACKGROUND Type 2 diabetes mellitus (T2DM) comprises the vast majority of all diabetes cases in adults, with alarmingly increasing prevalence over the past few decades worldwide. A particularly heavy healthcare burden of diabetes is noted in Europe, where 8.8% of the population aged 20-79 years is estimated to have diabetes according to the International Diabetes Federation. Multiple risk factors are implicated in the pathogenesis of T2DM with complex underlying interplay and intricate gene-environment interactions. Thus, intense research has been focused on studying the role of T2DM risk factors and on identifying vulnerable groups for T2DM in the general population which can then be targeted for prevention interventions. METHODS For this narrative review, we conducted a comprehensive search of the existing literature on T2DM risk factors, focusing on studies in adult cohorts from European countries which were published in English after January 2000. RESULTS Multiple lifestyle-related and sociodemographic factors were identified as related to high T2DM risk, including age, ethnicity, family history, low socioeconomic status, obesity, metabolic syndrome and each of its components, as well as certain unhealthy lifestyle behaviors. As Europe has an increasingly aging population, multiple migrant and ethnic minority groups and significant socioeconomic diversity both within and across different countries, this review focuses not only on modifiable T2DM risk factors, but also on the impact of pertinent demographic and socioeconomic factors. CONCLUSION In addition to other T2DM risk factors, low socioeconomic status can significantly increase the risk for prediabetes and T2DM, but is often overlooked. In multinational and multicultural regions such as Europe, a holistic approach, which will take into account both traditional and socioeconomic/socioecological factors, is becoming increasingly crucial in order to implement multidimensional public health programs and integrated community-based interventions for effective T2DM prevention.
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Acute Effects of Three Cooked Non-Cereal Starchy Foods on Postprandial Glycemic Responses and in Vitro Carbohydrate Digestion in Comparison with Whole Grains: A Randomized Trial.
Zhu, R, Fan, Z, Han, Y, Li, S, Li, G, Wang, L, Ye, T, Zhao, W
Nutrients. 2019;11(3)
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The consumption of refined rice is associated with increased risk of type 2 diabetes (T2D) and is prone to cause hyperglycaemia after meals, even in healthy adults. Whereas whole grains and pulses were reported to reduce the risk of T2D and relatively mild postprandial (after a meal) glycaemic responses. The main aim of this study was to investigate the possibility of integrating the three non-cereal starchy food i.e. the lotus seed, adlay, and dried lily bulb into a glycaemic management diet, and compare their glycaemic characteristics with millet, waxy black rice and adzuki bean. The study is single-blind randomised crossover design study which recruited ten young women aged between 18 and 26 years. Sequentially numbered containers were used to implement the random allocation sequence. Results indicate that out of the 3 starchy foods tested in the study, only the lotus seed meals could be regarded as low-glycaemic index food compared to the adzuki bean meals. Furthermore, the cooked dried lily bulb, adlay, black rice and millet resulted as high-glycaemic index, regardless of the cooking duration. Authors conclude that careful choice of whole grain materials, minimized pre-soaking, and moderate cooking may be critical factors for successful glycaemic management for people of impaired glucose management.
Abstract
Plant origin, processing, and domestic preparation may affect the postprandial glycemic response (PGR) of starchy foods. The objective of this study was to examine the possibility of integrating domestically cooked non-cereal starchy foods commonly consumed in Northeast Asia into glycemic management diet, and compare their glycemic characteristics with those of waxy and non-waxy whole grains and starchy beans. In a randomized crossover trial, ten healthy subjects consumed dried lily bulb (LB), lotus seed (LS), adlay (AD), waxy black rice (BR), millet (MI), and adzuki bean (AB), pre-soaked and each cooked for two time durations. Acute PGR tests and in vitro carbohydrate digestion were carried out for each test food. Both the LS and AB meals achieved low glycemic index (GI 21⁻51), while the other starchy foods failed to show significant difference with rice (GI 83⁻109). The hydrolysis indexes of LS and AB were 37.7%⁻61.1%, significantly lower than other test foods. The in vitro tests indicated that pre-soaking resulted in high rapidly digestible starch (RDS) and low resistant starch (RS). Careful choice of whole grain materials, minimized pre-soaking, and moderate cooking may be critical factors for successful postprandial glycemic management for diabetic and pre-diabetic.
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Vegetarian diets and risk of hospitalisation or death with diabetes in British adults: results from the EPIC-Oxford study.
Papier, K, Appleby, PN, Fensom, GK, Knuppel, A, Perez-Cornago, A, Schmidt, JA, Tong, TYN, Key, TJ
Nutrition & diabetes. 2019;9(1):7
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The identification of modifiable risk factors is vital for the reduction of the growing diabetes epidemic. Diet is one such lifestyle factor that might play a key role in the prevention of diabetes. The aim of the study was to investigate the association between vegetarianism and diabetes in a large, population-based study of British adults. The study is a prospective study of vegetarianism and diabetes risk in a cohort of 45,314 participants. Results indicate that the low meat eaters, fish eaters and vegetarians had a lower risk of developing diabetes compared to regular meat eaters. Authors conclude that people consuming a low or meat-free diet had a lower risk of hospitalisation or death with diabetes.
Abstract
BACKGROUND The global prevalence of diabetes is high and rapidly increasing. Some previous studies have found that vegetarians might have a lower risk of diabetes than non-vegetarians. OBJECTIVE We examined the association between vegetarianism and risk of hospitalisation or death with diabetes in a large, prospective cohort study of British adults. METHODS The analysed cohort included participants from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Oxford study who were diabetes free at recruitment (1993-2001), with available dietary intake data at baseline, and linked hospital admissions and death data for diabetes over follow-up (n = 45,314). Participants were categorised as regular meat eaters (≥50 g per day: n = 15,181); low meat eaters (<50 g of meat per day: n = 7615); fish eaters (ate no meat but consumed fish: n = 7092); and vegetarians (ate no meat or fish, including vegans: n = 15,426). We used multivariable Cox proportional hazards models to assess associations between diet group and risk of diabetes. RESULTS Over a mean of 17.6 years of follow-up, 1224 incident cases of diabetes were recorded. Compared with regular meat eaters, the low meat eaters, fish eaters, and vegetarians were less likely to develop diabetes (hazard ratio (HR) = 0.63, 95% confidence interval (CI) 0.54-0.75; HR = 0.47, 95% CI 0.38-0.59; and HR = 0.63, 95% CI 0.54-0.74, respectively). These associations were substantially attenuated after adjusting for body mass index (BMI) (low meat eaters: HR = 0.78, 95% CI 0.66-0.92; fish eaters: HR = 0.64, 95% CI 0.51-0.80; and vegetarians: HR = 0.89, 95% CI 0.76-1.05). CONCLUSIONS Low meat and non-meat eaters had a lower risk of diabetes, in part because of a lower BMI.
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Dietary Glycemic Index and Load and the Risk of Type 2 Diabetes: Assessment of Causal Relations.
Livesey, G, Taylor, R, Livesey, HF, Buyken, AE, Jenkins, DJA, Augustin, LSA, Sievenpiper, JL, Barclay, AW, Liu, S, Wolever, TMS, et al
Nutrients. 2019;11(6)
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It is generally accepted that certain diet and lifestyle choices contribute to a person’s risk of developing type 2 diabetes (T2D). In this meta-analysis, researchers set out to review previous studies and assess whether there is any evidence that the amount and type of carbohydrate (measured by Glycaemic Index (GI) and Glycaemic Load (GL)) in a person’s diet has a direct influence on their risk of developing T2D. The authors concluded with a high level of confidence that eating high GI and GL foods can lead to a higher risk of developing T2D. They suggest that nutrition advice that favours low GI and GL foods could produce significant cost savings for public healthcare.
Abstract
While dietary factors are important modifiable risk factors for type 2 diabetes (T2D), the causal role of carbohydrate quality in nutrition remains controversial. Dietary glycemic index (GI) and glycemic load (GL) have been examined in relation to the risk of T2D in multiple prospective cohort studies. Previous meta-analyses indicate significant relations but consideration of causality has been minimal. Here, the results of our recent meta-analyses of prospective cohort studies of 4 to 26-y follow-up are interpreted in the context of the nine Bradford-Hill criteria for causality, that is: (1) Strength of Association, (2) Consistency, (3) Specificity, (4) Temporality, (5) Biological Gradient, (6) Plausibility, (7) Experimental evidence, (8) Analogy, and (9) Coherence. These criteria necessitated referral to a body of literature wider than prospective cohort studies alone, especially in criteria 6 to 9. In this analysis, all nine of the Hill's criteria were met for GI and GL indicating that we can be confident of a role for GI and GL as causal factors contributing to incident T2D. In addition, neither dietary fiber nor cereal fiber nor wholegrain were found to be reliable or effective surrogate measures of GI or GL. Finally, our cost-benefit analysis suggests food and nutrition advice favors lower GI or GL and would produce significant potential cost savings in national healthcare budgets. The high confidence in causal associations for incident T2D is sufficient to consider inclusion of GI and GL in food and nutrient-based recommendations.
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Dietary Fiber Intake (Supplemental or Dietary Pattern Rich in Fiber) and Diabetic Kidney Disease: A Systematic Review of Clinical Trials.
Carvalho, CM, Gross, LA, de Azevedo, MJ, Viana, LV
Nutrients. 2019;11(2)
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Most of the financial burden of diabetes mellitus is related to management of its complications, and chronic kidney disease is the most expensive and debilitating. The aim of the study was to evaluate the effect of dietary fibre (supplemental or dietary pattern rich in fibre) on diabetic kidney disease. The study is a systemic review that included seven interventional clinical trials that comprised 161 patients with diabetes with an age range of 20 to 74 years. The mean fibre intake in the intervention was 24 g/day and 16 g/day in the control group. Results indicate that only the vegetarian dietary pattern was associated with beneficial kidney outcomes in both type 1 and type 2 diabetes mellitus. There were no other dietary patterns that had favourable effects on kidney outcomes. Authors conclude that a vegetarian dietary pattern may have a beneficial effects on renal outcomes.
Abstract
Fiber intake is associated with better glycemic control being an important nonpharmacologicaltreatment for diabetes (DM). We hypothesize that a dietary fiber intake can bringbenefits to diabetic kidney disease (DKD), improving renal outcomes. This systematic review aimedto evaluate the effect of dietary fiber (supplemental or dietary pattern rich in fiber) on DKD. Wesearched six databases to identify clinical trials that reported fiber intake and renal outcomes(albuminuria, proteinuria, estimated glomerular filtration rate (eGFR) dialysis) in patients with DM.From 1814 studies, 48 papers were fully evaluated. In the end, seven trials (161 patients, aged 58.3years, 49% females) were included. The studies were organized into three categories (vegetarian,Dietary Approaches to Stop Hypertension (DASH) diet, and fiber supplement), two evaluatedsupplements and five dietary patterns. Vegetarian diet reduced albuminuria in three trials, two inpatients with type 1 DM and one in patients with type 2 DM; and one study demonstrated a change inthe eGFR in type 1 DM. The individual quality of the studies was low/uncertain. A vegetarian dietarypattern may have a beneficial effect on these renal outcomes. However, the individual effect of theintake of fiber on DKD not was possible to be evaluated.
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The effect of a short-term low-carbohydrate, high-fat diet with or without postmeal walks on glycemic control and inflammation in type 2 diabetes: a randomized trial.
Myette-Côté, É, Durrer, C, Neudorf, H, Bammert, TD, Botezelli, JD, Johnson, JD, DeSouza, CA, Little, JP
American journal of physiology. Regulatory, integrative and comparative physiology. 2018;315(6):R1210-R1219
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Inflammation is associated with the pathogenesis of insulin resistance, type 2 diabetes (T2D), and related complications. Lifestyle therapy is a frontline treatment for improving glucose control in people with T2D. The main aim of this study was to determine whether reducing hyperglycaemia with a low-carbohydrate high-fat (LC) diet could lower markers of innate immune cell activation and systemic inflammation in people with T2D. A secondary aim was to examine if the combination of an LCHF diet with strategically timed postmeal walking was superior to an LCHF diet alone. The study is a randomised cross over study which enrolled Individuals with physician-diagnosed T2D to complete three short-term controlled-intervention periods. Sixteen participants were enrolled (men = 8 and women = 8) who were aged between 48 and 72 years. Results indicate that while LC and LC together with exercise (LC+Ex) led to superior improvements in glucose control and fasting proinsulin (the pro-hormone precursor to insulin) levels as compared with low-fat low glycaemic index diet (GL), all three diets (GL, LC and LC+Ex), appeared to lower a particular marker of cellular inflammation over the short-term. Authors conclude that an LCHF diet with or without daily postmeal walks improved four-day glycaemic control and fasting proinsulin levels compared with a GL diet.
Abstract
Lowering carbohydrate consumption effectively lowers glucose, but impacts on inflammation are unclear. The objectives of this study were to: 1) determine whether reducing hyperglycemia by following a low-carbohydrate, high-fat (LC) diet could lower markers of innate immune cell activation in type 2 diabetes (T2D) and 2) examine if the combination of an LC diet with strategically timed postmeal walking was superior to an LC diet alone. Participants with T2D ( n = 11) completed a randomized crossover study involving three 4-day diet interventions: 1) low-fat low-glycemic index (GL), 2) and 3) LC with 15-min postmeal walks (LC+Ex). Four-day mean glucose was significantly lower in the LC+Ex group as compared with LC (-5%, P < 0.05), whereas both LC+Ex (-16%, P < 0.001) and LC (-12%, P < 0.001) conditions were lower than GL. A significant main effect of time was observed for peripheral blood mononuclear cells phosphorylated c-Jun N-terminal kinase ( P < 0.001), with decreases in all three conditions (GL: -32%, LC: -45%, and LC+Ex: -44%). A significant condition by time interaction was observed for monocyte microparticles ( P = 0.040) with a significant decrease in GL (-76%, P = 0.035) and a tendency for a reduction in LC (-70%, P = 0.064), whereas there was no significant change in LC+Ex (0.5%, P = 0.990). Both LC (-27%, P = 0.001) and LC+Ex (-35%, P = 0.005) also led to significant reductions in circulating proinsulin. An LC diet improved 4-day glycemic control and fasting proinsulin levels when compared with GL, with added glucose-lowering benefits when LC was combined with postmeal walking.
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Circulating bile acids in healthy adults respond differently to a dietary pattern characterized by whole grains, legumes and fruits and vegetables compared to a diet high in refined grains and added sugars: A randomized, controlled, crossover feeding study.
Ginos, BNR, Navarro, SL, Schwarz, Y, Gu, H, Wang, D, Randolph, TW, Shojaie, A, Hullar, MAJ, Lampe, PD, Kratz, M, et al
Metabolism: clinical and experimental. 2018;83:197-204
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Bile acids are produced in the liver and are important for the absorption of fat and fat-soluble vitamins. About 95% of bile acids are reabsorbed. Circulating plasma bile acids can affect glucose metabolism and inflammation, and are thought to play a role in the development of metabolic syndrome. The aim of this study was to evaluate how plasma bile acid levels are influenced by a diet rich in whole grains, legumes, fruit and vegetables (low glycaemic load, GL) compared to a diet high in refined grains and sugar (high GL). The study evaluated data from a previous double-blind randomised, cross over feeding trial. 80 healthy adults had the low or high GL diet for four weeks, and after a four-week washout period, received the other diet for four weeks. Three specific plasma bile acids, which are thought to have a positive impact on glucose metabolism, were higher in the low GL group compared to the high GL group. Some individual plasma bile acids were positively associated with HOMA-IR (a measure of glucose metabolism/insulin resistance). There was no significant association between bile acid concentrations and C-reactive protein (a marker of inflammation). The authors conclude that the increase in certain bile acids on the low GL diet may be beneficial and that this effect may be to some extent mediated by the impact of the higher fibre content of the low GL diet on the gut microbial metabolism, which affects plasma bile acid levels.
Abstract
OBJECTIVE The effects of diets high in refined grains on biliary and colonic bile acids have been investigated extensively. However, the effects of diets high in whole versus refined grains on circulating bile acids, which can influence glucose homeostasis and inflammation through activation of farnesoid X receptor (FXR) and G protein-coupled bile acid receptor 1 (TGR5), have not been studied. MATERIALS AND METHODS We conducted a secondary analysis from a randomized controlled crossover feeding trial (NCT00622661) in 80 healthy adults (40 women/40 men, age 18-45 years) from the greater Seattle Area, half of which were normal weight (BMI 18.5-25.0 kg/m2) and half overweight to obese (BMI 28.0-39.9 kg/m2). Participants consumed two four-week controlled diets in randomized order: 1) a whole grain diet (WG diet), designed to be low in glycemic load (GL), high in whole grains, legumes, and fruits and vegetables, and 2) a refined grain diet (RG diet), designed to be high GL, high in refined grains and added sugars, separated by a four-week washout period. Quantitative targeted analysis of 55 bile acid species in fasting plasma was performed using liquid chromatography tandem mass spectrometry. Concentrations of glucose, insulin, and CRP were measured in fasting serum. Linear mixed models were used to test the effects of diet on bile acid concentrations, and determine the association between plasma bile acid concentrations and HOMA-IR and CRP. Benjamini-Hochberg false discovery rate (FDR) < 0.05 was used to control for multiple testing. RESULTS A total of 29 plasma bile acids were reliably detected and retained for analysis. Taurolithocholic acid (TLCA), taurocholic acid (TCA) and glycocholic acid (GCA) were statistically significantly higher after the WG compared to the RG diet (FDR < 0.05). There were no significant differences by BMI or sex. When evaluating the association of bile acids and HOMA-IR, GCA, taurochenodeoxycholic acid, ursodeoxycholic acid (UDCA), 5β‑cholanic acid‑3β,12α‑diol, 5‑cholanic acid‑3β‑ol, and glycodeoxycholic acid (GDCA) were statistically significantly positively associated with HOMA-IR individually, and as a group, total, 12α‑hydroxylated, primary and secondary bile acids were also significant (FDR < 0.05). When stratifying by BMI, chenodeoxycholic acid (CDCA), cholic acid (CA), UDCA, 5β-cholanic acid-3β, deoxycholic acid, and total, 12α-hydroxylated, primary and secondary bile acid groups were significantly positively associated with HOMA-IR among overweight to obese individuals (FDR < 0.05). When stratifying by sex, GCA, CDCA, TCA, CA, UDCA, GDCA, glycolithocholic acid (GLCA), total, primary, 12α‑hydroxylated, and glycine-conjugated bile acids were significantly associated with HOMA-IR among women, and CDCA, GDCA, and GLCA were significantly associated among men (FDR < 0.05). There were no significant associations between bile acids and CRP. CONCLUSIONS Diets with comparable macronutrient and energy composition, but differing in carbohydrate source, affected fasting plasma bile acids differently. Specifically, a diet characterized by whole grains, legumes, and fruits and vegetables compared to a diet high in refined grains and added sugars led to modest increases in concentrations of TLCA, TCA and GCA, ligands for FXR and TGR5, which may have beneficial effects on glucose homeostasis.