-
1.
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
-
-
-
Free full text
Plain language summary
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.
-
2.
Longitudinal association of dietary carbohydrate quality with visceral fat deposition and other adiposity indicators.
Zamanillo-Campos, R, Chaplin, A, Romaguera, D, Abete, I, Salas-Salvadó, J, Martín, V, Estruch, R, Vidal, J, Ruiz-Canela, M, Babio, N, et al
Clinical nutrition (Edinburgh, Scotland). 2022;41(10):2264-2274
-
-
-
-
Free full text
Plain language summary
Abdominal obesity, measured by waist circumference, a proxy of visceral fat, is increasing at an even greater rate than overall obesity alone. Diet plays a key role in body fat accumulation; however, recent evidence also indicates that, beyond quantity, the quality of certain nutrients may have an independent effect. The aim of this study was to determine the dynamic association between changes in overall dietary carbohydrate quality and changes in objectively measured visceral and overall adiposity distribution This study is a prospective cohort study based on data collected during the first year of the PREDIMED-Plus (PREvencion con DIeta MEDiterranea Plus) randomised controlled trial. In the PREDIMED-Plus trial, a total of 6874 people were randomly allocated in a 1:1 ratio to either the intervention or control group. Results show that a carbohydrate quality index increase was associated with a decrease in regional and overall adiposity. The observed associations were mostly driven by fibre and the wholegrains/total grains ratio. Authors conclude that the promotion of fibre-rich foods, including fruits, vegetables, legumes and nuts, and the substitution of refined grains by wholegrains, may be important dietary recommendations to adopt in clinical practice to promote a healthier body composition.
Expert Review
Conflicts of interest:
None
Take Home Message:
This prospective cohort of older adults with overweight/obesity and MetS, found that improvements in dietary carbohydrate quality over one year was associated with positive changes in visceral and overall fat deposition, largely due to dietary fibre and the wholegrain/total grain ratio.
Evidence Category:
-
A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)
-
B: Systematic reviews including RCTs of limited number
-
X
C: Non-randomized trials, observational studies, narrative reviews
-
D: Case-reports, evidence-based clinical findings
-
E: Opinion piece, other
Summary Review:
Background
Obesity prevalence is increasing worldwide and is associated with a range of metabolic and cardiovascular diseases. Excess visceral fat appears with increasing age but also with unhealthy dietary patterns and lifestyle behaviours, and it contributes to chronic diseases, particularly type 2 diabetes (T2D), insulin resistance, metabolic syndrome (MetS), and cardiovascular diseases (CVD).
Aim
This study determined the association between changes in overall dietary carbohydrate quality and changes in objectively-measured visceral and overall adiposity distribution. Three repeated measurements of diet and adiposity were conducted throughout a 1-year follow-up, using a dual-energy X-ray absorptiometry (DXA) scans for body composition assessment.
The study compared an intensive weight-loss (intervention group) using an energy-reduced Mediterranean Diet (MedDiet), with physical activity (PA), and behavioural support on the prevention of CVD events, compared to usual care and dietary counselling only.
This prospective cohort study analysed a subgroup of 1476 participants (men aged 55-75 years and women aged 60-75 years) enrolled in the PREDIMED-Plus randomized controlled trial. Participants were overweight or obese (BMI>27 kg/m2 and <40 kg/m2) with no previous cardiovascular events and at least three characteristics of metabolic syndrome (MetS): hypertension, hyper-triglyceridemia, lower high-density lipoprotein (HDL) cholesterol, hyperglycemia, or central obesity.
Dietary intake was measured at baseline, 6- and 12-months using a Spanish version of the validated 143-item semi-quantitative food-frequency questionnaire, via face-to-face interviews by trained dietitian-nutritionists. Carbohydrate quality index (CQI) was calculated using four criteria: total dietary fibre, glycemic index, wholegrain/total grain carbohydrate ratio, and solid/total carbohydrate ratio.
Results
Improvements in body composition and lifestyle factors were observed compared to baseline data (both study arms combined) (p < 0.05 for all). A higher Carbohydrate Quality Index CQI (p = 0.024) was observed at both the 6 and 12 month follow-up.
A 3-point increment in CQI over 12-month follow-up was associated with a decrease in visceral fat (β 0.067 z-score, 95% CI -0.088 to -0.046, p<0.001), android-to-gynoid fat ratio* (β -0.038, 95% CI -0.059 to -0.017, p<0.001) (*calculated by dividing the fat mass (g) from the specific regions), and total fat (β -0.064, 95% CI -0.080 to -0.047, p<0.001).
Fibre intake and the ratio of whole grain/total grain showed the strongest inverse associations with all adiposity indicators. Statistically significant differences were observed over time in all CQI components. The most relevant changes were the increase in consumption of carbohydrates from whole-grains and a decrease in refined grains, and an increase in dietary fibre intake. After evaluating each CQI component separately, the study found that fibre intake and the ratio of whole grain/total grain presented the strongest and statistically significant negative associations with all adiposity indicators (all p-values <0.01).
Limitations
Due to the observational nature of the study, causality cannot be inferred. The study population is based on older people with overweight/obesity and MetS from a Mediterranean area, which can limit the generalisability of findings to the general population.
The use of self-reported dietary data is subject to measurement error, where self-reports may be affected by a tendency to respond in a manner to avoid criticism or judgement and to seek social approval.
Clinical practice applications:
Evidence has shown that the quality of dietary carbohydrates, rather than the quantity, may have a greater impact on health and overall mortality.
While visceral fat constitutes only a small proportion of total fat, the available evidence indicates that it plays an important role in certain chronic diseases, such as T2D, MetS, CVD and cancer.
Findings from this study suggest a better CQI via the manipulation of carbohydrate quality may be associated with a decrease in visceral fat, which are independent of changes in total body fat.
Considerations for future research:
Future strategies to decrease visceral fat are warranted.
Robust reference ranges are needed for the interpretation of visceral fat in clinical practice and research settings.
Abstract
BACKGROUND & AIMS The quality of dietary carbohydrates rather than total carbohydrate intake may determine the accumulation of visceral fat; however, to date, few studies have examined the impact of diet on adiposity using specific imaging techniques. Thus, the aim of this prospective study was to investigate the association between concurrent changes in carbohydrate quality index (CQI) and objectively-quantified adiposity distribution over a year. METHODS We analyzed a cohort of 1476 participants aged 55-75 years with overweight/obesity and metabolic syndrome (MetS) from the PREDIMED-Plus randomized controlled trial. Dietary intake information was obtained at baseline, 6- and 12-months from a validated 143-item semi-quantitative food-frequency questionnaire, and CQI (range: 4 to 20) was calculated based on four dietary criteria: total dietary fibre, glycemic index, wholegrain/total grain carbohydrate ratio, and solid/total carbohydrate ratio. Overall and regional adiposity (total body fat, visceral fat and android-to-gynoid fat ratio) was quantified using dual-energy X-ray absorptiometry at all three time points. Multiple adjusted linear mixed-effects models were used to assess associations between concurrent changes in repeatedly measured CQI and adiposity over time. RESULTS After controlling for potential confounding factors, a 3-point increment in CQI over 12-month follow-up was associated with a decrease in visceral fat (β -0.067 z-score, 95% CI -0.088; -0.046, p < 0.001), android-to-gynoid fat ratio (-0.038, -0.059; -0.017, p < 0.001), and total fat (-0.064, -0.080; -0.047, p < 0.001). Fibre intake and the ratio of wholegrain/total grain showed the strongest inverse associations with all adiposity indicators. CONCLUSIONS In this prospective cohort of older adults with overweight/obesity and MetS, we found that improvements in dietary carbohydrate quality over a year were associated with concurrent favorable changes in visceral and overall fat deposition. These associations were mostly driven by dietary fibre and the wholegrain/total grain ratio. TRIAL REGISTRATION The trial was registered at the International Standard Randomized. CONTROLLED TRIAL (ISRCTN http://www.isrctn.com/ISRCTN89898870) with number 89898870 and registration date of 24 July 2014, retrospectively registered.
-
3.
Precision Medicine Approach to Alzheimer's Disease: Successful Pilot Project.
Toups, K, Hathaway, A, Gordon, D, Chung, H, Raji, C, Boyd, A, Hill, BD, Hausman-Cohen, S, Attarha, M, Chwa, WJ, et al
Journal of Alzheimer's disease : JAD. 2022;88(4):1411-1421
-
-
-
Free full text
-
Plain language summary
Neurodegenerative diseases such as Alzheimer’s disease are without effective therapeutics. The aim of this study was to compare the effects of a precision medicine approach to historical controls in patients with mild cognitive impairment or early dementia. This study is a proof-of-concept study which recruited twenty-five patients with Alzheimer’s disease or mild cognitive impairment, aged between 50–76 years. Patients were treated for nine months with a personalised, precision medicine protocol that addressed each patient’s identified potentially contributory factors. Results show that a precision medicine approach to the cognitive decline of Alzheimer’s disease and mild cognitive impairment may be an effective strategy, especially with continued optimization over time. Authors conclude that their findings indicate that it is possible to reverse cognitive decline in mild cognitive impairment and early dementia with a personalised, precision medicine (/systems medicine) protocol. This is a small study that requires larger scale initiatives, including examining the practicalities of integrating this approach into healthcare systems.
Abstract
BACKGROUND Effective therapeutics for Alzheimer's disease are needed. However, previous clinical trials have pre-determined a single treatment modality, such as a drug candidate or therapeutic procedure, which may be unrelated to the primary drivers of the neurodegenerative process. Therefore, increasing data set size to include the potential contributors to cognitive decline for each patient, and addressing the identified potential contributors, may represent a more effective strategy. OBJECTIVE To determine whether a precision medicine approach to Alzheimer's disease and mild cognitive impairment is effective enough in a proof-of-concept trial to warrant a larger, randomized, controlled clinical trial. METHODS Twenty-five patients with dementia or mild cognitive impairment, with Montreal Cognitive Assessment (MoCA) scores of 19 or higher, were evaluated for markers of inflammation, chronic infection, dysbiosis, insulin resistance, protein glycation, vascular disease, nocturnal hypoxemia, hormone insufficiency or dysregulation, nutrient deficiency, toxin or toxicant exposure, and other biochemical parameters associated with cognitive decline. Brain magnetic resonance imaging with volumetrics was performed at baseline and study conclusion. Patients were treated for nine months with a personalized, precision medicine protocol, and cognition was assessed at t = 0, 3, 6, and 9 months. RESULTS All outcome measures revealed improvement: statistically significant improvement in MoCA scores, CNS Vital Signs Neurocognitive Index, and Alzheimer's Questionnaire Change score were documented. No serious adverse events were recorded. MRI volumetrics also improved. CONCLUSION Based on the cognitive improvements observed in this study, a larger, randomized, controlled trial of the precision medicine therapeutic approach described herein is warranted.
-
4.
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
-
-
-
Free full text
Plain language summary
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.
-
5.
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
-
-
-
Free full text
Plain language summary
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.
-
6.
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
-
-
-
Free full text
-
Plain language summary
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.
-
7.
Dietary acrylamide and cancer risk: an updated meta-analysis.
Pelucchi, C, Bosetti, C, Galeone, C, La Vecchia, C
International journal of cancer. 2015;136(12):2912-22
-
-
-
Free full text
-
Plain language summary
Acrylamide is formed in a variety of foods, and some evidence suggests it may cause cancer. The aim of this study was to update their quantitative meta-analysis on dietary acrylamide intake and cancer risk. The study is a meta-analysis based on systemic-literature focusing on the estimate of total dietary acrylamide. A total of 32 publications were reviewed. Results indicate that there is a lack of association between dietary acrylamide and most cancer sites. However, there is a potential small increase in the risk between high levels of acrylamide intake and kidney, endometrial and ovarian cancer in non-smoking women. Authors conclude that dietary acrylamide is not related to the risk of most common cancers.
Abstract
The debate on the potential carcinogenic effect of dietary acrylamide is open. In consideration of the recent findings from large prospective investigations, we conducted an updated meta-analysis on acrylamide intake and the risk of cancer at several sites. Up to July 2014, we identified 32 publications. We performed meta-analyses to calculate the summary relative risk (RR) of each cancer site for the highest versus lowest level of intake and for an increment of 10 µg/day of dietary acrylamide, through fixed-effects or random-effects models, depending on the heterogeneity test. Fourteen cancer sites could be examined. No meaningful associations were found for most cancers considered. The summary RRs for high versus low acrylamide intake were 0.87 for oral and pharyngeal, 1.14 for esophageal, 1.03 for stomach, 0.94 for colorectal, 0.93 for pancreatic, 1.10 for laryngeal, 0.88 for lung, 0.96 for breast, 1.06 for endometrial, 1.12 for ovarian, 1.00 for prostate, 0.93 for bladder and 1.13 for lymphoid malignancies. The RR was of borderline significance only for kidney cancer (RR = 1.20; 95% confidence interval, CI, 1.00-1.45). All the corresponding continuous estimates ranged between 0.95 and 1.03, and none of them was significant. Among never-smokers, borderline associations with dietary acrylamide emerged for endometrial (RR = 1.23; 95% CI, 1.00-1.51) and ovarian (RR = 1.39; 95% CI, 0.97-2.00) cancers. This systematic review and meta-analysis of epidemiological studies indicates that dietary acrylamide is not related to the risk of most common cancers. A modest association for kidney cancer, and for endometrial and ovarian cancers in never smokers only, cannot be excluded.
-
8.
Glycemic index, glycemic load, and risk of type 2 diabetes: results from 3 large US cohorts and an updated meta-analysis.
Bhupathiraju, SN, Tobias, DK, Malik, VS, Pan, A, Hruby, A, Manson, JE, Willett, WC, Hu, FB
The American journal of clinical nutrition. 2014;100(1):218-32
-
-
-
Free full text
-
Plain language summary
Carbohydrates are the principle dietary components that effect blood glucose concentrations. The association between Type 2 diabetes (T2D) and diets with different levels of sugars and carbohydrates has been controversial in the prevention of T2D. Foods can be measured for their impact on blood glucose concentration using the Glycaemic Index (GI) and the Glycaemic Load (GL). The objective of this meta-analysis was to update previous studies and evaluate the association between the GI and GL of dietary intake and the risk of T2D. The authors found a significant association between the GI and GL of food intake and T2D risk and conclude that high GI and GL foods increase the risk of T2D. However, GI is more strongly associated to T2D than GL.
Abstract
BACKGROUND Epidemiologic evidence for the relation between carbohydrate quality and risk of type 2 diabetes (T2D) has been mixed. OBJECTIVE We prospectively examined the association of dietary glycemic index (GI) and glycemic load (GL) with T2D risk. DESIGN We prospectively followed 74,248 women from the Nurses' Health Study (1984-2008), 90,411 women from the Nurses' Health Study II (1991-2009), and 40,498 men from the Health Professionals Follow-Up Study (1986-2008) who were free of diabetes, cardiovascular disease, and cancer at baseline. Diet was assessed by using a validated questionnaire and updated every 4 y. We also conducted an updated meta-analysis, including results from our 3 cohorts and other studies. RESULTS During 3,800,618 person-years of follow-up, we documented 15,027 cases of incident T2D. In pooled multivariable analyses, those in the highest quintile of energy-adjusted GI had a 33% higher risk (95% CI: 26%, 41%) of T2D than those in the lowest quintile. Participants in the highest quintile of energy-adjusted GL had a 10% higher risk (95% CI: 2%, 18%) of T2D. Participants who consumed a combination diet that was high in GI or GL and low in cereal fiber had an ~50% higher risk of T2D. In the updated meta-analysis, the summary RRs (95% CIs) comparing the highest with the lowest categories of GI and GL were 1.19 (1.14, 1.24) and 1.13 (1.08, 1.17), respectively. CONCLUSION The updated analyses from our 3 cohorts and meta-analyses provide further evidence that higher dietary GI and GL are associated with increased risk of T2D.
-
9.
Effects of dietary composition on energy expenditure during weight-loss maintenance.
Ebbeling, CB, Swain, JF, Feldman, HA, Wong, WW, Hachey, DL, Garcia-Lago, E, Ludwig, DS
JAMA. 2012;307(24):2627-34
-
-
-
Free full text
-
Plain language summary
Many diets can produce weight loss over the short term, but most people struggle to maintain this loss over the long term. One explanation is that weight loss results in biological effects, such as a decline in energy expenditure and an increase in hunger, that promote weight regain. The aim of the study was to examine the effects of three different diets on energy expenditure, hormones (including leptin, insulin, cortisol and thyroid hormones) and metabolic indicators following a 10-15% weight loss. The three diets differed widely in macronutrient composition and were: low-fat/high glycaemic load (60% energy from carbohydrates, 20%, 20% protein) LF; low glycaemic index (40%-40%-20%) LGI; and very low carbohydrate/low glycaemic load (10%-60%-30%) VLC. Participants were assigned to one of the three diets for four weeks. Participants on the VLC diet had a resting energy expenditure (REE) of 67kcal/day greater than the LF diet, as well as a total energy expenditure (TEE) of 300kcal/day greater. The physiological basis for these differences is unclear. Although the VLC diet produced the greatest improvements in most metabolic syndrome markers, it also resulted in increased cortisol and inflammation markers. These could be deleterious to health in the long term.
Abstract
CONTEXT Reduced energy expenditure following weight loss is thought to contribute to weight gain. However, the effect of dietary composition on energy expenditure during weight-loss maintenance has not been studied. OBJECTIVE To examine the effects of 3 diets differing widely in macronutrient composition and glycemic load on energy expenditure following weight loss. DESIGN, SETTING, AND PARTICIPANTS A controlled 3-way crossover design involving 21 overweight and obese young adults conducted at Children's Hospital Boston and Brigham and Women's Hospital, Boston, Massachusetts, between June 16, 2006, and June 21, 2010, with recruitment by newspaper advertisements and postings. INTERVENTION After achieving 10% to 15% weight loss while consuming a run-in diet, participants consumed an isocaloric low-fat diet (60% of energy from carbohydrate, 20% from fat, 20% from protein; high glycemic load), low-glycemic index diet (40% from carbohydrate, 40% from fat, and 20% from protein; moderate glycemic load), and very low-carbohydrate diet (10% from carbohydrate, 60% from fat, and 30% from protein; low glycemic load) in random order, each for 4 weeks. MAIN OUTCOME MEASURES Primary outcome was resting energy expenditure (REE), with secondary outcomes of total energy expenditure (TEE), hormone levels, and metabolic syndrome components. RESULTS Compared with the pre-weight-loss baseline, the decrease in REE was greatest with the low-fat diet (mean [95% CI], -205 [-265 to -144] kcal/d), intermediate with the low-glycemic index diet (-166 [-227 to -106] kcal/d), and least with the very low-carbohydrate diet (-138 [-198 to -77] kcal/d; overall P = .03; P for trend by glycemic load = .009). The decrease in TEE showed a similar pattern (mean [95% CI], -423 [-606 to -239] kcal/d; -297 [-479 to -115] kcal/d; and -97 [-281 to 86] kcal/d, respectively; overall P = .003; P for trend by glycemic load < .001). Hormone levels and metabolic syndrome components also varied during weight maintenance by diet (leptin, P < .001; 24-hour urinary cortisol, P = .005; indexes of peripheral [P = .02] and hepatic [P = .03] insulin sensitivity; high-density lipoprotein [HDL] cholesterol, P < .001; non-HDL cholesterol, P < .001; triglycerides, P < .001; plasminogen activator inhibitor 1, P for trend = .04; and C-reactive protein, P for trend = .05), but no consistent favorable pattern emerged. CONCLUSION Among overweight and obese young adults compared with pre-weight-loss energy expenditure, isocaloric feeding following 10% to 15% weight loss resulted in decreases in REE and TEE that were greatest with the low-fat diet, intermediate with the low-glycemic index diet, and least with the very low-carbohydrate diet. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00315354.
-
10.
Glycemic response and health--a systematic review and meta-analysis: relations between dietary glycemic properties and health outcomes.
Livesey, G, Taylor, R, Hulshof, T, Howlett, J
The American journal of clinical nutrition. 2008;87(1):258S-268S
-
-
-
Free full text
-
Plain language summary
All carbohydrates are ranked based on their glycaemic impact, or the response they provoke in blood glucose after consumption. It has been proposed that diets with a low impact on blood glucose are associated with a reduction in disease risk, however the specific dietary factors and degree of influence of this association remains unclear. The aim of this meta-analysis was to assess which glycaemic impact factors are important for affecting the maintenance of health and management of disease. Data from 45 relevant publications were included to investigate various health risk markers of overweight and obesity, diabetes mellitus and coronary heart disease. This review found that diets with a reduced glycaemic impact and higher unavailable carbohydrate are associated with favourable changes for all examined health risk markers. The authors conclude that these interventions led to improved glycaemic control, therefore provide a compelling diet for managing chronic disease.
Abstract
BACKGROUND Reduction of dietary glycemic response has been proposed as a means of reducing the risk of diabetes and coronary heart disease. The impact of glycemic response on markers of health remains to be elucidated. OBJECTIVE We assessed the evidence relating the glycemic impact of foods to measures relevant for health maintenance and management of disease. DESIGN This was a systematic review and synthesis of interventional evidence from literature reported on glycemic index and markers of health through the use of meta-analyses and meta-regression models. RESULTS Data from 45 relevant publications were found to January 2005. Lower glycemic index (GI) diets reduced both fasting blood glucose and glycated proteins independently of variance in available and unavailable carbohydrate intakes. Elevated unavailable carbohydrate added to improvements in both blood glucose and glycated protein control. These effects were greater in persons with poor fasting blood glucose control. No effects were seen on fasting insulin<100 pmol/L; above this, study numbers were few but consistent with prevention of hyperinsulinemia in some but not all overweight persons. Insulin sensitivity according to a variety of measurement methods was improved by lower GI, higher unavailable carbohydrate interventions in persons with type 2 diabetes, in overweight and obese persons, and in all studies combined. Fasting triacylglycerol in addition to body weight reduction related more to glycemic load than to GI. Glycemic load reduction by >17 g glucose equivalents/d was associated with reduced body weight. CONCLUSIONS Consumption of reduced glycemic response diets are followed by favorable changes in the health markers examined. The case for the use of such diets looks compelling. Unavailable carbohydrate intake is equally important.