Whole-Grain Consumption Does Not Affect Obesity Measures: An Updated Systematic Review and Meta-analysis of Randomized Clinical Trials

Randomised controlled trial of lifestyle interventions for abdominal obesity in primary health care

AIM

Assess effects on waist circumference from diet with or without cereal grains and with or without long-term physical exercise.

BACKGROUND

Elevated waist circumference is an indicator of increased abdominal fat storage and is accordingly associated with increased cardiovascular mortality. This is likely due to the association between lifestyle-induced changes in waist circumference and cardiovascular risk factors. Reductions in waist circumference may be facilitated by diet without cereal grains combined with long-term physical exercise.

METHODS

Two-year randomised controlled trial with factorial trial design in individuals at increased risk of cardiovascular disease with increased waist circumference. Participants were allocated diet based on current Swedish dietary guidelines with or without cereal grains (baseline diet information supported by monthly group sessions) and with or without physical exercise (pedometers and two initial months of weekly structured exercise followed by written prescription of physical activity) or control group. The primary outcome was the change in waist circumference.

FINDINGS

The greatest mean intervention group difference in the change in waist circumference among the 73 participants (47 women and 26 men aged 23-79 years) was at one year between participants allocated a diet without cereal grains and no exercise and participants allocated a diet with cereal grains and no exercise [M = -5.3 cm and -0.9 cm, respectively; mean difference = 4.4 cm, 4.0%, 95% CI (0.0%, 8.0%), P = 0.051, Cohen's d = 0.75]. All group comparisons in the change in waist circumference were non-significant despite the greatest group difference being more than double that estimated in the pre-study power calculation. The non-significance was likely caused by too few participants and a greater than expected variability in the change in waist circumference. The greatest mean intervention group difference strengthens the possibility that dietary exclusion of cereal grains could be related to greater reduction in waist circumference.

The association of dietary carbohydrate quality and quantity with obesity among Iranian adolescents: a case-control study

BACKGROUND

Adolescent obesity is considered as a major health concern worldwide which is closely linked to the quality of diet. The purpose of the present study was to assess the carbohydrate quality and quantity in relation to odds of overweight and obesity in adolescents.

METHODS

This case-control study with a 1:1 ratio was conducted on 406 adolescents (14 to 18 years old) matched for age and gender. Participants were selected by multistage cluster random sampling method from March to October 2019 in Shiraz, Iran. Dietary intakes of the study population were assessed by a validated semi-quantitative food frequency questionnaire. Also anthropometric indices were measured using standard methods and demographic information was recorded via face to face interview. The relation between low carbohydrate diet score (LCDS) and carbohydrate quality index (CQI), and odds of obesity was evaluated by multiple Logistic regression.

RESULTS

After adjusting the role of potential confounders, the participants in the third tertiles of LCDS (OR = 0.443, 95% CI = (0.260 to 0.755)) and CQI (OR = 0.005, 95% CI = (0.001 to 0.025)) had less odds of being overweight and obese compared to the first tertile.

CONCLUSION

The present study found an inverse relationship between dietary quantity and quality of carbohydrate intake and the odds of overweight and obesity in a sample of Iranian adolescents.

Whole grain intake, diet quality and risk factors of chronic diseases: results from a population-based study in Finnish adults

OBJECTIVES

Better diet quality of whole grain consumers could contribute to the associations between whole grain intake and chronic disease risk factors. We examined whole grain intake in relation to diet quality and chronic disease risk factors (anthropometrics, blood pressure, cholesterol, triglycerides, C-reactive protein and glucose) and the role of diet quality in whole grains' associations with each risk factor.

METHODS

Our data included 5094 Finnish adults who completed a validated food frequency questionnaire and participated in a health examination within the National FinHealth 2017 Study. We assessed diet quality by the modified Baltic Sea Diet Score. P trends were calculated across whole grain intake quintiles by linear regression analysis. Interactions were assessed by including an interaction term in the analyses.

RESULTS

Higher whole grain intake was associated with slightly better diet quality compared with lower intakes in both sexes (P < 0.001). Whole grain intake was inversely associated with body mass index (P < 0.001), waist circumference (P < 0.001) and total cholesterol (P = 0.02) in men. Adjusting for medication use attenuated the inverse associations with diastolic blood pressure (P = 0.06) and HDL cholesterol (P = 0.14) in men. We observed no associations in women. Diet quality did not modify the associations between whole grain intake and chronic disease risk factors.

CONCLUSIONS

Our results suggest that whole grain intake was associated with small improvements in the chronic disease risk factors in men, regardless of diet quality. The sex differences may arise from varying health associations of whole grains from different cereal sources.

Effects of Wholegrain Compared to Refined Grain Intake on Cardiometabolic Risk Markers, Gut Microbiota, and Gastrointestinal Symptoms in Children: A Randomized Crossover Trial

BACKGROUND

Wholegrain intake is associated with lower risk of cardiometabolic diseases in adults, potentially via changes in the gut microbiota. Although cardiometabolic prevention should start early, we lack evidence on the effects in children.

OBJECTIVES

This study investigated the effects of wholegrain oats and rye intake on serum low-density lipoprotein (LDL) cholesterol and plasma insulin (coprimary outcomes), other cardiometabolic markers, body composition, gut microbiota composition and metabolites, and gastrointestinal symptoms in children with high body mass index (BMI).

METHODS

In a randomized crossover trial, 55 healthy Danish 8- to 13-y-olds received wholegrain oats and rye ("WG") or refined grain ("RG") products ad libitum for 8 wk in random order. At 0, 8, and 16 wk, we measured anthropometry, body composition by dual-energy absorptiometry, and blood pressure. Fasting blood and fecal samples were collected for analysis of blood lipids, glucose homeostasis markers, gut microbiota, and short-chain fatty acids. Gut symptoms and stool characteristics were determined by questionnaires. Diet was assessed by 4-d dietary records and compliance by plasma alkylresorcinols (ARs).

RESULTS

Fifty-two children (95%) with a BMI z-score of 1.5 ± 0.6 (mean ± standard deviation) completed the study. They consumed 108 ± 38 and 3 ± 2 g/d wholegrain in the WG and RG period, which was verified by a profound difference in ARs (P < 0.001). Compared with RG, WG reduced LDL cholesterol by 0.14 (95% confidence interval: -0.24, -0.04) mmol/L (P = 0.009) and reduced total:high-density lipoprotein cholesterol (P < 0.001) and triacylglycerol (P = 0.048) without altering body composition or other cardiometabolic markers. WG also modulated the abundance of specific bacterial taxa, increased plasma acetate, propionate, and butyrate and fecal butyrate and reduced fatigue with no other effects on gut symptoms.

CONCLUSION

High intake of wholegrain oats and rye reduced LDL cholesterol and triacylglycerol, modulated bacterial taxa, and increased beneficial metabolites in children. This supports recommendations of exchanging refined grain with wholegrain oats and rye among children. This trial was registered at clinicaltrials.gov as NCT04430465.

Non-Classical Aspects of Obesity Pathogenesis and Their Relative Clinical Importance for Obesity Treatment

Obesity is a chronic disease and a major public health problem due to its association with non-communicable diseases and all-cause mortality. An increased energy intake and decreased physical activity have been long recognized as the classical parameters that contribute to the development of obesity. However, several other, non-classical factors have also been associated with obesity through various complex mechanisms. Some of them are diet related, such as diet quality, dietary habits and speed of eating. Other factors are non-dietary, such as endocrine-disrupting chemicals, sleep quality and quantity, psychotropic medications and light at night. The scope of the present narrative review is to address these non-classical factors that are implicated in the pathogenesis of obesity, to clarify their potential role in the management of obesity and, where possible, to provide some practical clinical recommendations.

Comparative effectiveness of single foods and food groups on body weight: a systematic review and network meta-analysis of 152 randomized controlled trials

PURPOSE

This study aimed at quantifying and ranking the effects of different foods or food groups on weight loss.

METHODS

We searched PubMed, Scopus, Cochrane Central Register of Controlled Trials, and Embase to April 2021. We included randomized trials evaluating the comparative effects of two or more food groups, or compared a food group against a control group (usual diet, no intervention) for weight loss in adults. We conducted random-effects network meta-analysis with Bayesian framework to estimate mean difference [MD] and 95% credible interval [CrI] of the effect of food groups on weight loss.

RESULTS

152 RCTs with 9669 participants were eligible. Increased consumption of fish (MD - 0.85 kg, 95% CrI - 1.66, - 0.02; GRADE = low), whole grains (MD - 0.44 kg, 95% CrI - 0.88, 0.0; GRADE = very low), and nuts (MD - 0.37 kg, 95% CI - 0.72, - 0.01; GRADE = low) demonstrated trivial weight loss, well below minimal clinically important threshold (3.9 kg), when compared with the control group. Interventions with other food groups led to no weight loss when compared with either the control group or other food groups. The certainty of the evidence was rated low to very low with the point estimates for all comparisons less than 1 kg. None of the food groups showed an important reduction in body weight when restricted to studies conducted in participants with overweight or obesity.

CONCLUSIONS

Interventions with a single food or food group resulted in no or trivial weight loss, especially in  individuals with overweight or obesity. Further trials on single foods or food groups for weight loss should be highly discouraged.

Effects of whole grain intake on glucagon-like peptide 1 and glucose-dependent insulinotropic peptide: a systematic review and meta-analysis

CONTEXT

Whole grain intake may control help glycemia and reduce food intake by affecting the secretion of glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP).

OBJECTIVE

This systematic review and meta-analysis aimed to assess the postprandial and long-term effects of whole grains on GLP-1 and GIP levels.

DATA SOURCES

PubMed, Web of Science, and Scopus online databases were searched systematically to identify relevant randomized clinical trials (RCTs) published up to April 2021.

STUDY SELECTION

RCTs that evaluated the effects of whole grains, compared with refined grains, on the postprandial area under the curve (AUC) value, the postprandial serum concentration of incretins from 0 to 180 minutes, or the fasting level of incretins after at least 14 days of intervention were included.

RESULTS

Nineteen studies were included in the meta-analysis. The results showed that acute intake of whole grains could not significantly change the AUC value of GLP-1 or GIP. However, the AUC value of GIP was reduced more significantly in (1) unhealthy participants (standard mean difference [SMD] -1.08; 95%CI, -2.07 to -0.10; I2 = 75.9%) compared with healthy participants, and (2) those with a baseline fasting blood glucose of ≥99 mg/dL (SMD -0.71; 95%CI, -1.30 to -0.11; I2 = 74.4%) compared with those with a baseline value of < 99 mg/dL. On the other hand, the results of time-response evaluation during 0 to 180 minutes after the intake of test meals showed that serum concentrations of GIP decreased significantly from 0 to 30 minutes (coefficient = -44.72; P = 0.005), but increased from 60 to 180 minutes (coefficient = 27.03; P = 0.005). However, long-term studies found no significant effects of whole grains on fasting concentrations of GLP-1 or GIP.

CONCLUSION

Whole grain intake did not affect postprandial levels of GLP-1 but enhanced postprandial levels of GIP from 60 to 180 minutes. Further high-quality trials are required to assess the long-term effects of whole grain intake on serum levels of incretins.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42021256695.

Carbohydrate intake - current knowledge on weight management

PURPOSE OF REVIEW

Carbohydrates are the main contributor to daily energy intake and, thus, might play an essential role in the development and treatment of obesity. This nonsystematic literature overview summarized current knowledge about the association between carbohydrate intake (quantity and quality) and weight management.

RECENT FINDINGS

There is scientific evidence for the association between the quality of carbohydrates and body weight or metabolic parameters (e.g. fasting glucose). Thus, dietary intake of high-quality carbohydrates should be preferred over food with a low carbohydrate quality. In contrast, heterogeneous data are available for the association between the amount of carbohydrate intake and anthropometric parameters (e.g. body weight, body fat). Regulation of dietary intake and body weight is complex. For instance, gene-diet interactions might play a role in carbohydrate intake and metabolism.

SUMMARY

There is evidence for the association between intake of high-quality carbohydrates and body weight. However, for the treatment of obesity, a negative energy balance is crucial. The success in weight loss was independent of the quantity and quality of carbohydrate intake. To sum up, recently published literature does not change the current opinion about carbohydrate intake and obesity.

Do gluten peptides stimulate weight gain in humans?

Observations from animal and in vitro laboratory research, and anecdotal evidence, have led to the suggestion that gluten consumption stimulates weight gain by the presence of peptides expressing opioid activity. Another proposed mechanism is that gluten peptides decrease resting energy expenditure resulting in a positive energy balance. In order to induce such effects in vivo, intact food peptides must be absorbed in sufficient quantities, remain intact in the blood for sufficient time to have long‐lasting biological activity and bind to receptors involved in appetite, satiety and energy regulation. However, although peptides from food may pass from the intestine into the blood in extremely low quantities, they are generally rapidly degraded by plasma and vasculum‐bound aminopeptidases, resulting in very short half‐lives and loss of bioactivity. At present, gluten peptide sequences that influence regulators of energy metabolism have not been identified. Furthermore, data on the quantitative absorption of gluten peptides in the blood stream, their stability and lasting bioactivity are also lacking. Therefore, there is no evidence for proposed effects on driving appetite by the brain, nor on energy expenditure and weight gain. Furthermore, the level of overweight observed in various countries appears to be independent of the level of wheat consumption, and abundant observational evidence in humans shows that the levels of gluten consumption are neither related to daily calorie intake nor to BMI. This narrative review therefore discusses the proposed effects of gluten on bodyweight (BW) and putative biological mechanisms in the light of the current evidence.

Beneficial Effects of Partly Milled Highland Barley on the Prevention of High-Fat Diet-Induced Glycometabolic Disorder and the Modulation of Gut Microbiota in Mice

The nutritional functions of highland barley (HB) are superior to those of regular cereals and have attracted increasing attention in recent years. The objective of this study was to investigate whether partly milled highland barley (PHB) can regulate the serum glucose and lipid disorders of mice fed a high-fat diet (HFD) and to further explore their potential gut microbiota modulatory effect. Our results showed that PHB supplementation significantly reduced fasting blood glucose (FBG) and improved oral glucose tolerance. Histological observations confirmed the ability of PHB to alleviate liver and intestine damage. Furthermore, the results of 16S amplicon sequencing revealed that PHB prevented a HFD-induced gut microbiota dysbiosis, enriching some beneficial bacteria, such as Lactobacillus, Bifidobacterium, and Ileibacterium, and reducing several HFD-dependent taxa (norank_f_Desulfovibrionaceae, Blautia, norank_f_Lachnospiraceae, unclassified_f_Lachnospiraceae, and Colidextribacter). In addition, the increase of Lactobacillus and Bifidobacterium presence has a slightly dose-dependent relationship with the amount of the added PHB. Spearman correlation analysis revealed that Lactobacillus and Bifidobacterium were negatively correlated with the blood glucose level of the oral glucose tolerance test. Overall, our results provide important information about the processing of highland barley to retain its hypoglycemic effect and improve its acceptability and biosafety.

Adherence to a Plant-Based Diet and Consumption of Specific Plant Foods-Associations with 3-Year Weight-Loss Maintenance and Cardiometabolic Risk Factors: A Secondary Analysis of the PREVIEW Intervention Study

Plant-based diets are recommended by dietary guidelines. This secondary analysis aimed to assess longitudinal associations of an overall plant-based diet and specific plant foods with weight-loss maintenance and cardiometabolic risk factors. Longitudinal data on 710 participants (aged 26–70 years) with overweight or obesity and pre-diabetes from the 3-year weight-loss maintenance phase of the PREVIEW intervention were analyzed. Adherence to an overall plant-based diet was evaluated using a novel plant-based diet index, where all plant-based foods received positive scores and all animal-based foods received negative scores. After adjustment for potential confounders, linear mixed models with repeated measures showed that the plant-based diet index was inversely associated with weight regain, but not with cardiometabolic risk factors. Nut intake was inversely associated with regain of weight and fat mass and increments in total cholesterol and LDL cholesterol. Fruit intake was inversely associated with increments in diastolic blood pressure, total cholesterol, and LDL cholesterol. Vegetable intake was inversely associated with an increment in diastolic blood pressure and triglycerides and was positively associated with an increase in HDL cholesterol. All reported associations with cardiometabolic risk factors were independent of weight change. Long-term consumption of nuts, fruits, and vegetables may be beneficial for weight management and cardiometabolic health, whereas an overall plant-based diet may improve weight management only.

PROTOCOL: The association between whole-grain dietary intake and noncommunicable diseases: A systematic review and meta-analysis

Our primary research questions are: (1) What is the association between whole grains (WG) intake and the prevalence of NCDs (i.e., type 2 diabetes, cardiovascular disease, obesity, cancer, mortality) and their biomarkers? (2) Which biomarker(s) has/have the greatest association with WG intake when combining multiple biomarkers together in the same analysis? Our secondary research question is: (3) Are there dose-response relationships between WG intake and biomarkers and prevalence of NCDs which could help inform a universal recommendation for WG intake?

Fruit and vegetable consumption in relation to primary headaches: the MEPHASOUS study

BACKGROUND

Fruit and vegetable consumption may beneficially affect the odds of primary headaches due to their antioxidant contents. However, no study has examined the association between fruit and vegetable consumption and primary headaches among university students.

AIM

To assess the relation between fruit and vegetable intakes and primary headaches among Iranian university students.

METHODS

Overall, 83,214 university students with an age range of ≥ 18 years participated in the present study. Dietary intakes and also data on confounding variables were collected using validated questionnaires. Data on dietary intakes were collected using a validated dietary habits questionnaire. We used the International Classification of Headache Disorders-3 (ICHD-3) criteria to define primary headaches.

RESULTS

Fruit consumption was negatively associated with primary headaches; such that after controlling for potential confounders, greater intake of fruits was associated with 30% lower odds of primary headaches (OR: 0.70, 95% CI 0.58-0.84). Such an inverse association was also found for vegetable consumption. In the fully adjusted model, students in the top category of vegetable consumption were 16% less likely to have primary headaches compared with those in the bottom category (OR: 0.84, 95% CI 0.74-0.95). Subgroup analysis revealed that fruit consumption was inversely associated with primary headaches in females, unlike males, and vegetable consumption was inversely associated with these headaches in males, as opposed to females. Moreover, fruit and vegetable consumption was related to lower odds of primary headaches in normal-weight students.

CONCLUSION

Fruit and vegetable intakes were associated with reduced odds of primary headaches.

LEVEL OF EVIDENCE

Level III, cross-sectional analytic studies.

Effects of Whole Grain Intake, Compared with Refined Grain, on Appetite and Energy Intake: A Systematic Review and Meta-Analysis

Results from observational studies indicate that whole grain (WG) intake is inversely associated with BMI and risk of weight gain. WG intake may influence energy balance and body composition through effects on appetite and energy intake. To evaluate the impact of WG food consumption on appetite and energy intake, a systematic review and meta-analysis was performed of results from randomized controlled trials (RCTs) assessing WG food consumption, appetite, and energy intake in adults. A search of PubMed, Scopus, and Food Science and Technology Abstracts yielded 36 RCTs measuring subjective appetite ratings after consuming WG foods compared with refined grain (RG) controls. Thirty-two of these studies reported AUCs for subjective appetite (hunger, fullness, satiety, desire to eat, or prospective consumption) and/or energy intake and were included in the meta-analysis. Pooled estimates from meta-analyses are expressed as standardized mean differences (SMDs). Compared with RG foods, intake of WG foods resulted in significant differences in AUCs for subjective hunger (SMD: -0.34; 95% CI: -0.46, -0.22; P < 0.001), fullness (SMD: 0.49; 95% CI: 0.31, 0.66; P < 0.001), satiety (SMD: 0.33; 95% CI: 0.18, 0.47; P < 0.001), and desire to eat (SMD: -0.33; 95% CI: -0.46, -0.20; P < 0.001). There were small, nonsignificant reductions in prospective consumption ratings (P = 0.08) and energy intake (P = 0.07) with WG intake compared with RG. These results support the view that consumption of WG foods, compared with RG foods, significantly impacts subjective appetite, and might partly explain the inverse associations between WG food intake and risk of overweight, obesity, and weight gain over time. PROSPERO registration: CRD42020148217.

Trend of nutrition research in endocrine disorders, gaps, and future plans: a collection of experiences of an endocrinology research institute

BACKGROUND

Nutrition plays a pivotal role in the prevention and treatment of endocrine disorders. The aim of this study was to provide a window in order to display the 25-year activities of Endocrinology & Metabolism Research Institute (EMRI), and the gaps and future plans in the field of nutrition and endocrine disorders.

METHODS

To collect papers affiliated to the EMRI in field of nutrition from the inception to December 1st 2019, the electronic databases including PubMed/Medline, Web of Science, and Scopus were searched. Publications in English and Persian languages were included. Scientific Landscapes (VOS viewer) software version 1.6.13 was used to provide bibliometric maps.

RESULTS

Of 4082 studies identified in the initial search, 319 relevant papers were included. They contributed systematic review and meta-analysis/review (n = 76), clinical trials (n = 58), cross-sectional (n = 171), case-control studies (n = 11), and animal studies (n = 3). Accordingly, most nutrition studies were dedicated to the level of evidence III (cross-sectional studies: 53.60%) followed by systematic review studies (23.82%) with the level of evidence I. There was also an increasing trend in the nutrition studies through years, with a peak in 2019.

CONCLUSION

An increasing trend in the publications related to nutrition science is observed at EMRI. However, nutrition research and publications can grow further through expanding collaborations with other fields related to endocrine. Given nutritional assessments in national projects and focusing on the identification of preventive nutritional strategies, considering the situations of our society can be helpful to make nutritional findings more practical.

Breakfast consumption is inversely associated with primary headaches in university students: The MEPHASOUS study

OBJECTIVE

This study was conducted to examine the association between breakfast consumption pattern and primary headaches in a large population of university students.

METHODS

This cross-sectional study was done on the MEPHASOUS dataset that contained the information of 83,677 university students, aged ≥18 years, from 28 provinces of Iran. Dietary intakes and breakfast consumption pattern were assessed using a validated self-administered dietary habits questionnaire. Primary headaches were determined according to the International Classification of Headache Disorders-3 (ICHD-3) criteria. Binary logistic regression in different adjusted models was used to assess the association between breakfast consumption and primary headaches.

RESULTS

The mean age of participants was 21.50 ± 4.01. Primary headaches were prevalent among 9% of university students. A significant inverse association was seen between breakfast consumption and odds of primary headaches [odds ratio (OR): 0.57, 95 % confidence interval (CI): 0.51-0.62]. This association remained significant even after taking potential confounders into account; such that students who consumed breakfast frequently had 26 % lower odds of primary headaches compared with those who consumed it <1 day/week (OR: 0.74, 95 % CI: 0.65-0.85). Moreover, such a significant inverse association was observed in female students (OR: 0.54, 95 % CI: 0.49-0.61) as well as those with BMI < 25 kg/m² (OR: 0.68, 95 % CI: 0.58-0.79). However, it became non-significant in male students and those with overweight or obesity.

CONCLUSION

We found that frequent breakfast consumption is associated with a decreased odds of primary headaches in female students and those with BMI < 25 kg/m². Further prospective studies are needed to confirm our findings.

Nutrition beyond the first 1000 days: diet quality and 7-year change in BMI and overweight in 3-year old children from the Dutch GECKO Drenthe birth cohort

The identification of early-life determinants of overweight is crucial to start early prevention. As weight gain accelerates between 2 and 6 years, we studied the association between diet quality in children aged 3 years and the change in BMI and overweight incidence in the following 7 years. From the Dutch GECKO Drenthe birth cohort, 1001 children born in 2006 or 2007 with complete data on diet (food frequency questionnaire at the age of 3 years) and growth at the age of 3 and 10 years were included. Diet quality was estimated with the evidence-based Lifelines Diet Score (LLDS). Measured height and weight at the age of 3 and 10 years were used to calculate BMI z-scores standardized for age and sex. The associations of the LLDS (in quintiles) with BMI-z change and overweight incidence were studied with linear and logistic regression analyses. Overweight prevalence in the total study population increased from 8.3% at the age of 3 years to 16.7% at the age of 10 years. The increase in overweight prevalence ranged from 14.7% in Q1 to 3.5% in Q5. Children with a better diet quality (higher quintiles of LLDS) increased significantly less in BMI-z (confounder adjusted βLLDS = -0.064 (-0.101; -0.026)). Children with a poor diet quality at the age of 3 years had a considerably higher risk for overweight at the age of 10 years (confounder adjusted OR for Q1 vs. Q5 was 2.86 (95% CI 1.34-6.13). These results show the importance of diet in healthy development in the early life following the first 1000 days when new habits for a mature diet composed of food groups with lifelong importance are developed, providing a relevant window for overweight prevention early in life.

Whole Grain Food Definition Effects on Determining Associations of Whole Grain Intake and Body Weight Changes: A Systematic Review

Within epidemiological and intervention studies, whole grain consumption has generally shown positive associations with reductions in markers of overweight and obesity. However, studies use varied methods of determining whole grain intake, including different definitions of a whole grain food, which may explain varied results. This systematic review aimed to identify how different methods of reporting and calculating whole grain intake, including whole grain food definitions, affect reported associations between whole grain intake and body weight measures in adults. Systematic searching of PubMed, Scopus, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane Central Register for Controlled Trials (CENTRAL), and MEDLINE (all years to 11 June, 2020) identified eligible studies. Cohort and cross-sectional studies assessing whole grain intake and body weight measures in adults were included. Studies that did not specify methods used to calculate whole grain intake were excluded. Twenty-one cross-sectional studies (from 24 articles) and 9 prospective cohort studies (from 7 articles) were included in the review. Many cross-sectional studies showed whole grain intake was, to some degree, significantly associated with body weight measures, whereas associations varied greatly among cohort studies. Studies calculating whole grain intake using total grams of intake, USDA databases, or ≥25% whole grain in combination with listing specific foods, showed consistent beneficial effects of increasing whole grain intake on body weight. Studies with general lists of foods included as "whole grain foods" or lower cut-offs for whole grain content were inconsistent. The majority of studies reported whole grain intake as servings/day or grams whole grain/day. This review suggests that an association between whole grain and body weight measures remains likely, although precise associations are difficult to determine due to heterogeneity in methodologies and an inability to formally compare studies. Moving forward, application of a standardized methodology to calculate whole grain intake is essential.

The effect of vitamin E supplementation on selected inflammatory biomarkers in adults: a systematic review and meta-analysis of randomized clinical trials

The previous meta-analysis of clinical trials revealed a beneficial effect of vitamin E supplementation on serum C-reactive protein (CRP) concentrations; however, it is unknown whether this vitamin has the same influence on other inflammatory biomarkers. Also, several clinical trials have been published since the release of earlier meta-analysis. Therefore, we aimed to conduct a comprehensive meta-analysis to summarize current evidence on the effects of vitamin E supplementation on inflammatory biomarkers in adults. We searched the online databases using relevant keywords up to November 2019. Randomized clinical trials (RCTs) investigating the effect of vitamin E, compared with the placebo, on serum concentrations of inflammatory cytokines were included. Overall, we included 33 trials with a total sample size of 2102 individuals, aged from 20 to 70 years. Based on 36 effect sizes from 26 RCTs on serum concentrations of CRP, we found a significant reduction following supplementation with vitamin E (− 0.52, 95% CI − 0.80, − 0.23 mg/L, P < 0.001). Although the overall effect of vitamin E supplementation on serum concentrations of interleukin-6 (IL-6) was not significant, a significant reduction in this cytokine was seen in studies that used α-tocopherol and those trials that included patients with disorders related to insulin resistance. Moreover, we found a significant reducing effect of vitamin E supplementation on tumor necrosis factor-α (TNF-α) concentrations at high dosages of vitamin E; such that based on dose–response analysis, serum TNF-α concentrations were reduced significantly at the dosages of ≥ 700 mg/day vitamin E (P_{non-linearity} = 0.001). Considering different chemical forms of vitamin E, α-tocopherol, unlike other forms, had a reducing effect on serum levels of CRP and IL-6. In conclusion, our findings revealed a beneficial effect of vitamin E supplementation, particularly in the form of α-tocopherol, on subclinical inflammation in adults. Future high-quality RCTs should be conducted to translate this anti-inflammatory effect of vitamin E to the clinical setting.

Next Generation Health Claims Based on Resilience: The Example of Whole-Grain Wheat

Health claims on foods are a way of informing consumers about the health benefits of a food product. Traditionally, these claims are based on scientific evaluation of markers originating from a pharmacological view on health. About a decade ago, the definition of health has been rephrased to 'the ability to adapt' that opened up the possibility for a next generation of health claims based on a new way of quantifying health by evaluating resilience. Here, we would like to introduce an opportunity for future scientific substantiation of health claims on food products by using whole-grain wheat as an example. Characterization of the individual whole wheat grain food product or whole wheat flour would probably be considered as sufficiently characterized by the European Food Safety Authority, while the food category whole grain is not specific enough. Meta-analysis provides the scientific evidence that long-term whole-grain wheat consumption is beneficial for health, although results from single 'gold standard' efficacy studies are not always straight forward based on classic measurement methods. Future studies may want to underpin the scientific argumentation that long-term whole grain wheat consumption improves resilience, by evaluating the disruption and rate of a selected panel of blood markers in response to a standardized oral protein glucose lipid tolerance test and aggregated into biomarkers with substantiated physiological benefits, to make a next-generation health claim for whole-grain wheat achievable in the near future.

Effects of zinc supplementation on lipid profile in patients with type 2 diabetes mellitus: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND AIM

Findings on the effects of zinc supplementation on the lipid profile in patients with type 2 diabetes mellitus (T2DM) are conflicting. The current comprehensive systematic review and meta-analysis aimed to summarize available evidence in this regard.

METHODS AND RESULTS

After a systematic search in the online databases, we included the randomized controlled trials (RCTs) investigating the effect of zinc supplementation on lipid profile [total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglyceride (TG)] in patients with T2DM. Altogether, 9 studies with a total sample size of 424 patients with T2DM were included in the analysis. Combining 9 effect sizes from 9 RCTs, we found a significant lowering effect of zinc supplementation on serum levels of TG (weighted mean difference (WMD): -17.08, 95% CI: -30.59, -3.58 mg/dL, P = 0.01) and TC (WMD: -26.16, 95% CI: -49.69, -2.62 mg/dL, P = 0.02). Although the overall effect of zinc supplementation on LDL-C levels was not significant, a beneficial effect was seen in studies that administered <100 mg/d zinc. Based on the non-linear dose-response analysis, a greater reduction in serum levels of TC and LDL-C following zinc supplementation was seen at <12 weeks' duration of intervention. Unlike the overall effect size, we found a significant increasing effect of zinc supplementation on serum HDL-C concentrations in most subgroups of RCTs according to the subgroup analyses.

CONCLUSION

We found that zinc supplementation may beneficially influence lipid profile in patients with T2DM.

Dietary intake of total, animal, and plant proteins and risk of all cause, cardiovascular, and cancer mortality: systematic review and dose-response meta-analysis of prospective cohort studies

OBJECTIVE

To examine and quantify the potential dose-response relation between intake of total, animal, and plant protein and the risk of mortality from all causes, cardiovascular disease, and cancer.

DESIGN

Systematic review and meta-analysis of prospective cohort studies.

DATA SOURCES

PubMed, Scopus, and ISI Web of Science until December 2019, and references of retrieved relevant articles.

STUDY SELECTION

Prospective cohort studies that reported the risk estimates for all cause, cardiovascular, and cancer mortality in adults aged 18 or older.

DATA SYNTHESIS

Random effects models were used to calculate pooled effect sizes and 95% confidence intervals for the highest versus lowest categories of protein intake and to incorporate variation between studies. Linear and non-linear dose-response analyses were done to evaluate the dose-response relations between protein intake and mortality.

RESULTS

32 prospective cohort studies were included in the systematic review and 31 in the meta-analysis. During the follow-up period of 3.5 to 32 years, 113 039 deaths (16 429‬ from cardiovascular disease and 22 303‬ from cancer) occurred among 715 128 participants. Intake of total protein was associated with a lower risk of all cause mortality (pooled effect size 0.94, 95% confidence interval 0.89 to 0.99, I2=58.4%, P<0.001). Intake of plant protein was significantly associated with a lower risk of all cause mortality (pooled effect size 0.92, 95% confidence interval 0.87 to 0.97, I2=57.5%, P=0.003) and cardiovascular disease mortality (pooled hazard ratio 0.88, 95% confidence interval 0.80 to 0.96, I2=63.7%, P=0.001), but not with cancer mortality. Intake of total and animal protein was not significantly associated with risk of cardiovascular disease and cancer mortality. A dose-response analysis showed a significant inverse dose-response association between intake of plant protein and all cause mortality (P=0.05 for non-linearity). An additional 3% energy from plant proteins a day was associated with a 5% lower risk of death from all causes.

CONCLUSIONS

Higher intake of total protein was associated with a lower risk of all cause mortality, and intake of plant protein was associated with a lower risk of all cause and cardiovascular disease mortality. Replacement of foods high in animal protein with plant protein sources could be associated with longevity.

The effects of green coffee extract supplementation on glycemic indices and lipid profile in adults: a systematic review and dose-response meta-analysis of clinical trials

Background

The role of coffee consumption in the risk of cardiovascular diseases has been debated for many years. The current study aimed to summarize earlier evidence on the effects of green coffee extract (GCE) supplementation on glycemic indices and lipid profile.

Methods

We searched available online databases for relevant clinical trials published up to October 2019. All clinical trials investigating the effect of GCE supplementation, compared with a control group, on fasting blood glucose (FBG), serum insulin, total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) were included. Overall, 14 clinical trials with a total sample size of 766 participants were included in the current meta-analysis.

Results

We found a significant reducing effect of GCE supplementation on FBG (weighted mean difference (WMD): -2.35, 95% CI: − 3.78, − 0.92 mg/dL, P = 0.001) and serum insulin (WMD: -0.63, 95% CI: − 1.11, − 0.15 μU/L, P = 0.01). With regard to lipid profile, we observed a significant reduction only in serum levels of TC following GCE supplementation in the overall meta-analysis (WMD: -4.51, 95% CI: − 8.39, − 0.64, P = 0.02). However, subgroup analysis showed a significant reduction in serum TG in studies enrolled both genders. Also, such a significant reduction was seen in serum levels of LDL and HDL when the analyses confined to studies with intervention duration of ≥8 weeks and those included female subjects. In the non-linear dose-response analyses, we found that the effects of chlorogenic acid (CGA) dosage, the main polyphenol in GCE, on FBG, TG and HDL were in the non-linear fashions.

Conclusion

In conclusion, we found that GCE supplementation improved FBG and serum levels of insulin and TC. Also, there was a significant improvement in other markers of lipid profile in some subgroups of clinical trials.

The association between nutrient patterns and metabolic syndrome among Iranian adults: cross-sectional analysis of Shahedieh cohort study

OBJECTIVE

To assess the association between patterns of nutrient intake and metabolic syndrome (MetS) in a large sample of Iranian adults.

DESIGN

Baseline data from the Shahedieh cohort study were used in the current cross-sectional study. Dietary intakes were assessed through the use of a validated semi-quantitative FFQ. Nutrient patterns (NP) were derived using factor analysis. The MetS was defined according to criteria introduced from the National Cholesterol Education Program Adult Treatment Panel III, modified for Iranian adults.

SETTING

Yazd, Iran.

PARTICIPANTS

A total of 7325 Iranian adults aged between 30 and 75 years.

RESULTS

Three NP were identified. A significant positive association was found between adherence to semi-plant NP (characterised by the high intakes of P; vitamins B1, B3, B6 and B5; Se; Mg; Fe; protein; Cr; Cu; fibre; biotin; Mn; Zn and Na) and odds of MetS (OR 1·68, 95 % CI 1·43, 1·98). However, after adjusting for potential confounders, this association became non-significant. In addition, after taking potential confounders into account, individuals in the highest quintile of the semi-animal NP, rich in Ca; K; vitamins B2, B12, A, D, K and C; SFA; dietary cholesterol and trans-fatty acid, were 26 % more likely to have MetS compared with those in the lowest quintile (OR 1·26, 95 % CI 1·05, 1·51). No significant association was seen between adherence to the high-carbohydrate/low-fat NP and odds of MetS.

CONCLUSIONS

We found that adherence to a semi-animal NP was associated with increased odds of MetS.

The Ketogenic Diet: Evidence for Optimism but High-Quality Research Needed

For >50 y, dietary guidelines in the United States have focused on reducing intakes of saturated and total fat. However, rates of obesity and diabetes rose markedly throughout this period, with potentially catastrophic implications for public health and the economy. Recently, ketogenic diets have received substantial attention from the general public and nutrition research community. These very-low-carbohydrate diets, with fat comprising >70% of calories, have been dismissed as fads. However, they have a long history in clinical medicine and human evolution. Ketogenic diets appear to be more effective than low-fat diets for treatment of obesity and diabetes. In addition to the reductions in blood glucose and insulin achievable through carbohydrate restriction, chronic ketosis might confer unique metabolic benefits of relevance to cancer, neurodegenerative conditions, and other diseases associated with insulin resistance. Based on available evidence, a well-formulated ketogenic diet does not appear to have major safety concerns for the general public and can be considered a first-line approach for obesity and diabetes. High-quality clinical trials of ketogenic diets will be needed to assess important questions about their long-term effects and full potential in clinical medicine.

Effect of wheat species (Triticum aestivum vs T. spelta), farming system (organic vs conventional) and flour type (wholegrain vs white) on composition of wheat flour; results of a retail survey in the UK and Germany - 1. Mycotoxin content

Wheat is one of the main dietary sources for mycotoxins that can cause adverse health effects in humans. Here we report results of a 3-year survey which compared the effects of flour type (whole-grain vs white), wheat species (common vs spelt), and farming system (organic vs conventional) on mycotoxin concentrations in UK and German wheat flour brands. Wholegrain, conventional and organic flour contained 124, 31 and 9% higher concentrations of T-2/HT-2, DON and ZEA respectively, but concentrations of the three Fusarium mycotoxins assessed were ~10 times lower than the EC-maximum contamination levels (MCL). Thirty one percent of flour samples had Ochratoxin A (OTA) concentrations above the MCL (3 µg/kg), but OTA levels were no affected by wheat species, farming system and flour type. Results suggest that both organic and conventional primary production methods and postharvest quality assurance systems are effective for maintaining Fusarium mycotoxins, but not OTA concentrations, below the MCL.

The effect of green coffee extract supplementation on anthropometric measures in adults: A comprehensive systematic review and dose-response meta-analysis of randomized clinical trials

BACKGROUND AND AIM

Two meta-analyses summarized data on the effects of green coffee extract (GCE) supplementation on anthropometric measures. However, the accuracy of those meta-analyses is uncertain due to several methodological limitations. Therefore, we aimed to conduct a comprehensive systematic review and dose-response meta-analysis to summarize all available evidence on the effects of GCE supplementation on anthropometric measures by considering the main limitations in the previous meta-analyses.

METHODS

We searched available online databases for relevant publications up to January 2020, using relevant keywords. All randomized clinical trials (RCTs) investigating the effects of GCE supplementation, compared with a control group, on anthropometric measures [including body weight, body mass index (BMI), body fat percentage, waist circumference (WC) and waist-to-hip ratio (WHR)] were included.

RESULTS

After identifying 1871 studies from our initial search, 15 RCTs with a total sample size of 897 participants were included in the systematic review and meta-analysis. We found a significant reducing effect of GCE supplementation on body weight (weighted mean difference (WMD): -1.23, 95 % CI: -1.64, -0.82 kg,P < 0.001), BMI (WMD: -0.48, 95 % CI: -0.78, -0.18 kg/m², P = 0.001), and WC (WMD: -1.00, 95 % CI: -1.70, -0.29 cm, P = 0.006). No significant effect of GCE supplementation on body fat percentage and WHR was seen. In the dose-response analyses, there was no significant association between chlorogenic acid (CGA) dosage, as the main polyphenol in green coffee, and changes in anthropometric measures.

CONCLUSION

We found that GCE supplementation had a beneficial effect on body weight, BMI and WC. It provides a cost-effective and safe alternative for the treatment of obesity. Additional well-designed studies are required to further confirm our findings.

Perspective: Whole and Refined Grains and Health-Evidence Supporting "Make Half Your Grains Whole"

Research-based dietary guidelines suggest that consumers "make half their grains whole." Yet some advocate ingesting only whole-grain foods (WGFs) and avoiding all refined-grain foods (RGFs). Some even recommend avoiding all grain-based foods (GBFs). This article will provide arguments to counter negative deductions about GBFs and RGFs, especially staple ones, and to support dietary guidance recommending a balance of GBFs-achieved through the right mix, type, and quantity of WGFs and RGFs. Studies looking at early mortality, body weight, and glucose tolerance and diabetes will be used as examples to characterize the literature about GBFs. The following issues are highlighted: 1) inconsistent findings between epidemiological and interventional studies and impacts of GBFs on health outcomes, and the underreporting of findings showing RGFs neither raise nor lower health risks; 2) multiple confounding and potential interactions make adequate statistical adjustment difficult; 3) nonuniform WGF definitions among studies make comparison of results challenging, especially because some WGFs may contain 49-74% refined grain (RG); 4) binary categorization of GBFs creates bias because nearly all categories of WGFs are recommended, but nearly half the RGF categories are not; 5) ingestion of >5 (30-g) servings RGFs/d and <1 serving WFGs/d creates dietary imbalance; 6) pattern names (e.g., "white bread") may impugn RGFs, when names such as "unbalanced" or "few fruits and vegetables" may more fairly characterize the dietary imbalance; 7) avoidance of all enriched RGs may not only impair status of folate and other B vitamins and certain minerals such as iron and zinc but also decrease acceptability of WGFs; 8) extrapolation beyond median documented intakes in high-WGF consumers (∼48 g whole grain/d) in most cohorts is speculative; 9) recommended dietary patterns such as the Mediterranean diet demonstrate that the right mix of WGFs and RGFs contributes to positive health outcomes.

Weight loss induced by whole grain-rich diet is through a gut microbiota-independent mechanism

The prevalence of overweight and obesity has increased worldwide. Obesity is a well-known risk factor of type 2 diabetes mellitus and cardiovascular disease and raises public health concerns. Many dietary guidelines encourage the replacement of refined grains with whole grains (WGs) to enhance body weight management. Current evidence regarding interrelationships among WGs, body weight, and gut microbiota is limited and inconclusive. In this editorial, we comment on the article by Roager et al published in the recent issue of the Gut 2019; 68(1): 83-93. In the study, obese patients (25 < body mass index < 35 kg/m²) were randomly assigned to receive two 8-wk dietary controlling periods with WGs and refined grain-rich diet. The results showed significantly decreased body weight in the WG group. Either the composition of gut microbiota or short-chain fatty acids, the leading end product of fermentation of non-digestible carbohydrate by gut microbiota, did not differ between the two groups. The study highly indicated that a WG-rich diet reduced body weight independent of gut microbiota. We then raised some plausible mechanisms of how WGs might influence body weight and demonstrated more literature in line with WGs enhance body weight control through a microbiota-independent pathway. Possible mechanisms include: (1) The abundant dietary fiber contents of WGs increase satiety, satiation, energy excretion from stool, and energy expenditure simultaneously decreasing energy absorption and fat storage; (2) The plentiful amount of polyphenols of WGs improve energy expenditure by hampering adipocyte maturation and function; (3) The sufficient magnesium and zinc of WGs guarantee lean body mass growth and decrease fat mass; (4) The effect of WGs on brown adipose tissue is a key component of non-shivering thermogenesis; and (5) The increase of adiponectin by WGs enhances glucose utilization, lipid oxidation, and energy expenditure.

Factors Influencing British Adolescents' Intake of Whole Grains: A Pilot Feasibility Study Using SenseCam Assisted Interviews

High whole grain intake is beneficial for health. However, adolescents consume low levels of whole grain and the understanding of the underpinning reasons for this is poor. Using a visual, participatory method, we carried out a pilot feasibility study to elicit in-depth accounts of young people's whole grain consumption that were sensitive to their dietary, familial and social context. Furthermore, we explored barriers and suggested facilitators to whole grain intake and assessed the feasibility of using SenseCam to engage adolescents in research. Eight British adolescents (aged 11 to 16 years) wore a SenseCam device which auto-captured images every twenty seconds for three consecutive days. Participants then completed traditional 24-hour dietary recalls followed by in-depth interviews based on day three SenseCam images. Interview data were subjected to thematic analysis. Findings revealed that low adolescent whole grain intake was often due to difficulty in identifying whole grain products and their health benefits; and because of poor availability in and outside of the home. The images also captured the influence of parents and online media on adolescent daily life and choices. Low motivation to consume whole grains, a common explanation for poor diet quality, was rarely mentioned. Participants proposed that adolescent whole grain consumption could be increased by raising awareness through online media, improved sensory appeal, increased availability and variety, and tailoring of products for young people. SenseCam was effective in engaging young people in dietary research and capturing data relevant to dietary choices, which is useful for future research.