Influence of Ultra-High Hydrostatic Pressurizing Brown Rice on Cognitive Functions and Mental Health of Elderly Japanese Individuals: A 2-Year Randomized and Controlled Trial

Effects of whole grains on glycemic control: a systematic review and dose-response meta-analysis of prospective cohort studies and randomized controlled trials

PURPOSE

Whole grains have recently been promoted as beneficial to diabetes prevention. However, the evidence for the glycemic benefits of whole grains seems to conflict between the cohort studies and randomized control trials (RCTs). To fill the research gap, we conducted a meta-analysis to determine the effects of whole grains on diabetes prevention and to inform recommendations.

METHODS

We searched PubMed, Clarivate Web of Science, and Cochrane Library until March 2024. We used the risk ratio (RR) of type 2 diabetes to represent the clinical outcomes for cohort studies, while the biomarkers, including fasting blood glucose and insulin, HbA1C, and HOMA-IR, were utilized to show outcomes for RCTs. Dose-response relationships between whole grain intakes and outcomes were tested with random effects meta-regression models and restricted cubic splines models. This study is registered with PROSPERO, CRD42021281639.

RESULTS

Ten prospective cohort studies and 37 RCTs were included. Cohort studies suggested a 50 g/day whole grain intake reduced the risk of type 2 diabetes (RR = 0.761, 95% CI: 0.700 to 0.828, I2 = 72.39%, P < 0.001) and indicated a monotonic inverse relationship between whole grains and type 2 diabetes rate. In RCTs, whole grains significantly reduced fasting blood glucose (Mean difference (MD) = -0.103 mmol/L, 95% CI: -0.178 to -0.028; I2 = 72.99%, P < 0.01) and had modest effects on HbA1C (MD = -0.662 mmol/mol (-0.06%), 95% CI: -1.335 to 0.010; I2 = 64.55%, P = 0.05) and HOMA-IR (MD = -0.164, 95% CI: -0.342 to 0.013; I2 = 33.38%, P = 0.07). The intake of whole grains and FBG, HbA1C, and HOMA-IR were significantly dose-dependent. The restricted spline curves remained flat up to 150 g/day and decreased afterward. Subgroup analysis showed that interventions with multiple whole-grain types were more effective than those with a single type.

CONCLUSION

Our study findings suggest that a daily intake of more than 150 g of whole grain ingredients is recommended as a population approach for diabetes prevention.

A Comprehensive Review of the Effects of Glycemic Carbohydrates on the Neurocognitive Functions Based on Gut Microenvironment Regulation and Glycemic Fluctuation Control

Improper glycemic carbohydrates (GCs) consumption can be a potential risk factor for metabolic diseases such as obesity and diabetes, which may lead to cognitive impairment. Although several potential mechanisms have been studied, the biological relationship between carbohydrate consumption and neurocognitive impairment is still uncertain. In this review, the main effects and mechanisms of GCs' digestive characteristics on cognitive functions are comprehensively elucidated. Additionally, healthier carbohydrate selection, a reliable research model, and future directions are discussed. Individuals in their early and late lives and patients with metabolic diseases are highly susceptible to dietary-induced cognitive impairment. It is well known that gut function is closely related to dietary patterns. Unhealthy carbohydrate diet-induced gut microenvironment disorders negatively impact cognitive functions through the gut-brain axis. Moreover, severe glycemic fluctuations, due to rapidly digestible carbohydrate consumption or metabolic diseases, can impair neurocognitive functions by disrupting glucose metabolism, dysregulating calcium homeostasis, oxidative stress, inflammatory responses, and accumulating advanced glycation end products. Unstable glycemic status can lead to more severe neurological impairment than persistent hyperglycemia. Slow-digested or resistant carbohydrates might contribute to better neurocognitive functions due to stable glycemic response and healthier gut functions than fully gelatinized starch and nutritive sugars.

Acute repeated cage exchange stress modifies urinary stress and plasma metabolic profiles in male mice

Exposure to a novel environment is psychologically and physically stressful for humans and animals. The response has been reported to involve enhanced sympathetic nervous system activity, but changes in nutrient levels under stress are not fully understood. As a form of exposure to a novel environment, repeated cage exchange (CE, four times at 2-h intervals for 8 h from 08:00 h) during the light phase with no restraint on movement was applied to A/J mice, a strain particularly prone to stress. Body temperature was measured with a temperature-sensing microchip implanted in the interscapular region. The stress conditions and anxiety level were evaluated by measuring urinary catecholamines and corticosterone and by performing an anxiety-like behavior test, respectively. Major nutrients such as glucose, fatty acids, and amino acids in the plasma were also examined. CE mice showed a significant increase in body temperature with each CE. They also showed a significantly greater reduction of body weight change, more water intake, and higher levels of urinary catecholamines and corticosterone and anxiety-like behavior score than control mice. The model revealed a significantly lower plasma glucose level and higher levels of several essential amino acids, such as branched-chain amino acids and phenylalanine, than those of control mice. Meanwhile, free fatty acids and several amino acids such as arginine, aspartic acid, proline, threonine, and tryptophan in both sets of mice were significantly decreased from the corresponding levels at 08:00 h, while similar plasma levels were exhibited between mice with and without CE. In conclusion, repeated CE stress was associated with changes in glucose and amino acids in plasma. Although further study is needed to clarify how these changes are specifically linked to anxiety-like behavior, this study suggests the potential for nutritional intervention to counter stress in humans exposed to novel environments.

The Relationship between Whole-Grain Intake and Measures of Cognitive Decline, Mood, and Anxiety-A Systematic Review

Greater intake of whole grains, compared to refined grains, is consistently associated with a reduced risk of cardiovascular disease and type 2 diabetes, both of which are associated with cognitive decline. To better understand the relationship between whole-grain intake, cognition, mood, and anxiety, a systematic review was conducted to synthesize available evidence linking whole grains to these outcomes. Four electronic databases were searched from inception to August 2021 for potentially relevant observational and interventional studies. Risk of bias (RoB) assessments were performed using the newly developed Nutrition Quality Evaluation Strengthening Tools, and the Grades of Recommendation, Assessment, Development, and Evaluation approach was used to determine the strength of evidence for each outcome. In total, 23 studies [4 randomized controlled trials (RCTs) and 19 observational studies] met the predefined eligibility criteria. Of these,12 studies included analysis of whole-grain intake and cognitive decline, 9 included mood outcomes, and 2 included both cognition and mood outcomes. The overall evidence for an association between whole-grain intake and cognition is inconclusive. With respect to mood outcomes, evidence from RCTs prospective cohort and case-control studies suggest that higher intake is linked to improved outcomes for mood and depression although the evidence is mixed for cross-sectional studies. Reporting of whole-grain intake fell short of suggested standards, and the strength of available evidence was low or very low for all outcomes. A high RoB toward studies reporting results was also noted, complicating both the interpretation of some studies and the combined evidence. Of note, few well-designed RCTs assessing the effect of whole-grain intake on measures of cognition, mood, and anxiety were identified, highlighting the need for more studies in this area. The available, although limited, evidence suggests that greater whole-grain intake is associated with better mood and anxiety-related scores and is inconclusive regarding cognitive outcomes. PROSPERO registration: CRD42021266355.

Rice Intake Is Associated with Longer Reaction Time and Interacts with Blood Lipids and Hypertension among Qatari Adults

We aimed to assess the association between rice intake and cognitive function among Qatari adults and test the interactions with health conditions. Data from 1000 adults aged ≥18 years old who attended the Qatar Biobank (QBB) study were used. Rice dietary intake was measured by a food frequency questionnaire (FFQ), and mean reaction time (MRT) was used as an indicator of cognitive function. Linear regression and structure equation models were used. The mean rice consumption was 7.6 times/week (SD 2.0). The sample had a mean MRT of 717 milliseconds (SD 205). Rice consumption was positively associated with MRT. Across the quartiles of rice intake, the regression coefficients (95% CI) for MRT were 0.0 (reference), 22.4 (-7.8, 52.6), 36.3 (5.1, 67.5), and 34.5 (2.6, 66.4). There was a significant interaction between rice intake and hypertension, BMI, and blood lipids in relation to MRT. The association between rice intake and MRT was only observed among those with hypertension, overweight/obesity, low LDL, and low total cholesterol levels. Serum magnesium did not mediate the association. High rice consumption was associated with a higher MRT, especially among those with hypertension, overweight/obesity, low LDL, and or low total cholesterol levels. Further longitudinal studies are needed to confirm the findings.

Perilla seed oil improves bone health by inhibiting bone resorption in healthy Japanese adults: A 12-month, randomized, double-blind, placebo-controlled trial

Accumulating evidence suggests the beneficial effect of omega-3 polyunsaturated fatty acids (PUFAs) on bone mineral density (BMD). However, the effects of perilla (Perilla frutescens) seed oil (PO), a rich source of α-linoleic acid (LNA), on human bone have not yet been elucidated. This randomized, double-blind, placebo-controlled trial investigated the effects of long-term PO intake on bone health in Japanese adults. After screening for eligibility, 52 participants (mean age 54.2 ± 6.4 years) were randomly assigned to placebo (n = 25) and PO (n = 27) groups, which received 7.0 ml of olive oil and PO daily, respectively. At baseline and 12-month, quantitative ultrasound of the right calcaneus was measured with an ultrasound bone densitometer and percentage of the Young Adult Mean (%YAM) was calculated. Serum levels of tartrate-resistant acid phosphatase 5b (TRACP-5b), and bone alkaline phosphatase (BALP) were evaluated. In addition, PUFA levels in the erythrocyte plasma membrane (RBC-PM), serum biological antioxidant potential (BAP), and diacron reactive oxygen metabolites (d-ROM) were evaluated. Compared with the placebo group, %YAM levels increased and serum TRACP-5b levels decreased significantly in the PO group at 12-month, while serum BALP levels remained unchanged. Moreover, RBC-PM LNA levels and BAP/d-ROM ratios increased significantly in the PO compared with the placebo group. These results suggest that long-term PO intake may improve age-related BMD decline by suppressing bone resorption and increasing LNA levels.

A Non-Randomized Trial Investigating the Impact of Brown Rice Consumption on Gut Microbiota, Attention, and Short-Term Working Memory in Thai School-Aged Children

While dietary fiber has been shown to influence the composition of gut microbiota and cognitive function in adults, much less is known about the fiber-microbiome-cognition association in children. We profiled gut microbiota using quantitative PCR (qPCR) and evaluated cognitive function using the Corsi block-tapping test (CBT) and the psychomotor vigilance test (PVT) before, during, and after the dietary intervention of 127 school-aged children in northern Thailand. While we found that Sinlek rice (SLR) consumption did not significantly alter the abundance of gut microbiota or the cognitive performance of school-aged children, we did find age to be associated with variations in both the gut microbiota profiles and cognitive outcomes. Gammaproteobacteria was significantly lower in the control and SLR groups during the middle time points of both phases (Weeks 4 and 61), and its abundance was associated with age. Cognitive performance using CBT and PVT were also found to be age-sensitive, as older children outperformed younger children on both of these cognitive assessments. Finally, a multiple factor analysis (MFA) revealed that age and cognitive performance best explain individual variation in this study. Collectively, these findings further describe the influence of host variables on the microbial profiles and cognitive outcomes of school-aged children consuming Sinlek rice in Thailand.

White rice, brown rice and the risk of type 2 diabetes: a systematic review and meta-analysis

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.

Effect of the Intake of Brown Rice for Six Months on the Cognitive Function in Healthy Elderly Persons: A Study Protocol for a Pilot, Non-Randomized Controlled Trial

The nutritional components of brown rice have been reported to be effective against diabetes mellitus. Recent animal studies have suggested that it is also effective in maintaining cognitive function. Therefore, in this study, we examined the effect of a brown rice diet on cognitive function in individuals aged over 60 years. The study participants were recruited from a pool of individuals aged ≥60 years who were using elderly care facilities. The participants were provided with four servings of brown or white rice per week for 6 months, and their cognitive function was measured before and after the intervention period. Prior to the intervention, participants tasted the white and brown rice to determine which type they would like to be offered over the 6-month period. Since rice is the staple food of the participants in this study, they were allowed to decide whether they wanted to eat white or brown rice.

Effects of Nutrition on Cognitive Function in Adults with or without Cognitive Impairment: A Systematic Review of Randomized Controlled Clinical Trials

New dietary approaches for the prevention of cognitive impairment are being investigated. However, evidence from dietary interventions is mainly from food and nutrient supplement interventions, with inconsistent results and high heterogeneity between trials. We conducted a comprehensive systematic search of randomized controlled trials (RCTs) published in MEDLINE-PubMed, from January 2018 to July 2021, investigating the impact of dietary counseling, as well as food-based and dietary supplement interventions on cognitive function in adults with or without cognitive impairment. Based on the search strategy, 197 eligible publications were used for data abstraction. Finally, 61 articles were included in the analysis. There was reasonable evidence that dietary patterns, as well as food and dietary supplements improved cognitive domains or measures of brain integrity. The Mediterranean diet showed promising results, whereas the role of the DASH diet was not clear. Healthy food consumption improved cognitive function, although the quality of these studies was relatively low. The role of dietary supplements was mixed, with strong evidence of the benefits of polyphenols and combinations of nutrients, but with low evidence for PUFAs, vitamin D, specific protein, amino acids, and other types of supplements. Further well-designed RCTs are needed to guide the development of dietary approaches for the prevention of cognitive impairment.

The effect of brown rice compared to white rice on adiposity indices, lipid profile, and glycemic markers: a systematic review and meta-analysis of randomized controlled trials

A few randomized controlled trials (RCTs) have assessed the effect of brown rice consumption on metabolic parameters compared to white rice, with inconsistent findings. Therefore, the present systematic review and meta-analysis was designed to evaluate the effect of brown rice on adiposity indices, lipid profile, and glycemic markers in adult subjects compared to white rice. In this study, PubMed/Medline, Scopus, Web of Sciences, and Embase databases were comprehensively searched until March 2021. Thirteen RCTs were selected and then included in the meta-analysis. As reported, brown rice significantly reduced weight by -1.63 kg (95% CI: -2.15 to -1.11, I²=97%, n = 6), body mass index (BMI) by -0.58 kg/m² (95% CI: -0.78 to -0.37, I²=96%, n = 6), and waist circumference by -2.56 cm (95% CI: -4.86 to -0.26, I²=88%, n = 5) compared with white rice. Moreover, it had no significant effect on lipid profile and glycemic markers. Besides, pre-germinated brown rice significantly declined weight (-1.75 kg, 95% CI: -2.70 to -0.81, I²=99%, n = 4), total cholesterol (-24.22 mg/dl, 95% CI: -33.03 to -15.41, I²=78%, n = 5), triglyceride (TG) (-43.28 mg/dl, 95% CI: -74.05 to -12.50, I²=90%, n = 5), low-density lipoprotein (LDL) (-20.05 mg/dl, 95% CI: -29.57 to -10.52, I²=71%, n = 5), and fasting blood glucose (FBG) (-15.83 mg/dl, 95% CI: -25.20 to -6.46, I²=91%, n = 5). In accordance with Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, the certainly of the included evidence was low and very low. The results of the present study indicate that, brown rice has anti-obesity effects in comparison with white rice; however, it has no beneficial effects on lipid profile and glycemic markers. Contrary to brown rice, it was shown that, pre-germinated brown rice significantly decreases body weight and improves lipid profile and FBG levels compared to white rice. Accordingly, our results indicate that, pre-germinated brown rice has better functional effects on promoting lipid profile and FBG compared to brown rice.

The journey from white rice to ultra-high hydrostatic pressurized brown rice: an excellent endeavor for ideal nutrition from staple food

Although brown rice (BR) contains significantly higher levels of nutrients than the traditionally used polished white rice (WR), its consumption among the population is still not noteworthy. WR and BR are essentially same grain. The only difference between the two is the application of an exhaustive milling procedure during the processing of WR that removes all other layers of the grain except the portion of its white endosperm. BR, on the other hand, is prepared by removing only the outer hull of the rice seed. Thus, in addition to its inner endosperm, the bran and germ are also left on the BR. Hence, BR retains all its nutrients, including proteins, lipids, carbohydrates, fibers, vitamins, minerals, tocopherols, tocotrienols, γ-oryzanol, and γ-aminobutyric acid (GABA) packed into the bran and germ of the seed. Since BR tastes nutty and takes longer to cook than WR, it is not appreciated by the consumers. However, these problems have been circumvented using non-thermal ultra-high hydrostatic pressure (UHHP)-processing for the treatment of BR. A superior modification in the physicochemical and functional qualities of UHHPBR, along with its ability to curb human diseases may make it a more palatable and nutritious choice of rice over WR or the untreated-BR. Here, we have reviewed the mechanism by which UHHP treatment leads to the modification of nutrients such as proteins, lipids, carbohydrates, and fibers. We have focused on the effects of rice on cell and animal models of different conditions such as hyperlipidemia, diabetes, and hypertension and the possible mechanisms. Finally, we have emphasized the effects of UHHPBR in human cases with rare conditions such as osteoporosis and brain cognition - two age-related degenerative diseases of the elderly population.

The Effect of Healthy Diet on Cognitive Performance Among Healthy Seniors - A Mini Review

At present, a healthy diet appears to be one of the suitable strategies in slowing down cognitive decline in the process of aging. A number of evidence-based studies confirm its efficacy, safety, and cost-effectiveness. The aim of this mini review is to evaluate and describe recent randomized clinical and cohort studies exploring the effect of healthy diet on cognitive performance among healthy seniors, as well as to update the existing information on this research issue. For these reasons, the authors reviewed full-text, peer-reviewed journal articles written in English and available in Web of Science and PubMed between September 2017 and February 2020. Altogether nine original studies were detected. The results indicate that healthy diet and healthy diet components generally have a positive impact on the enhancement of cognitive functions. Furthermore, the findings reveal that dietary patterns, as well as single nutrients might have a significant effect on specific cognitive domains, such as memory in general, episodic memory, or processing speed. It also seems that a strict adherence to the dietary patterns and a higher diet variety have a more significant effect on the improvement of cognitive functions. Nevertheless, there seem to be gender differences in dietary behavior. More recently, personalized dietary interventions started to be used in delaying cognitive decline among healthy seniors. Therefore, more randomized control trials or N-of-1 trials should be performed in this research area in order to detect the most suitable dietary pattern or nutrients, which would, together with other modifiable lifestyle factors, contribute to the improvement of quality of life of the aging population.