Higher Fruit Intake Is Related to TNF-α Hypomethylation and Better Glucose Tolerance in Healthy Subjects

How Dietary Factors Affect DNA Methylation: Lesson from Epidemiological Studies

Over the past decades, DNA methylation has been proposed as a molecular mechanism underlying the positive or negative effects of diet on human health. Despite the number of studies on this topic is rapidly increasing, the relationship between dietary factors, changes in DNA methylation and health outcomes remains unclear. In this review, we summarize the literature from observational studies (cross-sectional, retrospective, or prospective) which examined the association of dietary factors (nutrients, foods, and dietary patterns) with DNA methylation markers among diseased or healthy people during the lifetime. Next, we discuss the methodological pitfalls by examining strengths and limitations of published studies. Finally, we close with a discussion on future challenges of this field of research, raising the need for large-size prospective studies evaluating the association between diet and DNA methylation in health and diseases for appropriate public health strategies.

Dietary natural products as epigenetic modifiers in aging-associated inflammation and disease

Covering: up to 2020Chronic, low-grade inflammation is linked to aging and has been termed "inflammaging". Inflammaging is considered a key contributor to the development of metabolic dysfunction and a broad spectrum of diseases or disorders including declines in brain and heart function. Genome-wide association studies (GWAS) coupled with epigenome-wide association studies (EWAS) have shown the importance of diet in the development of chronic and age-related diseases. Moreover, dietary interventions e.g. caloric restriction can attenuate inflammation to delay and/or prevent these diseases. Common themes in these studies entail the use of phytochemicals (plant-derived compounds) or the production of short chain fatty acids (SCFAs) as epigenetic modifiers of DNA and histone proteins. Epigenetic modifications are dynamically regulated and as such, serve as potential therapeutic targets for the treatment or prevention of age-related disease. In this review, we will focus on the role for natural products that include phytochemicals and short chain fatty acids (SCFAs) as regulators of these epigenetic adaptations. Specifically, we discuss regulators of methylation, acetylation and acylation, in the protection from chronic inflammation driven metabolic dysfunction and deterioration of neurocognitive and cardiac function.

Baseline Pro-inflammatory Diet Is Inversely Associated with Change in Weight and Body Fat 6 Months Following-up to Bariatric Surgery

OBJECTIVE

To evaluate whether the baseline Dietary Inflammatory Index (DII®) was associated with weight loss and body composition change after bariatric surgery.

METHODOLOGY

This longitudinal study included 132 women with obesity (BMI ≥ 35 kg/m², 43.0 ± 9.7 years), followed up for 6 months after bariatric surgery. The DII® was calculated from dietary data collected using 24-h dietary recall interviews. Anthropometric variables, socio demographic variables, health-related habits, history of disease, as well as gastrointestinal symptoms, both in the preoperative period (baseline) and 6 months after bariatric surgery were collected from the patients' medical records.

RESULTS

Individuals with a more pro-inflammatory diet (DII > 0.35 median value) preoperatively experienced smaller weight loss (- 22.7% vs. - 25.3%, p = 0.02) and fat mass loss (- 31.9 vs. - 36.2%, p = 0.026), with no difference in lean mass (p = 0.14). In a linear regression model, the baseline DII score was negatively associated with percentage change in weight and fat mass and positively associated with weight and fat mass in the sixth month after surgery. In addition, a pro-inflammatory baseline DII score was correlated with a lower intake of fruit (r = - 0.26, p = 0.006), vegetables (r = - 0.47, p = 0.001), and legumes (r = - 0.21, p = 0.003) in the postoperative period.

CONCLUSION

In this longitudinal study, a pro-inflammatory diet at baseline was associated with smaller reductions in weight and body fat and poorer dietary quality (reduced consumption of fruits, vegetables, and legumes) 6 months after bariatric surgery.

Branched-Chain amino acids intake is negatively related to body adiposity in individuals at cardiometabolic risk

ABSTRACT Objective To assess the relationship between branched-chain amino acids intake in the current diet and the metabolic and body adiposity markers in a population at cardiovascular risk. Methods This is a cross-sectional study with 282 adults and elderly people from the Cardiovascular Health Care Program of the Universidade Federal de Viçosa. Sociodemographic, anthropometric and body composition data, as well as metabolic biomarkers were collected using standardized protocols. Dietary intake of branched amino acids was assessed using a 24-hour recall. Results Individuals with a higher branched-chain amino acids intake (≥2.6g/day, median value) had lower body fat (29.6 vs 32.2%; p=0.019), and higher serum ferritin (113.2 vs. 60.1mg/dL; p=0.006) and uric acid concentrations (4.4 vs. 4.0; p=0.023). In addition, a lower prevalence of overweight and excessive abdominal fat (p<0.05) was found in the individuals with higher branched-chain amino acids intake. They also had a higher daily intake of fiber, copper, zinc, magnesium, and iron, as well as a lower intake of total lipids. Conclusion In the present study, the intake of branched amino acids is negatively related to total and central adiposity, but more studies are needed to fully elucidate this possible relationship. (Brazilian Registry of Clinical Trials, code RBR-5n4y2g).

A Review of the Potential of Chilean Native Berries in the Treatment of Obesity and its Related Features

Obesity is a major worldwide health threat. It is characterized by an abnormal adipose tissue overgrowth together with increased monocytes infiltration, causing inflammation and oxidative stress, events associated with several illnesses. Investigations have focused on the benefits of native fruit consumption, claiming these to be natural sources of bioactive compounds with antioxidant and anti-inflammatory characteristics. It has been widely stated that berries are a source of the most antioxidant compounds, and, thus, seem highly promising to endure research efforts on these vegetal matrices. The present article describes botanical, chemical and biomedical features of the Chilean native berries, Aristotelia chilensis, Ugni molinae, and Berberis microphylla. This work aims to potentiate incoming research focused on the search for novel treatments for first-order diseases with these particular plant sources.

Whole Fruits and Fruit Fiber Emerging Health Effects

Less than 10% of most Western populations consume adequate levels of whole fruits and dietary fiber with typical intake being about half of the recommended levels. Evidence of the beneficial health effects of consuming adequate levels of whole fruits has been steadily growing, especially regarding their bioactive fiber prebiotic effects and role in improved weight control, wellness and healthy aging. The primary aim of this narrative review article is to examine the increasing number of health benefits which are associated with the adequate intake of whole fruits, especially fruit fiber, throughout the human lifecycle. These potential health benefits include: protecting colonic gastrointestinal health (e.g., constipation, irritable bowel syndrome, inflammatory bowel diseases, and diverticular disease); promoting long-term weight management; reducing risk of cardiovascular disease, type 2 diabetes and metabolic syndrome; defending against colorectal and lung cancers; improving odds of successful aging; reducing the severity of asthma and chronic obstructive pulmonary disease; enhancing psychological well-being and lowering the risk of depression; contributing to higher bone mineral density in children and adults; reducing risk of seborrheic dermatitis; and helping to attenuate autism spectrum disorder severity. Low whole fruit intake represents a potentially more serious global population health threat than previously recognized, especially in light of the emerging research on whole fruit and fruit fiber health benefits.

Dopamine gene methylation patterns are associated with obesity markers and carbohydrate intake

INTRODUCTION

Dopamine (DA) is a neurotransmitter that regulates the rewarding and motivational processes underlying food intake and eating behaviors. This study hypothesized associations of DNA methylation signatures at genes modulating DA signaling with obesity features, metabolic profiles, and dietary intake.

METHODS

An adult population within the Methyl Epigenome Network Association project was included (n = 473). DNA methylation levels in white blood cells were measured by microarray (450K). Differentially methylated genes were mapped within the dopaminergic synapse pathway using the KEGG reference database (map04728). Subsequently, network enrichment analyses were run in the pathDIP portal. Associations of methylation patterns with anthropometric markers of general (BMI) and abdominal obesity (waist circumference), the blood metabolic profile, and daily dietary intakes were screened.

RESULTS

After applying a correction for multiple comparisons, 12 CpG sites were strongly associated (p < 0.0001) with BMI: cg03489495 (ITPR3), cg22851378 (PPP2R2D), cg04021127 (PPP2R2D), cg22441882 (SLC18A1), cg03045635 (DRD5), cg23341970 (ITPR2), cg13051970 (DDC), cg08943004 (SLC6A3), cg20557710 (CACNA1C), cg24085522 (GNAL), cg16846691 (ITPR2), and cg09691393 (SLC6A3). Moreover, average methylation levels of these genes differed according to the presence or absence of abdominal obesity. Pathway analyses revealed a statistically significant contribution of the aforementioned genes to dopaminergic synapse transmission (p = 4.78E-08). Furthermore, SLC18A1 and SLC6A3 gene methylation signatures correlated with total energy (p < 0.001) and carbohydrate (p < 0.001) intakes.

CONCLUSIONS

The results of this investigation reveal that methylation status on DA signaling genes may underlie epigenetic mechanisms contributing to carbohydrate and calorie consumption and fat deposition.

α-Tocopherol influences glycaemic control and miR-9-3 DNA methylation in overweight and obese women under an energy-restricted diet: a randomized, double-blind, exploratory, controlled clinical trial

Background

Excess weight is a strong risk factor for the development of dysglycaemia. It has been suggested that changes in the metabolism microRNAs, small non-coding RNAs that regulate gene expression, could precede late glycaemic changes. Vitamin E in turn may exert important functions in methylation and gene expression processes. This study aimed to determine the effect of α-tocopherol on glycaemic variables and miR-9-1 and miR-9-3 promoter DNA methylation in overweight women.

Methods

A randomized, double-blind, exploratory, placebo-controlled study was conducted in overweight and obese adult women (n = 44) who ingested synthetic vitamin E (all-rac-α-tocopherol), natural source vitamin E (RRR-rac-α-tocopherol) or placebo capsules and were followed up for a period of 8 weeks. Supplemented groups also received dietary guidance for an energy-restricted diet. An additional group that received no supplementation and did not follow an energy-restricted diet was also followed up. The intervention effect was evaluated by DNA methylation levels (quantitative real-time PCR assay) and anthropometric and biochemical variables (fasting plasma glucose, haemoglobin A1C, insulin, and vitamin E).

Results

Increased methylation levels of the miR-9-3 promoter region (P < 0.001) and reduced haemoglobin A1C (P < 0.05) were observed in the natural source vitamin E group after intervention. Increased fasting plasma glucose was observed in the synthetic vitamin E group, despite the significant reduction of anthropometric variables compared to the other groups.

Conclusions

α-Tocopherol from natural sources increased methylation levels of the miR-9-3 promoter region and reduced haemoglobin A1C in overweight women following an energy-restricted diet. These results provide novel information about the influence of vitamin E on DNA methylation.

Trial registration

ClinicalTrials.gov, NCT02922491. Registered 4 October, 2016.

Electronic supplementary material

The online version of this article (10.1186/s12986-018-0286-7) contains supplementary material, which is available to authorized users.

Epigenome-Wide Association Study of Dietary Fiber Intake in African American Adolescents

SCOPE

Low fiber intake is associated with increased risk for cardiovascular disease (CVD) and cancer. However, the underlying mechanisms are not well understood. Two hypotheses are tested: 1) dietary fiber would be associated with DNA methylation levels; 2) those DNA methylation changes would be associated with visceral adiposity and inflammation. Also the possibility that the associations between fiber and DNA methylation levels might be confounded with folic acid intake as sensitivity analysis are explored.

METHODS AND RESULTS

An epigenome-wide association study is conducted using Illumina 450K Bead-Chip on leukocyte DNA in 284 African American adolescents. Linear regression is performed to identify differentially methylated CpG sites associated with fiber. The methylation levels of 3 CpG sites (cg15200711, cg19462022, and cg07035602) in LPCAT1 and RASA3 genes are associated with fiber (false discovery rate [FDR] < 0.05) after adjustment for covariates including folic acid. The methylation levels of cg07035602 and cg19462022 are also associated with visceral adiposity and inflammation.

CONCLUSIONS

The data show that DNA methylation levels at LPCAT1 and RASA3 genes are associated with dietary fiber intake as well as with adiposity and inflammation. Future studies are warranted to determine whether epigenetic regulation may underlie the beneficial effects of fiber intake on adiposity and inflammation.

Association of low dietary folate intake with lower CAMKK2 gene methylation, adiposity, and insulin resistance in obese subjects

Folate deficiency has been putatively implicated in the onset of diverse metabolic abnormalities, including insulin resistance, by altering epigenetic processes on key regulatory genes. The calcium/calmodulin-dependent protein kinase kinase 2 (CAMKK2) is involved in the regulation of critical metabolic processes such as adiposity and glucose homeostasis. This study hypothesized associations between low folate intakes and lower methylation levels of the CAMKK2 gene, with the presence of metabolic alterations in subjects with obesity. A cross-sectional ancillary study was conducted in obese subjects (n=47) from the RESMENA study (Spain). Fat mass was measured by dual-energy x-ray absorptiometry. Dietary intake and metabolic profile were assessed by validated methods. DNA methylation and gene expression in peripheral white blood cells were analyzed by microarray approaches. A total of 51 cytosine-phosphate-guanine sites were associated with folate intake (false discovery rate values < 0.0001), including one located in the 5' untranslated region of the CAMKK2 gene (Illumina ID, cg16942632), which was selected and separately analyzed. Subjects with total folate intake lower than 300μg/d showed more fat mass (especially trunk fat), as well as statistically higher levels of glucose, insulin, homeostatic model assessment-insulin resistance (HOMA-IR) index, cortisol, and plasminogen activator inhibitor-1 than those consuming at least or more than 300μg/d. Of note, folate deficiency was related to lower CAMKK2 methylation. Interestingly, CAMKK2 methylation negatively correlated with the HOMA-IR index. Furthermore, CAMKK2 expression directly correlated with HOMA-IR values. In summary, this study suggests associations between low folate intakes, lower CAMKK2 gene methylation, and insulin resistance in obese individuals.

Prevention of metabolic diseases: fruits (including fruit sugars) vs. vegetables

PURPOSE OF REVIEW

To discuss recent evidence from observational and intervention studies on the relationship between fruit and vegetable (F&V) consumption and metabolic disease.

RECENT FINDINGS

Observational studies have consistently demonstrated a modest inverse association between the intake of fruit and leafy green vegetables, but not total vegetables, and biomarkers of metabolic disease as well as incident type 2 diabetes mellitus. This is in contrast to limited evidence from recently published randomized controlled dietary intervention trials, which - in sum - suggests little to no impact of increased F&V consumption on biomarkers of metabolic disease.

SUMMARY

Evidence from observational studies that fruit and leafy green vegetable intake is associated with lower type 2 diabetes risk and better metabolic health could not be confirmed by dietary intervention trials. It is unclear whether this discrepancy is because of limitations inherent in observational studies (e.g., subjective dietary assessment methods, residual confounding) or due to limitations in the few available intervention studies (e.g., short duration of follow-up, interventions combining whole fruit and fruit juice, or lack of compliance). Future studies that attempt to address these limitations are needed to provide more conclusive insight into the impact of F&V consumption on metabolic health.

[Epigenetics and obesity]

Current evidence supports the notion that exposure to various environmental conditions in early life may induce permanent changes in the epigenome that persist throughout the life-course. This article focuses on early changes associated with obesity in adult life. A review is presented on the factors that induce changes in whole genome (DNA) methylation in early life that are associated with adult onset obesity and related disorders. In contrast, reversal of epigenetic changes associated with weight loss in obese subjects has not been demonstrated. This contrasts with well-established associations found between obesity related DNA methylation patterns at birth and adult onset obesity and diabetes. Epigenetic markers may serve to screen indivuals at risk for obesity and assess the effects of interventions in early life that may delay or prevent obesity in early life. This might contribute to lower the obesity-related burden of death and disability at the population level. The available evidence indicates that epigenetic marks are in fact modifiable, based on modifications in the intrauterine environment and changes in food intake, physical activity and dietary patterns patterns during pregnancy and early years of adult life. This offers the opportunity to intervene before conception, during pregnancy, infancy, childhood, and also in later life. There must be documentation on the best preventive actions in terms of diet and physical activity that will modify or revert the adverse epigenetic markers, thus preventing obesity and diabetes in suceptible individuals and populations.