Prospective study of telomere length and LINE-1 methylation in peripheral blood cells: the role of B vitamins supplementation

Therapeutic Potential of Natural Compounds Acting through Epigenetic Mechanisms in Cardiovascular Diseases: Current Findings and Future Directions

Cardiovascular diseases (CVDs) remain a leading global cause of morbidity and mortality. These diseases have a multifaceted nature being influenced by a multitude of biochemical, genetic, environmental, and behavioral factors. Epigenetic modifications have a crucial role in the onset and progression of CVD. Epigenetics, which regulates gene activity without altering the DNA's primary structure, can modulate cardiovascular homeostasis through DNA methylation, histone modification, and non-coding RNA regulation. The effects of environmental stimuli on CVD are mediated by epigenetic changes, which can be reversible and, hence, are susceptible to pharmacological interventions. This represents an opportunity to prevent diseases by targeting harmful epigenetic modifications. Factors such as high-fat diets or nutrient deficiencies can influence epigenetic enzymes, affecting fetal growth, metabolism, oxidative stress, inflammation, and atherosclerosis. Recent studies have shown that plant-derived bioactive compounds can modulate epigenetic regulators and inflammatory responses, contributing to the cardioprotective effects of diets. Understanding these nutriepigenetic effects and their reversibility is crucial for developing effective interventions to combat CVD. This review delves into the general mechanisms of epigenetics, its regulatory roles in CVD, and the potential of epigenetics as a CVD therapeutic strategy. It also examines the role of epigenetic natural compounds (ENCs) in CVD and their potential as intervention tools for prevention and therapy.

Examining nutrition strategies to influence DNA methylation and epigenetic clocks: a systematic review of clinical trials

Nutrition has powerful impacts on our health and longevity. One of the mechanisms by which nutrition might influence our health is by inducing epigenetic modifications, modulating the molecular mechanisms that regulate aging. Observational studies have provided evidence of a relationship between nutrition and differences in DNA methylation. However, these studies are limited in that they might not provide an accurate control of the interactions between different nutrients, or between nutrition and other lifestyle behaviors. Here we systematically reviewed clinical studies examining the impact of nutrition strategies on DNA methylation. We examined clinical studies in community-dwelling adults testing the effects of nutrition interventions on i) global DNA methylation and its proxies, and ii) epigenetic clocks. We included 21 intervention studies that focused on the effects of healthy nutrition patterns, specific foods or nutrients, as well as the effect of multivitamin or multimineral supplements. In four studies on the methylation effects of healthy dietary patterns, as defined by being rich in vegetables, fruits, whole-grains, and nuts and reduced in the intake of added sugars, saturated fat, and alcohol, two of them suggested that a healthy diet, is associated with lower epigenetic age acceleration, one of them reported increases in global DNA methylation, while another one found no diet effects. Studies examining epigenetic effects of specific foods, nutrients, or mixtures of nutrients were scarce. For both folic acid and polyunsaturated fatty acids, the available independent studies produced conflicting findings. Although more evidence is still needed to draw firm conclusions, results begin to suggest that healthy dietary patterns have positive effects on DNA methylation. Additional evidence from large randomized-controlled clinical trials is needed to support the effects of healthy nutrition on the DNA methylome.

A Liquid Biopsy-Based Approach for Monitoring Treatment Response in Post-Operative Colorectal Cancer Patients

Monitoring the therapeutic response of colorectal cancer (CRC) patients is crucial to determine treatment strategies; therefore, we constructed a liquid biopsy-based approach for tracking tumor dynamics in non-metastatic (nmCRC) and metastatic (mCRC) patients (n = 55). Serial blood collections were performed during chemotherapy for measuring the amount and the global methylation pattern of cell-free DNA (cfDNA), the promoter methylation of SFRP2 and SDC2 genes, and the plasma homocysteine level. The average cfDNA amount was higher (p < 0.05) in nmCRC patients with recurrent cancer (30.4 ± 17.6 ng) and mCRC patients with progressive disease (PD) (44.3 ± 34.5 ng) compared to individuals with remission (13.2 ± 10.0 ng) or stable disease (12.5 ± 3.4 ng). More than 10% elevation of cfDNA from first to last sample collection was detected in all recurrent cases and 92% of PD patients, while a decrease was observed in most patients with remission. Global methylation level changes indicated a decline (75.5 ± 3.4% vs. 68.2 ± 8.4%), while the promoter methylation of SFRP2 and SDC2 and homocysteine level (10.9 ± 3.4 µmol/L vs. 13.7 ± 4.3 µmol/L) presented an increase in PD patients. In contrast, we found exact opposite changes in remission cases. Our study offers a more precise blood-based approach to monitor the treatment response to different chemotherapies than the currently used markers.

The Controversial Role of HCY and Vitamin B Deficiency in Cardiovascular Diseases

Plasma homocysteine (HCY) is an established risk factor for cardiovascular disease CVD and stroke. However, more than two decades of intensive research activities has failed to demonstrate that Hcy lowering through B-vitamin supplementation results in a reduction in CVD risk. Therefore, doubts about a causal involvement of hyperhomocysteinemia (HHcy) and B-vitamin deficiencies in atherosclerosis persist. Existing evidence indicates that HHcy increases oxidative stress, causes endoplasmatic reticulum (ER) stress, alters DNA methylation and, thus, modulates the expression of numerous pathogenic and protective genes. Moreover, Hcy can bind directly to proteins, which can change protein function and impact the intracellular redox state. As most mechanistic evidence is derived from experimental studies with rather artificial settings, the relevance of these results in humans remains a matter of debate. Recently, it has also been proposed that HHcy and B-vitamin deficiencies may promote CVD through accelerated telomere shortening and telomere dysfunction. This review provides a critical overview of the existing literature regarding the role of HHcy and B-vitamin deficiencies in CVD. At present, the CVD risk associated with HHcy and B vitamins is not effectively actionable. Therefore, routine screening for HHcy in CVD patients is of limited value. However, B-vitamin depletion is rather common among the elderly, and in such cases existing deficiencies should be corrected. While Hcy-lowering with high doses of B vitamins has no beneficial effects in secondary CVD prevention, the role of Hcy in primary disease prevention is insufficiently studied. Therefore, more intervention and experimental studies are needed to address existing gaps in knowledge.

The regulatory role of N6 -methyladenosine modification in the interaction between host and microbes

N⁶ -methyladenosine (m⁶ A) is the most prevalent posttranscriptional modification in eukaryotic mRNAs. Dynamic and reversible m⁶ A modification regulates gene expression to control cellular processes and diverse biological functions. Growing evidence indicated that m⁶ A modification is involved in the homeostasis of host and microbes (mostly viruses and bacteria). Disturbance of m⁶ A modification affects the life cycles of viruses and bacteria, however, these microbes could in turn change host m⁶ A modification leading to human disease including autoimmune diseases and cancer. Thus, we raise the concept that m⁶ A could be a "messenger" molecule to participate in the interactions between host and microbes. In this review, we summarize the regulatory mechanisms of m⁶ A modification on viruses and commensal microbiota, highlight the roles of m⁶ A methylation in the interaction of host and microbes, and finally discuss drugs development targeting m⁶ A modification. This article is categorized under: RNA in Disease and Development > RNA in Disease.

Telomere length as a biomarker of aging and diseases

As research related to healthspan and lifespan has become a hot topic, the necessity for a reliable and practical biomarker of aging (BoA), which can provide information about mortality and morbidity risk, along with remaining life expectancy, has increased. The chromosome terminus non-coding protective structure that prevents genomic instability is called a telomere. The continual shortening of telomeres, which affects their structure as well as function, is a hallmark of agedness. The aforementioned process is a potential cause of age-related diseases (ARDs), leading to a bad prognosis and a low survival rate, which compromise health and longevity. Hence, studies scrutinizing the BoAs often include telomere length (TL) as a prospective candidate. The results of these studies suggest that TL measurement can only provide an approximate appraisal of the aging rate, and its implementation into clinical practice and routine use as a BoA has many limitations and challenges. Nevertheless, measuring TL while determining other biomarkers can be used to assess biological age. This review focuses on the importance of telomeres in health, senescence, and diseases, as well as on summarizing the results and conclusions of previous studies evaluating TL as a potential BoA.

The Association between Dietary Magnesium Intake and Telomere Length in Adults with Hypertension

BACKGROUND

Dietary micronutrients are significantly associated with telomere length, as shown in multiple studies. However, no study has investigated the association between magnesium intake and telomere length in adults with hypertension.

METHODS

Participants were included from the National Health and Nutrition Examination Survey (NHANES) in 1999-2000 and 2001-2002. Dietary magnesium intake was assessed using the 24 - hour recall method and the telomere length of leukocytes was measured using polymerase chain reaction (PCR). A multivariate regression model was then used to assess the association between dietary magnesium intake and telomere length in adults with hypertension.

RESULTS

Our final analysis included 2199 hypertensive adults (46.79% males) with a mean dietary magnesium intake of 254.82±133.47 mg/day. Linear regression, adjusted for race, sex, age, smoking, uric acid, and other variables, showed that every 1 mg increase in dietary magnesium intake was associated with a 0.20 (95% CI: 0.01, 0.39, p = 0.043) longer telomere length in all participants. In the ≥45 years age group, there was a statistically significant association between the telomere length and dietary magnesium (95% CI: 0.16, 0.63, p <0.001).

CONCLUSIONS

This study suggests that increased magnesium intake is associated with a longer telomere length in hypertensive adults, especially in those ≥45 years of age. However, further research is needed to determine a causal relationship.

Telomeres and Age-Related Diseases

Telomeres are at the non-coding ends of linear chromosomes. Through a complex 3-dimensional structure, they protect the coding DNA and ensure appropriate separation of chromosomes. Aging is characterized by a progressive shortening of telomeres, which compromises their structure and function. Because of their protective function for genomic DNA, telomeres appear to play an important role in the development and progression of many age-related diseases, such as cardiovascular disease (CVD), malignancies, dementia, and osteoporosis. Despite substantial evidence that links telomere length with these conditions, the nature of these observations remains insufficiently understood. Therefore, future studies should address the question of causality. Furthermore, analytical methods should be further improved with the aim to provide informative and comparable results. This review summarize the actual knowledge of telomere biology and the possible implications of telomere dysfunction for the development and progression of age-related diseases. Furthermore, we provide an overview of analytical techniques for the measurement of telomere length and telomerase activity.

Environmental pollutants exposure: A potential contributor for aging and age-related diseases

Telomeres are "protective messengers" at the ends of eukaryotic chromosomes that protect them from degradation, end to end fusion and recombination. Admittedly, telomeres progressively shorten with age that can also be significantly accelerated by pathological conditions, which are often considered as potential contributors for cellular senescence. It is commonly believed that constant accumulation of senescent cells may lead to dysfunctional tissues and organs, thereby accelerating aging process and subsequent occurrence of age-related diseases. In particular, epidemiological data has indicated a significant association between environmental pollutants exposure and a high incidence of age-related diseases. Moreover, there is growing evidence that environmental toxicity has a detrimental impact on telomere length. Overall, a consensus is emerging that environmental pollutants exposure could lead to accelerated telomere erosion and further induce premature senescence, which may be responsible for the acceleration of aging and the high morbidity and mortality rates of age-related diseases.

Physical activity, a modulator of aging through effects on telomere biology

Aging is a complex process that is not well understood but involves finite changes at the genetic and epigenetic level. Physical activity is a well-documented modulator of the physiological process of aging. It has been suggested that the beneficial health effects of regular exercise are at least partly mediated through its effects on telomeres and associated regulatory pathways. Telomeres, the region of repetitive nucleotide sequences functioning as a "cap" at the chromosomal ends, play an important role to protect genomic DNA from degradation. Telomeres of dividing cells progressively shorten with age. Leucocyte telomere length (TL) has been associated with age-related diseases. Epidemiologic evidence indicates a strong relationship between physical activity and TL. In addition, TL has also been shown to predict all-cause and cardiovascular mortality. Experimental studies support a functional link between aerobic exercise and telomere preservation through activation of telomerase, an enzyme that adds nucleotides to the telomeric ends. However, unresolved questions regarding exercise modalities, pathomechanistic aspects and analytical issues limit the interpretability of available data. This review provides an overview about the current knowledge in the area of telomere biology, aging and physical activity. Finally, the capabilities and limitations of available analytical methods are addressed.

Periconceptional environment predicts leukocyte telomere length in a cross-sectional study of 7-9 year old rural Gambian children

Early life exposures are important predictors of adult disease risk. Although the underlying mechanisms are largely unknown, telomere maintenance may be involved. This study investigated the relationship between seasonal differences in parental exposures at time of conception and leukocyte telomere length (LTL) in their offspring. LTL was measured in two cohorts of children aged 2 yrs (N = 487) and 7–9 yrs (N = 218). The association between date of conception and LTL was examined using Fourier regression models, adjusted for age, sex, leukocyte cell composition, and other potential confounders. We observed an effect of season in the older children in all models [likelihood ratio test (LRT) χ²₂ = 7.1, p = 0.03; fully adjusted model]. LTL was greatest in children conceived in September (in the rainy season), and smallest in those conceived in March (in the dry season), with an effect size (LTL peak–nadir) of 0.60 z-scores. No effect of season was evident in the younger children (LRT χ²₂ = 0.87, p = 0.65). The different results obtained for the two cohorts may reflect a delayed effect of season of conception on postnatal telomere maintenance. Alternatively, they may be explained by unmeasured differences in early life exposures, or the increased telomere attrition rate during infancy.

Riboflavin supplementation alters global and gene-specific DNA methylation in adults with the MTHFR 677 TT genotype

DNA methylation is important in regulating gene expression and genomic stability while aberrant DNA methylation is associated with disease. Riboflavin (FAD) is a cofactor for methylenetetrahydrofolate reductase (MTHFR), a critical enzyme in folate recycling, which generates methyl groups for homocysteine remethylation to methionine, the pre-cursor to the universal methyl donor S-adenosylmethionine (SAM). A polymorphism (C677T) in MTHFR results in decreased MTHFR activity and increased homocysteine concentration. Previous studies demonstrated that riboflavin modulates this phenotype in homozygous adults (MTHFR 677 TT genotype), however, DNA methylation was not considered. This study examined DNA methylation, globally and at key MTHFR regulatory sites, in adults stratified by MTHFR genotype and the effect of riboflavin supplementation on DNA methylation in individuals with the 677 TT genotype. Samples were accessed from participants, screened for the MTHFR C677T polymorphism, who participated in observational (n = 80) and targeted riboflavin (1.6 mg/day) RCTs (n = 80). DNA methylation at LINE-1 and key regulatory regions of the MTHFR locus were analysed by pyrosequencing in peripheral blood leukocytes. LINE-1 (+1.6%; p = 0.011) and MTHFR south shelf (+4.7%, p < 0.001) were significantly hypermethylated in individuals with the MTHFR 677 TT compared to CC genotype. Riboflavin supplementation resulted in decreased global methylation, albeit only significant at one CpG. A significant reduction in DNA methylation at the MTHFR north shore (-1.2%, p < 0.001) was also observed in TT adults following intervention with riboflavin. This provides the first RCT evidence that DNA methylation may be modulated by riboflavin in adults with the MTHFR 677 TT genotype.

The Impact of Health Promotion Interventions on Telomere Length: A Systematic Review

Objectives:

The aim of this study was to evaluate the effectiveness of health promotion interventions in delaying telomere shortening (a biomarker for aging).

Data Source:

PubMed, PsychINFO, EMBASE, CINAHL, and Cochrane Library databases.

Study Inclusion and Exclusion Criteria:

Inclusion criteria: (1) empirical studies involving human subjects; (2) health promotion intervention studies including both randomized control trials (RCTs) and non-RCTs.; (3) measured telomere length as an intervention outcome; and (4) were written in English. Exclusion criteria: (1) observational studies without any health promotion intervention practices and (2) did not report intervention effects.

Data Extraction:

Data extraction was performed by two reviewers following the preferred reporting items for systematic reviews and meta-analysis guidelines.

Data Synthesis:

Substantial heterogeneity in intervention type and study design in the included studies precluded a meta-analysis. We conducted a narrative synthesis instead.

Results:

Thirty studies were included in the review, of which 16 were RCTs. One-third of the included studies reported significant intervention impacts in delaying telomere shortening, with relatively consistent significant results emerged from weight-loss interventions and interventions involving multiple lifestyle modification components (eg, diet and exercise). Most of supplement intervention studies observed null effects in telomere length.

Conclusions:

Weight-loss and comprehensive lifestyle intervention strategies show encouraging impacts in delaying telomere shortening. More rigorous studies targeting populations at different age stages through life span are needed.

Influence of nutrients involved in one-carbon metabolism on DNA methylation in adults—a systematic review and meta-analysis

Context

Aberrant DNA methylation is linked to various diseases. The supply of methyl groups for methylation reactions is mediated by S-adenosylmethionine, which depends on the availability of folate and related B vitamins.

Objectives

To investigate the influence of key nutrients involved in 1-carbon metabolism on DNA methylation in adults.

Data sources

Systematic literature searches were conducted in the Cochrane Library, Medline, Embase, Cumulative Index to Nursing and Allied Health Literature Plus, Scopus, and Web of Science databases. Studies that met the inclusion criteria and were published in English were included.

Data extraction

The first author, study design, sample size, population characteristics, type and duration of intervention, tissue type or cells analyzed, molecular techniques, and DNA methylation outcomes.

Data synthesis

A meta-analysis of randomized, controlled trials (RCTs) was conducted to investigate the effect of 1-carbon metabolism nutrients on global DNA methylation. Functional analysis and visualization were performed using BioVenn software.

Results

From a total of 2620 papers screened by title, 53 studies met the inclusion criteria. Qualitative analysis indicated significant associations between 1-carbon metabolism nutrients and DNA methylation. In meta-analysis of RCTs stratified by method of laboratory analysis, supplementation with folic acid alone or in combination with vitamin B12 significantly increased global DNA methylation in studies using liquid chromatography–mass spectrometry, which had markedly lower heterogeneity (n = 3; Z = 3.31; P = 0.0009; I2 = 0%) in comparison to other methods. Functional analysis highlighted a subset of 12 differentially methylated regions that were significantly related to folate and vitamin B12 biomarkers.

Conclusion

This study supports significant associations between 1-carbon metabolism nutrients and DNA methylation. However, standardization of DNA methylation techniques is recommended to reduce heterogeneity and facilitate comparison across studies.

Systematic Review registration

PROSPERO registration number: CRD42018091898.

Telomere length and associated factors in older adults with hypertension

Telomeres and telomerase play important roles in the occurrence and development of hypertension. This review was performed to clarify the factors that influence telomere length and telomerase activity in older patients and elucidate the association of these factors with hypertension. A PubMed search and critical review of studies assessing the risk factors underlying the association of hypertension with telomere length and telomerase activity was performed. Telomere length and telomerase activity were found to be associated with hypertension. The factors that influence telomere length and telomerase activity in older patients with hypertension include genetics, demographics, social and environmental factors, chronic disease, psychological factors, and antihypertensive drug treatment. A better understanding of the molecular mechanisms underlying the association of hypertension with telomere length and telomerase activity may help to reduce the incidence of hypertension.

Telomere length, vitamin B12 and mortality in persons undergoing coronary angiography: the Ludwigshafen risk and cardiovascular health study

Background: Vitamin B12 (B12) deficiency and excess are associated with increased risk of age-related-diseases and mortality. It has been suggested that high- and low-B12 concentrations link to increased mortality through accelerated genomic aging and inflammation. Evidence to support this is limited.

Results: B12 was associated with all-cause-mortality, RTL and hsCRP in a non-linear fashion. The association between B12 and mortality was not independent, as it lost significance after adjustment for potential confounders. In the lowest-(LB12) and highest-(HB12) quartiles of B12 mortality was higher than in the mid-range (HR:LB12:1.23;CI95%:1.06-1.43; HR:HB12:1.24;CI95%:1.06-1.44). We divided subjects with LB12 in quartiles of their RTL. Those with the longest-telomeres had a lower mortality-rate (HR:0.57;95%CI:0.39-0.83) and lower homocysteine than those with the shortest-telomeres. Amongst subjects with HB12, those with long-telomeres also had a lower mortality than those with short-telomeres (HR:0.40;95%CI:0.27-0.59). IL-6 and hsCRP concentrations were low in HB12LT but were high in HB12ST.

Methods: B12, homocysteine, telomere length (RTL), interleukin-6 (IL-6) and high-sensitive-C-reactive-protein (hsCRP) were measured in 2970 participants of the LURIC study.

Conclusions: Mortality, stratified according to B12 and RTL, seems to be driven by different mechanisms. In LB12 and HB12 subjects, mortality and accelerated telomere shortening might be driven by homocysteine and inflammation, respectively.

Discovery of potent telomerase activators: Unfolding new therapeutic and anti-aging perspectives

Telomere length, a marker of cellular aging, decreases with age and it has been associated with aging‑related diseases. Environmental factors, including diet and lifestyle factors, affect the rate of telomere shortening which can be reversed by telomerase. Telomerase activation by natural molecules has been suggested to be an anti‑aging modulator that can play a role in the treatment of aging‑related diseases. This study aimed to investigate the effect of natural compounds on telomerase activity in human peripheral blood mononuclear cells (PBMCs). The tested compounds included Centella asiatica extract formulation (08AGTLF), Astragalus extract formulation (Nutrient 4), TA‑65 (containing Astragalus membranaceus extract), oleanolic acid (OA), maslinic acid (MA), and 3 multi‑nutrient formulas (Nutrients 1, 2 and 3) at various concentrations. The mean absorbance values of telomerase activity measured following treatment with some of the above‑mentioned formulations were statistically significantly higher compared to those of the untreated cells. In particular, in order of importance with respect to telomerase activation from highest to lowest, 08AGTLF, OA, Nutrient 4, TA‑65, MA, Nutrient 3 and Nutrient 2, triggered statistically significant increase in telomerase activity compared to the untreated cells. 08AGTLF reached the highest levels of telomerase activity reported to date, at least to our knowledge, increasing telomerase activity by 8.8 folds compared to untreated cells, while Nutrient 4 and OA were also potent activators (4.3‑fold and 5.9‑fold increase, respectively). On the whole, this study indicates that the synergistic effect of nutrients and natural compounds can activate telomerase and produce more potent formulations. Human clinical studies using these formulations are required to evaluate their mode of action. This would reveal the health benefits of telomerase activation through natural molecules and would shed new light onto the treatment of aging‑related diseases.

Association of nutraceutical supplements with longer telomere length

Telomeres are nucleotide tandem repeats located at the tip of eukaryotic chromosomes that maintain genomic integrity. The gradual shortening of telomeres leads to cellular senescence and apoptosis, a key mechanism of aging and age‑related chronic diseases. Epigenetic factors, such as nutrition, exercise and tobacco can affect the rate at which telomeres shorten and can modify the risk of developing chronic diseases. In this study, we evaluated the effects of a combination of nutraceutical supplements (NS) on telomere length (TL) in healthy volunteers with no medical history of any disease. Participants (n=47) were selected from healthy outpatients visiting a private clinic and were divided into the experimental group (n=16), that received the NS and the control group (n=31). We estimated the length of single telomeres in metaphase spread leukocytes, isolated from peripheral blood, using quantitative‑fluorescent in situ hybridization (Q‑FISH) analysis. The length of the whole telomere genome was significantly increased (P<0.05) for the mean, 1st quartile and median measurements in the experimental group. Similar findings were observed for short TL (20th percentile) (P<0.05) for the median and 3rd quartile measurements in the NS group, compared to the control group. The beneficial effects of the supplements on the length of short telomeres remained significant (P<0.05) following adjustment for age and sex. Telomeres were moderately longer in female patients compared to the male patients. On the whole, the findings of this study suggest that the administration of NS may be linked to sustaining the TL.

Subclinical inflammation, telomere shortening, homocysteine, vitamin B6, and mortality: the Ludwigshafen Risk and Cardiovascular Health Study

Purpose

Short telomeres and B vitamin deficiencies have been proposed as risk factors for age-related diseases and mortality that interact through oxidative stress and inflammation. However, available data to support this concept are insufficient. We aimed to investigate the predictive role of B vitamins and homocysteine (HCY) for mortality in cardiovascular patients. We explored potential relationships between HCY, B vitamins, relative telomere length (RTL), and indices of inflammation.

Methods

Vitamin B6, HCY, interleukin-6 (IL-6), high-sensitive-C-reactive protein (hs-CRP), and RTL were measured in participants of the Ludwigshafen Risk and Cardiovascular Health Study. Death events were recorded over a median follow-up of 9.9 years.

Results

All-cause mortality increased with higher concentrations of HCY and lower vitamin B6. Patients in the 4th quartile of HCY and vitamin B6 had hazard ratios (HR) for all-cause mortality of 2.77 (95% CI 2.28–3.37) and 0.41(95% CI 0.33–0.49), respectively, and for cardiovascular mortality of 2.78 (95% CI 2.29–3.39) and 0.40 (95% CI 0.33–0.49), respectively, compared to those in the 1st quartile. Multiple adjustments for confounders did not change these results. HCY and vitamin B6 correlated with age-corrected RTL (r = − 0.086, p < 0.001; r = 0.04, p = 0.031, respectively), IL-6 (r = 0.148, p < 0.001; r = − 0.249, p < 0.001, respectively), and hs-CRP (r = 0.101, p < 0.001; r = − 0.320, p < 0.001, respectively). Subjects with the longest telomeres had a significantly higher concentration of vitamin B6, but lower concentrations of HCY, IL-6, and hs-CRP. Multiple regression analyses identified HCY as an independent negative predictor of age-corrected RTL.

Conclusions

In conclusion, hyperhomocysteinemia and vitamin B6 deficiency are risk factors for death from any cause. Hyperhomocysteinemia and vitamin B6 deficiency correlate with increased mortality. This correlation might, at least partially, be explained by accelerated telomere shortening induced by oxidative stress and systemic inflammation in these circumstances.

Electronic supplementary material

The online version of this article (10.1007/s00394-019-01993-8) contains supplementary material, which is available to authorized users.

Telomere biology and age-related diseases

Telomeres are the protective end caps of chromosomes and shorten with every cell division. Telomere length has been proposed as a biomarker of biological age and a risk factor for age-related diseases. Epidemiologic studies show an association between leukocyte telomere length (LTL) and mortality. There is solid evidence that links LTL with cardiovascular disease. Short telomeres promote atherosclerosis and impair the repair of vascular lesions. Alzheimer's disease patients have also a reduced LTL. Telomeres measured in tumor tissue from breast, colon and prostate are shorter than in healthy tissue from the same organ and the same patient. In healthy tissue directly adjacent to these tumors, telomeres are also shorter than in cells that are more distant from the cancerous lesion. A reduced telomere length in cancer tissue from breast, colon and prostate is associated with an advanced disease state at diagnosis, faster disease progression and poorer survival. By contrast, results regarding LTL and cancer are inconsistent. Furthermore, the majority of studies did not find significant associations between LTL, bone mineral density (BMD) and osteoporosis. The present manuscript gives an overview about our current understanding of telomere biology and reviews existing knowledge regarding the relationship between telomere length and age-related diseases.

Dietary Folate Intake Is Negatively Associated with Excess Body Weight in Brazilian Graduates and Postgraduates (CUME Project)

Folate, vitamin B6, and vitamin B12 intake can be important regulators for obesity development. Thus, we investigated the possible association between the intake of these vitamins and the excess body weight or obesity prevalence in the participants of the Cohort of Universities in Minas Gerais (CUME project). This study analyzed cross-sectional data of 2695 graduates and postgraduates from universities in the state of Minas Gerais (801 men, 1894 women, ages 36.2 ± 9.4). The first step consisted of collecting data online, and the second step consisted of blood collecting in the subsample living in the city of Viçosa and its region (Minas Gerais). Excess body weight and obesity prevalence were 38.1% and 10.1%, respectively. Inadequate intake of folate, B6, and B12 were 12, 6.3, and 11.1%, respectively. Beans/lentils and French bread presented the highest contribution to folate intake (23.45% and 10.01%, respectively). Those individuals in the third tertile for folate intake (≥511.12 μg/d) had a lower excess body weight [prevalence ratio (PR): 0.79, confidence interval (CI): 0.71⁻0.8] and obesity prevalence (PR: 0.60, CI: 0.45⁻0.78). These associations were maintained when the sample was categorized by sex. In addition, serum folate was positively associated with dietary folate (p for trend = 0.032) and negatively associated with serum homocysteine (p for trend = 0.003) in the subsample. Dietary folate intake was negatively associated with excess body weight and obesity in CUME participants, indicating the relevance of this vitamin dietary assessment.

Telomere length as a biomarker of accelerated aging: is it influenced by dietary intake?

PURPOSE OF REVIEW

There is increasing interest in exploring whether age-related diseases can be prevented by dietary means through nutrients or food bioactives, whole foods, or specific dietary patterns. Because of the slow nature of the aging process, biomarkers such as telomere length are helpful for this purpose. Here we update the developments in the area during the last 2 years.

RECENT FINDINGS

Most data stem from epidemiologic studies, often cross-sectional in design. Recent articles strengthened the link between consumption of sugar-sweetened beverages and telomere shortening, whereas a novel association between telomere length and drinking coffee has been uncovered. Controversy on meat consumption and telomere length persists, mostly because of the presumed different effects of total meat and processed meat. In general terms, increasing consumption of antioxidant-rich plant foods relates to maintained telomere length. Feeding intervention trials with outcomes on telomere length are few and thus far have contributed little to further knowledge on this topic.

SUMMARY

Epidemiologic studies provide support for the putative effects of diet components on telomere length and on the aging process in general. Dietary associations with telomere length should be confirmed with adequately powered randomized controlled trials.

Effects of dietary interventions on DNA methylation in adult humans: systematic review and meta-analysis

DNA methylation is a key component of the epigenetic machinery that is responsible for regulating gene expression and, therefore, cell function. Patterns of DNA methylation change during development and ageing, differ between cell types, are altered in multiple diseases and can be modulated by dietary factors. However, evidence about the effects of dietary factors on DNA methylation patterns in humans is fragmentary. This study was initiated to collate evidence for causal links between dietary factors and changes in DNA methylation patterns. We carried out a systematic review of dietary intervention studies in adult humans using Medline, EMBASE and Scopus. Out of 22 149 screened titles, sixty intervention studies were included, of which 65% were randomised (n 39). Most studies (53%) reported data from blood analyses, whereas 27% studied DNA methylation in colorectal mucosal biopsies. Folic acid was the most common intervention agent (33%). There was great heterogeneity in the methods used for assessing DNA methylation and in the genomic loci investigated. Meta-analysis of the effect of folic acid on global DNA methylation revealed strong evidence that supplementation caused hypermethylation in colorectal mucosa (P=0·009). Meta-regression analysis showed that the dose of supplementary folic acid was the only identified factor (P<0·001) showing a positive relationship. In summary, there is limited evidence from intervention studies of effects of dietary factors, other than folic acid, on DNA methylation patterns in humans. In addition, the application of multiple different assays and investigations of different genomic loci makes it difficult to compare, or to combine, data across studies.

Serum lipophilic antioxidants levels are associated with leucocyte telomere length among US adults

BACKGROUND

To examine the association between serum concentrations of antioxidant and telomere length (TL) in U.S adults.

METHODS

Participants of the National Health and Nutrition Examination Survey (NHANES) with data available on TL measures from 2001 to 2002 were included. Serum lipophilic antioxidants level was measured using high performance liquid chromatography with photodiode array detection. We used analysis of co-variance and multivariable-adjusted linear regression models, accounting for the survey design and sample weights.

RESULTS

Of the 5992 eligible participants, 47.5% (n = 2844) were men. The mean age was 46.9 years overall, 47.2 years in men and 46.6 in women (p = 0.071). In age, sex, race, education, marital status, adiposity, smoking, C-reactive protein adjusted linear regressions, antioxidant, serum α-carotene, trans-β-carotene, cis- β-carotene, β-cryptoxanthin and combined Lutein/zeaxanthin were positively and significantly associated with TL (all p < 0.001).

CONCLUSIONS

Our findings support a possible positive association between serum concentrations of lipophylic antioxidant and TL. The implications of this association deserve further investigation.

Nutriepigenetics and cardiovascular disease

PURPOSE OF REVIEW

We present a current perspective of epigenetic alterations that can lead to cardiovascular disease (CVD) and the potential of dietary factors to counteract their actions. In addition, we discuss the challenges and opportunities of dietary treatments as epigenetic modifiers for disease prevention and therapy.

RECENT FINDINGS

Recent epigenome-wide association studies along with candidate gene approaches and functional studies in cell culture and animal models have delineated mechanisms through which nutrients, food compounds and dietary patterns may affect the epigenome. Several risk factors for CVD, including adiposity, inflammation and oxidative stress, have been associated with changes in histone acetylation, lower global DNA methylation levels and shorter telomere length. A surplus of macronutrients such as in a high-fat diet or deficiencies of specific nutrients such as folate and other B-vitamins can affect the activity of DNA methyltransferases and histone-modifying enzymes, affecting foetal growth, glucose/lipid metabolism, oxidative stress, inflammation and atherosclerosis. Bioactive compounds such as polyphenols (resveratrol, curcumin) or epigallocatechin may activate deacetylases Sirtuins (SIRTs), histone deacetylases or acetyltransferases and in turn the response of inflammatory mediators. Adherence to cardioprotective dietary patterns, such as the Mediterranean diet (MedDiet), has been associated with altered methylation and expression of genes related to inflammation and immuno-competence.

SUMMARY

The mechanisms through which nutrients and dietary patterns may alter the cardiovascular epigenome remain elusive. The research challenge is to determine which of these nutriepigenetic effects are reversible, so that novel findings translate into effective dietary interventions to prevent CVD or its progression.

Telomere length and mortality in the Ludwigshafen Risk and Cardiovascular Health study

INTRODUCTION

Short telomeres have been associated with adverse lifestyle factors, cardiovascular risk factors and age-related diseases, including cardiovascular disease (CVD), myocardial infarction, atherosclerosis, hypertension, diabetes, and also with mortality. However, previous studies report conflicting results.

OBJECTIVES

The aim of the present study has been to investigate the involvement of telomere length in all-cause and CVD mortality in subjects hospitalized for diagnostic coronary angiography of the Ludwigshafen Risk and Cardiovascular Health (LURIC) study.

METHODS

Relative telomere length (RTL) was measured with a Q-PCR based method in 3,316 participants of the LURIC study. Age-corrected RTL was calculated as the ratio between RTL and age. Median follow-up was 9.9 years. Cox regression and Kaplan-Maier analyses were performed to evaluate the role of RTL for all-cause and cardiovascular mortality.

RESULTS

RTL correlated negatively with age (r = -0.09; p<0.001). In surviving patients the correlation between age and RTL was statistically significant (r = -0.088; p<0.001), but not in patients who died during follow-up (r = -0.043; p = 0.20). Patients in quartiles 2-4 of RTL had a lower hazard ratio for all-cause mortality (HR:0.822; 95%CI 0.712-0.915; p = 0.008) and CVD-mortality (HR:0.836; 95%CI 0.722-0.969; p = 0.017) when compared to those in the 1st quartile. Adjustment for major cardiovascular risk factors did not change this result, however additional adjustment for age attenuated this effect. Patients in the 4th quartile of age-corrected RTL compared to those in the 1st quartile had a lower hazard ratio for all-cause mortality, even with adjustment for major cardiovascular risk factors.

CONCLUSIONS

The present study supports the hypothesis that short telomere length increases the risk of all-cause and CVD mortality. Age appears to be an important co-variate that explains a substantial fraction of this effect. It remains unclear whether short telomeres contribute directly to the increase in mortality or if they are simply a surrogate marker for other adverse processes of aging.

Effect of adding B-vitamins to vitamin D and calcium supplementation on CpG methylation of epigenetic aging markers

BACKGROUND AND AIM

B-vitamins may influence DNA methylation. We studied the effects of vitamin D + Ca + B versus D + Ca on epigenetic age markers and biological age.

METHODS AND RESULTS

Participants (mean ± SD of age = 68.4 ± 10.1 years) were randomized to receive 1200 IE vitamin D3 plus 800 mg Ca-carbonate alone (n = 31) or with 0.5 mg B9, 50 mg B6, and 0.5 mg B12 (n = 32). The CpG methylation of 3 genes (ASPA, ITGA2B, and PDE4C) and the changes in methylation were compared between the groups after 1 year. The changes of ASPA methylation from baseline were higher in the D + Ca + B than in the D + Ca group (1.40 ± 4.02 vs. -0.96 ± 5.12, respectively; p = 0.046, adjusted for age, sex, and baseline methylation). The changes in PDE4C from baseline were slightly higher in the D + Ca + B group (1.95 ± 3.57 vs. 0.22 ± 3.57; adjusted p = 0.062). Methylation of ITGA2B and its changes from baseline were not different between the intervention groups. Sex-adjusted odds ratio of accelerated aging (chronological age < biological age at 1 year) was 5.26 (95% confidence interval 1.51-18.28) in the D + Ca + B compared with the D + Ca group. Accelerated aging in both groups was associated with younger age. In the D + Ca + B group, it was additionally associated with lower baseline homocysteine.

CONCLUSIONS

Vitamin D + Ca + B and D + Ca differentially affected epigenetic age markers, although the effect size appeared to be small after 1 year. B-vitamins effect in young subjects with low homocysteine requires further investigation. ClinicalTrials.gov ID: NCT02586181.

Environmental Influences on the Epigenome: Exposure- Associated DNA Methylation in Human Populations

DNA methylation is the most well studied of the epigenetic regulators in relation to environmental exposures. To date, numerous studies have detailed the manner by which DNA methylation is influenced by the environment, resulting in altered global and gene-specific DNA methylation. These studies have focused on prenatal, early-life, and adult exposure scenarios. The present review summarizes currently available literature that demonstrates a relationship between DNA methylation and environmental exposures. It includes studies on aflatoxin B₁, air pollution, arsenic, bisphenol A, cadmium, chromium, lead, mercury, polycyclic aromatic hydrocarbons, persistent organic pollutants, tobacco smoke, and nutritional factors. It also addresses gaps in the literature and future directions for research. These gaps include studies of mixtures, sexual dimorphisms with respect to environmentally associated methylation changes, tissue specificity, and temporal stability of the methylation marks.

The shortening of leukocyte telomere length relates to DNA hypermethylation of LINE-1 in type 2 diabetes mellitus

BACKGROUND

We aim to investigate the cross-talking of leukocyte telomere length (LTL) and DNA methylation of LINE-1 in type 2 diabetes mellitus (T2DM).

RESULTS

LTL (ratio of the copy number of telomere [T] repeats to that of a single [S] gene) was significantly shortened in T2DM compared with controls (0.94 ± 0.41 vs. 1.14 ± 0.48, P < 0.001), and decreased steadily with age in both controls and T2DM. Conversely, significant increase of LINE-1 DNA methylation was found in T2DM compared with controls (49.60 ± 14.55 vs. 37.81 ± 9.07, P < 0.001). Moreover, age, HbA1c, and LINE-1 methylation ratio were stably negatively related with LTL after multi-adjustment. Shorter LTL was associated with an increased risk of T2DM [adjusted OR (95% CI) = 2.458 (1.192, 5.070), P = 0.015], while lower LINE-1 DNA methylation levels could reduce the risk of T2DM [adjusted OR (95% CI) = 0.189 (0.089, 0.400), P < 0.001].

MATERIALS AND METHODS

We performed a hospital-based case-control study of 205 T2DM patients and 213 subjects of healthy control with sex and age matched. LTL and DNA methylation of LINE-1 was measured by quantitative PCR and quantitative methylation-specific PCR (qMSP), respectively.

CONCLUSIONS

Our research demonstrates the association between shorter LTL and LINE-1 hyper-methylation in Chinese T2DM patients. These findings suggest that shorter LTL might be associated with T2DM in a manner dependent of epigenetic level.

Novel Approaches to Investigate One-Carbon Metabolism and Related B-Vitamins in Blood Pressure

Hypertension, a major risk factor for heart disease and stroke, is the world's leading cause of preventable, premature death. A common polymorphism (677C→T) in the gene encoding the folate metabolizing enzyme methylenetetrahydrofolate reductase (MTHFR) is associated with increased blood pressure, and there is accumulating evidence demonstrating that this phenotype can be modulated, specifically in individuals with the MTHFR 677TT genotype, by the B-vitamin riboflavin, an essential co-factor for MTHFR. The underlying mechanism that links this polymorphism, and the related gene-nutrient interaction, with hypertension is currently unknown. Previous research has shown that 5-methyltetrahydrofolate, the product of the reaction catalysed by MTHFR, appears to be a positive allosteric modulator of endothelial nitric oxide synthase (eNOS) and may thus increase the production of nitric oxide, a potent vasodilator. Blood pressure follows a circadian pattern, peaking shortly after wakening and falling during the night, a phenomenon known as 'dipping'. Any deviation from this pattern, which can only be identified using ambulatory blood pressure monitoring (ABPM), has been associated with increased cardiovascular disease (CVD) risk. This review will consider the evidence linking this polymorphism and novel gene-nutrient interaction with hypertension and the potential mechanisms that might be involved. The role of ABPM in B-vitamin research and in nutrition research generally will also be reviewed.

The relationship between peripheral blood mononuclear cells telomere length and diet - unexpected effect of red meat

BACKGROUND

Repeated nucleotide sequences combined with proteins called telomeres cover chromosome ends and dictate cells lifespan. Many factors can modify telomere length, among them are: nutrition and smoking habits, physical activities and socioeconomic status measured by education level. The aim of the study was to determine the influence of above mentioned factors on peripheral blood mononuclear cells telomere length.

METHODS

Study included 28 subjects (seven male and 21 female, age 18-65 years.), smokers and non-smokers without any serious health problems in past and present. Following a basic medical examination, patients completed the food frequency questionnaire with 17 foods and beverages most common groups and gave blood for testing. PBMC telomere length were measured with qualitative real-time Polymerase Chain Reaction (rtPCR) method and expressed as a T/S ratio.

RESULTS

Among nine food types (cereal, fruits, vegetables, diary, red meat, poultry, fish, sweets and salty snacks) and eight beverages (juices, coffee, tea, mineral water, alcoholic- and sweetened carbonated beverages) only intake of red meat was related to T/S ratio. Individuals with increased consumption of red meat have had higher T/S ratio and the strongest significant differences were observed between consumer groups: "never" and "1-2 daily" (p = 0.02). Smoking habits, physical activity, LDL and HDL concentrations, and education level were not related to telomere length, directly or as a covariates.

CONCLUSIONS

Unexpected correlation of telomere length with the frequency of consumption of red meat indicates the need for further in-depth research and may undermine some accepted concepts of adverse effects of this diet on the health status and life longevity.

One-carbon metabolites and telomere length in a prospective and randomized study of B- and/or D-vitamin supplementation

BACKGROUND

Vitamin B deficiency is common in elderly people and has been associated with an increased risk of developing age-related diseases. B-vitamins are essential for the synthesis and stability of DNA. Telomers are the end caps of chromosomes that shorten progressively with age, and short telomers are associated with DNA instability.

OBJECTIVE

In the present randomized intervention study, we investigated whether the one-carbon metabolism is related to telomere length, a surrogate marker for cellular aging.

DESIGN

Sixty-five subjects (>54 years) were randomly assigned to receive either a daily combination of vitamin D3 (1200 IU), folic acid (0.5 mg), vitamin B₁₂ (0.5 mg), vitamin B₆ (50 mg) and calcium carbonate (456 mg) (group A) or vitamin D3 and calcium carbonate alone (group B). Blood testing was performed at baseline and after 1 year of supplementation. The concentrations of several metabolites of the one-carbon pathway, as well as relative telomere length (RTL) and 5,10-methylenetetrahydrofolate reductase C677T genotype, were analyzed.

RESULTS

At baseline, age- and gender-adjusted RTL correlated with total folate and 5-methyltetrahydrofolate (5-methylTHF). Subjects with RTL above the median had higher concentrations of total folate and 5-methylTHF compared to subjects below the median. At study end, gender- and age-adjusted RTL correlated in group A with methylmalonic acid (MMA; r = -0.460, p = 0.0012) and choline (r = 0.434, p = 0.0021) and in group B with 5,10-methenyltetrahydrofolate (r = 0.455, p = 0.026) and dimethylglycine (DMG; r = -0.386, p = 0.047). Subjects in the group A with RTL above the median had lower MMA and higher choline compared to subjects below the median.

CONCLUSIONS

The present pilot study suggests a functional relationship between one-carbon metabolism and telomere length. This conclusion is supported by several correlations that were modified by B-vitamin supplementation. In agreement with our hypothesis, the availability of nucleotides and methylation groups seems to impact telomere length. Due to the small sample size and the limitations of the study, further studies should confirm the present results in a larger cohort.