Dietary fish and omega-3 fatty acid consumption and heart rate variability in US adults

Lower heart rate variability is associated with loss of muscle mass and sarcopenia in community-dwelling older Chinese adults

BACKGROUND/PURPOSE

Autonomic nervous system (ANS) disorders may occur in skeletal muscle disease, but the link between them has not been fully established. Studying the relationship between them may yield insights into the mechanisms and treatment of disease. This study aimed to explore the association between heart rate variability (HRV), sarcopenia, and subscales of sarcopenia (muscle mass, muscle strength, and physical mobility).

METHODS

2514 community-dwelling older Chinese participants were included in this study. The Asian Working Group for Sarcopenia guidelines were used to define sarcopenia. HRV was measured by 90-s electrocardiogram RR interval data. All HRV parameters were transformed using natural logarithms. Multiple regression analysis and multivariate linear regression was performed using potential correlates.

RESULTS

The overall prevalence of sarcopenia was 15.1 % (18.5 % in males and 12.6 % in females). In the logistic regression analysis model, there was a significant association between log-transformed standard deviation of RR interval (lnSDNN) (OR = 0.736, p = 0.019), log-transformed coefficient of variation of RR intervals (lnCVRR) (OR = 0.751, p = 0.020), log-transformed low-frequency power (lnLF) (OR = 0.861, p = 0.008), log-transformed high-frequency power (lnHF) (OR = 0.864, p = 0.003) and sarcopenia in the general population after adjusting for age, sex, body mass index (BMI), daily activity levels, hypertension, heart disease and cardiac drugs. In addition, in multivariate linear regression, lnSDNN (β = 0.146, p = 0.001), lnCVRR (β = 0.120, p = 0.010), lnLF (β = 0.066, p = 0.002) and lnHF (β = 0.065, p < 0.001) remained significantly positively associated with muscle mass, but there were no significant differences in grip strength and walking speed.

CONCLUSION

Sarcopenia was independently associated with lower heart rate variability in a community-dwelling elderly Chinese population. In addition, muscle mass was positively associated with heart rate variability in the elderly.

How to properly evaluate cardiac vagal tone in oncology studies: a state-of-the-art review

Heart rate variability (HRV) analysis provides an assessment of cardiac vagal tone and consequently global cardiac health as well as systemic condition. In systemic diseases such as cancer and during treatments that affect the whole body, like chemotherapy, the vagus nerve activity is low and deregulated. Some studies focus on using HRV to predict mortality in oncology. However, in cancer patients, systemic alterations substantially increase artifacts during HRV measurement, especially atrial ectopic beats. Moreover, HRV may be altered by various factors (duration and time of measurement, breathing, drugs, and other confounding factors) that alter each metric in different ways. The Standard Deviation of all Normal to Normal intervals (SDNN) is the most commonly used metric to evaluate HRV in oncology, but it does not appear to be specific to the cardiac vagal tone. Thus, cardiac vagal activity diagnosis and vital prognosis of cancer patients can be biased. Our review presents the main HRV metrics that can be currently used in oncology studies and their links with vagus nerve and cancer. We present the influence of external factors and the required duration and time of measurement. Considering all these parameters, this review proposes seven key points for an assessment of HRV and cardiac vagal tone in patients with cancer.

A randomized clinical trial of omega-3 fatty acid and vitamin D supplementation on electrocardiographic risk profiles

Beneficial and adverse associations with arrhythmias have been reported for omega-3 fatty acids (omega-3 FA) and Vitamin D. The 12 lead electrocardiogram (ECG) contains quantitative measures reflecting diverse aspects of electrophysiology that might provide insights into mechanisms underlying these associations. In a pre-specified ancillary study of the VITaminD and omegA-3 (VITAL) trial, we examined the effect of 1 g of marine omega-3 FA per day, comprised of 460 mg eicosapentanoic acid and 380 mg of docosahexaenoic acid, and 2000 IU VitaminD3 per day on ECG characteristics associated with atrial and ventricular arrhythmias among individuals age 50 years or greater. A total of 911 study participants underwent ECGs at baseline and again at 2 years after the randomization. Individuals randomized to active omega-3 FA demonstrated significant net increase in PR-interval duration (p = 0.005) and P-wave duration (p = 0.03) as well significant net decrease in P-wave amplitude (p = 0.037) as compared to placebo. RMSSD increased to a greater extent in the omega-3 FA arm compared to placebo (p = 0.040). For Vitamin D3, the Cornell voltage increased to a lesser extent in the participants assigned to active treatment as compared to placebo (p = 0.044). There were no other significant differences in QRS, QTc, Cornell voltage or heart rate. Thus, randomized treatment with omega-3 FA supplements resulted in changes on the ECG that are potentially reflective of heightened vagal tone and/or slowing of intraatrial and AV conduction. Vitamin D3 supplementation resulted in modest reductions in progressive LV voltage suggestive of a potential antihypertrophic effect.Trial registration ClinicalTrials.gov Identifiers: NCT01169259, NCT02178410 (06/26/2010 and 06/30/2014).

Living in ancestrally diverse states of the United States is associated with greater vagal tone

Historically, exposure to dissimilar others ("strangers") was a physiologically arousing event-resulting in avoidance, distrust, and even conflict. Despite this, contemporary migration patterns are increasing intergroup contact. What gives rise to an individual's ability to regulate their arousal such that social engagement with outgroup members is possible? We propose that cultural practices that evolve in ancestrally diverse, compared to ancestrally homogeneous, societies provide more opportunities for society members to engage in emotion regulation. This regulatory exercise, in turn, promotes higher vagal tone-a physiological indicator of one's ability to effectively manage arousal in social interaction. In a secondary analysis of data from the MIDUS 2 Biomarker Project, we find that the ancestral diversity of the states of the United States significantly predicts the average vagal tone of the state's citizens. The findings suggest that social context is associated with predictable and significant adaptations of human physiology over individual lifetimes.

Role of Omega-3 Fatty Acids as Non-Photic Zeitgebers and Circadian Clock Synchronizers

Omega-3 fatty acids (ω-3 FAs) are well-known for their actions on immune/inflammatory and neurological pathways, functions that are also under circadian clock regulation. The daily photoperiod represents the primary circadian synchronizer (‘zeitgeber’), although diverse studies have pointed towards an influence of dietary FAs on the biological clock. A comprehensive literature review was conducted following predefined selection criteria with the aim of updating the evidence on the molecular mechanisms behind circadian rhythm regulation by ω-3 FAs. We collected preclinical and clinical studies, systematic reviews, and metanalyses focused on the effect of ω-3 FAs on circadian rhythms. Twenty animal (conducted on rodents and piglets) and human trials and one observational study providing evidence on the regulation of neurological, inflammatory/immune, metabolic, reproductive, cardiovascular, and biochemical processes by ω-3 FAs via clock genes were discussed. The evidence suggests that ω-3 FAs may serve as non-photic zeitgebers and prove therapeutically beneficial for circadian disruption-related pathologies. Future work should focus on the role of clock genes as a target for the therapeutic use of ω-3 FAs in inflammatory and neurological disorders, as well as on the bidirectional association between the molecular clock and ω-3 FAs.

The influence on fish and seafood consumption, and the attitudes and reasons for its consumption in the Croatian population

Fish makes an important part of the Mediterranean diet, which has been scientifically proven to help preserve human health by protecting against major chronic and inflammatory diseases. Eating fish and seafood is very important, not only for its proven health benefits but also for its positive impact on the environment. Due to many fish and seafood significant positive effects on human health, this study aimed to investigate the socio-demographic factors associated with the consumption of fish and seafood in the population of Primorsko-goranska County in Croatia. Another aim was to determine people's attitudes, choices, and reasons for the consumption of fish and seafood. Self-reported data from 2,910 participants were used. According to the European dietary recommendations for fish consumption, the participants were divided into two groups; the very low to low fish consumption group and the moderate to high fish consumption group, in order to examine the differences in socio-demographic and lifestyle variables, and their attitudes, opinions, and reasons for fish and seafood consumption. More fish and seafood were consumed by women, the elderly, the more educated, non-smokers, and more physically active participants. Age, the highest level of education, and a diet even moderately adherent to the Mediterranean diet was found to significantly increase the likelihood of recommended fish consumption. Participants considered the best reasons to consume more fish lower prices, buy much more locally produced fishery products, and prefer to eat wild-caught fish rather than farmed fish. The study has found a slight increase in fish consumption, although still lower than the European average. It also showed significant socio-demographic associations, also the reasons and attitudes toward higher fish and seafood consumption of the Croatian population. The obtained research data are valuable for planning future public health programs in Croatia aimed at greater consumption of fish and seafood, as well as their promotion as an important part of a sustainable diet.

Amyloid fibril formation by casein and fatty acid composition in breast milk of mastitis patients

Mastitis can cause changes in the nutrient composition of breast milk, which may be harmful to both newborns and lactating mothers. In this study we preliminarily evaluated amyloid fibrils formation by casein and fatty acids (FA), as well as their potential relation with each other in the breast milk of mastitis patients. Six healthy volunteers and six mastitis patients were recruited from the Maternal and Child Health Care Hospital in Changchun were enrolled. Amyloid fibril content was assessed by thioflavin T fluorescence analysis, transmission electron microscope, circular dichroism, and proton nuclear magnetic resonance. FA contents were measured by gas chromatography. Healthy breast milk contained no amyloid fibrils but inflammatory breast milk did. Several FAs (hendecanoic acid, myristolenic acid, pentadecenoic acid, eicosatrienoic acid) differed significantly between the two groups (p < .05). The concentrations of the eicosatrienoic acid and eleven carbonic acids in the inflammatory groups were lower than those in the healthy groups, but the myristolenic acid and pentadecenoic acid were the opposite trend. Early detection of amyloid fibrils should be performed in lactating mothers with mastitis. Changes in FAs may reflect the importance of abnormal metabolism in amyloid fibril formation. PRACTICAL APPLICATIONS: The work preliminarily clarified the relationship between inflammation, fibril content, and fatty acid (FA) composition in breast milk. Healthy milk contained no amyloid fibril formed by casein but the inflammatory milk did. FAs were also significantly different between the two groups. Thus, an early determination of amyloid fibrils in milk should be considered for lactating women with mastitis to avoid the further malignant development. Additionally, the changes in FAs may reflect the importance of abnormal metabolism and oxidative pathways in amyloid fibril formation in the breast. Therefore, this study provided foundations for further investigation on the association between inflammation, fibril content and FA composition in breast milk.

Fish Consumption and Cardiovascular Health: A Systematic Review

Studies evaluating fish consumption and cardiovascular disease events have shown inconsistent results. We performed a systematic review of peer-reviewed publications from an extensive query of Ovid MEDLINE, Ovid Embase, Ovid Cochrane Database of Systematic Reviews, Scopus, and Web of Science from database inception to September 2020 for observational studies that reported the association between fish consumption and cardiovascular disease events. We identified and reviewed 24 studies related to fish consumption and the effect on cardiovascular outcomes. The study population included a total of 714,526 individuals and multiple cohorts from several countries. We found that nonfried fish consumption is probably associated with a reduced risk of overall cardiovascular disease events and myocardial infarction risk. In contrast, fried fish consumption is probably associated with an increased risk of overall cardiovascular disease events and myocardial infarction risk. No studies to date have shown any significant association between fish consumption and stroke. Our analysis suggests that fish consumption may reduce cardiovascular disease events, but fried fish consumption was associated with an increased risk of cardiovascular events.

Association between diet quality indices and arterial stiffness in youth with type 1 diabetes: SEARCH for Diabetes in Youth Nutrition Ancillary Study

AIMS

We studied the association of three distinct diet quality indices and two measures of arterial stiffness in youth and young adults (YYA) aged 10 to 30 with T1D.

METHODS

Cross-sectional (n = 1421) and longitudinal (n = 520) analyses were conducted in T1D YYA participating in the SEARCH for Diabetes in Youth Study. The diet quality indices included the Dietary Approaches to Stop Hypertension (DASH) index, the Healthy Eating Index 2015 (HEI-2015), and a modified Mediterranean Diet Quality Index (mKIDMED). Arterial stiffness was measured with pulse wave velocity (PWV) and augmentation index (AIx) obtained using a SphygmoCor-Vx device and tonometer.

RESULTS

Average diet quality was moderate to poor, with mean scores of 41 (DASH, range 0-80), 55 (HEI-2015, range 0-100), 3.7 (mKIDMED, range - 3-12). None of the diet quality scores was associated with the central PWV or Aix, independent of demographic, clinical and lifestyle factors, body mass index and HbA1c. Longitudinal data yielded consistent findings with cross-sectional results.

CONCLUSIONS

This study suggests that diet quality may not function as an independent risk factor for arterial stiffening in YYA with T1D. These findings do not diminish the importance of consuming a quality diet for the management of diabetes, as demonstrated in previous work.

Vitamin D Supplementation during Winter: Effects on Stress Resilience in a Randomized Control Trial

Vitamin D status may be important for stress resilience. This study investigated the effects of vitamin D supplements during winter on biological markers of stress resilience such as psychophysiological activity, serotonin, and cortisol in a placebo-controlled, randomized clinical trial. Eighty-six participants were randomly assigned to the Intervention (vitamin D) or Control (placebo) groups. Before and after the intervention participants were exposed to an experimental stress procedure. Psychophysiological activity was measured during three main conditions: baseline, stress, and recovery. Fasting blood samples were taken in the morning and saliva samples were collected at seven different time points across 24 h. Prior to intervention both groups had normal/sufficient vitamin D levels. Both groups showed a normal pattern of psychophysiological responses to the experimental stress procedure (i.e., increased psychophysiological responses from resting baseline to stress-condition, and decreased psychophysiological responses from stress-condition to recovery; all p < 0.009). Post-intervention, the Intervention group showed increased vitamin D levels (p < 0.001) and normal psychophysiological responses to the experimental stress procedure (p < 0.001). Importantly, the Control group demonstrated a classic nadir in vitamin D status post-intervention (spring) (p < 0.001) and did not show normal psychophysiological responses. Thus, physiologically the Control group showed a sustained stress response. No significant effects of vitamin D were found on serotonin and cortisol.

A systematic review of the determinants of seafood consumption

Although seafood is considered to be an important part of a balanced diet, many national food consumption surveys suggest that seafood is not consumed in sufficient amounts. As consumers are moving to diversify their diet from animal-based protein, it is important to understand the factors influencing consumption of marine foods. This review aims to assess the characteristics of seafood consumers as well as the influences on seafood consumption in Europe, USA, Canada, Australia and New Zealand. Systematic search strategies were used to identify relevant journal articles from three electronic databases (PubMed, Web of Science and Embase). Three searches were carried out and identified 4405 unique publications from which 121 met the criteria for the review process. The reviewed studies revealed that seafood consumers were more likely to be older, more affluent and more physically active and were less likely to smoke compared with non-seafood consumers. Sex and BMI did not appear to have a directional association with seafood consumption. The most commonly reported barriers to seafood consumption were cost, followed by sensory or physical barriers, health and nutritional beliefs, habits, availability and cooking skills. The most commonly reported influences were beliefs about the contribution of seafood to health, environmental influences and personal preferences. Based on the findings of this review, future intervention strategies to increase seafood consumption may need to consider affordability and education in terms of health, nutrition and cooking skills. More research is needed to explore the effectiveness of specific interventions at increasing the consumption of seafood.

Intake of fish and long-chain n-3 polyunsaturated fatty acids and risk of diseases in a Japanese population: a narrative review

Since the 1970s, the potential benefit of fish intake in terms of noncommunicable diseases has been one of the most important themes in disease prevention. Epidemiological studies have revealed the extent to which fish consumption affects the incidence of and mortality from diseases. Meta-analyses summarized the effect of fish and long-chain n-3 polyunsaturated fatty acid intake on noncommunicable diseases, especially cardiovascular diseases in Western countries. However, few reviews have spotlighted the effect of fish intake in East-Asian countries that have high population levels of fish intake such as Japan. We narratively reviewed the epidemiological studies concerned with the associations of fish and long-chain n-3 polyunsaturated fatty acid intake with risk of noncommunicable diseases, mainly of cardiovascular disease, among Japanese, whose fish intake has been twice or more than that of most Westerners. Overall, fish or long-chain n-3 polyunsaturated fatty acid intake may be beneficial for prevention of noncommunicable diseases, especially coronary heart disease and heart failure in Japanese as well as in Westerners. However, the beneficial effects of their intakes seemed to be nonlinear and varied according to disease severity and culture. Studies on other noncommunicable disease were also narratively reviewed.

Fish Consumption and Coronary Heart Disease: A Meta-Analysis

Epidemiological studies on the impact of fish consumption on coronary heart disease (CHD) incidence have shown inconsistent results. In addition, in terms of CHD mortality, although previous meta-analyses showed that fish consumption reduces the risk of CHD, six newly incorporated studies show that fish consumption has no impact on CHD. Therefore, the results still need to be verified. The purpose of this study is to quantitatively evaluate the impact of fish consumption on CHD incidence and mortality. Relevant studies were identified from PubMed, Web of Science, and Embase databases up to October 2019. The multivariate-adjusted relative risks (RRs) for the highest versus the lowest fish consumption categories and the 95% confidence intervals were computed with a random-effect model. A restricted cubic spline regression model was used to assess the dose–response relationship between fish consumption and CHD incidence and mortality. Forty prospective cohort studies were incorporated into research. Among them, 22 studies investigated the association between fish consumption and CHD incidence (28,261 cases and 918,783 participants), and the summary estimate showed that higher fish consumption was significantly associated with a lower CHD incidence [RR: 0.91, 95% CI: (0.84, 0.97); I² = 47.4%]. Twenty-seven studies investigated the association between fish consumption and CHD mortality (10,568 events and 1,139,553 participants), and the summary estimate showed that higher fish intake was significantly associated with a lower CHD mortality [RR: 0.85, 95% CI: (0.77, 0.94); I² = 51.3%]. The dose–response analysis showed that the CHD incidence and mortality were reduced by 4%, respectively, with a 20 g/day increment in fish consumption. This meta-analysis indicates that fish consumption is associated with a lower CHD incidence and mortality.

Heart Rate Variability and Omega-3 Index in Euthymic Patients with Bipolar Disorders

Background:

Affective disorders are associated with an increased risk of cardiovascular disease, which, at least partly, appears to be independent of psychopharmacological treatments used to manage these disorders. Reduced heart rate variability (SDNN) and a low Omega-3 Index have been shown to be associated with increased risk for death after myocardial infarction. Therefore, we set out to investigate heart rate variability and the Omega-3 Index in euthymic patients with bipolar disorders.

Methods:

We assessed heart rate variability (SDNN) and the Omega-3 Index in 90 euthymic, mostly medicated patients with bipolar disorders (Bipolar-I, Bipolar-II) on stable psychotropic medication, free of significant medical comorbidity and in 62 healthy controls. Heart rate variability was measured from electrocardiography under a standardized 30 minutes resting state condition. Age, sex, BMI, smoking, alcohol consumption and caffeine consumption as potential confounders were also assessed.

Results:

Heart rate variability (SDNN) was significantly lower in patients with bipolar disorders compared to healthy controls (35.4 msec versus 60.7 msec; P < 0.0001), whereas the Omega-3 Index did not differ significantly between the groups (5.2% versus 5.3%). In a linear regression model, only group membership (patients with bipolar disorders versus healthy controls) and age significantly predicted heart rate variability (SDNN).

Conclusion:

Heart rate variability (SDNN) may provide a useful tool to study the impact of interventions aimed at reducing the increased risk of cardiovascular disease in euthymic patients with bipolar disorders. The difference in SDNN between cases and controls cannot be explained by a difference in the Omega-3 Index.

Fatty Fish Intervention and Psychophysiological Responses to Mental Workload in Forensic Inpatients

Abstract. The overall aim of this randomized controlled trial was to investigate the effect of a long-term fatty fish intervention during winter time on psychophysiological responses, that is, heart rate variability (HRV), to mental workload. Forty-seven forensic inpatients were randomly assigned into a fish group (FG) or a control group (CG). HRV responses to an experimental test procedure consisting of a resting baseline, mental workload, and a resting recovery were measured pre- and post-intervention. The results revealed that the FG showed attenuated physiological responses to mental workload from pretest to posttest by a significant increase in HRV. Additionally, the FG showed a higher HRV during recovery compared to the baseline and test conditions at both pretest and posttest. The CG showed no changes in psychophysiological responses from pretest to posttest to mental workload. Importantly, the CG showed impaired recovery at posttest, indicating a sustained physiological arousal after the stressor (mental workload) ended. Thus, the results indicate that increased fatty fish intake has the potential to increase resilience to mild cognitive stress in human beings with psychiatric illnesses.

Effects of oily fish intake on cardiometabolic markers in healthy 8- to 9-y-old children: the FiSK Junior randomized trial

BACKGROUND

Fish oil improves cardiometabolic markers in adults, but results in children are inconsistent. Few children meet the recommended fish intake and no randomized trials have investigated how fish intake per se affects children's cardiometabolic profile.

OBJECTIVE

We investigated whether oily fish consumption modulated serum triacylglycerol and diastolic blood pressure (coprimary outcomes) and other cardiometabolic markers in healthy Danish children and whether effects were sex-specific.

METHODS

In a randomized controlled 12-wk trial, 199 children (aged 8-9 y) received ∼300 g/wk of oily fish or poultry (control). We measured blood pressure, heart rate, and heart rate variability (HRV) via 3-h continuous electrocardiograms and collected fasting blood samples for analysis of erythrocyte EPA [20:5n-3 (ω-3)] + DHA (22:6n-3) and serum triacylglycerol, LDL and HDL cholesterol, glucose, and insulin.

RESULTS

One hundred and ninety-seven children (99%) completed the trial. The fish group consumed a median (IQR) of 375 (325-426) g oily fish/wk and the poultry group consumed 400 (359-452) g poultry/wk, which resulted in 2.25 (95% CI: 1.88, 2.62) fatty acid percentage-point higher erythrocyte EPA + DHA in the fish group (P < 0.001). In the fish group, serum triacylglycerol decreased by 0.05 mmol/L (95% CI: 0.00, 0.11 mmol/L) (P = 0.04) and HDL cholesterol increased by 0.07 mmol/L (95% CI: 0.01, 0.13 mmol/L) (P = 0.02); the triacylglycerol effect showed dose-dependency with erythrocyte EPA + DHA (r = -0.15, P = 0.04), whereas HDL showed a tendency for such an association(r = 0.13, P = 0.08). Additional analyses indicated sex-specificity (Pdiet*sex < 0.10), because triacylglycerol was reduced by 0.09 mmol/L (95% CI: 0.02, 0.16 mmol/L) in boys only (girls: -0.00; 95% CI: -0.07, 0.07 mmol/L) and heart rate was reduced by 3.4 bpm (95% CI: 0.2, 6.6 bpm) in girls only (boys: 0.6; 95% CI: -2.6, 3.8 bpm). Blood pressure, HRV, and glucose homeostasis were unaffected.

CONCLUSIONS

Oily fish intake improved serum triacylglycerol and HDL cholesterol in a dose-dependent manner in 8- to 9-y-old children, but had no effect on blood pressure, HRV, or glucose homeostasis. This supports recommendations for fish intake in children and underlines the importance of initiatives to increase children's intake of oily fish. This trial was registered at clinicaltrials.gov as NCT02809508.

The combined effect of vitamin C and omega-3 polyunsaturated fatty acids on fatigue following coronary artery bypass graft surgery: a triple-blind clinical trial

Background Fatigue is a common compliant among patients who undergo coronary artery bypass graft (CABG) surgery. This may affect patients' function in all aspects. A few studies have already assessed the influence of complementary therapies on minimizing fatigue. This study aimed to investigate the combined effect of vitamin C and omega-3 polyunsaturated fatty acids (n-3 PUFA) on fatigue following CABG surgery. Methods In this randomized, triple-blind placebo-controlled trial, 160 patients who already underwent CABG surgery were randomly assigned into an experimental or a control groups. Each group consisted of 80 patients. The experimental group was given both n-3 PUFA and vitamin C the day before surgery. They also received the same supplements in the first 5 days of operation. The control group received only placebo. Subjects in both groups responded to Multidimensional Fatigue Inventory (MFI-20) scale in the beginning, and at the end of the intervention as well as on the fifth day of the operation. Chi-square test and independent t-test were used for data analysis. Results The mean fatigue score in experimental and control groups came up to 62.01 ± 4.06 and 67.92 ± 4.95 (p<0.0001), respectively, which was greater than that of the values we had before intervention. The mean difference of fatigue score was 3.97 ± 3.49 and 9.56 ± 6.41 (p<0.0001) prior and following the intervention, correspondingly. Conclusion Combination of vitamin C and n-3 PUFA effectively reduces post-operative fatigue among patients who undergo CABG surgery.

Heart-rate variability: a biomarker to study the influence of nutrition on physiological and psychological health?

As the influence of diet on health may take place over a period of decades, there is a need for biomarkers that help to identify those aspects of nutrition that have either a positive or a negative influence. The evidence is considered that heart-rate variability (HRV) (the time differences between one beat and the next) can be used to indicate the potential health benefits of food items. Reduced HRV is associated with the development of numerous conditions for example, diabetes, cardiovascular disease, inflammation, obesity and psychiatric disorders. Although more systematic research is required, various aspects of diet have been shown to benefit HRV acutely and in the longer term. Examples include a Mediterranean diet, omega-3 fatty acids, B-vitamins, probiotics, polyphenols and weight loss. Aspects of diet that are viewed as undesirable, for example high intakes of saturated or trans-fat and high glycaemic carbohydrates, have been found to reduce HRV. It is argued that the consistent relationship between HRV, health and morbidity supports the view that HRV has the potential to become a widely used biomarker when considering the influence of diet on mental and physical health.

Heart Rate Variability: A Potential Tool for Monitoring Immunomodulatory Effects of Parenteral Fish Oil Feeding in Patients With Sepsis

Fish oil, rich in the very-long chain omega (ω)-3 polyunsaturated fatty acids (PUFAs), has been found to have immunomodulatory effects in different groups of critically ill patients. In addition, its parenteral administration seems to attenuate the inflammatory response within 2 to 3 days. The activation of the cholinergic anti-inflammatory pathway has been suggested to mediate such immunoregulatory effects. As different experimental studies have convincingly illustrated that enhanced vagal tone can decrease pro-inflammatory cytokine secretion, novel monitoring tools of its activity at the bedside could be developed, to evaluate nutritional manipulation of immune response in the critically ill. Heart rate variability (HRV) is the variability of R-R series in the electrocardiogram and could be a promising surrogate marker of immune response and its modulation during fish oil feeding, rich in ω-3 PUFAs. Heart rate variability is an indirect measure of autonomic nervous system (ANS) output, reflecting mainly fluctuations in ANS activity. Through HRV analysis, different "physiomarkers" can be estimated that could be used as early and more accurate "smart alarms" because they are based on high-frequency measurements and are much more easy to get at the bedside. On the contrary, various "biomarkers" such as cytokines exhibit marked interdependence, pleiotropy, and their plasma concentrations fluctuate from day to day in patients with sepsis. In this respect, an inverse relation between different HRV components and inflammatory biomarkers has been observed in patients with severe sepsis and septic shock, whereas a beneficial effect of ω-3 PUFAs on HRV has been demonstrated in patients with cardiovascular diseases. Consequently, in this article, we suggest that a beneficial effect of ω-3 PUFAs on HRV and clinical outcome in patients with sepsis merits further investigation and could be tested in future clinical trials as a real-time monitoring tool of nutritional manipulation of the inflammatory response in the critically ill.

Omega-3 fatty acids and anxiety: A systematic review of the possible mechanisms at play

Introduction: Anxiety is prevalent, costly, and associated with significant adverse outcomes. The importance of nutrition is underestimated in the management of mental health disorders. In particular, omega-3 fatty acids (ω-3 FAs) are a critical component for healthy development and have been shown to reduce anxiety symptoms. Objective: This paper reviews the current state of the research to identify potential mechanisms underlying the relationship between ω-3 FAs and anxiety reduction. Method: Studies were identified using PubMed, PsycINFO, and CINAHL databases. Results: Of the 197 full-text studies screened, six met criteria for inclusion. Four mechanisms were identified based on primary outcomes reported by each study, Inflammatory Response, Brain-Derived Neurotrophic Factor (BDNF), Cortisol, and Cardiovascular Activity. Conclusion: Five key recommendations are provided to guide future research examining ω-3 FAs and anxiety. They include: (1) standardization of dosage and duration of ω-3 supplementation, (2) more rigorous measurement of variables, (3) effective blinding of participants, (4) designing experiments that test mediation, and (5) increasing sample diversity.

Seafood Long-Chain n-3 Polyunsaturated Fatty Acids and Cardiovascular Disease: A Science Advisory From the American Heart Association

Since the 2002 American Heart Association scientific statement "Fish Consumption, Fish Oil, Omega-3 Fatty Acids, and Cardiovascular Disease," evidence from observational and experimental studies and from randomized controlled trials continues to emerge to further substantiate the beneficial effects of seafood long-chain n-3 polyunsaturated fatty acids and cardiovascular disease. A recent American Heart Association science advisory addressed the specific effect of n-3 polyunsaturated fatty acid supplementation on clinical cardiovascular events. This American Heart Association science advisory extends that review and offers further support to include n-3 polyunsaturated fatty acids from seafood consumption. Several potential mechanisms have been investigated, including antiarrhythmic, anti-inflammatory, hematologic, and endothelial, although for most, longer-term dietary trials of seafood are warranted to substantiate the benefit of seafood as a replacement for other important sources of macronutrients. The present science advisory reviews this evidence and makes a suggestion in the context of the 2015-2020 Dietary Guidelines for Americans and in consideration of other constituents of seafood and the impact on sustainability. We conclude that 1 to 2 seafood meals per week be included to reduce the risk of congestive heart failure, coronary heart disease, ischemic stroke, and sudden cardiac death, especially when seafood replaces the intake of less healthy foods.

Effects of omega-3 polyunsaturated fatty acids on psychophysiological symptoms of post-traumatic stress disorder in accident survivors: A randomized, double-blind, placebo-controlled trial

BACKGROUND

Psychophysiological symptoms (e.g., pounding heart) are known to be a prominent feature of post-traumatic stress disorder (PTSD). Although omega-3 polyunsaturated fatty acids (PUFAs) have a beneficial potential pharmacological effect of preventing these psychophysiological symptoms, no clinical data is yet available. Therefore, we conducted a randomized, double-blind, placebo-controlled trial of Japanese accident survivors.

METHODS

A total of 83 participants received either omega-3 PUFAs (1470mg docosahexaenoic acid and 147mg eicosapentaenoic acid per day) or placebo within 10 days of the accidental injury. After 12-week supplementation, participants performed script-driven imagery of their traumatic event during monitoring of their heart rate and skin conductance.

RESULTS

Analysis revealed that heart rate during both rest and script-driven imagery was significantly lower in the omega-3 group than the placebo group, whereas baseline heart rate was comparable between the two groups.

LIMITATIONS

The present trial was conducted at a single-center in Japan and psychophysiological symptoms of PTSD in most participants were not serious.

CONCLUSION

These findings suggest that post-trauma supplementation of omega-3 PUFAs might be effective for the secondary prevention of psychophysiological symptoms of PTSD.

Saturated Fat Intake Is Related to Heart Rate Variability in Women with Polycystic Ovary Syndrome

Background/Aims: There is a heightened risk for cardiovascular diseases in women with polycystic ovary syndrome (PCOS). Alterations in heart rate variability (HRV) may reflect subclinical cardiovascular disease, with a putative association between HRV and dietary fat. This study evaluated HRV in PCOS and control women based on the dietary intake of saturated fatty acid (SFA). Methods: Biochemical/hormonal profile, resting metabolic rate, physical activity, HRV in response to the Stroop test, and dietary intake were assessed in 84 PCOS and 54 control women stratified by median SFA intake in the PCOS group (8.5% of daily energy intake). Results: Body mass index (p = 0.041), blood pressure (p < 0.01), and HOMA-IR (p = 0.003) were higher in PCOS vs. controls. PCOS women had higher testosterone (p = 0.001), dehydroepiandrosterone sulfate (p = 0.012), and free androgen index (p = 0.001), and lower sex hormone-binding globulin levels than controls (p = 0.001). In both groups, the clinical profile and calorie intake were similar between SFA categories. In PCOS, testosterone was lower when SFA intake <8.5%. PCOS women with SFA <8.5% consumed more beans, fruits, and vegetables and had better frequency and time domain HRV indices. No differences in HRV were detected between SFA categories in controls. In PCOS, age and SFA intake were independent predictors of HRV. Conclusions: Lower SFA intake is related to improved cardiovascular autonomic function in PCOS.

Hidden Signals-The History and Methods of Heart Rate Variability

The understanding of heart rate variability (HRV) has increased parallel with the development of modern physiology. Discovered probably first in 1847 by Ludwig, clinical applications evolved in the second part of the twentieth century. Today HRV is mostly used in cardiology and research settings. In general, HRV can be measured over shorter (e.g., 5-10 min) or longer (12 or 24 h) periods. Since 1996, most measurements and calculations are made according to the standard of the Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. As the first step, the series of times between successive R-peaks in the ECG are in milliseconds. It is crucial, however, to identify and remove extrasystoles and artifacts according to standard protocols. The series of QRS distances between successive heartbeats can be analyzed with simple or more sophisticated algorithms, beginning with standard deviation (SDNN) or by the square root of the mean of the sum of squares of differences between adjacent normal RR (rMSSD). Short-term HRV is frequently analyzed with the help of a non-parametric fast Fourier transformation quantifying the different frequency bands during the measurement period. In the last decades, various non-linear algorithms have been presented, such as different entropy and fractal measures or wavelet analysis. Although most of them have a strong theoretical foundation, their clinical relevance is still debated.

Modulation of heart rate and heart rate variability by n-3 long chain polyunsaturated fatty acids: Speculation on mechanism(s)

Heart rate (HR) and heart rate variability (HRV) are valuable markers of health. Although the underlying mechanism(s) are controversial, it is well documented that n-3 long chain polyunsaturated fatty acid (LCPUFA) intake improves HR and HRV in various populations. Autonomic modulation and/or alterations in cardiac electrophysiology are commonly cited as potential mechanisms responsible for these effects. This article reviews existing evidence for each and explores a separate mechanism which has not received much attention but has scientific merit. Based on presented evidence, it is proposed that n-3 LCPUFAs affect HR and HRV directly by autonomic modulation and indirectly by altering circulating factors, both dependently and independently of the autonomic nervous system. The evidence for changes in cardiac electrophysiology as the mechanism by which n-3 LCPUFAs affect HR and HRV needs strengthening.

The future for long chain n-3 PUFA in the prevention of coronary heart disease: do we need to target non-fish-eaters?

Dietary guidelines in many countries include a recommendation to consume oily fish, mainly on the basis of evidence from prospective cohort studies that fish consumption is cardioprotective. However, average intakes are very low in a large proportion of the UK population. Some groups, such as vegans and vegetarians, purposely omit fish (along with meat) from their diet resulting in zero or trace intakes of long chain (LC) n-3 PUFA. Although the efficacy of dietary fish oil supplementation in the prevention of CVD has been questioned in recent years, the balance of evidence indicates that LC n-3 PUFA exert systemic pleiotropic effects through their influence on gene expression, cell signalling, membrane fluidity and by conversion to specialised proresolving mediators; autacoid lipid mediators that resolve inflammatory events. The long-term impact of reduced tissue LC n-3 PUFA content on cardiovascular health is surprisingly poorly understood, particularly with regard to how low proportions of LC n-3 PUFA in cell membranes may affect cardiac electrophysiology and chronic inflammation. Randomised controlled trials investigating effects of supplementation on prevention of CHD in populations with low basal LC n-3 PUFA tissue status are lacking, and so the clinical benefits of supplementing non-fish-eating groups with vegetarian sources of LC n-3 PUFA remain to be determined. Refocusing dietary LC n-3 PUFA intervention studies towards those individuals with a low LC n-3 PUFA tissue status may go some way towards reconciling results from randomised controlled trials with the epidemiological evidence.

A comparison of heart rate variability, n-3 PUFA status and lipid mediator profile in age- and BMI-matched middle-aged vegans and omnivores

Low heart rate variability (HRV) predicts sudden cardiac death. Long-chain (LC) n-3 PUFA (C20-C22) status is positively associated with HRV. This cross-sectional study investigated whether vegans aged 40-70 years (n 23), whose diets are naturally free from EPA (20 : 5n-3) and DHA (22 : 6n-3), have lower HRV compared with omnivores (n 24). Proportions of LC n-3 PUFA in erythrocyte membranes, plasma fatty acids and concentrations of plasma LC n-3 PUFA-derived lipid mediators were significantly lower in vegans. Day-time interbeat intervals (IBI), adjusted for physical activity, age, BMI and sex, were significantly shorter in vegans compared with omnivores (mean difference -67 ms; 95 % CI -130, -3·4, P50 % and high-frequency power) were similarly lower in vegans, with no differences during sleep. In conclusion, vegans have higher 24 h SDNN, but lower day-time HRV and shorter day-time IBI relative to comparable omnivores. Vegans may have reduced availability of precursor markers for pro-resolving lipid mediators; it remains to be determined whether there is a direct link with impaired cardiac function in populations with low-n-3 status.

The effects of body weight status on orthostatic intolerance and predisposition to noncardiac syncope

Orthostatic intolerance (OI) is frequently the mechanism underlying the occurrence of noncardiac syncope (NCS) and is associated with substantial risk for injury. Body weight status appears to be a modifier of orthostatic responses and possibly influences the propensity to NCS. The majority of cross-sectional studies have found that the lower the body mass index (BMI) the greater the predisposition to OI is, accompanied with both down-regulation of sympathetic nervous system activity and up-regulation of parasympathetic nervous system activity. These changes appear to occur across the whole spectrum of BMI values from underweight to obesity, while they may be associated more strongly with central body fat than total body fat. Weight loss following bariatric surgery has been consistently found to increase OI, attributed first to the effects of weight loss per se, second to the specific type of surgical procedure and third to the potential postoperative autonomic neuropathy due to vitamin deficiency. The increased OI following bariatric surgery renders this intervention not easily tolerable for the affected individuals, mandating increased fluid and salt intake, pharmacological measures or surgical adjustments to attenuate OI. All future studies investigating orthostatic responses and NCS should implement a matching of the population arms for BMI and ideally for body fat.

Can natural ways to stimulate the vagus nerve improve seizure control?

The vagus nerve (VN) is the longest cranial nerve, innervating the neck, thorax and abdomen, with afferent fibers transmitting a range of interoceptive stimuli and efferent fibres to somatic structures and autonomic preganglions. Over the last few decades, electrical stimulation of the VN using implanted devices (VNS) has been developed leading to its approval for the treatment of epilepsy and depression. More recently, non-invasive devices to stimulation the VN have been developed. The VN has many functions and the activity that is most amenable to assessment is its effect in controlling the cardiac rhythm. This can be easily assessed by measuring heart rate variability (HRV). Decreased HRV is a result of poorer vagal parasympathetic tone and is associated with a wide range of ill health conditions including a higher risk of early mortality. People with epilepsy, particularly those with poorly controlled seizures, have been shown to have impaired parasympathetic tone. So, might natural ways to stimulate the VN, shown to improve parasympathetic tone as indicated by increased HRV, improve seizure control? There are numerous natural ways that have been shown to stimulate the VN, improving HRV and hence parasympathetic tone. These natural ways fall mainly into 3 categories - stress reduction, exercise, and nutrition. Though the natural ways to stimulate the VN have been shown to increase HRV, they have not been shown to reduce seizures. The exception is listening to Mozart's music, which has been shown to increase parasympathetic tone and decrease seizures. Clearly much more work is required to examine the effect of the various ways to increase HRV on seizure occurrence.

Long-chain omega-3 fatty acids and optimization of cognitive performance

Low consumption of the omega-3 fatty acids, eicosapentaenoic and docosahexaenonic acids, is linked to delayed brain development and, in late life, increased risk for Alzheimer's disease. The current review focuses on cognitive functioning during midlife and summarizes available scientific evidence relevant to the hypothesis that adequate dietary consumption of the long-chain omega-3 fatty acids is necessary for optimal cognitive performance. Taken together, the findings suggest that raising the currently low consumption among healthy adults may improve some aspects of cognitive performance. Nonetheless, evidence from randomized clinical trials is comparatively sparse and leaves unclear: (a) whether such effects are clinically significant, (b) whether effects of eicosapentaenoic acid and DHA differ, (c) which dimensions of cognitive function are affected, (d) the dose-response relationships, or (e) the time course of the response. Clarification of these issues through both laboratory and clinical investigations is a priority given the broad implications for public health, as well as for military personnel and other positions of high performance demand and responsibility.

Dietary and pharmacological intervention to mitigate the cardiopulmonary effects of air pollution toxicity

BACKGROUND

Exposure to air pollution contributes importantly to excess morbidity and mortality. And while regulatory actions under the "Clean Air Act" have saved millions of lives by improving air quality, there are still millions of people in the U.S. who live in areas where particulate air pollution (PM) levels exceed the U.S. Environmental Protection Agency's National Ambient Air Quality Standards. Therefore, apart from such localities working to attain such standards the protection of the health of public and in particular those at high risk might benefit from interventional strategies that would ameliorate air pollution's adverse health effects. Because inflammation and oxidative stress appear to mediate the health effects of air pollution, one interventional approach to consider is the use of dietary supplementation or medication with anti-inflammatory or antioxidant properties to block the biological responses that initiate the pathophysiological process that culminates in adverse health effects.

SCOPE OF REVIEW

This article reviews the capability of dietary supplementation, such as antioxidant vitamins, polyunsaturated fatty acids, and medications as a strategy to mitigate air pollution-induced subclinical cardiopulmonary effects.

MAJOR CONCLUSIONS

Antioxidant vitamins C and E protect the lungs against short-term ozone and PM exposure. Polyunsaturated fatty acids, such as fish oil and olive oil appear to offer protection against short-term air pollution-induced adverse cardiovascular responses.

GENERAL SIGNIFICANCE

Taking dietary supplements or medications with antioxidant or anti-inflammatory properties has the potential to provide at least partial protection against air pollution-induced adverse health effects in those individuals who are known to be most susceptible, namely those with pre-existing respiratory and cardiovascular diseases. This article is part of a Special Issue entitled Air Pollution, edited by Wenjun Ding, Andrew J. Ghio and Weidong Wu.

Omega-3 fatty acid supplementation combined with acute aerobic exercise does not alter the improved post-exercise insulin response in normoglycemic, inactive and overweight men

PURPOSE

The aim of this study was to determine if omega-3 (n-3) supplementation combined with acute aerobic exercise would improve glucose and insulin responses in normoglycemic, inactive, overweight men.

METHODS

In a random order, ten inactive and normoglycemic men (30.6 ± 10 years, 85.4 ± 11 kg, 26.7 ± 4 BMI) completed a rest (R) and exercise trial (EX) without n-3 supplementation. Following 42 days of n-3 supplementation, participants again completed a rest (R + n-3) and exercise trial (EX + n-3) with continued n-3 supplementation. The exercise trial consisted of 3 days of ~70 % VO2peak for 60 min/session. N-3 supplementation entailed 4.55 g/day of n-3 (EPA 2.45 g, DHA 1.61 g). A 75 g oral glucose tolerance (OGTT) test was administered 14-16 h after each trial.

RESULTS

Relative to R (35,278 ± 9169 pmol/L), EX without n-3 reduced the incremental area under the curve for insulin (iAUCinsulin) during an OGTT by 21.3 % (27765 ± 4925 pmol/L, p = 0.018) and 20.6 % after the EX + n-3 trial (27,999 ± 8370 pmol/L; p = 0.007). In addition, EX (96 ± 21 pmol/L; p = 0.006) reduced C-peptide by 13.5 % when compared to R (111 ± 26 pmol/L). No difference was observed between R and n-3 trials for iAUCinsulin and iAUCC-peptide. Only EX improved insulin sensitivity index by 5.6 % (p = 0.02) when compared to R.

CONCLUSIONS

These data suggest that n-3 supplementation does not add any additional benefit beyond the exercise induced insulin responses in inactive men. Furthermore, n-3 supplementation alone does not appear to impair insulin action in normoglycemic, inactive, overweight men.

Omega 3 and atrial fibrillation: Where are we?

Anti-arrhythmic properties of n-3 polyunsaturated fatty acids, at least in part mediated by anti-oxidant, anti-inflammatory and anti-fibrotic power, have been widely proved. Effect of fish oil on atrial fibrillation, both in primary and in secondary prevention and after cardiac surgery, are controversial, mostly due to lack of homogeneity between studies but also due to individual variability in response to fatty acids administration. Inclusion of measurement of incorporation of fish oil into cell membranes, appears to be essential in future studies, to assess their antiarrhythmic effect.

Reduction of circulating FABP4 level by treatment with omega-3 fatty acid ethyl esters

Background

Fatty acid-binding protein 4 (FABP4/A-FABP/aP2) mainly expressed in adipocytes is secreted and acts as an adipokine. Increased circulating FABP4 level is associated with obesity, insulin resistance and atherosclerosis. However, little is known about the modulation of serum FABP4 level by drugs including anti-dyslipidemic agents.

Methods

Patients with dyslipidemia were treated with omega-3 fatty acid ethyl esters (4 g/day; n = 14) containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) for 4 weeks. Serum FABP4 level was measured before and after treatment. Expression and secretion of FABP4 were also examined in mouse 3T3-L1 adipocytes treated with EPA or DHA.

Results

Treatment with omega-3 fatty acid ethyl esters significantly decreased triglycerides and serum FABP4 level (13.5 ± 1.5 vs. 11.5 ± 1.1 ng/ml, P = 0.017). Change in FABP4 level by omega-3 fatty acids was negatively correlated with change in levels of EPA + DHA (r = −0.643, P = 0.013), EPA (r = −0.540, P = 0.046) and DHA (r = −0.650, P = 0.011) but not change in the level of triglycerides or other fatty acid composition. Treatment of 3T3-L1 adipocytes with EPA or DHA had no effect on short-term (2 h) secretion of FABP4. However, gene expression and long-term (24 h) secretion of FABP4 were significantly reduced by treatment with EPA or DHA.

Conclusions

Omega-3 fatty acids decrease circulating FABP4 level, possibly by reducing expression and consecutive secretion of FABP4 in adipocytes. Reducing FABP4 level might be involved in suppression of cardiovascular events by omega-3 fatty acids.

Advances in heart rate variability signal analysis: joint position statement by the e-Cardiology ESC Working Group and the European Heart Rhythm Association co-endorsed by the Asia Pacific Heart Rhythm Society

Following the publication of the Task Force document on heart rate variability (HRV) in 1996, a number of articles have been published to describe new HRV methodologies and their application in different physiological and clinical studies. This document presents a critical review of the new methods. A particular attention has been paid to methodologies that have not been reported in the 1996 standardization document but have been more recently tested in sufficiently sized populations. The following methods were considered: Long-range correlation and fractal analysis; Short-term complexity; Entropy and regularity; and Nonlinear dynamical systems and chaotic behaviour. For each of these methods, technical aspects, clinical achievements, and suggestions for clinical application were reviewed. While the novel approaches have contributed in the technical understanding of the signal character of HRV, their success in developing new clinical tools, such as those for the identification of high-risk patients, has been rather limited. Available results obtained in selected populations of patients by specialized laboratories are nevertheless of interest but new prospective studies are needed. The investigation of new parameters, descriptive of the complex regulation mechanisms of heart rate, has to be encouraged because not all information in the HRV signal is captured by traditional methods. The new technologies thus could provide after proper validation, additional physiological, and clinical meaning. Multidisciplinary dialogue and specialized courses in the combination of clinical cardiology and complex signal processing methods seem warranted for further advances in studies of cardiac oscillations and in the understanding normal and abnormal cardiac control processes.

Somatic, but not cognitive-affective, symptoms are associated with reduced heart rate variability in individuals with dysphoria

Background: Somatic, but not cognitive–affective, symptoms of depression have been associated with reduced heart rate variability (HRV), and with poor prognosis in cardiovascular patients. However, factors concomitant with cardiovascular diseases may confound the relationship between somatic symptoms of depression and reduced HRV. Therefore, this study examined whether reduced HRV was differentially associated with cognitive–affective and somatic symptoms of depression in medically healthy individuals with and without dysphoria.

Methods: Self-reported cognitive–affective and somatic symptoms as measured with the Beck Depression Inventory-II questionnaire and time and frequency domain parameters of HRV were collected in 62 medically healthy individuals, of whom 25 with and 37 without dysphoria.

Results: Somatic, but not cognitive–affective, symptoms of depression were inversely associated with SD of NN intervals (β = -0.476, p < 0.05), number of interval differences of successive NN intervals greater than 50 ms (NN50; β = -0.498, p < 0.03), and HRV total power (β = -0.494, p < 0.04) in the group with dysphoria, after controlling for sex, anxiety, and lifestyle factors. Cognitive–affective and somatic symptoms were not related to any of the HRV parameters in the group without dysphoria (all ps > 0.24).

Conclusion: By showing that the relationship between somatic depressive symptoms and reduced HRV extends to medically healthy individuals with dysphoria, the present findings suggest that this association is independent of factors concomitant with cardiovascular diseases. The present study also suggests that individuals with somatic rather than cognitive–affective subsets of depressive symptoms may be at greater risk for developing cardiovascular diseases.

The autonomic nervous system and cardiovascular disease: role of n-3 PUFAs

In the last decades, a large body of experimental and clinical evidence has been accumulated showing that cardiovascular diseases are often accompanied by an imbalance in the sympathetic-vagal outflow to the heart, resulting in a chronic adrenergic activation. The arterial baroreceptor system is a key component of mechanisms contributing to the neural regulation of the cardiovascular system. Several methods have been proposed to assess autonomic activity by analyzing heart rate and blood pressure changes either spontaneously occurring or following provocations. The autonomic nervous system has been regarded as one of the putative mechanisms involved into the beneficial effects of exposure to n-3 fatty acids observed in epidemiological studies. The aim of the present review is to provide an update on the clinical evidence proposed so far linking exposure to n-3 fatty acids to autonomic nervous system modulation.

Exploratory multivariate analysis of the effect of fatty fish consumption and medicinal use on heart rate and heart rate variability data

The overall aim of the present study was to explore the relationship between medicinal use and fatty fish consumption on heart rate variability (HRV) and heart rate (HR) in a group of forensic inpatients on a variety of medications. A total of 49 forensic inpatients, randomly assigned to a fish group (n = 27) or a control group (n = 22) were included in the present study. Before and by the end of the food intervention period HR and HRV were measured during an experimental test procedure. An additional aim of this paper is to show how multivariate data analysis can highlight differences and similarities between the groups, thus being a valuable addition to traditional statistical hypothesis testing. The results indicate that fish consumption may have a positive effect on both HR and HRV regardless of medication, but that the influence of medication is strong enough to mask the true effect of fish consumption. Without correcting for medication, the fish group and control group become indistinguishable (p = 0.0794, Cohen’s d = 0.60). The effect of medication is demonstrated by establishing a multivariate regression model that estimates HR and HRV in a recovery phase based on HR and HRV data recorded during psychological tests. The model performance is excellent for HR data, but yields poor results for HRV when employed on participants undergoing the more severe medical treatments. This indicates that the HRV behavior of this group is very different from that of the participants on no or lower level of medication. When focusing on the participants on a constant medication regime, a substantial improvement in HRV and HR for the fish group compared to the control group is indicated by a principal component analysis and t-tests (p = 0.00029, Cohen’s d = 2.72). In a group of psychiatric inpatients characterized by severe mental health problems consuming different kinds of medication, the fish diet improved HR and HRV, indices of both emotional regulation and physical health.

Reduced anxiety in forensic inpatients after a long-term intervention with Atlantic salmon

The aim of the present study was to investigate the effects of Atlantic salmon consumption on underlying biological mechanisms associated with anxiety such as heart rate variability (HRV) and heart rate (HR) as well as a measure of self-reported anxiety. Moreover, these biological and self-reported outcome measures were investigated in relation to specific nutrients; vitamin D status, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Ninety-five male forensic inpatients were randomly assigned into a Fish (Atlantic salmon three times per week from September to February) or a Control group (alternative meal, e.g., chicken, pork, or beef three times per week during the same period). HRV measured as the root mean square of successive differences (rMSSD), HR, state- and trait-anxiety (STAI), were assessed before (pre-test) and at the end of the 23 weeks dietary intervention period (post-test). The Fish group showed significant improvements in both rMSSD and HR. The Fish group also showed significant decreases in state-anxiety. Finally, there was a positive relationship between rMSSD and vitamin D status. The findings suggest that Atlantic salmon consumption may have an impact on mental health related variables such as underlying mechanisms playing a key role in emotion-regulation and state-anxiety.

Influence of polyunsaturated fatty acids on blood pressure, resting heart rate and heart rate variability among French Polynesians

OBJECTIVE

To analyze the associations between marine n-3 polyunsaturated fatty acids (PUFAs) and blood pressure (BP), resting heart rate (HR), and heart rate variability (HRV) in a population highly exposed to methylmercury through the diet.

METHODS

Concentrations of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) in erythrocytes membranes were measured in 180 French Polynesian adults (≥18 years) residing in Tubuai, which is a community with a traditional lifestyle, or Papeete, which has a modern lifestyle. HRV was measured using a 2-hour ambulatory electrocardiogram (Holter). Resting HR and BP were measured using standardized protocols and pulse pressure (PP) was calculated as systolic BP - diastolic BP. The associations between n-3 PUFAs and the dependent variables were studied using simple and multiple linear regressions.

RESULTS

Increasing DHA concentration was associated with lower resting HR (β = -2.57, p = 0.005) and diastolic BP (β = -1.96, p = 0.05) and higher HRV in multivariable models. Specifically, DHA was associated with high frequency (HF; β = 0.19, p = 0.02) and the square root of the mean squared differences of successive R-R intervals (difference between two consecutive R waves; rMSSD; β = 0.08, p = 0.03), which are specific indices of the parasympathetic activity of the autonomic nervous system.

CONCLUSION

DHA was associated with lower BP and resting HR and higher HRV among French Polynesians who are also exposed to high methylmercury levels.

Physical activity and heart rate variability in older adults: the Cardiovascular Health Study

BACKGROUND

Cardiac mortality and electrophysiological dysfunction both increase with age. Heart rate variability (HRV) provides indices of autonomic function and electrophysiology that are associated with cardiac risk. How habitual physical activity among older adults prospectively relates to HRV, including nonlinear indices of erratic sinus patterns, is not established. We hypothesized that increasing the levels of both total leisure-time activity and walking would be prospectively associated with more favorable time-domain, frequency-domain, and nonlinear HRV measures in older adults.

METHODS AND RESULTS

We evaluated serial longitudinal measures of both physical activity and 24-hour Holter HRV over 5 years among 985 older US adults in the community-based Cardiovascular Health Study. After multivariable adjustment, greater total leisure-time activity, walking distance, and walking pace were each prospectively associated with specific, more favorable HRV indices, including higher 24-hour standard deviation of all normal-to-normal intervals (Ptrend=0.009, 0.02, 0.06, respectively) and ultralow-frequency power (Ptrend=0.02, 0.008, 0.16, respectively). Greater walking pace was also associated with a higher short-term fractal scaling exponent (Ptrend=0.003) and lower Poincaré ratio (Ptrend=0.02), markers of less erratic sinus patterns.

CONCLUSIONS

Greater total leisure-time activity, and walking alone, as well, were prospectively associated with more favorable and specific indices of autonomic function in older adults, including several suggestive of more normal circadian fluctuations and less erratic sinoatrial firing. Our results suggest potential mechanisms that might contribute to lower cardiovascular mortality with habitual physical activity later in life.

Effect of 8-week exercise-based cardiac rehabilitation on cardiac autonomic function: A randomized controlled trial in myocardial infarction patients

PURPOSE

The purpose of this study is to evaluate the effects of an 8-week exercise-based cardiac rehabilitation program on traditional and nonlinear heart rate variability (HRV) indexes, assessing the potential confounding influences of habitual physical activity (PA) and dietary intake.

METHODS

In this parallel-group trial, 96 patients (56 ± 10 years old) were randomized to the exercise group (EG) or to the control group (CG) 4 weeks after an acute myocardial infarction. Exercise-based cardiac rehabilitation program consisted of aerobic exercise at 70% to 85% of maximal heart rate for 3 sessions per week plus usual care. The CG received only usual care. The baseline and final assessments comprised resting short-term HRV (primary outcome) by a Polar R-R recorder under controlled breathing (12 breaths per minute), habitual PA by accelerometers, and dietary intake by a 4-day food diary.

RESULTS

Two patients in each group dropped out and were not included in the intention-to-treat analysis. In the remaining 92 patients (EG = 47 and CG = 45), at baseline, only a difference in the proportion of nitrate medication use was significant between groups. After 8 weeks, no significant changes were found between groups on traditional and nonlinear HRV indexes (eg, ln HF, EG from 5.7 ± 1.5 to 5.9 ± 1.3 and CG from 5.5 ± 1.6 to 5.5 ± 1.5), habitual PA, and dietary intake.

CONCLUSION

Eight weeks of exercise-based cardiac rehabilitation program is an insufficient stimulus to improve cardiac autonomic function in post-myocardial infarction patients under optimal medication and with high levels of traditional and nonlinear HRV indexes at baseline.

Global metabolomic profiling reveals an association of metal fume exposure and plasma unsaturated fatty acids

Background

Welding-associated air pollutants negatively affect the health of exposed workers; however, their molecular mechanisms in causing disease remain largely unclear. Few studies have systematically investigated the systemic toxic effects of welding fumes on humans.

Objectives

To explore the effects of welding fumes on the plasma metabolome, and to identify biomarkers for risk assessment of welding fume exposure.

Methods

The two-stage, self-controlled exploratory study included 11 boilermakers from a 2011 discovery panel and 8 boilermakers from a 2012 validation panel. Plasma samples were collected pre- and post-welding fume exposure and analyzed by chromatography/mass spectrometry.

Results

Eicosapentaenoic or docosapentaenoic acid metabolic changes post-welding were significantly associated with particulate (PM_2.5) exposure (p<0.05). The combined analysis by linear mixed-effects model showed that exposure was associated with a statistically significant decline in metabolite change of eicosapentaenoic acid [(95% CI) = −0.013(−0.022∼−0.004); p = 0.005], docosapentaenoic acid n₃ [(95% CI) = −0.010(−0.018∼−0.002); p = 0.017], and docosapentaenoic acid n₆ [(95% CI) = −0.007(−0.013∼−0.001); p = 0.021]. Pathway analysis identified an association of the unsaturated fatty acid pathway with exposure (p_Study−₂₀₁₁ = 0.025; p_Study−₂₀₁₂ = 0.021; p_Combined = 0.009). The functional network built by these fatty acids and their interactive genes contained significant enrichment of genes associated with various diseases, including neoplasms, cardiovascular diseases, and lipid metabolism disorders.

Conclusions

High-dose exposure of metal welding fumes decreases unsaturated fatty acids with an exposure-response relationship. This alteration in fatty acids is a potential biological mediator and biomarker for exposure-related health disorders.