Exploring the effects of oily fish consumption on measures of acute and long-term stress in healthy 8-9-year-old children: the FiSK Junior randomised trial.

Long-chain n-3 PUFA (n-3 LCPUFA) are known to reduce blood pressure (BP), heart rate and vagal tone, but potential stress-mitigating effects of n-3 LCPUFA are not well investigated. We explored the effects of oily fish consumption on long-term stress and the stress response in schoolchildren. Healthy 8-9-year-old children were randomised to receive about 300 g/week of oily fish or poultry for 12 weeks (199 randomised, 197 completing). At baseline and endpoint, we measured erythrocyte n-3 LCPUFA, hair cortisol and the response to a 1-min cold pressor test (CPT) on saliva cortisol, BP and continuous electrocardiogram recordings. Post-intervention hair cortisol did not differ between the groups, but sex-specificity was indicated (Psex × group = 0·074, boys: -0·9 (95 % CI -2·9, 1·0) ng/g, girls: 0·7 (95 % CI -0·2, 1·6) ng/g). Children in the fish group tended to be less prone to terminate CPT prematurely (OR 0·20 (95 % CI 0·02, 1·04)). Mean heart beat interval during CPT was 18·2 (95 % CI 0·3, 36·6) ms longer and high frequency power increased (159 (95 % CI 29, 289) ms2) in the fish v. poultry group. The cardiac autonomic response in the 10 min following CPT was characterised by a sympathetic peak followed by a parasympathetic peak, which was most pronounced in the fish group. This exploratory study does not support a strong effect of oily fish consumption on stress but indicates that oily fish consumption may increase vagal cardiac tone during the physiological response to CPT. These results warrant further investigation.

Marine n-3 PUFA, heart rate variability and ventricular arrhythmias in patients on chronic dialysis: a cross-sectional study.

Marine n-3 PUFA may improve autonomic dysfunction by an increase in heart rate variability (HRV) and may reduce the risk of malignant ventricular arrhythmias. Only a few smaller studies have examined such effects in patients on chronic dialysis, who often have autonomic dysfunction and a high risk of sudden cardiac death, which accounts for almost 30 % of all deaths. This cross-sectional study investigated the association between the plasma phospholipid content of n-3 PUFA and 24-h HRV or ventricular arrhythmias in patients on chronic dialysis. A 48-h Holter monitoring was performed on 169 patients on in-centre dialysis (83 %), home haemodialysis (10 %) or peritoneal dialysis (7 %) obtaining data on arrhythmias (n 152) and 24-h HRV (n 135). The mean overall HRV (standard deviation of normal intervals (SDNN)) was low and 71 % had a reduced overall HRV (SDNN<100 ms) indicating autonomic dysfunction. No significant associations between plasma phospholipid content of total marine n-3 PUFA, EPA (22 : 5n-3) or DHA (22 : 6n-3) and time-domain or frequency-domain HRV were detected in crude or adjusted linear regression analysis. However, a higher plasma phospholipid content of DHA was associated with a significantly lower proportion of patients with ventricular tachycardia (higher DHA-tertile: 9 % v. lower DHA-tertile: 28 %, P=0·02). In conclusion, the content of marine n-3 PUFA in plasma phospholipids was not associated with 24-h HRV, but a higher plasma phospholipid content of DHA was associated with a lower occurrence of ventricular tachycardia suggesting an antiarrhythmic effect of marine n-3 PUFA in patients on chronic dialysis.

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.

Effects of Marine n-3 Polyunsaturated Fatty Acids on Heart Rate Variability and Heart Rate in Patients on Chronic Dialysis: A Randomized Controlled Trial.

Marine n-3 polyunsaturated fatty acids (PUFA) may improve autonomic dysfunction, as indicated by an increase in heart rate variability (HRV) and reduce the risk of sudden cardiac death. Hence, the aim of this study was to investigate the effects of marine n-3 PUFA on 24-h HRV in patients on chronic dialysis, who have a high risk of sudden cardiac death. Between June 2014 and March 2016, 112 patients on chronic dialysis from Denmark were allocated to a daily supplement of 2 g marine n-3 PUFA or control for three months in a randomized, double-blinded, controlled trial. A 48-h Holter monitoring was performed and mean 24-h HRV indices for the two days were available in 85 patients. The mean age was 62.3 years (SD: 14.3) and median dialysis vintage was 1.7 years (IQR: 0.5, 6.4). Within-group and between-group changes in outcome were evaluated by a paired and two sample t-test, respectively. Marine n-3 PUFA did not change the primary endpoint SDNN (SD of all RR-intervals) reflecting overall HRV, but other HRV indices increased and the mean RR-interval increased significantly, corresponding to a decrease in heart rate by 2.5 beats per minute (p = 0.04). In conclusion, marine n-3 PUFA did not change SDNN, but the mean heart rate was significantly reduced and changes in other HRV-indices were also observed, indicating an increase in vagal modulation that might be protective against malignant ventricular arrhythmias.