Effect of α-linolenic acid on 24-h ambulatory blood pressure in untreated high-normal and stage I hypertensive subjects.

Results of intervention studies on the effects of α-linolenic acid (ALA; C18 : 3n-3) on blood pressure (BP) are conflicting. Discrepancies between studies may be due to differences in study population, as subjects with increased baseline BP levels may be more responsive. Therefore, we examined specifically the effects of ALA on 24-h ambulatory blood pressure (ABP) in (pre-)hypertensive subjects. In a double-blind, randomised, placebo-controlled parallel study, fifty-nine overweight and obese adults (forty males and nineteen females) with (pre-)hypertension (mean age of 60 (sd 8) years) received daily 10 g refined cold-pressed flaxseed oil, providing 4·7 g (approximately 2 % of energy) ALA (n 29) or 10 g of high-oleic sunflower oil as control (n 30) for 12 weeks. Compliance was excellent as indicated by vial count and plasma phospholipid fatty-acid composition. Compared with control, the changes of -1·4 mmHg in mean arterial pressure (MAP; 24 h ABP) after flaxseed oil intake (95 % CI -4·8, 2·0 mmHg, P=0·40) of -1·5 mmHg in systolic BP (95 % CI -6·0, 3·0 mmHg, P=0·51) and of -1·4 mmHg in diastolic BP (95 % CI -4·2, 1·4 mmHg, P=0·31) were not statistically significant. Also, no effects were found for office BP and for MAP, systolic BP, and diastolic BP when daytime and night-time BP were analysed separately and for night-time dipping. In conclusion, high intake of ALA, about 3-5 times recommended daily intakes, for 12 weeks does not significantly affect BP in subjects with (pre-)hypertension.

Dietary patterns and cardiometabolic risk factors among adolescents: systematic review and meta-analysis.

This study systematised and synthesised the results of observational studies that were aimed at supporting the association between dietary patterns and cardiometabolic risk (CMR) factors among adolescents. Relevant scientific articles were searched in PUBMED, EMBASE, SCIENCE DIRECT, LILACS, WEB OF SCIENCE and SCOPUS. Observational studies that included the measurement of any CMR factor in healthy adolescents and dietary patterns were included. The search strategy retained nineteen articles for qualitative analysis. Among retained articles, the effects of dietary pattern on the means of BMI (n 18), waist circumference (WC) (n 9), systolic blood pressure (n 7), diastolic blood pressure (n 6), blood glucose (n 5) and lipid profile (n 5) were examined. Systematised evidence showed that an unhealthy dietary pattern appears to be associated with poor mean values of CMR factors among adolescents. However, evidence of a protective effect of healthier dietary patterns in this group remains unclear. Considering the number of studies with available information, a meta-analysis of anthropometric measures showed that dietary patterns characterised by the highest intake of unhealthy foods resulted in a higher mean BMI (0·57 kg/m²; 95 % CI 0·51, 0·63) and WC (0·57 cm; 95 % CI 0·47, 0·67) compared with low intake of unhealthy foods. Controversially, patterns characterised by a low intake of healthy foods were associated with a lower mean BMI (-0·41 kg/m²; 95 % CI -0·46,-0·36) and WC (-0·43 cm; 95 % CI -0·52,-0·33). An unhealthy dietary pattern may influence markers of CMR among adolescents, but considering the small number and limitations of the studies included, further studies are warranted to strengthen the evidence of this relation.

Involvement of NLRP3 inflammasome in the impacts of sodium and potassium on insulin resistance in normotensive Asians.

Salt, promoting oxidative stress, contributes to insulin resistance, whereas K, inhibiting oxidative stress, improves insulin sensitivity. Oxidative stress activation of NLRP3 inflammasome is a central player in the induction of insulin resistance. Therefore, we hypothesised that NLRP3 inflammasome may mediate the effects of salt and K on insulin resistance. In all, fifty normotensive subjects were recruited from a rural community of Northern China. The protocol included a low-salt diet for 7 d, then a high-salt diet for 7 d and a high-salt diet with K supplementation for another 7 d. In addition, THP-1 cells were cultured in different levels of Na with and without K. The results showed that salt loading elevated fasting blood glucose, insulin and C-peptide levels, as well as insulin resistance, whereas K supplementation reversed them. Meanwhile, additional K reversed the active effects of high salt on NLRP3 inflammasome in both the subjects and THP-1 cells, and the change of insulin resistance index notably related with the alteration of plasma IL-1ß, the index of NLRP3 inflammasome activation, during intervention in the subjects. Additional K ameliorated oxidative stress induced by high salt in both the subjects and cultured THP-1 cells, and the change of oxidative stress related with the alteration of plasma IL-1ß during intervention in the subjects. In vitro, antioxidant N-acetyl-l-cysteine significantly prevented the active effects of high Na or oxidant Rosup on NLRP3 inflammasome, so did K. Our study indicates that oxidative stress modulation of NLRP3 inflammasome may be involved in the impacts of Na and K on insulin resistance.

Genetic predisposition to salt-sensitive normotension and its effects on salt taste perception and intake.

Salt sensitivity is an independent CVD and mortality risk factor, which is present in both hypertensive and normotensive populations. It is genetically determined and it may affect the relationship between salt taste perception and salt intake. The aim of this study was to explore the genetic predisposition to salt sensitivity in a young and a middle-aged adult population and its effects on salt taste perception and salt intake. The effects of Na loading on blood pressure (BP) were investigated in twenty normotensive subjects and salt sensitivity defined as the change in BP after 7 d of low-Na (51·3 mmol Na/d) and 7 d of high-Na diet (307·8 mmol Na/d). Salt taste perception was identified using the British Standards Institution sensory analysis method (BS ISO 3972:2011). Salt intake was assessed with a validated FFQ. DNA was genotyped for SNP in the SLC4A5, SCNN1B and TRPV1 genes. The subjects with AA genotype of the SLC4A5 rs7571842 exhibited the highest increase in BP (∆ systolic BP=7·75 mmHg, P=0·002, d=2·4; ∆ diastolic BP=6·25 mmHg, P=0·044, d=1·3; ∆ mean arterial pressure=6·5 mmHg, P=0·014, d=1·7). The SLC4A5 rs10177833 was associated with salt intake (P=0·037), and there was an association between salt taste perception and salt sensitivity (r s 0·551, P=0·041). In conclusion, there is a genetic predisposition to salt sensitivity and it is associated with salt taste perception. The association between salt taste perception and discretionary salt use suggests that preference for salty taste may be a driver of salt intake in a healthy population and warrants further investigation.

Nutrient profiling and adherence to components of the UK national dietary guidelines association with metabolic risk factors for CVD and diabetes: Airwave Health Monitoring Study.

CVD is the leading cause of death worldwide. Diet is a key modifiable component in the development of CVD. No official UK diet quality index exists for use in UK nutritional epidemiological studies. The aims of this study are to: (i) develop a diet quality index based on components of UK dietary reference values (DRV) and (ii) determine the association between the index, the existing UK nutrient profile (NP) model and a comprehensive range of cardiometabolic risk markers among a British adult population. A cross-sectional analysis was conducted using data from the Airwave Health Monitoring Study (n 5848). Dietary intake was measured by 7-d food diary and metabolic risk using waist circumference, BMI, blood lipid profile, glycated Hb (HbA1c) and blood pressure measurements. Diet quality was assessed using the novel DRV index and NP model. Associations between diet and cardiometabolic risk were analysed via multivariate linear models and logistic regression. A two-point increase in NP score was associated with total cholesterol (ß -0·33 mmol/l, P<0·0001) and HbA1c (ß -0·01 %, P<0·0001). A two-point increase in DRV score was associated with waist circumference (ß -0·56 cm, P<0·0001), BMI (ß -0·15 kg/m2, P<0·0001), total cholesterol (ß -0·06 mmol/l, P<0·0001) and HbA1c (ß -0·02 %, P=0·002). A one-point increase in DRV score was associated with type 2 diabetes (T2D) (OR 0·94, P=0·01) and obesity (OR 0·95, P<0·0001). The DRV index is associated with overall diet quality and risk factors for CVD and T2D, supporting its application in nutritional epidemiological studies investigating CVD risk in a UK population.

Dietary nitrate lowers ambulatory blood pressure in treated, uncontrolled hypertension: a 7-d, double-blind, randomised, placebo-controlled, cross-over trial.

Dietary nitrate has been shown to increase nitrate/nitrite levels and decrease blood pressure (BP) in multiple populations. There are few reports among hypertensives and these reports have provided conflicting evidence. We aimed to assess the effect of daily nitrate compared with placebo in subjects with uncontrolled hypertension (HTN). On day 0, hypertensives wore an ambulatory BP monitor (ABPM) for 24 h and blood was taken. Subjects were then randomised to 7-d nitrate-rich beetroot juice (NO3 -) (12·9 mmol nitrate) followed by 7-d nitrate-depleted beetroot juice (0·5 mmol nitrate) or vice versa. ABPM and blood were assessed before and after both conditions. In all, twenty subjects with treated yet uncontrolled HTN entered and completed the trial (mean age=62·5 years, mean BMI=30·7 kg/m2). Baseline BP was 137/80 (sd 7/7) mmHg. Dietary nitrate was well tolerated and resulted in significantly increased plasma nitrite (P=0·0004) and decreased 24-h systolic BP and diastolic BP compared with placebo (-8 mmHg; P=0·012 and -4 mmHg; P=0·018, respectively). Our results support the existing data suggesting an anti-hypertensive effect of dietary nitrate in treated yet uncontrolled hypertensives. Targeted dietary strategies appear promising contributors to BP control.

Adherence to a Dietary Approaches to Stop Hypertension (DASH)-type diet over the life course and associated vascular function: a study based on the MRC 1946 British birth cohort.

Little is known about long-term associations between the Dietary Approaches to Stop Hypertension (DASH) diet and conventional cardiovascular (CV)-risk factors as well as novel measures of vascular function. This study aimed to examine whether long-term adherence to a DASH-type diet in a British birth cohort is associated with conventional CV-risk factors and two vascular function markers, carotid intima-media thickness (cIMT) and pulse wave velocity (PWV). Data came from 1409 participants of the Medical Research Council (MRC) National Survey of Health and Development. Dietary intake was assessed at 36, 43, 53 and 60-64 years using 5-d estimated food diaries. The DASH-type diet score was calculated using the Fung index. Conventional CV-risk factors (blood pressure (BP) and lipids), cIMT in the right and/or left common carotid artery and PWV was measured when participants were 60-64 years. Associations between the DASH-type diet score and outcomes were assessed using multiple regression models adjusted for socioeconomic position, BMI, smoking and physical activity. Participants in higher sex-specific quintiles (Q) of the long-term DASH-type diet had lower BP (P≤0·08), higher HDL-cholesterol (P<0·001) and lower TAG (P<0·001) compared with people in Q1. Participants in Q5 of the long-term DASH-type diet had lower PWV (-0·28 sd; 95 % CI -0·50, -0·07, P trend=0·01) and cIMT (-0·24 sd; 95 % CI -0·44, -0·04, P trend=0·02) compared with participants in the Q1. This association was independent of the conventional CV-risk factors. Greater adherence to a DASH diet over the life course is associated with conventional CV-risk factors and independently associated with cIMT and PWV.

Effect of increased calcium consumption from fat-free milk in an energy-restricted diet on the metabolic syndrome and cardiometabolic outcomes in adults with type 2 diabetes mellitus: a randomised cross-over clinical trial.

We investigated the effects of high-Ca fat-free milk phase (MD) (prescription of approximately 1500 mg of Ca/d) v. low-Ca phase (CD) (prescription of approximately 800 mg of Ca/d) in an energy-restricted diet on the metabolic syndrome (MetS) and cardiometabolic measures in individuals with type 2 diabetes mellitus (T2DM) and low habitual Ca consumption (<600 mg/d). In this randomised cross-over design, fourteen adults with T2DM (49·5 (sd 8·6) years, BMI 29·4 (sd 4·5) kg/m2) consumed either MD or CD for 12 weeks, with a washout of 18 weeks between phases. A breakfast shake containing 700 mg (MD) or 6·4 mg (CD) of Ca was consumed in the laboratory. In addition, energy-restricted diets were prescribed (800 mg of dietary Ca/d). Waist circumference (WC), fasting glucose, fasting TAG, systolic (SBP) and diastolic blood pressure (DBP), fasting total cholesterol, fasting LDL-cholesterol, fasting HDL-cholesterol, HDL:LDL ratio, HDL:TAG ratio and lipid accumulation product (LAP) index were assessed at baseline and after each phase. Ca consumption during the study was equivalent to 1200 mg/d during MD and 525 mg/d during CD. There was a greater reduction in WC, SBP, DBP and LAP index after MD compared with CD. HDL:LDL ratio increased and total cholesterol, LDL-cholesterol, SBP, DBP and LAP index decreased only in MD. The consumption of approximately 1200 mg of Ca/d (700 mg from fat-free milk+500mg from other dietary sources) associated with an energy-restricted diet decreased some of the MetS components and cardiometabolic measures in adults with T2DM.

Associations between adherence to the Danish Food-Based Dietary Guidelines and cardiometabolic risk factors in a Danish adult population: the DIPI study.

Diet is recognised as one modifiable lifestyle factor for ischaemic heart disease (IHD). We aimed at investigating the associations between adherence to the Danish Food-Based Dietary Guidelines (FBDG) indicated by a Dietary Quality Index (DQI) and selected cardiometabolic risk factors in a cross-sectional study with 219 Danish adult participants (59 %women; age 31-65years) with a minimum of one self-rated risk marker of IHD. Information regarding diet was obtained using web-based dietary assessment software and adherence to the Danish FBDG was expressed by a DQI calculated from 5 food and nutrient indicators (whole grain, fish, fruit and vegetables, energy from saturated fat and from added sugar). Background information, blood samples and anthropometrics were collected and blood pressure was measured. Linear regression analyses were used to evaluate the association between DQI and cardiometabolic risk factors. DQI was inversely associated with LDL:HDL ratio and TAG (-0·089 per unit; 95 % CI -0·177, -0·002 and -5 % per unit; 95 % CI -9, 0, respectively) and positively associated with HDL-cholesterol (0·047 mmol/l per unit; 95 % CI 0·007, 0·088). For men, DQI was inversely associated with BMI (-3 %per unit; 95 % CI -5, -1), trunk fat (-1 % per unit; 95 % CI -2, -1), high-sensitivity C-reactive protein (-30 % per unit; 95 % CI -41, -16 %), HbA1c (-0·09 % per unit; 95 % CI -0·14, -0·04), insulin (-13 % per unit; 95 % CI -19, -7) and homoeostatic model assessment-insulin resistance (-14 % per unit; 95 % CI -21, -7). In women, DQI was positively associated with systolic blood pressure (2·6 mmHg per unit; 95 % CI 0·6, 4·6). In conclusion, higher adherence to the current Danish FBDG was associated with a more beneficial cardiometabolic risk profile in a Danish adult population with a minimum of one self-rated risk factor for IHD.

Effects of NWT-03, an egg-protein hydrolysate, on blood pressure in normotensive, high-normotensive and mild-hypertensive men and women: a dose-finding study.

Angiotensin-converting enzyme (ACE) inhibitors are important agents in blood pressure (BP) management. It was recently shown that the egg-protein hydrolysate NWT-03 inhibited ACE in Zucker diabetic fatty rats. We therefore designed a dose-finding study to assess the effects of 1, 2 and 5 g NWT-03 on daytime, 36-h, and night-time systolic and diastolic BP (SBP and DBP) in ninety-two generally healthy subjects with normal BP (n 29), high-normal BP (n 34) or mild hypertension (n 29). The study had a cross-over design with six treatment arms (1 g NWT-03 or placebo in period 1 and placebo or 1 g NWT-03 in period 2, 2 g NTW-03 or placebo in period 1 and placebo or 2 g NWT-03 in period 2, or 5 g NTW-03 or placebo in period 1 and placebo or 5 g NTW-03 in period 2). A comparable number of subjects from each BP class were included in each study arm. Duration of both treatments in each arm was 7 d, separated by 5-d wash-out periods. BP was measured with an ambulatory BP monitor before and after the treatments. In mild-hypertensive subjects, 2 g NWT-03 significantly decreased daytime SBP (7·9 mmHg; P=0·006), daytime DBP (4·2 mmHg; P=0·009), 36-h SBP (6·9 mmHg; P=0·015) and 36-h DBP (3·5 mmHg; P=0·035) compared with placebo subjects. In addition, in mild-hypertensive subjects, 5 g NWT-03 significantly decreased night-time SBP (14·8 mmHg; P=0·008) and night-time DBP (8·4 mmHg; P=0·020) compared with that in placebo subjects. To conclude, we found that 2 g NWT-03 lowered daytime and 36-h BP in subjects with mild hypertension, and 5 g NWT-03 lowered night-time BP in subjects with mild hypertension. As no dose-response relationship was evident, these results should be interpreted with care, and additional studies are needed.

Soft drink consumption is associated with increased incidence of the metabolic syndrome only in women.

Prospective studies on the association between soft drink consumption and incident risk of the metabolic syndrome (MetS) have not been carried out in Asians. We explored the sex-specific association between soft drink consumption and incident risk of the MetS in Korean adults during 10 years of follow-up. A total of 5797 subjects who were free of the MetS at baseline were studied. Soft drink consumption was assessed using a semi-quantitative FFQ. Time-dependent Cox proportional hazard model was used to examine hazard ratios (HR) of incidence of the MetS and its components in relation to soft drink consumption. In women, the multivariable-adjusted HR for developing the MetS was 1·8-fold higher in frequent consumers of soft drinks (≥4 servings/week) compared with rare consumers (95 % CI 1·23, 2·64). The adjusted HR for elevated blood pressure increased by 2-fold (95 % CI 1·24, 3·14) and for hypertriacylglycerolaemia by 1·9-fold (95 % CI 1·19, 2·88) in frequent consumers of soft drinks compared with rare consumers. However, in men, there was no association between soft drink consumption and incident risk of the MetS or its components. Frequent soft drink consumption was associated with increased risk of developing the MetS and its components only in middle-aged Korean women, suggesting sex differences for the risk of the MetS related to diet.

Transferrin saturation concentrations associated with telomeric ageing: a population-based study.

There are limited data on the association between Fe overload and leucocyte telomere length (LTL), known as a useful biomarker of the replicative ageing of cells. The aim of the study was to evaluate associations between Fe-status biomarkers and LTL. A cross-sectional study included 1174 men and women aged 50-79 years who provided blood samples for assays of Fe-status biomarkers including ferritin, transferrin saturation (TSAT), total Fe-binding capacity (TIBC) and relative LTL. They were free of hepatitis, potential infection or Fe deficiency. In multiple linear regression analysis adjusted for potential confounding variables, log-transformed LTL was positively associated with TIBC (adjusted coefficient estimate for its highest quartile: 0·17 (se 0·03), P45 %) but also with high-normal concentrations (35-45 %) of TSAT had shorter LTL compared with those with low-normal concentrations (<30 %) (P<0·05). We also observed that less-active or obese persons with high TSAT concentrations had shorter LTL than others. Our findings that cellular ageing is influenced not only by Fe overload but also by high-normal concentrations of TSAT support the hypothesis regarding the detrimental effects of labile Fe, which has a potent pro-oxidant activity in the body.

Polymorphisms of the TNF-α gene interact with plasma fatty acids on inflammatory biomarker profile: a population-based, cross-sectional study in São Paulo, Brazil.

The aim of the present study was to investigate the relationship of four TNF-α SNP with inflammatory biomarkers and plasma fatty acids (FA), and the interaction among them in a population-based, cross-sectional study in São Paulo, Brazil. A total of 281 subjects, aged >19 and <60 years, participated in a cross-sectional, population-based study performed in Brazil. The following SNP spanning the TNF-α gene were genotyped: -238G/A (rs361525), -308G/A (rs1800629), -857C/T (rs1799724) and -1031T/C (rs1799964). In all, eleven plasma inflammatory biomarkers and plasma FA profile were determined. To analyse the interaction between TNF-α SNP and plasma FA, a cluster analysis was performed to stratify individuals based on eleven inflammatory biomarkers into two groups used as outcome: inflammatory (INF) and non-inflammatory clusters. The -238A allele carriers had higher TNF-α (P=0·033), IL-6 (P=0·013), IL-1ß (P=0·037), IL-12 (0·048) and IL-10 (P=0·010) than the GG genotype. The -308A allele carriers also had lower levels of plasma palmitoleic acid (P=0·009), oleic acid (P=0·039), total MUFA (P=0·014), stearoyl-CoA desaturase (SCD) activity index-16 (P=0·007), SCD-18 (P=0·020) and higher levels of PUFA (P=0·046) and DHA (P=0·044). Significant interactions modifying the risk of belonging to the INF cluster were observed with inflammatory cluster as outcome between -857C/T and plasma α-linolenic acid (P=0·026), and also between -308G/A and plasma stearic acid (P=0·044) and total SFA (P=0·040). Our study contributes to knowledge on TNF-α SNP and their association with inflammatory biomarker levels, plasma FA and the interaction among them, of particular interest for the Brazilian population.

Chronic administration of grape-seed polyphenols attenuates the development of hypertension and improves other cardiometabolic risk factors associated with the metabolic syndrome in cafeteria diet-fed rats.

The effects of grape-seed polyphenols against the development of hypertension and other cardiometabolic conditions associated with the metabolic syndrome (MetS) were studied in rats fed a high-fat, high-carbohydrate diet, known as the cafeteria (CAF) diet. Two groups of Wistar rats were fed standard (STD) or CAF diets for 12 weeks. The CAF diet-fed rats were administered different doses of a low-molecular-weight grape-seed polyphenol extract (LM-GSPE) (25, 100 and 200 mg/kg per d) or vehicle daily, and the STD diet-fed rats were administered LM-GSPE (100 mg/kg per d) or vehicle using ten animals per group. Body weight (BW), waist perimeter (WP) and systolic and diastolic blood pressures (BP) by the tail-cuff method were recorded weekly. The animals were housed in metabolic chambers every 2 weeks to estimate daily food and liquid intakes and to collect faeces and urine samples. The plasma lipid profile was analysed at time 0 and on the 4th, 7th, 10th and 12th weeks of the experiment. Moreover, plasma leptin was measured at the end of the experiment. Results demonstrated that LM-GSPE, when administered with the CAF diet, attenuated the increase in BP, BW, WP and improved lipid metabolism in these animals. However, although the 25- and 100-mg/kg per d doses were sufficient to produce beneficial effects on BP and lipid metabolism, a 200-mg/kg per d dose was necessary to have an effect on BW and WP. The present findings suggest that LM-GSPE is a good candidate for a BP-lowering agent that can also ameliorate other conditions associated with the MetS.

Frequency of takeaway food consumption and its association with major food group consumption, anthropometric measures and blood pressure during adolescence.

We prospectively assessed the (1) frequency and socio-economic correlates of takeaway food consumption during adolescence; and (2) association between frequent takeaway food consumption with intakes of major food groups and anthropometric measures and blood pressure (BP). In total, 699 Sydney schoolchildren (380 girls and 319 boys) who had dietary data at both 12 and 17 years of age were included for analyses. Takeaway food consumption was self-reported and based on a single question. Anthropometric measures and BP were collected. The proportion of participants who ate takeaway foods once per week or more increased significantly over 5 years from the age of 12 to 17 years: 35·5-44·1 % (P<0·0001). In total, 12-year-old girls compared with boys had reduced odds of takeaway foods once per week or more at the age of 17 years (P=0·01), multivariable-adjusted OR 0·63 (95 % CI 0·44, 0·90). In total, 12-year-old children who ate takeaway foods once per week or more had significantly lower mean fruit (220·3 v. 253·0 g/d; P=0·03) and vegetable consumption (213·2 v. 247·7 g/d; P=0·004), 5 years later (at 17 years of age). Frequent takeaway food consumption at the age of 12 years was not associated with anthropometric indices and BP at the age of 17 years. Consumption of takeaway foods became more frequent during adolescence, particularly among boys, and it was associated with reduced intake of fruits and vegetables.

Low fruit consumption and omission of daily meals as risk factors for increased blood pressure in adults.

A population-based cross-sectional survey with cluster sampling design and with inverse sampling was conducted in 2010, in a sample of 1590 adults (19-60 years old) exposed to a high prevalence of food insecurity, in the municipality of Duque de Caxias, metropolitan region of Rio de Janeiro, Brazil. The objective of the study was to evaluate the association of socio-demographic factors, the consumption of fruits and vegetables and the number of meals with increased blood pressure (BP). A hierarchical model that considered variables related to the basic, intermediate and immediate determinants of increased BP was adopted. By using Poisson's regression, univariate models were tested to obtain the prevalence ratio (PR) and its respective 95 % CI. After fitting the model, age (age group 50-59 years) (PR 1·62; 95 % CI 1·09, 2·41), low consumption of fruits in a week (PR 1·37; 95 % CI 1·07, 1·74), fewer meals per day (PR 1·72; 95 % CI 1·21, 2·43) and overweight (PR 1·78; 95 % CI 1·31, 2·20) remained significantly associated with increased BP. Therefore, the results found here reinforce the importance of encouraging and developing strategies that ensure access to healthy foods to minimise increased BP in similar populations.

How reliable are randomised controlled trials for studying the relationship between diet and disease? A narrative review.

Large numbers of randomised controlled trials (RCT) have been carried out in order to investigate diet-disease relationships. This article examines eight sets of studies and compares the findings with those from epidemiological studies (cohort studies in seven of the cases). The studies cover the role of dietary factors in blood pressure, body weight, cancer and heart disease. In some cases, the findings from the two types of study are consistent, whereas in other cases the findings appear to be in conflict. A critical evaluation of this evidence suggests factors that may account for conflicting findings. Very often RCT recruit subjects with a history of the disease under study (or at high risk of it) and have a follow-up of only a few weeks or months. Cohort studies, in contrast, typically recruit healthy subjects and have a follow-up of 5-15 years. Owing to these differences, findings from RCT are not necessarily more reliable than those from well-designed prospective cohort studies. We cannot assume that the results of RCT can be freely applied beyond the specific features of the studies.

The importance of blood lipids in the association between BMI and blood pressure among Chinese overweight and obese children.

We aimed to examine the contribution of blood lipids to the association between BMI and blood pressure (BP) in children with overweight and obesity. Data were collected in elementary and high schools of Chaoyang District, Beijing, China in 2012. Participants' weight, height, BP and fasting plasma lipid profile were measured by standard protocols. Mediation analysis was used to examine the mediation role of blood lipids on the relation between BMI and BP, with age included as a covariate. We found that in boys 8·29 % (mediation effect=0·106, P=0·012) of the association between BMI and systolic BP was mediated through TAG. TAG mediated 12·53 % (mediation effect=0·093, P=0·018) and LDL-cholesterol mediated 7·75 % (mediation effect=0·57, P=0·046) of the association between BMI and diastolic BP was mediated by TAG and LDL-cholesterol, respectively. However, blood lipids did not show the mediation effect in girls. Our findings suggested that there was a sex difference in the contribution of blood lipids to the association between BMI and BP. Controlling TAG or LDL-cholesterol may be beneficial for reducing the risk of the BMI-related high BP in overweight boys; however, this outcome is not the case when controlling TAG or LDL-cholesterol in girls. This study may provide clues to explore the underlying mechanism of the association between obesity and hypertension.

No difference in acute effects of supplemental v. dietary calcium on blood pressure and microvascular function in obese women challenged with a high-fat meal: a cross-over randomised study.

Recent studies suggest that supplemental Ca (SC) increases the risk of cardiovascular events, whereas dietary Ca (DC) decreases the risk of cardiovascular events. Although frequently consumed with meals, it remains unclear whether Ca can mitigate or aggravate the deleterious effects of a high-fat meal on cardiovascular risk factors. This study aimed to evaluate the effects of SC or DC on blood pressure (BP) and microvascular function (MVF) in the postprandial period in obese women challenged with a high-fat meal. In this cross-over controlled trial, sixteen obese women aged 20-50 years were randomly assigned to receive three test meals (2908 kJ (695 kcal); 48 % fat): high DC (HDCM; 547 mg DC), high SC (HSCM; 500 mg SC-calcium carbonate) and low Ca (LCM; 42 mg DC). BP was continuously evaluated from 15 min before to 120 min after meals by digital photoplethysmography. Before and 120 min after meals, participants underwent evaluation of serum Ca and microvascular flow after postocclusive reactive hyperaemia (PORH) by laser speckle contrast imaging. Ionised serum Ca rose significantly only after HSCM. Systolic BP increased after the three meals, whereas diastolic BP increased after LCM and HDCM. Hyperaemia peak, hyperaemia amplitude and AUC evaluated after PORH decreased with LCM. After HDCM, there was a reduction in hyperaemia peak and hyperaemia amplitude, whereas HSCM decreased only hyperaemia peak. However, comparative analyses of the effects of three test meals on serum Ca, BP and MVF revealed no significant meal×time interaction. This study suggests that in obese women SC and DC do not interfere with the effects of a high-fat meal on BP and MVF.

Dietary sodium and potassium intake in relation to non-alcoholic fatty liver disease.

A few epidemiological data are available assessing the associations of intakes of sodium (Na) and potassium (K) with non-alcoholic fatty liver disease (NAFLD). We aimed to examine the associations of dietary intake of Na and K with the prevalence of ultrasound-diagnosed NAFLD. We performed a cross-sectional study of 100 177 participants (46 596 men and 53 581 women) who underwent a health screening examination and completed a FFQ at the Kangbuk Samsung Hospital Total Healthcare Centers, South Korea, between 2011 and 2013. NAFLD was defined by ultrasonographic detection of fatty liver in the absence of excessive alcohol intake or other known causes of liver disease. The proportion of NAFLD was 35·6 % for men and 9·8 % for women. Increasing prevalence of NAFLD was observed with increasing Na intake. The multivariable-adjusted prevalence ratios (PR) of NAFLD comparing the highest with the lowest quintile of energy-adjusted Na intake were 1·25 (95 % CI 1·18, 1·32; P trend<0·001) in men and 1·32 (95 % CI 1·18, 1·47; P trend <0·001) in women. However, when we additionally adjusted for body fat percentage, the association became attenuated; the corresponding PR of NAFLD were 1·15 (95 % CI 1·09, 1·21) in men and 1·06 (95 % CI 0·95, 1·17) in women. No inverse association was observed for energy-adjusted K intake. Our findings suggest that higher Na intake is associated with a greater prevalence of NAFLD in young and middle-aged asymptomatic adults, which might be partly mediated by adiposity.