Dietary fatty acids and the risk of hypertension in middle-aged and older women

Reported fried food consumption and the incidence of hypertension in a Mediterranean cohort: the SUN (Seguimiento Universidad de Navarra) project

Reported associations between the consumption of fried foods and the incidence of obesity or weight gain make it likely that fried food consumption might also be associated with the development of hypertension. However, evidence from long-term prospective studies is scarce. Therefore, the aim of the present study was to longitudinally evaluate this association in a prospective cohort. The SUN (Seguimiento Universidad de Navarra) project is a Mediterranean cohort study of university graduates conducted in Spain, which started in December 1999 and is still ongoing. In the present study, we included 13,679 participants (5059 men and 8620 women), free of hypertension at baseline with a mean age of 36·5 (SD 10·8) years. Total fried food consumption was estimated at baseline. The outcome was the incidence of a medical diagnosis of self-reported hypertension during the follow-up period. To assess the association between the consumption of fried foods and the subsequent risk of developing incident hypertension during the follow-up period, Cox regression models were used. During a median follow-up period of 6·3 years, 1232 incident cases of hypertension were identified. After adjusting for potential confounders, the adjusted hazard ratios for developing hypertension were 1·18 (95% CI 1·03, 1·36) and 1·21 (95% CI 1·04, 1·41) for those consuming fried foods 2-4 and >4 times/week, respectively, compared with those consuming fried foods < 2 times/week (P for trend = 0·009). In conclusion, frequent consumption of fried foods at baseline was found to be associated with a higher risk of hypertension during the follow-up period in a Mediterranean cohort of university graduates.

Higher erythrocyte n-3 PUFAs are associated with decreased blood pressure in middle-aged and elderly Chinese adults

Previous studies suggested that blood fatty acids (FAs) might affect blood pressure (BP), but the findings have been inconclusive. This study evaluated the cross-sectional and prospective associations of erythrocyte FAs with BP in middle-aged and elderly Chinese individuals. Between 2008 and 2010, 1834 participants (1364 women and 470 men) aged 57 ± 5 y had baseline measurements taken of their erythrocyte FAs and BP. A total of 1477 participants (1103 women and 374 men) had their BP measured again after 3.09 ± 0.32 y (range: 2.91-3.26 y). In the cross-sectional analyses (n = 1834), the erythrocyte saturated FA (SFA) content was positively associated with BP, whereas total cis polyunsaturated FAs (PUFAs), their subtypes cis n-3 (ω-3) PUFAs and cis n-6 (ω-6) PUFAs, and the PUFA-to-SFA ratio were inversely associated with BP (all P-trends < 0.05). The longitudinal results (n = 1477) showed marginally inverse associations between cis n-3 PUFAs and the n-3:n-6 PUFA ratio and BP. For individual cis n-3 PUFAs, higher contents of 20:5n-3, 22:5n-3, and 22:6n-3 were significantly associated with reduced increases in SBP over time (the mean change range between quartile 4 and quartile 1 was -0.917 to -0.749 mm Hg for SBP; all P-trends < 0.01), and 20:5n-3 was inversely associated with DBP change (the mean change between quartile 4 and quartile 1 was -0.631; P-trend < 0.001). Path analyses suggested that the associations between cis n-3 PUFAs and BP might be mediated by decreasing serum triglycerides (TGs) and body mass index (BMI). Our findings revealed that a higher content of cis n-3 PUFAs (mainly very long-chain cis n-3 PUFAs) may benefit BP progress, probably mediated by decreasing serum TGs and BMI.

Effect of the amount and type of dietary fat on cardiometabolic risk factors and risk of developing type 2 diabetes, cardiovascular diseases, and cancer: a systematic review

The effects of both the amount and quality of dietary fat have been studied intensively during the past decades. Previously, low-fat diets were recommended without much attention to the quality of fat, whereas there is general emphasis on the quality of fat in current guidelines. The objective of this systematic review (SR) was to assess the evidence of an effect of the amount and type of dietary fat on body weight (BW), risk factors, and risk of non-communicable diseases, that is, type 2 diabetes (T2DM), cardiovascular diseases (CVD), and cancer in healthy subjects or subjects at risk for these diseases. This work was performed in the process of updating the fourth edition of the Nordic Nutrition Recommendations from 2004. The literature search was performed in October 2010 covering articles published since January 2000. A complementary search was done in February 2012 covering literature until December 2011. Two authors independently selected articles for inclusion from a total of about 16,000 abstracts according to predefined criteria. Randomized controlled trials (RCT) and prospective cohort studies (PCS) were included as well as nested case-control studies. A few retrospective case-control studies were also included when limited or no data were available from other study types. Altogether 607 articles were quality graded and the observed effects in these papers were summarized. Convincing evidence was found that partial replacement of saturated fat (SFA) with polyunsaturated fat (PUFA) or monounsaturated fat (MUFA) lowers fasting serum/plasma total and LDL cholesterol concentrations. The evidence was probable for a decreasing effect of fish oil on concentration of serum/plasma total triglycerides as compared with MUFA. Beneficial effect of MUFA both on insulin sensitivity and fasting plasma/serum insulin concentration was considered as probable in comparisons of MUFA and carbohydrates versus SFA, whereas no effect was found on fasting glucose concentration in these comparisons. There was probable evidence for a moderate direct association between total fat intake and BW. Furthermore, there was convincing evidence that partial replacement of SFA with PUFA decreases the risk of CVD, especially in men. This finding was supported by an association with biomarkers of PUFA intake; the evidence of a beneficial effect of dietary total PUFA, n-6 PUFA, and linoleic acid (LA) on CVD mortality was limited suggestive. Evidence for a direct association between total fat intake and risk of T2DM was inconclusive, whereas there was limited-suggestive evidence from biomarker studies that LA is inversely associated with the risk of T2DM. However, there was limited-suggestive evidence in biomarker studies that odd-chain SFA found in milk fat and fish may be inversely related to T2DM, but these associations have not been supported by controlled studies. The evidence for an association between dietary n-3 PUFA and T2DM was inconclusive. Evidence for effects of fat on major types of cancer was inconclusive regarding both the amount and quality of dietary fat, except for prostate cancer where there was limited-suggestive evidence for an inverse association with intake of ALA and for ovarian cancer for which there was limited-suggestive evidence for a positive association with intake of SFA. This SR reviewed a large number of studies focusing on several different health outcomes. The time period covered by the search may not have allowed obtaining the full picture of the evidence in all areas covered by this SR. However, several SRs and meta-analyses that covered studies published before year 2000 were evaluated, which adds confidence to the results. Many of the investigated questions remain unresolved, mainly because of few studies on certain outcomes, conflicting results from studies, and lack of high quality-controlled studies. There is thus an evident need of highly controlled RCT and PCS with sufficient number of subjects and long enough duration, specifically regarding the effects of the amount and quality of dietary fat on insulin sensitivity, T2DM, low-grade inflammation, and blood pressure. New metabolic and other potential risk markers and utilization of new methodology in the area of lipid metabolism may provide new insight.

Impact of omega-6 fatty acids on cardiovascular outcomes: A review

Poly unsaturated fatty acids (PUFAs) have usually been associated with beneficial health effects on early life and later life disease such as cardiovascular diseases (CVD). Emerging evidence, however, suggests that PUFA species (n-3, n-6) have differential health effects. N-6 PUFAs, in particular, have sparked a scientific debate regarding their role in human physiological processes. Current dietary recommendations for n-6 fatty acids have been based on animal studies, insufficient epidemiological evidence and mixed PUFA interventions, therefore, require reconsideration. This review has analyzed human epidemiological and interventional studies, published in the last five years, focusing on n-6 fatty acids' impact on CVD outcomes (CVD events, blood lipids, blood pressure, inflammation, oxidative stress/atherosclerosis). The evidence is mixed, with differential effects within the n-6 fatty acid series. These outcomes are also dependent on ethnicity and background health status. Further, data from developing countries are sparse, thus, well designed intervention trials and population based studies in developing country settings on specific n-6 fatty acid intake and health effects are desired.

Effects of a diet high in salt, fat, and sugar on telemetric blood pressure measurements in conscious, unrestrained adult Yucatan miniature swine (Sus scrofa)

Radiotelemetry was used to evaluate diet-related elevation of blood pressure in adult Yucatan miniature swine. Systolic arterial blood pressure (SAP), diastolic atrial blood pressure (DAP), heart rate, and locomotor activity were assessed in 9- or 11-mo-old Yucatan miniature pigs fed a standard diet or a North American-type diet high in salt, fat, and sugar (HSFS). Compared with pigs fed standard diet, pigs fed HSFS diet showed markedly elevated SAP (132 ± 3 compared with 156 ± 6 mm Hg), whereas DAP was unchanged (92 ± 2 compared with 99 ± 5 mm Hg). In addition, all pigs were modestly sensitive to short-term changes in dietary salt, as indicated by a 6% to 7% response in blood pressure parameters. According to these data, the increase in SAP for pigs on the HSFS diet was too large to be explained by the NaCl content of the diet alone. We found no evidence of endothelial dysfunction, and the relaxation responses of isolated coronary arteries actually were enhanced in the HSFS group. In conclusion, in a Yucatan miniature pigs model chronically fed a HSFS diet, DAP did not increase, but SAP and pulse pressure appeared to be affected by high dietary levels of fat or sugar (or both).

Associations of plasma n-3 polyunsaturated fatty acids with blood pressure and cardiovascular risk factors among Chinese

The relationship between plasma fatty acid (FA) levels and hypertension in Chinese is not fully understood. The aim of this study was to examine relationships between plasma phospholipid (PL) FAs and hypertension in Chinese subjects. One thousand one hundred and fifty-four subjects in Hangzhou, China, were recruited in this cross-sectional study. Two hundred and fourteen (160 males, 54 females) subjects with hypertension and 940 (664 males, 276 females) healthy subjects were identified. The prevalence of hypertension in females (19.6%) was significantly higher than that in males (16.4%). Compared with healthy subjects, hypertensive subjects showed significantly lower plasma PL 22:5n-3 (p = 0.017), 22:6n-3 (p = 0.008), PL polyunsaturated fatty acids (PUFAs; p < 0.001), n-3 PUFA (p = 0.015), n-6 PUFA (p < 0.001) and 20:4n-6 (p < 0.010). PL n-3 PUFA [odds ratio (OR) = 0.43, 95% confidence interval (CI) = 0.29-1.19] and n-3:n-6 (OR = 0.48, 95% CI = 0.12-1.86) were inversely associated with hypertension. However, plasma saturated fatty acid (SFA; OR = 2.01, 95% CI = 1.05-2.98) was significantly positively associated with hypertension. PL SFA was significantly positively associated with systolic blood pressure (p = 0.048), whereas plasma PL monounsaturated FA was significantly positively associated with diastolic blood pressure (DBP; p = 0.009) in hypertensive subjects. PL PUFA (p = 0.022) and n-3 PUFA (p = 0.047) were significantly negatively associated with DBP in hypertensive subjects. Our results suggest that plasma PL n-3 PUFA was significantly inversely associated with hypertension in Chinese. It would seem appropriate for hypertensive subjects to increase their dietary n-3 PUFA which may help reduce BP.

Erythrocyte fatty acid composition is associated with the risk of hypertension in middle-aged and older women

Experimental studies have suggested different effects of various fats on blood pressure. However, epidemiologic evidence of these relations remains limited and inconsistent. We therefore assessed the association of fatty acid (FA) composition in erythrocyte membranes with the risk of hypertension. We selected 516 cases of incident hypertension and 516 matched controls during 12.9 y of follow-up in the Women's Health Study. Erythrocyte FA was measured in baseline bloods using GC. After controlling matching factors and lifestyle factors, erythrocyte SFA showed a positive association, whereas total cis PUFA, cis (n-3) PUFA, and the ratio of PUFA:SFA (PS ratio) showed an inverse association with the risk of hypertension. The multivariable RR of hypertension across the increasing quartiles of erythrocyte FA subtypes were 1.00, 1.19, 1.44, and 1.76 for total SFA; 1.00, 0.84, 0.88, and 0.56 for total cis PUFA; 1.00, 0.87, 0.66, and 0.65 for cis (n-3) PUFA; and 1.00, 0.99, 0.70, and 0.51 for the PS ratio. After further adjusting for obesity-related metabolic factors, these associations were attenuated and remained significant only for the PS ratio. cis MUFA, cis (n-6) PUFA, and trans unsaturated FA in erythrocyte membranes were not associated with the risk of hypertension. Our study showed that FA composition in erythrocyte membranes is associated with the risk of hypertension in middle-aged and older women. However, after controlling for obesity-related metabolic factors, the associations remained significant only for the PS ratio.

Dairy intake, blood pressure and incident hypertension in a general British population: the 1946 birth cohort

PURPOSE

We aimed to examine the association between intake of different subgroups of dairy products and blood pressure and incident hypertension 10 years later, adjusting for confounding factors.

METHODS

We studied 1,750 British men and women from the 1946 British birth cohort from 1989 to 1999 (age 43 and 53 years, respectively). Diet was assessed by 5-day food diaries using photographs in the estimation of portion size. Systolic (sbp) and diastolic (dbp) blood pressure and prevalent hypertension were assessed at age 43 and 53 years. Linear regression and logistic regression were used to examine 10-year blood pressure levels and incident hypertension by baseline dairy intake.

RESULTS

There was a weak non-significant trend of a protective effect of total dairy intake on blood pressure and incident hypertension, but no evidence for a dose-response relationship (OR for incident hypertension: 0.88 (95% CI 0.68;1.14) 2nd vs. 1st tertile and 0.93 (95% CI 0.72;1.18) 3rd vs. 1st tertile). Higher intake of low-fat and fermented dairy was linked to a higher sbp but in a nonlinear manner. Adjustment for other dietary factors, health behaviours and BMI attenuated these associations.

CONCLUSIONS

Total dairy intake and specific dairy subgroups were not associated with blood pressure and incident hypertension among a representative sample of British adults after adjustment for confounding factors.

Sex-specific associations of nutrition with hypertension and systolic blood pressure in Alaska Natives findings from the GOCADAN study

OBJECTIVES

To examine sex-specific associations of nutritional factors with prevalent hypertension (HTN) and systolic blood pressure (SBP) in Alaska Natives. Diet is known to affect SBP, a major risk factor for cardiovascular disease.

STUDY DESIGN

Cross-sectional analysis of participants without diabetes in the Genetics of Coronary Artery Disease in Alaska Natives study.

METHODS

Macronutrients such as fat, carbohydrate and protein and micronutrients such as sodium were investigated. HTN was defined as SBP≥140 mmHg, diastolic blood pressure≥90 mmHg and/or taking anti-HTN medication. Analyses were stratified by sex and covariates included age, body mass index (BMI), energy intake, smoking and physical activity.

RESULTS

Mean age was 42 years for men (n=456) and women (n=602). Men with HTN (n=106) compared to men without HTN consumed a higher proportion of calories from total (p=0.01), saturated (p<0.01) and trans fatty acid (p=0.03) fats. Women with HTN (n=99) compared to women without HTN consumed more total (p=0.03) and monounsaturated (p=0.04) fat, higher protein (p=0.02) and lower total (p<0.01) and simple (p<0.01) carbohydrates. After covariate adjustment, men not on anti-HTN medications (n=407) had significantly higher average SBP with increasing quartiles of trans fatty acid intake (p for linear trend=0.01) and sodium intake (p for linear trend=0.02). For women not on anti-HTN medications (n=528), after covariate adjustment, average SBP decreased with increasing quartiles of omega 3 fatty acid intake (p for linear trend <0.01).

CONCLUSIONS

Prospective evaluation of the sex-specific associations of nutritional factors with HTN and SBP on outcomes is needed along with novel interventions to lower the risk of cardiovascular disease.

Targeting energy expenditure via fuel switching and beyond

Since over-nutrition accelerates the development of obesity, progression to type 2 diabetes, and the associated co-morbidity and mortality, there has been a keen interest in therapeutic interventions targeting mechanisms that may curb appetite, increase energy expenditure or at least attenuate insulin resistance. Over the past decade, numerous peri-mitochondrial targets in the de novo lipid synthesis pathway have been linked to an increase in energy expenditure and the drug development industry has pursued the gene products involved as candidates to develop drugs against. The basis of this link, and specifically the premise that lowering tissue and cellular malonyl-CoA can increase energy expenditure, is scrutinised here. The argument presented is that fuel switching as effected by changes in cellular malonyl-CoA concentrations will not trigger the mitochondria to increase energy expenditure because: (1) an increase in beta-oxidation by lowering respiratory exchange ratio (indicative of the metabolic fuel consumed) does not equal an increase in energy expenditure (how rapidly fuel is consumed); (2) the ATP:oxygen ratios (i.e. ATP energy made:oxygen required for the reaction) are similar when metabolising lipids (2.8) vs glucose (3.0); (3) substrate availability (NEFA) does not drive energy expenditure in vivo; and (4) the availability of ADP in the mitochondrial matrix determines the rate of energy expenditure, not the availability of fuel to enter the mitochondrial matrix. To increase mitochondrial energy expenditure, work must be done (exercise) and/or the mitochondrial proton leak must be enhanced, both of which increase availability of ADP. In fact, despite the historic taboo of chemical uncoupling, this mechanism validated in humans is closest on task to increasing whole-body energy expenditure. Chemical uncoupling mimics the naturally occurring phenomenon of proton leak, accelerating the metabolism of glucose and lipids. However, it is completely non-genomic (i.e. the target is a location, not a gene product) and is not associated with addiction or mood alterations common to satiety agents. A significant hurdle for drug development is to discover a safe mitochondrial uncoupler and to formulate it potentially as a pro-drug and/or oral pump, to avoid the issue of overdosing experienced in the 1930s. The potential therapeutic impact of such a compound for an over-nutritioned patient population could be profound. If effective, the mitochondrial uncoupler mechanism could resolve many of the associated diseases such as type 2 diabetes, hypertension, obesity, depression, sleep apnoea, non-alcoholic steatohepatitis, insulin resistance and hyperlipidaemia, therefore becoming a 'disease-modifying therapy'.