N-6 Fatty acids and cardiovascular health: A review of the evidence for dietary intake recommendations

Nutritional Epidemiology Research Unit, UMR INSERM U557, INRA U1125, CNAM, UP13, CRNH-IdF, Faculté SMBH, 74 rue Marcel Cachin, 93017 Bobigny, France.
The British journal of nutrition (Impact Factor: 3.45). 09/2010; 104(6):788-96. DOI: 10.1017/S0007114510002096
Source: PubMed


n-6 PUFA are well known for their critical role in many physiological functions and seem to reduce risks of CHD. However, some argue that excessive consumption of n-6 PUFA may lead to adverse effects on health and therefore recommend reducing dietary n-6 PUFA intake or fixing an upper limit. In this context, the present work aimed to review evidence on the link between n-6 PUFA and risks of CVD. Epidemiological studies show that n-6 PUFA dietary intake significantly lowers blood LDL-cholesterol levels. In addition, n-6 PUFA intake does not increase several CVD risk factors such as blood pressure, inflammatory markers, haemostatic parameters and obesity. Data from prospective cohort and interventional studies converge towards a specific protective role of dietary n-6 PUFA intake, in particular linoleic acid, against CVD. n-6 PUFA benefits are even increased when SFA intake is also reduced. In regards to studies examined in this narrative review, recommendation for n-6 PUFA intake above 5 %, and ideally about 10 %, of total energy appears justified.

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    • "Regarding possible adverse effects associated with excessive consumption of n-3 PUFAs, data are not sufficient to establish a threshold for a tolerable upper intake level, but it has been concluded that supplemental intakes of EPA and DHA combined at doses up to 5 g a day do not raise safety concerns for adults (EFSA Panel on Dietetic Products, 2012). Earlier recommendations have been based on the analysis of both observational and experimental studies proposing n-6 PUFAs as ''highly recommended'' because associated with decreased risk of CVD (Czernichow et al., 2010). Nevertheless, a major limitation of earlier studies relied on the fact that those randomized controlled trials (RCTs) published from 1965 to 1989 included the simultaneous use of both n-6 PUFAs and plant or marine n-3 PUFAs. "
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    ABSTRACT: Polyunsaturated fatty acids (PUFAs) have been considered of great interest for human health due to their potential anti-inflammatory action that may protect from a number of chronic-degenerative diseases with an inflammatory pathogenesis. This review aimed to report the most updated evidence of both n-3 and n-6 PUFAs effect on cardiovascular disease, cancer, and depression in humans. Attention has been also paid to those studies exploring the effects of the ratio intake. Results from pooled analyses of human studies reported a general positive effect of n-3 PUFAs intake on all outcomes considered. In contrast, the role of n-6 PUFAs on human health needs to be better assessed in order to clearly identify which compound exerts beneficial/harmful effects. Only a limited number of clinical studies considered the n-3:n-6 PUFAs ratio, rather reporting contrasting results. A number of limitations when considering the ratio between these two families of PUFAs have risen.
    No preview · Article · Aug 2015 · International Journal of Food Sciences and Nutrition
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    • "It is also argued that higher dietary intake of n-6 PUFA may lead to a competition between n-6 and n-3 metabolism resulting in a reduced production of anti-inflammatory molecules from n-3 PUFA.[47] However, in human subjects, higher intakes of n-6 fatty acids do not appear to be associated with elevated levels of inflammatory markers and there are no data from human studies that support a detrimental effect of dietary n-6 fatty acids on coronary heart disease.[4849] The present results are in contrast to customary assumption that high intake of n-6 fatty acids antagonizes the anti-inflammatory effects of n-3 fatty acids. "
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    ABSTRACT: Background: Atherosclerosis, with its major manifestation, coronary artery disease (CAD) is a chronic inflammatory disease. Dietary fatty acids intakes favorably effect on inflammatory responses. This study was conducted to examine the association between dietary fatty acid intakes and inflammatory markers, interleukin 6 (IL-6) and high sensitivity C-reactive protein (hs-CRP), in CAD patients among Iranian population. Materials and Methods: This hospital-based, cross-sectional study was conducted in Chamran Heart Hospital, Isfahan, Iran in 2012. Patients aged ≥45 years with first ever symptomatic CAD confirmed by angiography were included. A semi-quantitative food frequency questionnaire (FFQ) was used to assess the usual intakes of dietary fatty acids. Results: The energy-adjusted daily intakes (mean ± SD) of saturated fatty acid (SFA), monounsaturated fatty acid (MUFA), linoleic acid, α-linolenic acid, and eicosapentaenoic acid and docosahexaenoic acid (EPA + DHA) were 27 ± 9, 22 ± 6, 21 ± 5, 0.4 ± 0.32, and 0.85 ± 0.82 g/d; respectively. After adjustment for potential confounders, SFA was directly related to hs-CRP (P = 0.01) and IL-6 (P < 0.001) concentrations. Intakes of EPA + DHA and MUFA, were significantly adversely related to plasma hs-CRP concentration (P = 0.002 and 0.001, respectively) but not IL-6, albeit MUFA was modestly inversely related to IL-6 (P = 0.08). No significant relationships were observed for other fatty acids, α-linolenic acid, and linoleic acid. Conclusions: These findings suggest that saturated fatty acids, EPA + DHA and MUFA were significantly related to plasma inflammatory markers in CAD patients.
    Full-text · Article · Sep 2014
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    • "We did not expect the elevated risk of male cardiovascular mortality associated with higher intake of n-6 PUFA, as several studies have shown inverse associations between n-6 PUFA intake and CVD [43]. This finding could represent a chance phenomenon, since it was not observed in women. "
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    ABSTRACT: It may be useful to examine associations of fat intakes with total mortality as a basis for dietary recommendations. We aimed to elucidate associations between dietary fat and total mortality among Japanese populations with low fat intake. We conducted a prospective study consisting of 58,672 men and women aged 40 to 79 years. Fat intakes were estimated using a food frequency questionnaire. Multivariate-adjusted hazard ratios (HRs) for mortality by sex were computed according to quintiles of energy-adjusted fat intakes. During the follow-up period (median duration, 19.3 years), 11,656 deaths were recorded. In men, we found no clear association between total fat and total mortality. HRs across quintiles of total fat intake were 1.00, 1.03 (95% confidence interval [CI], 0.95-1.12), 1.02 (0.94-1.10), 0.98 (0.90-1.07), and 1.07 (0.98-1.17). No significant association was detected in regard to types of fat. In women, HR was lowest in the fourth quintile of total fat intake followed by the top quintile; HRs across quintiles were 1.00, 1.03 (0.94-1.11), 1.00 (0.92-1.09), 0.88 (0.81-0.96), and 0.94 (0.86-1.03). Regarding types of fat in women, total mortality was inversely associated with intakes of saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA); the lowest HR was in the top quintile of intake for SFA, MUFA, and PUFA: 0.91 (95% CI, 0.83-1.00), 0.91 (0.83-0.99) and 0.88 (0.80 - 0.97), respectively (trend P across quintiles, 0.020, 0.012, and 0.029, respectively). Causes of death other than cancer and cardiovascular disease contributed most to decreases in HRs for total and types of fat. In women, analysis with finer categories revealed that the lowest risk for total mortality appeared at total fat intake of 28% of energy. Our findings from a large cohort study among populations with relatively low fat intake provide evidence regarding optimal levels of fat intakes.
    Full-text · Article · Mar 2014 · Nutrition & Metabolism
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