الفهرس 
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Abstract
Dietary fatty acid sources affect multiple pathophysiological processes and hence the cardiovascular disease (CVD), inflammation and diabetes. In contrast, fish intake is inversely associated with CVD incidence and mortality. The mechanism of the apparent benefit of dietary development of disease. Excess intake of red meat predicts higher risk of metabolic syndrome, fish is not fully understood, but fish intake is negatively associated with several CVD risk factors, including insulin resistance and hypertension. Vegetarian diets are also associated in meta-analyses with lower BP, total cholesterol and LDL-cholesterol, and lower risk of diabetes and CVD.
Long chain omega-3 polyunsaturated fatty acids (n-3 LC-PUFAs) mediate many cardiometabolic effects of fish intake. Oily fish is the main dietary source of n-3 LC-PUFA’s. Marine n-3 LC-PUFA supplementation lowers the risk of CVD. A high omega-3 index (O3I) is protective against CVD mortality. One possible explanation for this is that DHA and EPA supplements lower systolic (SBP) and diastolic (DBP) BP. N-3 LC-PUFA intake is also associated with decreased estimated stearoyl coenzyme A desaturase (SCD) activity, an enzyme that is linked to risk of obesity and metabolic syndrome. Further, in human studies, n-3 LC-PUFAs have anti-inflammatory properties by reducing production of IL-6, TNF-α, CRP, and the predominantly proinflammatory arachidonic acid (ARA)-derived mediators, prostaglandin E2 (PGE2) and leukotriene (LTB4).
In healthy adults, red meat consumption is associated with higher circulating ARA while fish intake was not. Despite the physiological roles of ARA, its free levels in cells are kept very low, as its accumulation is cytotoxic. PGE2, LTB4 and thromboxane A2 (TXA2) are ARA-derived bioactive lipids that play key roles in the inflammation, thrombotic events, and oxidative stress underlying the pathophysiology of CVD.
It follows that adopting a diet low in red meat and high in fish might be expected to raise plasma n-3 LC-PUFAs and lower ARA, and thus benefit cardiometabolic health.
We studied the time-scale of plasma fatty acid changes during transition to an exclusively plant- and fish-based diet in healthy adults. In pursuit of a religious fast, 36 adults abstained from eating poultry, meat, dairy products and eggs, while increasing fish intake for 6 weeks. Participants were assessed at the week preceding the fast (W0), first and 6th week following the fast (W1) and (W6) for their fasting plasma fatty acids, proinflammatory PGE2 and LTB4 and inflammatory marker CRP
We observed that healthy adults who adopt the dietary change experience rapid and sustained elevation of their plasma n-3-LC-PUFAs and declines in specific n-6 PUFAs that start as early as one week after the diet change, along with a big upgrade of the O3I, an important marker of CVD protection. The plasma fatty acid changes were associated with declines in systolic and diastolic BP, but no consistent changes in SCD activity indices despite previous human and animal evidence suggesting negative regulation of SCD by n-3 PUFAs.