Effects of an energy-restricted diet rich in plant-derived α-linolenic acid on systemic inflammation and endothelial function in overweight-to-obese patients with metabolic syndrome traits

Abstract

Plant-derived a-linolenic acid (ALA) may reduce the risk of CVD, possibly by decreasing systemic inflammation and improving endothelial function. In the present study, the effects of a hypoenergetic diet rich in ALA (3·4 g/d) on the biomarkers of systemic inflammation and vascular function were investigated in eighty-one overweight-to-obese patients with metabolic syndrome traits in comparison with a hypoenergetic diet low in ALA (0·9 g/d, control). After a 6-month dietary intervention, there were significant decreases in the serum concentrations of C-reactive protein (CRP), TNF-a, IL-6, soluble intercellular adhesion molecule-1 (sICAM-1), soluble endothelial selectin (sE-selectin) and asymmetric dimethylarginine in both dietary groups. However, no inter-group differences were observed for all these changes. The serum concentration of YKL-40 (human cartilage glycoprotein 39 or chitinase-3-like protein 1) decreased after the ALA diet when compared with the control diet (P,0·05 for time £ treatment interaction). Plasma concentrations of fibrinogen did not significantly change in the two dietary groups. The decreases in the serum concentrations of sICAM-1, sE-selectin, CRP and YKL-40 were significantly correlated with the decreases in body fat mass. In conclusion, the present study indicates that in overweight-to-obese patients with metabolic syndrome traits, both vascular function and inflammation are improved during body-weight loss. The high ALA intake led to a more pronounced reduction in the serum concentration of YKL-40 compared with the intake of the low-ALA control diet, indicating the existence of independent favourable physiological effects of ALA during weight loss.

Association of endothelial proliferation with the magnitude of weight loss during calorie restriction

“…However, the same study has revealed a large heterogeneity in FMD response to weight loss, which appeared to be related not only to the degree of weight reduction, but also to the presence of co-morbidities, the type of diet taken, and the concomitant use of medication and exercise therapy. Similar improvement in endothelial cell function, but also similar variability, has been demonstrated by using biochemical parameters of endothelial cell status, such as adhesion molecules (sICAM-1, E-selectin, VCAM-1) or hemostasis regulators (PAI-1, t-PA, vWF) [4,7,10,12].…”

“…The lack of an unequivocal answer in this respect results mainly from large variability across the populations in the parameters assessed [7,12,13]. It may signify the true absence of such an effect, but it may also indicate that the parameters chosen to reflect the endothelial cell status are not sensitive enough.…”

Metabolism and functional effects of plant-derived omega-3 fatty acids in humans

“…Hypercholesterolaemic patients who consumed 6-8 g/d ALA for 2 years had a 12.5% decrease in blood CRP concentration, although there was no change in sICAM-1, IL-6 or IL-10 concentrations [261]. Egert et al reported that consuming 0.9 g/d or 3.4 g/d ALA significantly decreased the serum concentrations of CRP, TNF-α, IL-6, sICAM-1 and sEselectin in male and female subjects [257]. High ALA intake led to more a pronounced reduction in the serum concentration of YKL-40 compared to the lower intake of ALA [257].…”

“…Egert et al reported that consuming 0.9 g/d or 3.4 g/d ALA significantly decreased the serum concentrations of CRP, TNF-α, IL-6, sICAM-1 and sEselectin in male and female subjects [257]. High ALA intake led to more a pronounced reduction in the serum concentration of YKL-40 compared to the lower intake of ALA [257]. Two recent studies which investigated the effect of increased ALA intake in patients receiving haemodialysis reported significant decreases in CRP concentrations after 8 weeks consuming 40 g/d ground flaxseed [244] or after consuming 30 g/d milled sesame, pumpkin and flaxseed mixture for 12 weeks [146].…”

“…These inconsistencies seem not to be related to dose of ALA used. Table 10 summarises the findings of intervention studies where haemostatic factors have been investigated after increased consumption of ALA [119,123,128,129,139,151,228,234,235,257]. Most studies (9 out of 10) reported no significant effect of increasing ALA intake on haemostatic factors (e.g., fibrinogen concentration, prothrombin time, PAI-1 activity or factor VII activity), even when high intakes (up to 20 g/day) [128,129,139,234,235] and long durations (up to 48 weeks) [123,139,234] were used (Table 10).…”