Flaxseed oil does not affect inflammatory markers and lipid profile compared to olive oil, in young, healthy, normal weight adults

Objective. Olive oil (OO) is a rich source of monounsaturated fat and bioactive components that exert strong anti-oxidant and anti-inflammatory properties. Flaxseed oil (FO) is rich in αlpha linolenic n3 fatty acid (ALA), which also exhibits anti-inflammatory effects.This randomized, cross-over study aimed at exploring whether diet's enrichment with FO could beneficially alter inflammatory markers and lipid profile, compared to OO, in a sample of normal weight, apparently healthy young adults. Materials and Methods. Participants were supplied with 15 mL/day of either FO or OO. Each intervention and the wash-out period lasted 6 weeks. Dietary, anthropometric and physical activity variables were recorded at the beginning and the end of each intervention. Serum biochemical and inflammatory markers were measured. Compliance to the intervention was evaluated by fatty acid analysis in erythrocytes. Repeated Measures ANOVA was used to assess the effect of the treatment. Results. Thirty seven participants completed the study. No difference between the two interventions was observed in adiponectin, TNFα, high sensitivity CRP or glucose levels and lipid profile. At the end of the FO period, participants exhibited significant reductions in total (−5.0%) and LDL-cholesterol (−6.7%) levels. During the FO and the OO period serum adiponectin changes were significantly correlated with changes in erythrocyte %ALA and in erythrocyte %EPA, respectively. Conclusions. Daily consumption of FO did not confer any benefit in inflammatory or biochemical markers in normal weight young adults, who traditionally use olive oil as the main edible oil. (Authors abstract)

In western countries where olive oil is not a common food, polyunsaturated fatty acids (PUFA) and oils rich in PUFA have received greater attention over the years, given that substitution of saturated and trans fats by unsaturated ones and maintaining a low ratio of n6:n3 fatty acids intake have been proposed as measures of lowering the risk for coronary heart disease.
Given the declining stocks of marine fish and high pollution in some fishing areas, alternative ways of increasing n3 fatty acids consumption and lowering the n6 to n3 ratio are looked for, with flaxseed oil consumption still being suggested as a potential alternative for salad dressings or an enrichment strategy for industrially produced foods. Moreover, regarding ALA conversion, increasing ALA intake has been suggested more efficacious than lowering linoleic acid intake. The aim of the present study was to explore whether diet's enrichment with FO could favourably affect the inflammatory markers and lipid profile of normal weight, apparently healthy young adults, who traditionally use olive oil. FO effects were tested against OO and no differences between the two periods were observed. Compliance to the intervention was evaluated through erythrocyte membrane fatty acid analysis, according to which the FO intervention was successful, since both %ALA and %EPA concentrations were significantly increased at the end of the FO period. Changes in plasma adiponectin levels were positively correlated with changes in erythrocytes %ALA and %EPA during the FO and OO period, respectively. In the present study, the lack of a significant effect of FO intake and of the resultant low dietary n6:n3 fatty acids ratio on the selected outcomes, could be partly attributed to the low levels of the inflammatory markers that subjects had already at baseline; however adiponectin levels could have been changed, but such an effect was not observed. Lack of a significant impact of FO supplementation in the present study could be partly attributed to the good quality of the participants’ usual diet and hence adherence to the Mediterranean diet may affect the impact of FO intake on circulating inflammatory indices. One could also speculate that the lack of any significant finding could be due to inadequate FO dosage or to a short intervention period. In conclusion, diet's enrichment with FO did not induce any effects on inflammatory markers and lipid profile in young, normalweight individuals,witha relativelyhealthybackground diet. Hence no need for ALA supplements or consumption of ALA enriched foods is justified in such populations. Whether FO intake would benefit participants less adherent to the Mediterranean
dietary pattern remains uncertain. Furthermore, dietary changes resulting in increases in erythrocyte %ALA could be beneficial through potential increases in the circulating adiponectin levels; however this needs further investigation as the results of the studies available are contradictory.  (Editors comments)