Changes in relative and absolute concentrations of plasma phospholipid fatty acids observed in a randomized trial of Omega-3 fatty acids supplementation in Uganda

Abstract

Expressing circulating phospholipid fatty acids (PLFAs) in relative concentrations has some limitations: the total of all fatty acids are summed to 100%; therefore, the values of individual fatty acid are not independent. In this study we examined if both relative and absolute metrics could effectively measure changes in circulating PLFA concentrations in an intervention trial. 66 HIV and HHV8 infected patients in Uganda were randomized to take 3g/d of either long-chain omega-3 fatty acids (1,856 mg EPA and 1,232 mg DHA) or high—oleic safflower oil in a 12-week double-blind trial. Plasma samples were collected at baseline and end of trial. Relative weight percentage and absolute concentrations of 41 plasma PLFAs were measured using gas chromatography. Total cholesterol was also measured. Intervention-effect changes in concentrations were calculated as differences between end of 12-week trial and baseline. Pearson correlations of relative and absolute concentration changes in individual PLFAs were high (>0.6) for 37 of the 41 PLFAs analyzed. In the intervention arm, 17 PLFAs changed significantly in relative concentration and 16 in absolute concentration, 15 of which were identical. Absolute concentration of total PLFAs decreased 95.1 mg/L (95% CI: 26.0, 164.2; P = 0.0085), but total cholesterol did not change significantly in the intervention arm. No significant change was observed in any of the measurements in the placebo arm. Both relative weight percentage and absolute concentrations could effectively measure changes in plasma PLFA concentrations. EPA and DHA supplementation changes the concentrations of multiple plasma PLFAs besides EPA and DHA.

Investigating associations of omega-3 fatty acids, lung function decline, and airway obstruction

“…Fatty acids proportions and absolute concentrations are generally well correlated, suggesting the use of relative versus absolute concentrations is unlikely to influence interpretation of our results. 42,43 Finally, our sample had limited numbers of Asian and Hispanic participants; although we found significant positive associations of DHA with lung function decline in Hispanic participants, our analyses may have been underpowered to detect other associations in these groups. For our MR study, the genetic instruments for the different omega-3 fatty acids included SNPs in genetic loci associated with multiple fatty acids, limiting the specificity of the results.…”

Dietary long-chain fatty acids and carbohydrate biomarker evaluation in a controlled feeding study in participants from the Women’s Health Initiative cohort ,

“…Because we ln transformed the PLFA data for statistical analyses, we present the geometric mean of the relative and absolute concentrations of the 41 PLFAs and the 95% confidence range of the sample (Table 2). The arithmetic mean 6 SD and correlations that were derived with the use of the original scales are presented in Supplemental Table 3 to facilitate the comparison of the data to those in previous studies (13,26). Correlations between the relative weight-percentage concentration and the absolute concentration were high for most PLFAs (.0.6 for 36 of 41 PLFAs).…”

Mechanisms of Arachidonic Acid In Vitro Schistosomicidal Potential

“…mansoni − and additionally reveal the distinct properties of the worm surface tegument and body. High surface membrane nSMase activity could be deleterious, as it is readily increased after exposure to the high levels of unsaturated fatty acids in the portal and mesenteric circulation. ,,,− Excessive nSMase activation will lead to SM hydrolysis, surface membrane disintegration, and worm death. Strangely, nSMase activity in surface membrane extracts of male worms significantly declined following exposure to ARA, which considerably increased the nSMase activity in the surface membrane and homogenate extracts of female worms.…”

“…mansoni and S. hematobium has been documented in vitro and in vivo in rodents. ,,− Lung-stage schistosomula and liver and small intestine-derived parasite eggs , are sensitive to as low as 50 μM ARA = 15 μg/mL, the most physiological and easily attained human serum level. , For complete cessation of movement and death, adult worms require 30 to 60 min exposure to up to 10 mM ARA, a level difficult to reach even in the portal circulation. However, adult worms may succumb to significantly lower serum ARA levels if the exposure is continuously maintained, for days or weeks.…”