Effects of Flaxseed Interventions on Circulating Inflammatory Biomarkers: A Systematic Review and Meta-Analysis of Randomized Controlled Trials
Advances in Nutrition, Volume 10, Issue 6, November 2019, Pages 1108–1119, https://doi.org/10.1093/advances/nmz048
ABSTRACT
There have been various clinical studies on the effect of flaxseed-derived products on circulating inflammatory biomarkers, but the findings from these are contradictory. The aim of the present study was to clarify any association. A comprehensive literature search was conducted from inception to May 2018. From the eligible trials, 32 articles describing studies conducted on adults aged 18–70 y were selected for the meta-analysis. Meta-analyses using the random-effects model were performed to investigate the data and results showed significant effects of flaxseed intake on circulating high-sensitivity CRP (hs-CRP) [weighted mean difference (WMD) = −0.75; 95% CI: −1.19, −0.30; P < 0.001] and TNFα (WMD = −0.38; 95% CI: −0.75,–0.01; P = 0.04). However, no significant changes were found in IL6 concentration (WMD = −0.24; 95% CI: –0.70, 0.21; P = 0.28) and C-reactive protein (CRP) (WMD = −0.34; 95% CI:–0.89, 0.20; P = 0.22). Moreover, by eliminating 1 of the studies from the sensitivity analysis, changes in IL6 concentration were significant (WMD = −0.44; 95% CI: –0.81, –0.08). The changes in inflammatory biomarkers were dependent on study design (parallel or crossover), supplement type (flaxseed, flaxseed oil, or lignan), study quality (high or low), and participants’ age and BMI. According to this meta-analysis, flaxseed significantly reduced circulating concentrations of hs-CRP and TNFα, but did not affect IL6 and CRP. Further research is needed to examine the effect of different doses and long-term benefits of flaxseed and its derivatives on inflammatory factors.
オメガ3系の脂肪酸に抗炎症作用があることを示した系統的レビュー。ただ、その効果はかなり微細なもののようだ。
食卓に魚料理が並ぶ機会が多い日本では、わざわざ高い金を出して亜麻仁油や紫蘇油を購入する必要はないのだが、そうではない国や地域の人(あるいはどうしても魚が食べられない人)には重要な情報かもしれない。
注意が必要なのは、ビタミンCやEなどの抗酸化物質の摂取量が少ない人の場合、オメガ3系の脂肪酸の摂取が、むしろ逆に炎症マーカーを増加させてしまうなどという研究結果も存在していることである。「魚さえ食べていれば安心」というわけではないのである。
