Effects of α-linolenic acid intake on blood lipid profiles：a systematic review and meta-analysis of randomized controlled trials

To investigate the effect of ALA intake on blood lipid profiles, including triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), very-low-density lipoprotein (VLDL-C) and ratio of TC to HDL-C. We systematically searched randomized controlled trials of ALA intervention on PubMed, Embase, Cochrane library and related references up to March 2018. The final values were calculated as weighted mean difference (WMD) by using a random effects model. Subgroup analysis and meta-regression were used to explore the source of heterogeneity. Generalized least square was performed for dose–response analysis. Forty-seven studies with 1305 individuals in the ALA arm and 1325 individuals in the control arm were identified. Compared with control group, dietary intake of ALA significantly reduced the concentrations of TG (WMD −0.101 mmol/L; 95% CI: −0.158 to −0.044 mmol/L; <i>P =</i> 0.001), TC (WMD −0.140 mmol/L; 95% CI: −0.224 to −0.056 mmol/L; <i>P =</i> 0.001), LDL-C (WMD −0.131 mmol/L; 95% CI: −0.191 to −0.071 mmol/L; <i>P &lt;</i> 0.001), VLDL-C (WMD −0.121 mmol/L; 95% CI: −0.170 to −0.073 mmol/L; <i>P &lt;</i> 0.001), TC/HDL-C ratio (WMD −0.165 mmol/L; 95% CI: −0.317 to −0.013 mmol/L; <i>P =</i> 0.033) and LDL-C/HDL-C ratio (WMD −0.158 mmol/L; 95% CI: −0.291 to −0.025 mmol/L; <i>P =</i> 0.02). There is no effect of ALA intake on HDL-C (WMD 0.008 mmol/L; 95% CI: −0.018 to 0.034 mmol/L; <i>P =</i> 0.541). Dose–response analysis indicated that 1 g per day increment of ALA was associated with a 0.0016 mmol/L, 0.0071 mmol/L, 0.0015 and 0.0061 mmol/L reduction in TG (95% CI: −0.0029 to −0.0002 mmol/L), TC (95% CI: −0.0085 to −0.0058 mmol/L), HDL-C (95% CI: −0.0020 to −0.0011 mmol/L) and LDL-C (95% CI: −0.0073 to −0.0049 mmol/L) levels, respectively. The effects of ALA intake on TG, TC and LDL-C concentrations were more obvious among Asian participants, and also more obvious on patients with hyperlipidemia or hyperglycemia compared to healthy individuals. Dietary ALA intervention improves blood lipid profiles by decreasing levels of TG, TC, LDL and VLDL-C. Our findings add to the evidence that increasing ALA intake could potentially prevent risk of cardiovascular diseases.

为探究α-亚麻酸（ALA）摄入对血脂谱的影响，包括甘油三酯（TG）、总胆固醇（TC）、高密度脂蛋白胆固醇（HDL-C）、低密度脂蛋白胆固醇（LDL-C）、极低密度脂蛋白胆固醇（VLDL-C）及总胆固醇与高密度脂蛋白胆固醇的比值。本研究系统性检索了截至2018年3月PubMed、Embase、Cochrane图书馆及相关参考文献中关于ALA干预的随机对照试验。最终采用随机效应模型计算加权均数差（WMD），通过亚组分析与Meta回归探索异质性来源，并运用广义最小二乘法开展剂量反应分析。最终纳入47项研究，ALA干预组共1305名受试者，对照组共1325名受试者。与对照组相比，膳食ALA摄入可显著降低甘油三酯（WMD = -0.101 mmol/L；95%置信区间（CI）：-0.158 ~ -0.044 mmol/L；*P* = 0.001）、总胆固醇（WMD = -0.140 mmol/L；95%置信区间：-0.224 ~ -0.056 mmol/L；*P* = 0.001）、低密度脂蛋白胆固醇（WMD = -0.131 mmol/L；95%置信区间：-0.191 ~ -0.071 mmol/L；*P* < 0.001）、极低密度脂蛋白胆固醇（WMD = -0.121 mmol/L；95%置信区间：-0.170 ~ -0.073 mmol/L；*P* < 0.001）、总胆固醇/高密度脂蛋白胆固醇比值（WMD = -0.165 mmol/L；95%置信区间：-0.317 ~ -0.013 mmol/L；*P* = 0.033）及低密度脂蛋白胆固醇/高密度脂蛋白胆固醇比值（WMD = -0.158 mmol/L；95%置信区间：-0.291 ~ -0.025 mmol/L；*P* = 0.02）的水平。ALA摄入对高密度脂蛋白胆固醇无显著影响（WMD = 0.008 mmol/L；95%置信区间：-0.018 ~ 0.034 mmol/L；*P* = 0.541）。剂量反应分析显示，ALA每日摄入量每增加1g，甘油三酯、总胆固醇、高密度脂蛋白胆固醇及低密度脂蛋白胆固醇水平分别降低0.0016 mmol/L（95%置信区间：-0.0029 ~ -0.0002 mmol/L）、0.0071 mmol/L（95%置信区间：-0.0085 ~ -0.0058 mmol/L）、0.0015 mmol/L（95%置信区间：-0.0020 ~ -0.0011 mmol/L）及0.0061 mmol/L（95%置信区间：-0.0073 ~ -0.0049 mmol/L）。亚组分析结果表明，ALA摄入对甘油三酯、总胆固醇及低密度脂蛋白胆固醇的改善作用在亚洲受试者中更为显著；与健康个体相比，该干预效果在高脂血症或高血糖患者中同样更为突出。膳食ALA干预可通过降低甘油三酯、总胆固醇、低密度脂蛋白胆固醇及极低密度脂蛋白胆固醇水平改善血脂谱。本研究结果进一步补充了相关证据，表明增加ALA摄入或可降低心血管疾病的发病风险。