Does flaxseed supplementation affect apo- lipoproteins? A GRADE- assessed systematic review and meta-analysis

Several studies indicated the ameliorating effects of flaxseed supplementation
on apolipoproteins, although others have conflicting results. Therefore, the present research
was conducted in order to accurately and definitively understand the effect of flaxseed
on apolipoproteins in adults. All articles published up to June 2024 were systematically
searched through PubMed, Scopus, Embase, and Web of Science to collect all randomized
clinical trials (RCTs). A random effects model was used to measure the combined effect sizes.
Also, standardized mean difference (SMD) and 95 % confidence interval (CI) were used to
report the combined effect size. Our results showed that flaxseed supplementation significantly
reduced apo-BI (SMD: −0.57; 95 % CI: −0.95, −0.19, p = 0.003; I 2  = 83.2 %, heterogeneity p <
0.001) and lipo(a) decreased (SMD: −0.34; 95 % CI: −0.59, −0.09, p=0.007; I 2 =30.3 %,
heterogeneity p=0.197). However, flaxseed did not change apo-AI levels (SMD: −0.37; 95 % CI:
−0.87, 0.13, p = 0.146; I 2  = 89.2 %, p-heterogeneity < 0.001). This meta-analysis including 18
studies has shown that flaxseed supplementation may have beneficial effects on apolipoproteins by reducing the levels of apo-BI and Lipo (a). Future high-quality, long-term clinical trials are needed to confirm our results.