More evidence needed to understand anti-inflammatory, antioxidant effects of tocotrienols

Tocotrienol supplementation may help reduce levels of C-reactive protein (CRP) but not of interleukin (IL)-6, tumour necrosis factor-alpha (TNF-α) and malonaldehyde (MDA), a recent meta-analysis reports.

However, the literature presents low-quality clinical evidence regarding the effect of tocotrienols on inflammation and oxidative stress, underscoring the need for future studies.

Drawing from the databases of PubMed, Cochrane Central Register of Controlled Trials, and Scopus, the researchers retrieved 19 eligible studies for qualitative analysis and 13 for quantitative meta-analysis.

Eight of the included studies looked at the inflammatory marker CRP (n=547). Tocotrienol supplementation led to a significant reduction in CRP levels (weighted mean difference [WMD], –0.52 mg/L, 95 percent confidence interval [CI], –0.73 to –0.32; p<0.001), with no substantial heterogeneity in evidence or publication bias.

However, sensitivity analysis showed that the dampening effect of tocotrienol supplementation on CRP was driven mostly by one study, which used δ-tocotrienols, accounting for 87.53 percent of the weightage. Exclusion of this study showed that supplementation with mixed tocotrienols had no significant impact on CRP levels (WMD, 0 mg/L, 95 percent CI, –0.57 to 0.58; p=0.992).

Similarly, tocotrienol supplementation had no significant impact on other inflammatory markers such as IL-6 (WMD, 0.03 pg/mL, 95 percent CI, –1.51 to 1.58; p=0.966) and TNF-α (WMD, –0.28 pg/mL, 95 percent CI, –1.24 to 0.68; p=0.571). A null effect was likewise detected for MDA, which was used as a marker of oxidative stress (WMD, –0.42 µmol/L, 95 percent CI, –1.05 to 0.21; p=0.189).

“More randomized controlled trials are warranted to confirm the anti-inflammatory and antioxidant effects of tocotrienols by assessing validated inflammatory and oxidative stress biomarkers determined using state-of-the-art technologies,” the researchers said.

“In addition, the effects of different isoforms and dosages of tocotrienols, and populations that are most likely to benefit from the supplementation, such as populations with suboptimal baseline plasma tocotrienols concentration or known active inflammatory diseases, should also be investigated,” they added.