In healthy adult men, taking 6.26 grams of n−3 fatty acids from menhaden oil daily for six weeks raises levels of malondialdehyde and lipid peroxides in the blood, which are markers of lipid peroxidation, and taking 900 IU of vitamin E daily alongside does not stop this increase.

We analyzed one assertion on this topic and found that taking 6.26 grams of n−3 fatty acids from menhaden oil daily for six weeks appears to raise levels of malondialdehyde and lipid peroxides in the blood of healthy men. These are markers of lipid peroxidation, a process where fats in cell membranes break down due to oxidative stress. The same assertion shows that taking 900 IU of vitamin E daily alongside the n−3 fatty acids did not prevent this rise in markers [1]. We have no studies that contradict this finding. What we’ve found so far leans toward the idea that high doses of menhaden oil may increase lipid peroxidation in healthy men, and that vitamin E at this dose does not counteract it. We don’t know if this change has any long-term effect on health, or if it’s temporary or reversible. The evidence we’ve reviewed is limited to just one assertion, and we don’t have data on women, older adults, or people with different health conditions. We also don’t know if lower doses of n−3 fatty acids or different forms of vitamin E would behave the same way. For now, if someone is taking a high dose of fish oil like this, they should be aware that it may increase certain oxidative stress markers, and adding vitamin E at this level doesn’t seem to stop it.