You've Been LIED TO About Seed Oils! | Educational Video | Biolayne

Layne Norton highlights a new study where participants consumed 30 grams per day of soybean oil (rich in linoleic acid) or palm oil (rich in saturated fat). The soybean oil group ingested far more polyunsaturated fat, yet showed no rise in inflammatory markers or oxidized LDL compared to the palm oil group. This adds to a growing literature that the theoretical conversion of linoleic acid to arachidonic acid does not meaningfully affect systemic inflammation because the enzymatic pathways are tightly regulated and do not simply track substrate availability. Norton points out that oxidized LDL is not produced primarily in the blood—where antioxidants protect it—but in the artery wall after LDL particles penetrate and get retained. Once trapped in the endothelium, the apoB particle is enzymatically modified, which triggers local oxidation and inflammation. Because LDL penetration is concentration-dependent and saturated fat raises LDL cholesterol levels, a diet high in saturated fat is actually the bigger driver of oxidized LDL. Thus, the argument that seed oils are inflammatory or increase oxidized LDL fails both direct measurement and mechanistic scrutiny.

Norton walks through the biology: LDL does not get oxidized in the blood because plasma is rich in antioxidants. Instead, LDL particles penetrate the endothelium and become trapped in the intima, where they can be retained for days or weeks. Once there, enzymatic modification of the apoB particle attracts inflammation and oxidation. Some of that oxidized LDL can later leak back into the bloodstream, which is why higher circulating oxidized LDL correlates with heart disease—but it is a downstream marker, not the initiating cause. The critical step is the penetration and retention of LDL particles, which is a concentration-dependent process. Diets high in saturated fat increase the number of LDL particles in the blood, thereby increasing the probability of endothelial penetration and subsequent oxidation. Therefore, even though polyunsaturated fats are chemically more prone to oxidation, they do not raise LDL concentrations and thus do not drive the in vivo process that actually produces oxidized LDL in the artery wall. Saturated fat, by raising LDL, is the real culprit.