Sesamin is the most prominent lignan compound found in sesame seeds, one of the two highest sources of lignans in the human diet (the other being flax). Sesamin is catered to be a nutritional supplement that confers antioxidant and antiinflammatory effects (if touting its health properties) or possibly being an estrogen receptor modulator and fat burner (if targeting atheltes or persons wishing to lose weight). Sesamin has a few mechanisms, and when looking at it holistically it can be summed up as a fatty acid metabolism modifier. It appears to inhibit an enzyme known as delta-5-desaturase (Δ5-desaturase) which is a rate-limiting enzyme in fatty acid metabolism; inhibiting this enzyme results in lower levels of both eicosapentaenoic acid (EPA, one of the two fish oil fatty acids) as well as arachidonic acid, and this mechanism appears to be relevant following oral ingestion. The other main mechanism is inhibiting a process known as Tocopherol-ω-hydroxylation, which is the rate limiting step in the metabolism of Vitamin E; by inhibiting this enzyme, sesamin causes a relative increase of vitamin E in the body but particularly those of the gamma subset (γ-tocopherol and γ-tocotrienol) and this mechanism has also been confirmed to be active following oral ingestion. Sesamin is a potent and specific inhibitor of delta 5 desaturase in polyunsaturated fatty acid biosynthesis. Sesamin inhibits a particular CYP3A enzymes that is involved in vitamin E metabolism, where the enzyme initially ω-hydroxylates vitamin E (required step) and then the rest of vitamin E is subject to fat oxidation. By inhibiting this step, sesamin causes an increase in circulating and organ concentrations of vitamin E. Sesamin is thought to have PPARα activating potential in the liver, but it is uncertain how much practical relevance this has in humans due to this being a mechanism that differs between species.