Levels of bioactive lipids in cooking oils: olive oil is the richest source of oleoyl serine

Abstract

Background: Rates of osteoporosis are significantly lower in regions of the world where olive oil consumption is a dietary cornerstone. Olive oil may represent a source of oleoyl serine (OS), which showed efficacy in animal models of osteoporosis. Here, we tested the hypothesis that OS as well as structurally analogous N-acyl amide and 2-acyl glycerol lipids are present in the following cooking oils: olive, walnut, canola, high heat canola, peanut, safflower, sesame, toasted sesame, grape seed, and smart balance omega.

Methods: Methanolic lipid extracts from each of the cooking oils were partially purified on C-18 solid-phase extraction columns. Extracts were analyzed with high-performance liquid chromatography-tandem mass spectrometry, and 33 lipids were measured in each sample, including OS and bioactive analogs.

Results: Of the oils screened here, walnut oil had the highest number of lipids detected (22/33). Olive oil had the second highest number of lipids detected (20/33), whereas grape-seed and high-heat canola oil were tied for lowest number of detected lipids (6/33). OS was detected in 8 of the 10 oils tested and the levels were highest in olive oil, suggesting that there is something about the olive plant that enriches this lipid.

Conclusions: Cooking oils contain varying levels of bioactive lipids from the N-acyl amide and 2-acyl glycerol families. Olive oil is a dietary source of OS, which may contribute to lowered prevalence of osteoporosis in countries with high consumption of this oil.

Figure 1

Levels of (A) OS, (B) OEA, and (C) 2-OG in cooking oils. All oils were purchased from a local organic foods store, brought directly to the laboratory, and stored at room temperature in a closed box to reduce any further exposure to light. Olive oil (Bionaturae; North Franklin, CT, USA); walnut oil (La Tourangelle; Berkley, CA, USA); canola, high-heat canola, safflower, peanut, sesame, toasted sesame, and grape-seed oils (Spectrum; Boulder, CO, USA); and smart balance omega (Smart Balance; Paramus, NJ, USA).