evidence: But while it was assumed for years that vegetable oils were unquestionably the heart-healthy fat option, renewed scrutiny has revealed that the presence of fatty acids in different varieties of vegetable oils make certain oils much less healthy than others. The fatty acids omega-6 and omega-3, which our bodies don’t produce but which we get from our diet, are important in processes like blood clotting and inflammation. While these acids are supposed to be present in a fairly balanced ratio, many Western diets contribute to a huge excess of omega-6 fatty acids. Omega-6 acids are stored in body fat, have negative effects on our cell membrane health, and are widely believed to contribute to inflammation. Some inflammation is necessary in helping the body recover from injury and disease. However, chronic inflammation of the body tissues is a known risk factor for leading to heart attacks, cancer, diabetes, arthritis, and other issues. [...] Another danger of supposedly healthy vegetable oils is the likelihood that they’ve been "refined" in some way. In order to make them more shelf-stable, many oils go through a process of chemical purification. Sometimes heat is used in order to extract more oils from the source. The problem is, many vegetable oils contain unsaturated fats that oxidize above a certain temperature, a process which causes inflammation and instability of the blood vessels when consumed. (For this reason, while it’s great to choose an unrefined, cold-pressed oil when you’re shopping for oils to cook with, it’s also important to be aware of their smoke points.)