Trans fat has been in our mainstream food now since the 1950s. Since then, it has become very clear that its introduction did us no favors. It was first seen as a good thing because it allows food to keep longer, but it causes harmful buildup in the body. Trans fat has no nutritional value anyway. What is it? It’s an unsaturated fat (having double carbon bonds) that have hydrogen atoms oriented in opposite directions. This happens when hydrogen atoms are added to the fatty acid (hydrogenation) or when oils with low smoke points are cooked at too high temperatures for too long. It also occurs naturally in small amounts, mostly in animal-based foods.

Luckily, trans fats can be avoided pretty easily. Things to look for are what ingredients are listed in the food, and how it was prepared. Always stay away from margarine or highly processed foods with long shelf lives. Both usually have lots of trans fat. When cooking or baking at high temperatures, try to stay away from oils with low smoke points and oils that are high in polyunsaturated fats. Oils with low smoke points are best used for vinaigrettes or microwaving. Microwaving causes oil to boil quicker at lower temperatures, allowing less time for degradation. When frying, always use fresh oil. The darker the oil is in color, the more oxidation it has undergone.

While understanding the chemistry of trans fat is important in knowing how to avoid it, there is another component involved. Having an understanding of different oils’ smoke points is key. The smoke point is the temperature required for an oil to break down and burn. There are several different sources and charts available. If the oil you use isn’t listed in the table I have linked, I’m sure its smoke point will be listed somewhere. Knowing the smoke points will help make healthier decisions in the kitchen. Another thing to be wary of are nutrition facts because sometimes companies do not list everything. If ever in doubt, call them for the missing information.

Trans Fat in Oils and Smoke Points