Soybean oil is the most used edible oil in the United States. It’s in almost everything. I did a search through my kitchen and found soybean oil in things like chocolate sprinkles, 3 kinds of salad dressing, mayonnaise, tartar sauce, cocktail sauce, ice cream cones, soup mixes and my favorite Belgian waffle mix. It’s used in several flavors of popular potato chips.  Almost every type of margarine and shortening has soybean oil. It’s used in non-dairy creamers, artificial cheese products, baked goods, whipped toppings and breads, and more. So, unless you buy almost nothing from the store, you are probably buying products that contain some amount of soybean oil. Do your own home inventory. You might be surprised.
So, with all that soybean oil you might be consuming, is it healthy? According to the United Soybean Board, “Liquid soybean oil is low in saturated fat, contains no trans fat, and is high in poly- and monounsaturated fats. It's also the principal source of omega-3 fatty acids and the primary commercial source of vitamin E in the U.S. diet.”
Let’s take this one item at a time. It’s low in saturated fat. We now know that the harm of saturated fats is a myth, or better yet, really old, wrong speculation . So, statement #1 is completely meaningless. It contains no trans fat. Statement #2 is certainly a benefit. #3 says that it is high in poly- monounsaturated fats. Polyunsaturated fats have been linked to arterial inflammation linked to heart disease. Healthy oils like extra-virgin olive oil is high in monounsaturated fats. So, probably not the worst thing. Then “the principal source of omega-3 fatty acids and the primary commercial source of vitamin E in the U.S. diet”. This may be true, and if so, it’s kind of sad. There are much healthier ways to be getting your omega-3 fatty acids, like wild caught fish, and wheat germ or sunflower oils are healthier sources of vitamin E.
At best, statements promoting the health benefits of soybean oil offer a mixed bag of risks vs. benefits. Because of this confusion over whether soybean oil is healthy or not, Dr. Aviram, the person who introduced us to the heart-healthy benefits of pomegranate juice, was involved in a study on mice. He stated that there had been a rise in the consumption of soybean oil and its major polyunsaturated fatty acid linoleic acid. The researchers fed mice an emulsion containing soybean oil or linoleic acid for a month. The results showed that overeating soybean oil or linoleic acid led to the formation of foam cells (fat-laden macrophages), which are an indication of plaque buildup and ultimately atherosclerosis (hardening of the arteries). 
I’m not recommending that you throw out everything in your kitchen that contains soybean oil. I didn’t. But I will certainly pay more attention to the products I buy and look to see what kind of oil they contain. I will try to avoid products that contain soybean, canola or vegetable oil. I also like making my own mayonnaise from olive oil. There are all kinds of recipes for making your own mayo from olive oil and once you have that you have the base for things like healthy salad dressings.
As always, live longer
- Rom, O., Jeries, H., Hayek, T. and Aviram, M. (2016), Supplementation with linoleic acid-rich soybean oil stimulates macrophage foam cell formation via increased oxidative stress and diacylglycerol acyltransferase1-mediated triglyceride biosynthesis. BioFactors. doi:10.1002/biof.1319