Cis and Trans Fatty Acids and Your Health

The direct link between diets high in saturated fats and heart disease is well known. Saturated fatty acids are usually found in solid or semisolid fats, while unsaturated fatty acids are usually found in oils. As a result, nutritionists recommend the use of liquid vegetable oils for cooking, and people are generally aware of this. However, what is less well known is that partially hydrogenated oils are a health hazard because of the formation of trans fatty acids during the process by which margarine and semisolid cooking fats are made. Hydrogen is added to the C=C double bonds in unsaturated fats (oils) to convert the to a solid or semisolid fat that has better consistence and less chance for spoilage. This hydrogenation process decreases the number of double bonds but also forms unnatural trans fatty acids from natural cis fatty acids. The trans fatty acids are not metabolized in the human system, but they can be stored for the life of the individual because the trans fatty acids are "straight" molecular structures and pack together like the saturated fatty acids. By contrast, the cis fatty acids are bent and do not pack well.

You can reduce the health risks of trans fatty acids by not eating processed vegetable fats. How do you know which products were made with processed vegetable fats ? Read the label. For example, a box of cookies or crackers may say on the label "made with 100% pure vegetable shorting .... (partially hydrogenated soybean oil with hydrogenated cottonseed oil). Although soybean oil and cottonseed oil are low in saturated fats, the hydrogenation process converts cottonseed oil to saturated fat and the partially hydrogenated soybean oil contains trans fatty acids.