Trans fat gives crackers and cookies their crisp crunch or chewy moistness. In stick margarine, trans fat adds the firmness that makes it seem like eating real butter. Although it adds to the flavor appeal of many foods, trans fat may do real damage to our bodies.

Brain damage, heart disease, Alzheimer’s disease, Type 2 diabetes, colon cancer, breast cancer and an increase in LDL cholesterol are reportedly just a few of the negative effects associated with consuming trans fat.

A study carried out by scientists at the Medical University of South Carolina experimented with middle-aged rats, roughly equivalent in age to a 60-year-old human, and concluded that consuming trans fat can lead to memory loss in old age and problems performing simple tasks.

One group of rats was given a high-fat diet with 12% soybean oil and the other a high-fat diet with 10% trans fat and 2% cholesterol. When having to recall the location of hidden platforms in a water-filled maze, the trans fat-fed rats did five times worse than the other rat group.

Comparing animals to humans is somewhat tricky, but the results did raise some concern. Although a range of research already has proven that high-fat and high-cholesterol diets can contribute to learning and memory glitches in the brain, the MUSC study points to trans fat as the biggest troublemaker.

What are consumers to do? Read the labels. Choosing snacks such as crackers and popcorn that are reduced-fat means munching on a treat that has less total fat, less saturated fat and less trans fat per serving. Small amounts of trans fat lurk naturally in dairy products, but are found in abundance in foods with partially hydrogenated oils listed on their ingredient panels — crackers, cake mixes, snack cakes, donuts, chips, biscuits, waffles, popcorn and packaged cookies among them.

To make a more stable, solid form of oil, a food manufacturer infuses it with hydrogen gas. This process changes the chemical structure of the fat, resulting in trans fat. The AIB bulletin notes that food manufacturers are experimenting with a new process called interesterification, a process where “fully hydrogenated components, such as cottonseed oil, can be blended with liquid components and subsequently interesterified to improve the melting curve and crystallization properties.”

It’s not yet known how much trans fat Americans consume on a daily basis, but 2006 may heed the answer once manufacturers disclose the amounts of trans fat used in their products. Until that time, look for partially hydrogenated oil or shortening on the ingredient panel. If they are listed as one of the first three ingredients and the product contains a substantial amount of total fat, you can bet that the resulting amount of trans fat is proportionately hefty.