FRIDAY JUNE 20, 2008 --   (foodconsumer.org) -- Many consumers do not know how to interpret the meaning of trans fat content on the nutrition facts panel, according to a new marketing study published in the Journal of Public Policy & Marketing.

The study showed this is particularly the case for those who do not have any specific prior knowledge about trans fat and its negative health effects.

One example is that many consumers do not have any idea whether 4 grams of trans fat is high or low, the study found.

Labeling of trans fat on processed food packaging is required by the Food and Drug Administration starting in January 2006 because this fat lowers good cholesterol and increase bad cholesterol in the blood and is associated with an estimated 100,000 deaths each year in the US, according to Harvard nutritionists and epidemiologists.

Betsy Howlett, professor of marketing in the Sam M. Walton College of Business and colleagues from other universities said the new labeling requirement does not help consumers unless marketers and policymakers make a significant effort to educate consumers about the effects of trans fat and how much means too much.

Trans fat, commonly present at high concentrations in partially hydrogenated vegetable oils which are commonly used in processed foods and foods prepared and served at restaurants.

Scientists have come to a consensus that trans fat does not provide any nutrition value except that it serves as a source of calories.  

One possible consequence of consuming trans fat is that the fat may get stuck somewhere in cells or tissue affecting physiological functions.   Research has found trans fat impacts pancreatic cells and is implicated in diabetes.   It may raise risk of some other chronic diseases, but few studies have been done to provide an understanding of their adverse effects.

The FDA recommends daily intake of trans fat should not exceed 2 grams a day. A common American may eat about 4 or 5 grams a day.   A serving of French fries from a fast food restaurant may contain up to 7 grams of trans fat.

The FDA recommendation is not based on the needs of the body for the chemical as a nutrient. Rather the agency argues that a complete ban would lead consumers to follow an unbalanced diet, which would cause other nutritional tissues.

One loophole is that food processors can claim "Zero trans fat" when one serving of a food contains less than 0.5 grams of trans fat. This can be a trick as the serving size becomes smaller; the trans fat content on the label will eventually become smaller enough for the manufacturer to legally label it as "Zero trans fat".

Trans fat in most cases is added to food to make the foods more shelf-stable or have an extended shelf life.  Trans fat can render a food certain texture and even flavor.   It is not an easy task for food manufacturers to "change oil" because of options are limited.

In addition to added trans fat, trans fat forms naturally in processed food containing vegetable oils.   Cooking in the Kitchen can also transform some natural oil into trans fat.

To avoid trans fat, one needs to avoid cooking food/oil at high heat, and milk/beef, which contain some naturally occurring trans fat that cows may handle.