There are four kinds of fats: monounsaturated fat, polyunsaturated fat, saturated fat, and trans fat. Monounsaturated fat and polyunsaturated fat are the "good" fats. It is generally accepted that consumption of saturated fat should be kept low, especially for adults.

Trans fat (which means trans fatty acids) is the worst kind of fat, far worse than saturated fat.

Partial hydrogenation is an industrial process used to make a perfectly good oil, such as soybean oil, into a perfectly bad oil. The process is used to make an oil more solid; provide longer shelf-life in baked products; provide longer fry-life for cooking oils, and provide a certain kind of texture or "mouthfeel." The big problem is that partially hydrogenated oil is laden with lethal trans fat.

It is only the trans fat created by the partial hydrogenation of vegetable oils that we are concerned about and that should be eliminated completely from your diet.

We at BanTransFats.com are not concerned with the kind of naturally occurring trans fat found in small amounts in pomegranates, cabbage, peas, or the type found in the meat and milk of cows, sheep and goats.

Partially hydrogenated oils are commonly found in processed foods like commercial baked products such as cookies, cakes and crackers, and even in bread. They are also used as cooking oils (called "liquid shortening") for frying in restaurants.

If you are not interested in the science, you can skip to the next section for the health effects. If you are interested in the science, here is a brief explanation.

In the illustration above, the light grey rounded areas are hydrogen atoms and the dark grey areas are carbon atoms. Note the different positioning of the hydrogen atoms in the middle, which is caused by partial hydrogenation. The hydrogen atoms in the middle are in a "trans" position, which makes this a "trans" fatty acid. The effect is to straighten out the molecules so they can pack together more closely and make the oil less liquid and more solid.

For a deeper discussion of the science, see the BanTransFats website.

One of the reasons that partially hydrogenated oils are used is to increase the product's shelf life, but they decrease your shelf life.

Trans fats cause significant and serious lowering of HDL (good) cholesterol and a significant and serious increase in LDL (bad) cholesterol; make the arteries more rigid; cause major clogging of arteries; cause insulin resistance; cause or contribute to type 2 diabetes; and cause or contribute to other serious health problems.

In one cross-over diet trial, scientists randomly assigned 29 healthy men and women to a diet high in trans fat, or a high saturated fat diet in which the trans fat was replaced by saturated fats. The trans fat came mostly from partially hydrogenated soybean oil and the saturated fat came from palm kernel oil.

After four weeks on one diet, the subjects were crossed over to the other diet. For each subject, the researchers took four measurements of artery dilation in the arm. They found that the ability of the blood vessels to dilate was 29 percent lower in people who ate the high trans fat diet compared those on the saturated fat diet. Blood levels of HDL cholesterol were 21 percent lower in the high trans fat group compared to the high saturated fat group.

In another study conducted in Australia, scientists acquired dietary information as well as fat biopsy samples from 79 people. Each had just had a first heart attack. The researchers obtained similar information and biopsy samples from 167 people without heart problems. The researchers inquired specifically about the participants' type and amount of fat intake. The heart patients and healthy individuals were also matched for age, gender, and socioeconomic background.

Analysis revealed that trans fats from both animal and vegetable sources were significantly more abundant in the fat tissues of heart attack patients than in the healthy volunteers. The relationship of abundant trans fats with heart risk remained even after the scientists statistically accounted for the effect of saturated fats in the participants' diets.

Here is an extract from a New York Times article on HDL cholesterol:

A recent study indicates that keeping HDL cholesterol high may help to reduce the risk of clot-related stroke in elderly men.

Top nutritionists at Harvard have stated as follows:

On January 12, 2005, the U.S. Department of Agriculture (USDA) and the U.S. Department of Health and Human Services (HHS) issued their “Dietary Guidelines for Americans, 2005”.  These Guidelines include the following recommendation:

“Consume 10 percent of calories from saturated fatty acids and less than 300 mg/day of cholesterol, and keep trans fatty acid consumption as low as possible”.

The Guidelines also contain the following strong message to the food industry:

“Because trans fatty acids produced in the partial hydrogenation of vegetable oils account for more than 80 percent of total intake, the food industry has an important role in decreasing trans fatty acid content of the food supply.”

Tommy Thompson, the Secretary of HHS, said at a news conference on the Guidelines on January 12, 2005 that the FDA may recommend that daily intake of trans fat be less than 2 grams, perhaps less than 1 gram.  In effect, that would mean totally avoiding any food containing partially hydrogenated oils.

In March 2003, Denmark issued new regulations limiting the amount of trans fat in processed foods.  Denmark's food minister said: "We put the public health above the industry's interests." 

Why can't the United States do the same?

In a recent survey, five popular restaurant or takeout foods were randomly selected and analyzed for their trans fat content.  Trans fats were found in all of the products that were tested:

For those of you who eat at McDonald's in the United States, one large French fries contains 8 grams.  A baked apple pie contains 4.5 grams.

Incidentally, don't think that the problem is only at McDonald's or other fast-food chains.  Nothing could be further from the truth.  Many other restaurants, including "quality" restaurants, fry their food in partially hydrogenated oil and served baked goods containing partially hydrogenated oil. 

At least McDonald's is diligently trying to reduce trans fats in its cooking oil and has had some success in reducing it in its fried chicken products.  Many other restaurant operations are not even trying.

Some of us are consuming virtually none, because we are being extremely selective about what we eat.  Some of us are consuming in excess of 20 grams of trans fat per day.