Trans fat is the common name for unsaturated fat. Trans fats may be monounsaturated or polyunsaturated but never saturated. Only unsaturated fats can be trans fats. You’ll see trans fat listed on nutritional labels and ingredient lists as “partially-hydrogenated” or “unsaturated fat”.

Be warned, however, under FDA regulations, “if the serving contains less than 0.5 gram [of trans fat], the content, when declared, shall be expressed as zero.”  You could easily consume, for example, 1.2 grams of trans fat if you ate one serving of three different products. (all stating 0 grams of fat but actually containing 0.4 grams) So be sure to check the ingredients list. If the words “partially hydrogenated”  or “shortening” appear in the ingredients, the product contains trans fat.

A type of trans fat occurs naturally in the milk and body fat of cattle and sheep. Animal-based fats were once the only trans fats consumed, but by far the largest amount of trans fat consumed today is created by the processed food industry using partially hydrogenating unsaturated plant fats (generally vegetable oils). These partially-hydrogenated fats have displaced natural solid fats and liquid oils in many areas, notably in the fast food, snack food, fried food and baked goods industries.

Unlike other dietary fats, trans fats are not essential, and they do not promote good health. The consumption of trans fats increases the risk of coronary heart disease by raising levels of “bad” LDL cholesterol and lowering levels of “good” HDL cholesterol. Health authorities worldwide recommend that consumption of trans fat be reduced to trace amounts. Trans fats from partially hydrogenated oils are more harmful than naturally occurring oils.

The risk of coronary heart disease roughly doubles for each 2% increase in trans fat calories consumed (instead of carbohydrate calories). By contrast, it takes more than a 15% increase in saturated fat calories (instead of carbohydrate calories) to produce a similar increase in risk.

American Heart Association recommends not consuming unsaturated fats, and limiting saturated fat intake to less than 7% of total calories. Examples of foods containing a high proportion of saturated fat (healthier natural fat) include:

• dairy products (especially cream and cheese but also butter and ghee)
• animal fats such as suet, tallow, lard and fatty meat
• coconut oil, cottonseed oil, palm kernel oil
• chocolate
• eggs
• nuts
• fish

The National Academy of Sciences (NAS), who advises the United States and Canadian governments on nutritional science, states that while both saturated and trans fats increase levels of LDL cholesterol (so-called bad cholesterol), trans fats also lower levels of HDL cholesterol (good cholesterol), thus increasing the risk of coronary heart disease. The NAS has concluded there is no safe level of trans fat consumption and that there is no adequate level, recommended daily amount or tolerable upper limit for trans fats. This is because any incremental increase in trans fat intake increases the risk of coronary heart disease.

There are suggestions that the negative consequences of trans fat consumption go beyond the cardiovascular risk. In general, there is much less scientific consensus that eating trans fat specifically increases the risk of other chronic health problems:

• Alzheimer’s Disease
• Cancer
• Diabetes
• Obesity
• Liver Dysfunction
• Infertility in women