Examples of Trans Fats
The primary examples of trans fats are partially hydrogenated vegetable oils, which are found in commercially prepared foods like cookies, crackers, baked goods, fried foods, and some margarines. 1
Industrial vs. Natural Trans Fats
Trans fatty acids (TFAs) can be categorized into two main types:
Industrial Trans Fats
- Partially hydrogenated vegetable oils - The major source of trans fats in the diet 1
- Typically contain 30-60% trans fatty acids
- Used for commercial deep frying
- Found in baked goods
- Present in packaged snacks
- Used as shortening
- Restaurant and fast-food chain oils - Often contain high levels of trans fatty acids 1
- Trans fats formed through industrial processes 1:
- Oil deodorization
- High temperature cooking
Natural Trans Fats
- Found in small amounts in meats and milk of ruminant animals (cow, sheep, goat) 1
- Formed by gut microorganisms in these animals
- Contribute minimally to diet (<0.5% of energy intake)
- Do not associate with cardiovascular disease risk 1
- Some natural trans fats like trans-16:1n-7 (a dairy fat biomarker) may actually be linked to lower risk of diabetes and sudden death 1
Health Effects of Trans Fats
Industrial trans fats have been shown to:
- Increase LDL cholesterol levels 1
- Reduce HDL cholesterol levels 1
- Raise triglycerides 1
- Increase apolipoprotein B 1
- Raise lipoprotein(a) 1
- Lower apolipoprotein A1 1
- Promote inflammation 1
- Cause endothelial vasodilator dysfunction 1
- Increase insulin resistance 1
- Promote visceral adiposity 1
- Increase risk of arrhythmia 1
Common Food Sources of Trans Fats
- Baked goods: Cookies, crackers, cakes, pie crusts 1
- Fried foods: Commercially prepared fried foods, especially fast food 1
- Margarines: Particularly stick margarines (though many brands have reformulated) 1
- Packaged snacks: Many processed snack foods 1
- Restaurant foods: Oils used in restaurant frying often contain high levels of trans fats 1
Recommendations for Trans Fat Intake
The American Heart Association recommends limiting trans fatty acid intake as much as possible, with a goal of less than 1% of total energy intake 1. This is because even a 2% absolute increase in energy intake from trans fat has been associated with a 23% increase in cardiovascular risk 2.
Important Considerations
- Trans fat labeling rules allow products containing <0.5g trans fat per serving to claim "0g trans fat" 2
- Multiple servings of these "0g trans fat" products can lead to significant trans fat intake
- The most harmful trans fats appear to be the 18:2 TFA isomers 1
- Because partially hydrogenated oils are food additives with clear adverse effects, their elimination is considered a public health priority 1
While industrial trans fats should be avoided, it's important to note that complete elimination of trans fats is not possible in a balanced diet that includes dairy and meat products, as these naturally contain small amounts of trans fats 2.