Health effects of trans-fatty acids: experimental and observational evidence

If there is a dietary villain the evidence convicts cleanly, it’s industrial trans fat — and this review is among the documents that built the case for banning it.

Synthesizing controlled feeding trials and prospective cohorts, the authors show trans-fatty acids doing nearly everything wrong at once: raising LDL (“bad” cholesterol), lowering HDL (“good” cholesterol), and worsening inflammation and endothelial function. The epidemiology matches the biology — each 2% of energy from trans fat associates with a 20–32% higher risk of coronary heart disease, an unusually steep dose-response for a single nutrient.

The practical takeaway is unambiguous and largely already enacted: eliminate industrial trans fats (partially hydrogenated oils) from the food supply. The resistance came from manufacturers reliant on those oils and policymakers slow to regulate — resistance this body of evidence ultimately overcame.

We rate the evidence strong: consistent findings across multiple study designs including meta-analysis, an extensive reference base, NIH funding, and no disclosed conflicts. Its clinical significance is high and historically validated — this is the kind of evidence that drove trans-fat bans and food reformulation worldwide, improving cardiovascular outcomes at the population scale rather than one patient at a time.