Parallel declines in erythrocyte trans fatty acids and US fatal ischemic heart disease rates

Ischemic heart disease (IHD) is a leading cause of mortality in the United States. There is substantial evidence that a sustained intake of industrially-produced trans fatty acids (IP-TFA) is associated with increased risk of fatal IHD. This has led many regulatory agencies to pressure dietary oil producers to remove IP-TFA from their products. That this has resulted in lower blood levels of IP-TFA in the United States is clear, but whether this has been accompanied by a reduction in the incidence of fatal IHD is unknown. To test the hypothesis that declining IP-TFA levels are associated with declining rates of fatal IHD, we compared the IP-TFA levels in red blood cells (RBC) analyzed in our laboratory between 2009 and 2016 (n = 53 194) with yearly US-specific IHD mortality rates. We found that decreasing RBC IP-TFA levels were strongly correlated with decreasing rates of fatal IHD (R² = 0.9552, P < .0001). Recognizing the limitations of observational studies in addressing causation questions, our findings nevertheless support our hypothesis and suggest that efforts to remove IP-TFA from the food supply in the United States may be having the desired effect.