Saturated fats including trans fat can lead to a increased risk of cardiovascular disease mainly by raising cholesterol and causing a poor LDL:HDL ratio (1). Trans fat is thought to be more atherogenic because it has also been found to lower HDL cholesterol in studies (1-3).
But what about diabetes risk?
In 2006 a review on the literature of trans fats versus saturated fats in insulin resistance noted that while high intake of saturated fats may promote insulin resistance, it is too early to determine if trans fats create increased risk(3). However, a 2008 rat study published in Asia Pac J Clin Nutr (2) showed that rats fed a diet higher in saturated fats had decreased peripheral insulin sensitivity, but that if trans fat was included the effect was greater.
Biochemically the reason for the effects on insulin sensitivity from dietary trans fat may have to do with its potential interference with cell membrane functions and decreasing insulin concentration (3-5). Ultimately both saturated and trans fats decrease insulin concentration, but trans fat more so (3-5). Interestingly, a review in Atheroscler Suppl pointed out that conjugated trans fat appears to be the “most dramatic” of all fatty acids in impairing insulin sensitivity (5).
1. Gropper SS, Smith JL, Groff JL. Advanced Nutrition and Human Metabolism. Belmont, CA: Thomson Wadsworth, 2009.
2. Ghafoorunissa G. Role of trans fatty acids in health and challenges to their reduction in Indian foods. Asia Pac J Clin Nutr 2008;17 Suppl 1:212-5.
3. Odegaard AO, Pereira MA. Trans fatty acids, insulin resistance, and type 2 diabetes. Nutr Rev 2006;64:364-72.
4. Bhathena SJ. Relationship between fatty acids and the endocrine and neuroendocrine system. Nutr Neurosci 2006;9:1-10.
5. Riserus U. Trans fatty acids and insulin resistance. Atheroscler Suppl 2006;7:37-9.