Trans fatty acids: effects on metabolic syndrome, heart disease and diabetes

Trans fatty acids, which are largely consumed from partially hydrogenated vegetable oils, adversely affect circulating lipid and lipoprotein levels and endothelial function, trigger systemic inflammation, and might increase visceral adiposity, body weight, and insulin resistance. The authors provide an overview of these adverse effects and their relationships with clinical endpoints, with a focus on potential effects on insulin resistance and diabetes. The major dietary sources of trans fatty acids (TFAs) in most countries are partially hydrogenated vegetable oils. TFA consumption is a modifiable dietary risk factor for metabolic syndrome, diabetes mellitus, and coronary heart disease. Here, we review the available data on various effects of TFAs, including metabolic and signaling pathways that mediate these effects, affected tissues, and relationships with clinical end points. TFA consumption causes metabolic dysfunction: it adversely affects circulating lipid levels, triggers systemic inflammation, induces endothelial dysfunction, and, according to some studies, increases visceral adiposity, body weight, and insulin resistance. Dietary TFAs influence the function of multiple cell types, including hepatocytes, adipocytes, macrophages and endothelial cells. Among dietary fats and nutrients, TFAs seem to have a unique cardiometabolic imprint that is linked to insulin-resistance and metabolic-syndrome pathways. Consistent with these adverse physiological effects, consumption of even small amounts of TFAs (2% of total energy intake) is consistently associated with a markedly increased incidence of coronary heart disease. Relationships between TFA consumption and diabetes mellitus have been less consistent, possibly owing to differences in study designs. Nevertheless, the documented adverse effects of TFAs underscore their potential to cause harm and the importance of policy measures to minimize consumption of industrially produced TFAs. Key Points Dietary trans fatty acids (TFAs) derive from industrial, partial hydrogenation of vegetable oils or from ruminant products Dietary TFAs influence the function of multiple cell types, including hepatocytes, adipocytes, macrophages and endothelial cells TFA consumption affects multiple metabolic risk factors, including lipid and lipoprotein levels, systemic inflammation, endothelial function, adiposity, and glucose–insulin homeostasis TFA consumption increases risk of clinical coronary heart disease and likelihood of