Trans fatty acids are isomers of cis fatty acids. There are two main dietary sources of trans fatty acids- those derived from ruminant products such as milk, beef meat and those formed by the partial catalytic hydrogenation of vegetable and marine oils in the production of solid and liquid fats used in many industrially produced foods such as baked goods, frying fats and margarines.
 From epidemiological studies, increased coronary heart disease risk was associated with trans fatty acids. In addition, an excessive intake of trans fatty acids increased LDL-cholesterol level and decreased HDL-cholesterol. This paper reviews the outline of the trans fatty acids, the relation to disease and the intake situation of the trans fatty acids.