Vegetable oils are partially hydrogenated to produce trans fatty acids, which are difficult for the human body to accept and digest, and can easily lead to multiple dysfunctions in physiological functions, which are very harmful to the human body. Trans fatty acids will increase the viscosity and cohesion of human blood, which can easily lead to the formation of blood clots; when trans fatty acids are combined in brain lipids, they will adversely affect the brain development and nervous system development of infants and young children; trans fatty acids will reduce the secretion of male hormones, which will negatively affect the activity of sperm and interrupt the reaction process of sperm in the body; those who have poor dietary habits in their youth and adulthood will suffer from Alzheimer's disease in old age. Alzheimer's disease (dementia) in old age is greater, because trans fatty acids have a resistance to a type of cholesterol that can promote human memory; trans fatty acids are not easy to be digested by the human body, easy to accumulate in the abdomen, leading to obesity; trans fatty acids can make the cholesterol that effectively prevents heart disease and other cardiovascular diseases (HDL) levels drop, easy to cause coronary heart disease.