Abstract: Animal fat had long been considered as the main reason of raising cholesterol level in serum, and causing arteriosclerosis.Therefore, animal fat was replaced by vegetable oil as major edible oil.With large amount of vegetable oil was consumed, there was a huge impact on processing and selling of animal products.However, many diseases such as cancer, cardiovascular disease, and allergy had gradually threaten the people's health.People began to focus on edible oil and started to find causes of diseases.In this paper we contrasted the physiological effects of n-6 and n-3 fatty acids on animal fat with vegetable oil, moreover, studied the significance of two types oil's radio of (n-6)/(n-3), and proved the vegetable oil contains trace harmful factor.By providing valuable data, vegetable oil was proved to generate environmental hormone and trans-fatty acids through hydrogenation, which the environmental hormone could cause a decreasing in male sperm and neurological abnormalities, and the trans-fatty acids could cause cardiovascular and cerebrovascular diseases.Its proved that animal fat was not contain harmful trace factors and generate hormonelike substances.Under the low caloric diet condition, saturated fatty acid would not cause illness.Therefore, this article proved that animal fat was more safety than vegetable oil within the scope of normal human daily intake of edible oil.

Key words: animal fat; vegetable oil; safety analysis; evaluation