Vegetarians and vegans are often asked where they get their protein from. For vegetarians the answer is a bit easier as they consume dairy products and eggs. In vegans case, it is a bit harder to understand that even vegetable sources contain proteins, and here is an example from Young and Raw: Everything you need to know about protein.
In the early 1970s, tests were performed on laboratory animals. These tests were not meant to compare low-fat versus high-fat diet, but rather to verify the beneficial effect of vegetable oils. So, saturated fat was replaced by polyunsaturates. The outcome was quite surprising, it suggested that vegetable oils can cause cancer.