Fred Kummerow told America in 1957 that the fat in margarine was turning up in the arteries of the dead. The government acted on it in 2015. He was 100. He was a biochemist at the University of Illinois, and what he had done was simple and slightly grim. He got hold of tissue from people who had died of heart disease and looked at what their arteries were made of. They were full of trans fats, a kind of fat that barely exists in nature and came, in 1957, from one place: the hydrogenated vegetable shortening and margarine the country had just been told to eat in place of butter. He published it in Science. He was 43. What followed was a career spent being ignored by experts. The oil industry had friends on every committee. His funding grew thin. In 1968 he talked a panel of the American Heart Association into warning about trans fats, and the warning was pulped and reprinted without it after the shortening makers saw a draft. Kummerow kept working. He kept his laboratory into his nineties. And he kept eating, quite deliberately and in front of journalists, the diet he had been told would kill him. Eggs cooked in butter. Whole milk. Red meat. He had looked inside the arteries himself and he had not found breakfast in there. In 2009, aged 94, he filed a formal petition asking the Food and Drug Administration to ban artificial trans fats. The law gave the agency 180 days to answer. Four years later it had not, so in 2013, at 98, he sued the United States government. Three months after that the FDA announced it agreed with him. The ban was confirmed in 2015. The gap between his paper and the decision was 58 years, which is longer than most of the people who ate the margarine got. He died in 2017, at 102. And he spent those last years on a second warning, which has been received exactly as the first one was. The problem, he said, was never the cholesterol in the egg. It is the vegetable oil in the fryer, heated and reheated until it oxidises, and then eaten. On the record so far, that one is due to be acted upon in about 2070.