The Guardian has an article called The Sugar Conspiracy which recaps the story of how fat and cholesterol were demonized in the 1970s as the drivers of heart disease and obesity, when in fact the true culprit was sugar, either consumed as fructose or as excess starches.
I doubt the article was named by the author, because the blame shifting from sugar to fat was not a conspiracy at all. There were no shadowy Mississippi sugar magnates manipulating the data, no Caribbean sugar pushers seducing our scientists. The cries of “conspiracy” actually came from the opposite direction: mainstream nutritionists routinely accused the anti-sugar researchers of being in cahoots with the meat and dairy industries.
If there was no pro-sugar conspiracy, why did “science” go whole hog for the campaign against fat? Because “science” is not a thing, while scientists are subject to the exact same social pressures the rest of us are: deference to received opinion, herding around charismatic leaders, fear of ridicule, confirmation bias, overconfidence in one set of methods (here, epidemiology) while dismissing others (here, endocrinology).
Optimists will point out that science is starting to correct the anti-fat paradigm and there is a growing campaign against sugar, but it has taken forty years, and in the meantime obesity and diabetes have reached epidemic proportions and statins are handed out like candy.
The people who were wrong could not accept that the people who were right did not have ulterior motives for deviating from accepted wisdom. The editors at the Guardian label the people who were wrong as “sugar conspirators” when they were no such things. Why do we need to believe in conspiracies? In part because we refuse to admit that we are less rational and less competent than we would like to imagine. So if an expert is wrong, it can’t be that expertise is mistaken, it must be a moral failing.