I think that as you read around Dr Kendrick's subjects, you become ever more aware of the mechanisms that corrode the whole scientific process. People jumped to various conclusions, and then told everyone to follow a set of dietary guidelines. The guidelines were not only wrong, but they also helped to cement the associated science so that new ideas were almost unthinkable.
Medical ideas result in medical charities that promote the ideas, and they in turn collect a lot of money from the public. Admitting that the ideas were wrong, so that money, collected on the streets, has been wasted giving people bad advice, is almost impossible. Meanwhile charities get large donations from drug companies that encourage the idea that the answer is to be found in yet more drugs rather than changing dietary advice. All this feeds back on the science establishment itself. Much science is performed using money from charities, so researchers try to avoid embarrassing the charities.
The feedback loops are horrendous, and would probably be catastrophic, if it were not for the fact that a lot of people are cussed (or perhaps use common sense). They liked their bacon and eggs, and kept on eating them despite all the warnings. Likewise, a lot of people hate taking statins because they make them feel unwell in a variety of ways - so they don't discuss the problem with the doctor - just throw their drugs away!
There has been a recent discussion on Kendrick's blog about whether it is right to impose a sugar tax. Although Dr. Kendrick recognises that too many people eat way too much sugar, he opposes such a tax, because he points out that if the 'nanny state' (probably a British expression) had imposed a saturated fat tax, people's health would be far worse than it is now!
Biology is clearly almost unfathomably complex, and maybe no idea can really be cast in stone. For example:
The reason why you die in type I diabetes has little to do with blood sugar levels. You die because, without insulin, fats escape from adipose tissue and travels to the liver as free fatty acids.
However, a lot of people also comment on that blog that sugar in the blood binds to proteins in all sorts of unhelpful ways - so maybe the truth isn't quite that simple. I like to think of the body, as rather like a complex machine - e.g. an analog radio set (only more complicated, of course). Such a radio contains hundreds of components, all of which have tolerance levels - a resistor won't be exactly 10^6 ohms (say), samples of that component will have a narrow range of values. However, a repair man will adjust the radio so that that particular radio works at its best. Now suppose that he received guidelines, and was pushed into adjusting things that were working well, just to satisfy the guidelines - disregarding how an individual radio performed.......
Roughly similar feedback loops are clearly a danger to every scientific endeavour. For example, if Alexander Unzicker is right, the whole process of detecting particles whose lifetimes are ludicrously short, is a nonsense. However, scientists find it incredibly hard to stand up and say such a thing (at least while they are still employed) because the waste of billions on the LHC and related accelerators, is too awful to contemplate.
To take another example, if the physics Nobel prizewinner, Ivar Giaever is right, the whole concept of global warming is nonsense - but after spending billions to decarbonise our power supplies, and after vast numbers of well meaning people have joined the cause, the embarrassment is too great to even contemplate the idea!
Anyone who tries to chip away at the feedback loops that hold scientific ideas fixed (but maybe untrue) are derided as "Anti-science" - the thought that people might start to take them seriously, is just unthinkable!
It is a mess!
David