And it does not help that...

[momowuwen]

Dear teachers,

First, thank you for your arduous work. I have learned a lot in this forum. Now I have a question, hoping you can give ma a hand.

In the following passage, the red line confused me, especially the "It does not help that...". What does that mean? Is that a fixed expression? What does the "It" indicate?

Thank you!

None of this is to say that people must immediately bin all vitamin-containing substances; vitamins are, after all, essential nutrients. Moreover, untangling cause and effect in studies like these is notoriously tricky. And it does not help that the boffins themselves seem baffled by the results. That said, they ought to give pause to the most voracious supplement poppers. The Centre for Responsible Nutrition, an American group representing the industry which caters to them, promptly condemned the research as “a hunt for harm”. That response was predictable—more than 150m Americans take vitamins each year, spending about $27 billion on the stuff.

[BobK]

'It' is the fact that 'the boffins themselves seem baffled by the results'. The boffins' confusion made it harder to untangle cause and effect.
'It doesn't help that...' is a way of saying 'it makes it harder that...'.

b