I hold no brief at all to defend McDonalds, but my understanding is that its food is high in fat and salt and that's about it. I have a young nephew with a neurological disorder, and he is intensely allergic to artificial flavourings, preservatives, sweeteners, etc. They send him hyperactive (ever seen a genuinely hyperactive child? Believe me, you don't want to.) Although he is also not allowed beef, he can eat McDonalds chicken processed thingies and chips with no ill effects. What he must avoid at all costs are normal sweets, which have about 100 e-numbers in them.
What really pees me off about food labelling, apart from the examples quoted above, is lines like "no added sugar". That means it has aspartame in it. Or "no artificial sweeteners or flavourings". That means it does have artificial preservatives. And so on.
Werthers Originals? Bleeuurgh! Jelly babies, now THERE'S something worth getting addicted to. High in glucose sugar, too, just the job for marathoning.