Hydrogentated and trans fats, and multi-vitamin supplements

[utterlyconfused]

My ds has just been diagnosed with mild dyspraxia. I know this is a very basic question, but please would someone tell me about hydrogenated and trans fats, which we have been told to avoid. My kids only get home cooking anyway, but should I be cutting butter out of his sandwiches, and cheese out of his diet? Why, what difference would that make to him?
The other thing is I have been advised to give him a multi-vitamin/mineral supplement (he already gets Omega 3). Can anyone recommend one? I know there are so many of these things on the market, but I think probably a chewy "pill" (rather than capsule) would probably be best. You never know what these things are like until you've bought them and then it's too late and very expensive if they then refuse to take them!

Hydrogenated fats are liquid fats (like vegetable oils) that are processed so they become more solid, so most margarines, butter substitutes, and so-called 'spreadable' butters usually contain hydrogenated fats, as do things like biscuits, ready meals, etc. Trans fats are produced by a reaction in any fat to heat, so tend to be found in fried food, especially deep fried food.

Real butter (as opposed to spreadable stuff) should be OK in moderation (but it is high in saturated fat, which is linked to high cholesterol, etc), as should good quality hard cheese (but not spreadable cheeses). As you mostly cook at home, as long as you limit fried food, I would have thought you should be doing fine.

I don't know what difference that should make to your ds, though. And I'm afraid I can't help with the vitamin question.