Question about taking iron after eating something with calcium

I've read here that we shouldn't be taking iron pills within 2 hours of eating anything with calcium in it.

But I don't understand this.  The reason I don't understand it is because I thought that we were unable to absorb vitamins from our food after RNY, and that the whole reason I'm taking calcium supplements is because I can't absorb it from the cheese, milk, and yogurt I eat and drink.

So if I can't absorb calcium from food, then why would I have to worry about taking iron pills too soon before or after eating food with calcium?

If you have something with calcium ie milk, yogurt etc with in 2hrs of taking an iron pill that calcium binds with the iron and prevents it was being absorbed. Prevents the iron from being absorbed...

We do absorb calcium  and iron from our food the same way we do from the pills. BUT we do not absorb a lot of it at a time.

That is why we need to take more. We need to take more to make sure we get enough.

The body prefers to absorb calcium over Iron so we need to watch the spacing of those.

If possible you should try not to take pills to close to eating calcium in food to get the most calcium absorbed in total according to my nut. I rarely can space it out with my iron and calcium containing food. I know I lose some if I have it in food to but never have it within the two hours of my iron. I pay to much for the iron. LOL.

For me, I prefer to take my iron when I go to bed that way I don't have to worry so much about the spacing of food. 

We can still absorb calcium from our food and other minerals (other than iron) fairly well (though less than before surgery) but we can't possibly get enough of what we need without the supplements due to our reduced intake. What we cannot easily absorb are iron (due to bypassed duodenum) and vitamins from vegetarian sources which are incomplete in the form they are ingested in for absorption. For example, beta-carotene (a precursor to vitamin A) must be converted in the body to vitamin A and we can no longer do that effectively due to intestinal bypassing which doesn't allow for mixing with digestive enzymes and absorption at the most absorptive parts of our small intestines. Most vitamins in fruits, vegetables and grains cannot be directly absorbed by the body, but must first be 'converted' and it is this converting we can't do very well anymore. Vitamin A from meat however, can be immediately absorbed and used by the body as it is already in vitamin A form and does not need to be made into vitamin A by the body.

As for calcium and iron specifically, calcium and iron compete for the same receptors in order to be absorbed by the body. Calcium is a bully and pushes iron out of the way, it out competes iron for the available receptors. So if you take iron and calcium at the same time, or take iron with a calcium rich meal, your body will only absorb the calcium. This is why you cannot count the iron that is in a multivitamin, if there is also calcium in your multivitamin - the presence of calcium cancels out iron. Also, given that RNYers have their entire duodenum bypassed, it is of critical importance that they take a separate iron supplement, of a type pf iron that is easily absorbed in the stomach and available small intestine (polysaccharide, carbonyl, or heme irons) in order to avoid anemia.

Hopefully that is helpful!