So this is the fourth lecture on this series about kidney stones.

And I think it's time to say that about 80% of kidney stones either contain calcium oxalate

or calcium phosphate or they contain both.

And I explained in the last lecture that despite calcium being a major player in

stones, you don't want to decrease the calcium in your diet too much because what happens is

the calcium won't bind with the oxalate in the gut. So you're going to increase the oxalate absorption

and therefore increase the excretion of oxalate into your urinary tract. So unless your calcium

intake is very, very high, we're really not looking to decrease the calcium intake in

your diet if you make calcium stones.

However, we do want to decrease the intake of oxalate.

That's actually a very good therapeutic intervention that you can do that you don't need medication for,

although there are medications that can also reduce oxalate.

One of those is colostaramine. So we usually give colostaramine to bind bile salts in the gut,

but it may also be used to decrease oxalate absorption because colostaramine does bind oxalate.

The other thing that can bind oxalate is citrate,

and then, of course, as I already mentioned, calcium. So sometimes you can take calcium carbonate,

such as tums, and that will bind excess oxalate. So if you're prone to oxalate stones, you really have to pull up a list of foods and see what their oxalate content is.

So you definitely want to avoid some really high oxalate foods like beets and rhubarb and spinach.

But unfortunately, chocolate is a food that can contain a lot of oxalate, though it kind of depends

on what kind of chocolate.

So dry cocoa, higher content of oxalate compared to unsweetened chocolate, which has a higher

content of oxalate compared to milk chocolate.

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