@drsmlopez Not sure I can recommend a brand, but Calcium Citrate was recommended to me, as I guess it's supposed to be easier on the stomach and absorbed better. I just use the generic Walmart brand, because I only wanted 400 mg. (It comes with an extra 500 IU of Vit-D3 also, so heads-up on your daily total). See pic. Otherwise, I personally like Nature's Made brand as it is a reputable company, with 3rd party verification and has the USP seal.