Colas and Chronic Kidney Disease

Does drinking colas increase one's risk of chronic kidney disease (as compared to non-cola carbonated drinks)? According to this article, it does. A group from the NIH did a case-control study looking at about 500 patients with chronic kidney disease (CKD) compared to normal patients. They found that the odds ratio of having CKD if one drank more than two colas per day to be around 2, after controlling for other factors. However, the same effect was not found if subjects drank non-cola sodas (Sprite, I presume?).

Apparently, there was anecdotal evidence that this was the case prior to this study (see image at left). However, the summary of the paper left me with a few questions. First, I happen to like a carbonated cola drink myself, so perhaps I am biased, but this study merely links CKD to poor diet, rather than proving anything. If the researchers are serious about this, they should do a randomized, double-blind, placebo-controlled, yada-yada trial and prove that cola causes CKD. That is probably harder to do in practice, but still, it must be done for the results to really say anything.

Second, why is the NIH spending money on this? While CKD is an important cause of morbidity and mortality in this country, did we really need to spend this money proving that Coke is bad for people with kidney disease, most likely due to diabetes? I would hope CKD patients would know to abstain from such things (unless I guess if they are on dialysis, but that's another story). Since in an abstract sense federal funding is fungible, this money could have been better spent raising awareness about diabetes and CKD and improving diabetes education. Maybe I am wrong, but that is where the real need is.